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Sposta i file binari e gli originali già elaborati in `90 Allegati` e collegali dalla relativa scheda fonte. - [x] freeCodeCamp/GaugeHow — 3D Printing & Additive Manufacturing Full Course: trascrizione acquisita, tradotta e trasformata in note; originale spostato in [[90 Allegati/3D Printing & Additive Manufacturing – Full Course|3D Printing & Additive Manufacturing – Full Course]], vedi [[SRC - freeCodeCamp GaugeHow - 3D Printing and Additive Manufacturing Full Course]]. +- [x] Zhou et al. 2024, "Additive Manufacturing: A Comprehensive Review" (Sensors, CC BY 4.0): riassunto e scheda fonte creati, originale spostato in `90 Allegati`, vedi [[SRC - Zhou et al. 2024 - Additive Manufacturing A Comprehensive Review]]. +- [x] ADDITIVA — schede tecniche leghe metalliche per SLM/DMLS (AlSi10Mg, Inconel 718, Scalmalloy, Stainless Steel 316L, Titanium Ti6Al4V): tradotte in 5 note di concetto in `03 Materiali`, originali spostati in `90 Allegati`, vedi [[SRC - ADDITIVA - Schede tecniche leghe metalliche per AM]]. [[Metodo di lavoro]] diff --git a/03 Materiali/Aluminium AlSi10Mg per SLM-DMLS.md b/03 Materiali/Aluminium AlSi10Mg per SLM-DMLS.md new file mode 100644 index 0000000..6c54c25 --- /dev/null +++ b/03 Materiali/Aluminium AlSi10Mg per SLM-DMLS.md @@ -0,0 +1,52 @@ +--- +id: "am-aluminium-alsi10mg-slm-dmls" +title: "Aluminium AlSi10Mg per SLM/DMLS" +type: "concetto" +status: "da_verificare" +created: "2026-09-10" +updated: "2026-09-10" +language: "it" +tags: ["am/concetto", "am/materiale"] +aliases: ["AlSi10Mg", "Alluminio AlSi10Mg"] +sources: ["[[SRC - ADDITIVA - Schede tecniche leghe metalliche per AM]]"] +material: "lega di alluminio (AlSi10Mg)" +process: "powder bed fusion (SLM/DMLS)" +--- + +# Aluminium AlSi10Mg per SLM/DMLS + +## In breve +AlSi10Mg è una lega di alluminio da fonderia (Al-Si-Mg) processabile per powder bed fusion metallica (SLM/DMLS), con buon rapporto resistenza/peso, usata tipicamente per componenti a parete sottile e geometrie complesse. [Fonte: scheda tecnica produttore ADDITIVA; [[SRC - ADDITIVA - Schede tecniche leghe metalliche per AM]]] + +## Spiegazione +Lega da fonderia con buona colabilità; nei processi convenzionali di fusione viene tipicamente trattata termicamente con ciclo T6 (solubilizzazione, tempra, invecchiamento artificiale) per migliorare le proprietà meccaniche. Nel processo SLM/DMLS, la fusione e risolidificazione molto rapide producono nello stato "as-built" proprietà meccaniche indicate dal produttore come paragonabili a quelle di un getto trattato T6 (affermazione del produttore, non una misura comparativa indipendente in questa scheda). Applicazioni tipiche indicate: automotive e aerospaziale, in particolare scatole cambio, alloggiamenti e staffe soggette a carichi significativi. Lavorabilità post-stampa dichiarata: lavorazione meccanica, elettroerosione, saldatura, pallinatura (shot-peening), lucidatura, rivestimento. + +## Condizioni di applicazione +Dati riferiti al processo SLM/DMLS in polvere metallica, stato "as-built" (dopo stampa) o "stress relieved" (distensione: 300 °C per 2 ore, con rampa 20→300 °C in 1 ora, secondo la scheda). Macchina, fornitore di polvere e parametri di processo (potenza laser, velocità di scansione, spessore layer) non specificati: i valori sono indicativi del produttore ADDITIVA e non generalizzabili ad altri fornitori/macchine. + +## Dati o formule +Composizione chimica (% in peso, dato produttore): Al bilancio; Si 9,0–11,0%; Mg 0,20–0,45%; Fe ≤0,55%; Mn ≤0,45%; Ti ≤0,15%; Cu ≤0,10%; Zn ≤0,10%; Ni ≤0,05%; C ≤0,05%. + +Designazioni citate: USA UNS A03600–A13600; EN AC-43000; ASTM B85 A360.0 (F3318); DIN Al 4046-3.2381 — **queste corrispondenze incrociate tra norme sono riportate come nella scheda originale, non verificate singolarmente in questa nota.** + +Proprietà fisiche: densità relativa ≈99,9%; densità 2,67 g/cm³. + +Dati tecnici: accuratezza dimensionale tipica ±0,2/0,3 mm (quota <150 mm), ±0,05 mm ogni 25 mm (quota ≥150 mm); rugosità superficiale as-built Ra 5–9 µm, dopo lavorazione/lucidatura Ra <1,6 µm. + +Proprietà meccaniche (metodo di prova ASTM E8/E8M, provino non lavorato, asse Z): +| Proprietà | As-built | Distensione (stress relieved) | +|---|---|---| +| Resistenza a trazione Rm | 400 ± 5 MPa | 270 ± 5 MPa | +| Snervamento Rp0,2% | 255 ± 5 MPa | 160 ± 5 MPa | +| Allungamento a rottura | 4,5 ± 1% | 11 ± 1% | +| Modulo di Young | 70 ± 3 GPa | 70 ± 3 GPa | +| Durezza Brinell (DIN EN ISO 6506-1) | 120 ± 5 HBW | — | +| Conducibilità termica (ASTM E1461-13) | 110 ± 5 W/m°C | 170 ± 10 W/m°C | + +Tutti i valori sono dati del produttore, non misure indipendenti: il disclaimer della scheda originale esclude l'uso per specifiche di progettazione o controllo qualità. + +## Esempio +Non applicabile (nota di dati di materiale, non caso applicativo documentato). + +## Fonti e collegamenti +[[SRC - ADDITIVA - Schede tecniche leghe metalliche per AM]] · [[Leghe Metalliche per AM (Alluminio, Rame, Titanio, Superleghe Inconel)]] · [[Powder Bed Fusion (SLS, SLM, DMLS, EBM)]] · [[Indice - Materiali]] diff --git a/03 Materiali/Inconel 718 per SLM-DMLS.md b/03 Materiali/Inconel 718 per SLM-DMLS.md new file mode 100644 index 0000000..0f67b35 --- /dev/null +++ b/03 Materiali/Inconel 718 per SLM-DMLS.md @@ -0,0 +1,55 @@ +--- +id: "am-inconel-718-slm-dmls" +title: "Inconel 718 per SLM/DMLS" +type: "concetto" +status: "da_verificare" +created: "2026-09-10" +updated: "2026-09-10" +language: "it" +tags: ["am/concetto", "am/materiale"] +aliases: ["INCONEL 718", "Superlega Inconel 718", "Alloy 718"] +sources: ["[[SRC - ADDITIVA - Schede tecniche leghe metalliche per AM]]"] +material: "superlega a base nichel-cromo (Inconel 718)" +process: "powder bed fusion (SLM/DMLS)" +--- + +# Inconel 718 per SLM/DMLS + +## In breve +INCONEL® 718 è una superlega nichel-cromo ad alta resistenza e resistenza alla corrosione, versione indurita per invecchiamento della "sorella" lega 625, processabile per powder bed fusion metallica (SLM/DMLS). Intervallo di temperatura di esercizio dichiarato: da -196 °C a 700 °C. [Fonte: scheda tecnica produttore ADDITIVA; [[SRC - ADDITIVA - Schede tecniche leghe metalliche per AM]]] + +## Spiegazione +L'indurimento per invecchiamento (precipitation hardening) produce precipitati nella microstruttura che ancorano i grani del metallo, aumentandone significativamente la resistenza. La scheda indica caratteristiche di saldabilità notevoli, in particolare resistenza alla cricca post-saldatura, e buone resistenze a trazione, fatica, creep e rottura. Applicazioni tipiche indicate dal produttore: motori a getto, razzi a propellente liquido, anelli, casse e parti metalliche per motori aeronautici e turbine a gas terrestri, serbatoi criogenici, elementi di fissaggio ad alta temperatura; impiegata anche nel settore oil & gas per resistenza a cloruri, corrosione da sforzo e cricche da solfuri. Lavorabilità post-stampa dichiarata: lavorazione meccanica, saldatura, pallinatura, lucidatura, rivestimento. + +## Condizioni di applicazione +Dati riferiti al processo SLM/DMLS, stato "as-built" o trattato termicamente secondo il ciclo AMS 5662 (vedi sotto). Macchina, fornitore di polvere e parametri di processo non specificati: valori indicativi del produttore ADDITIVA, non generalizzabili. + +## Dati o formule +Composizione chimica (% in peso, dato produttore): Ni 50,0–55,0%; Cr 17,0–21,0%; Nb 4,7–5,5%; Mo 2,8–3,3%; Ti 0,6–1,2%; Al 0,2–0,8%; Co ≤1,0%; Cu ≤0,3%; C ≤0,08%; Mn ≤0,35%; Si ≤0,35%; P ≤0,015%; S ≤0,015%. + +Designazioni citate: UNS N07718; AMS 5596–5832; ASTM B670–F3055; DIN 2.4668 — riportate come nella scheda originale, non verificate singolarmente in questa nota. + +Proprietà fisiche: densità relativa ≈99,9%; densità 8,15 g/cm³. + +Trattamento termico dichiarato (AMS 5662), in due fasi: 1) ricottura, 20→980 °C, mantenimento 980 °C per 1 ora, raffreddamento a 20 °C; 2) invecchiamento, 20→720 °C, mantenimento 720 °C per 8 ore, 720→620 °C, mantenimento 620 °C per 10 ore, raffreddamento a 20 °C. + +Dati tecnici: accuratezza dimensionale tipica ±0,2/0,3 mm (quota <150 mm), ±0,05 mm ogni 25 mm (quota ≥150 mm); rugosità superficiale as-built Ra 5–9 µm, dopo lavorazione/lucidatura Ra <1,6 µm. + +Proprietà meccaniche (metodo di prova ISO 6892-1:2009(B) Annex D): +| Proprietà | As-built | Trattato termicamente (AMS 5662) | +|---|---|---| +| Resistenza a trazione | 1020 ± 15 MPa | 1400 ± 15 MPa | +| Snervamento Rp0,2% | 630 ± 15 MPa | 1140 ± 15 MPa | +| Allungamento a rottura | 30 ± 5% | 10 ± 2% | +| Modulo di Young | 185 ± 10 GPa | 210 ± 10 GPa | +| Durezza (DIN EN ISO 6508-1) | 30 HRC | 46 HRC | + +Proprietà termiche: temperatura massima di esercizio a lungo termine ≈700 °C (1300 °F); conducibilità termica 6–12 W/mK. + +Tutti i valori sono dati del produttore, non misure indipendenti: il disclaimer della scheda originale esclude l'uso per specifiche di progettazione o controllo qualità. + +## Esempio +Non applicabile (nota di dati di materiale, non caso applicativo documentato). + +## Fonti e collegamenti +[[SRC - ADDITIVA - Schede tecniche leghe metalliche per AM]] · [[Leghe Metalliche per AM (Alluminio, Rame, Titanio, Superleghe Inconel)]] · [[Powder Bed Fusion (SLS, SLM, DMLS, EBM)]] · [[Indice - Materiali]] diff --git a/03 Materiali/Indice - Materiali.md b/03 Materiali/Indice - Materiali.md index 4479c07..059f0fe 100644 --- a/03 Materiali/Indice - Materiali.md +++ b/03 Materiali/Indice - Materiali.md @@ -19,6 +19,11 @@ Indice da sviluppare: Metalli; polimeri; ceramici; compositi; feedstock; conserv - [[Polimeri per Material Extrusion (PLA, ABS, PETG, Nylon)]] - [[Resine Fotopolimeriche per SLA (Standard, Tough, Flexible, Dental)]] - [[Leghe Metalliche per AM (Alluminio, Rame, Titanio, Superleghe Inconel)]] +- [[Aluminium AlSi10Mg per SLM-DMLS]] (dati produttore ADDITIVA) +- [[Inconel 718 per SLM-DMLS]] (dati produttore ADDITIVA) +- [[Scalmalloy per SLM-DMLS]] (dati produttore ADDITIVA) +- [[Stainless Steel 316L per SLM-DMLS]] (dati produttore ADDITIVA) +- [[Titanium Ti6Al4V (Grado 23) per SLM-DMLS]] (dati produttore ADDITIVA) ## Domande da sviluppare - Quali concetti e definizioni servono per questo ambito? diff --git a/03 Materiali/Leghe Metalliche per AM (Alluminio, Rame, Titanio, Superleghe Inconel).md b/03 Materiali/Leghe Metalliche per AM (Alluminio, Rame, Titanio, Superleghe Inconel).md index b1f36d6..1a3e3b5 100644 --- a/03 Materiali/Leghe Metalliche per AM (Alluminio, Rame, Titanio, Superleghe Inconel).md +++ b/03 Materiali/Leghe Metalliche per AM (Alluminio, Rame, Titanio, Superleghe Inconel).md @@ -95,4 +95,7 @@ Esempi illustrativi citati dal docente (non casi di prova documentati con dati m - Prezzi del titanio e delle altre leghe in rupie indiane per kg di polvere: non verificati, nessuna data di riferimento o fonte di mercato citata; da trattare come ordine di grandezza indicativo, non come dato di costo affidabile. - Riferimenti a ISRO, Agnikool, Skyroot e uso di CuCrZr per componenti di razzi: citati dal docente senza fonte primaria nel video, da trattare come aneddoto di settore fino a verifica. +> [!info] Dati di produttore disponibili per leghe specifiche +> Le stime generiche di questa nota (non verificate, senza lega/produttore specifico) possono essere confrontate con dati di scheda tecnica reali, per lega e stato (as-built/trattato termicamente), nelle note: [[Aluminium AlSi10Mg per SLM-DMLS]], [[Inconel 718 per SLM-DMLS]], [[Scalmalloy per SLM-DMLS]], [[Stainless Steel 316L per SLM-DMLS]], [[Titanium Ti6Al4V (Grado 23) per SLM-DMLS]] — fonte: [[SRC - ADDITIVA - Schede tecniche leghe metalliche per AM]]. Sono comunque dati di un singolo produttore/service bureau, non una norma: il confronto va fatto con cautela (lega, lotto polvere e macchina non sono gli stessi). + [[Indice - Materiali]] · [[SRC - freeCodeCamp GaugeHow - 3D Printing and Additive Manufacturing Full Course]] · [[RIA - freeCodeCamp GaugeHow - 3D Printing and Additive Manufacturing Full Course]] · [[Polimeri per Material Extrusion (PLA, ABS, PETG, Nylon)]] · [[Resine Fotopolimeriche per SLA (Standard, Tough, Flexible, Dental)]] diff --git a/03 Materiali/Scalmalloy per SLM-DMLS.md b/03 Materiali/Scalmalloy per SLM-DMLS.md new file mode 100644 index 0000000..fa6b9f4 --- /dev/null +++ b/03 Materiali/Scalmalloy per SLM-DMLS.md @@ -0,0 +1,54 @@ +--- +id: "am-scalmalloy-slm-dmls" +title: "Scalmalloy per SLM/DMLS" +type: "concetto" +status: "da_verificare" +created: "2026-09-10" +updated: "2026-09-10" +language: "it" +tags: ["am/concetto", "am/materiale"] +aliases: ["Scalmalloy®", "Lega Al-Mg-Sc"] +sources: ["[[SRC - ADDITIVA - Schede tecniche leghe metalliche per AM]]"] +material: "lega alluminio-magnesio-scandio (Scalmalloy)" +process: "powder bed fusion (SLM/DMLS)" +--- + +# Scalmalloy per SLM/DMLS + +## In breve +Scalmalloy è una lega alluminio-magnesio-scandio ad alto rapporto resistenza/peso, elevata rigidità, buona saldabilità e duttilità, sviluppata come alternativa alle leghe di alluminio serie 7000 ad alta resistenza. [Fonte: scheda tecnica produttore ADDITIVA; [[SRC - ADDITIVA - Schede tecniche leghe metalliche per AM]]] + +## Spiegazione +La bassa densità permette proprietà specifiche (normalizzate per densità) indicate dal produttore come competitive anche rispetto alle leghe più resistenti in assoluto. Rispetto ad altre leghe di alluminio per manifattura additiva, il produttore dichiara una resistenza alla corrosione particolare e una microstruttura stabile fino a 250 °C. Applicazioni tipiche indicate: componenti fortemente sollecitati in aerospaziale, robotica, settore marino e motorsport; materiale approvato secondo regolamento FIA (affermazione del produttore, normativa specifica non verificata in questa scheda). Lavorabilità post-stampa dichiarata: lavorazione meccanica, saldatura, pallinatura, lucidatura, rivestimento. + +## Condizioni di applicazione +Dati riferiti al processo SLM/DMLS, stato "as-built" o trattato termicamente (distensione: 20→325 °C in 1 ora, mantenimento 325 °C per 4 ore, raffreddamento a 20 °C). Macchina, fornitore di polvere e parametri di processo non specificati: valori indicativi del produttore ADDITIVA, non generalizzabili. + +## Dati o formule +Composizione chimica (% in peso, dato produttore): Al bilancio; Mg 4,0–4,9%; Sc 0,6–0,8%; Mn 0,3–0,8%; Zr 0,2–0,5%; Fe ≤0,4%; Si ≤0,4%; Zn ≤0,25%; Ti ≤0,15%; Cu ≤0,10%. + +Proprietà fisiche: densità relativa ≈99,5%; densità 2,67 g/cm³. + +Dati tecnici: accuratezza dimensionale tipica ±0,2/0,3 mm (quota <150 mm), ±0,05 mm ogni 25 mm (quota ≥150 mm); rugosità superficiale as-built Ra 5–9 µm, dopo lavorazione/lucidatura Ra <1,6 µm. + +Proprietà meccaniche (metodo di prova ASTM E8/E8M, provino non lavorato, asse Z): +| Proprietà | As-built | Trattato termicamente | +|---|---|---| +| Resistenza a trazione Rm | 330 ± 5 MPa | 555 ± 10 MPa | +| Snervamento Rp0,2% | 260 ± 5 MPa | 515 ± 10 MPa | +| Allungamento a rottura | 19 ± 2% | 14 ± 2% | +| Modulo di Young | n.d. | 72 ± 3 GPa | +| Durezza Hv10 | n.d. | 160 | +| Conducibilità termica (ASTM E1461-13) | n.d. | 95 W/m·K | + +("n.d." = non dichiarato per lo stato as-built nella scheda originale.) + +Confronto qualitativo riportato dal produttore (testo web complementare): a temperatura ambiente Scalmalloy ha resistenza significativamente superiore a quella di AlSi10Mg — **confronto diretto non quantificato nella fonte, riportato come affermazione del produttore**; vedi [[Aluminium AlSi10Mg per SLM-DMLS]] per i valori dell'altra lega. + +Tutti i valori sono dati del produttore, non misure indipendenti: il disclaimer della scheda originale esclude l'uso per specifiche di progettazione o controllo qualità. + +## Esempio +Non applicabile (nota di dati di materiale, non caso applicativo documentato). + +## Fonti e collegamenti +[[SRC - ADDITIVA - Schede tecniche leghe metalliche per AM]] · [[Aluminium AlSi10Mg per SLM-DMLS]] · [[Leghe Metalliche per AM (Alluminio, Rame, Titanio, Superleghe Inconel)]] · [[Powder Bed Fusion (SLS, SLM, DMLS, EBM)]] · [[Indice - Materiali]] diff --git a/03 Materiali/Stainless Steel 316L per SLM-DMLS.md b/03 Materiali/Stainless Steel 316L per SLM-DMLS.md new file mode 100644 index 0000000..a832e02 --- /dev/null +++ b/03 Materiali/Stainless Steel 316L per SLM-DMLS.md @@ -0,0 +1,46 @@ +--- +id: "am-stainless-steel-316l-slm-dmls" +title: "Stainless Steel 316L per SLM/DMLS" +type: "concetto" +status: "da_verificare" +created: "2026-09-10" +updated: "2026-09-10" +language: "it" +tags: ["am/concetto", "am/materiale"] +aliases: ["Acciaio inossidabile 316L", "AISI 316L", "SS 316L"] +sources: ["[[SRC - ADDITIVA - Schede tecniche leghe metalliche per AM]]"] +material: "acciaio inossidabile austenitico (316L)" +process: "powder bed fusion (SLM/DMLS)" +--- + +# Stainless Steel 316L per SLM/DMLS + +## In breve +L'acciaio inossidabile 316L è una lega austenitica cromo-nichel-molibdeno a basso tenore di carbonio, con alta resistenza alla corrosione, processabile per powder bed fusion metallica (SLM/DMLS). [Fonte: scheda tecnica produttore ADDITIVA; [[SRC - ADDITIVA - Schede tecniche leghe metalliche per AM]]] + +## Spiegazione +Il molibdeno conferisce elevata resistenza alla corrosione; il basso tenore di carbonio migliora la resistenza alla corrosione intergranulare e la saldabilità, rendendo generalmente non necessario un trattamento termico post-saldatura. Il produttore dichiara assenza di suscettibilità a corrosione per vaiolatura (pitting) o interstiziale in soluzioni ricche di cloruri. Applicazioni tipiche indicate: prototipi resistenti ad acidi/corrosione e componenti in serie unica o di produzione in automotive, cantieristica navale, aerospaziale, settore alimentare/bevande (tubi e contenitori resistenti alla corrosione), chimico, farmaceutico, oil & gas; esempi applicativi citati nel testo web complementare: collettori di scarico, componenti per forni, scambiatori di calore, parti di motori a getto, attrezzature farmaceutiche/fotografiche, componenti di valvole e pompe, apparecchiature per processi chimici, serbatoi, evaporatori, attrezzature per l'industria della carta/pasta di cellulosa/tessile e parti esposte ad ambienti marini. Lavorabilità post-stampa dichiarata: lavorazione meccanica, saldatura, pallinatura, lucidatura, rivestimento. + +## Condizioni di applicazione +Dati riferiti al processo SLM/DMLS, stato "as-built" (la scheda riporta un solo set di valori meccanici, non un confronto as-built/trattato termicamente come per le altre leghe di questa serie). Distensione (stress relief) indicata come opzionale, per parti sensibili a deformazione: 20→550 °C in 3 ore, mantenimento 550 °C per 6 ore, raffreddamento a 20 °C. Macchina, fornitore di polvere e parametri di processo non specificati: valori indicativi del produttore ADDITIVA, non generalizzabili. + +## Dati o formule +Composizione chimica (% in peso, dato produttore): Fe bilancio; Cr 16–18%; Ni 11–13%; Mo 2,0–3,0%; Mn ≤2,00%; Si ≤0,75%; Cu ≤0,50%; P ≤0,25%; N ≤0,10%; S ≤0,10%; O ≤0,10%; C ≤0,03%. + +Designazioni citate: UNS S31603; AMS 5507–5653; ASTM A240; DIN 1.4404 – ISO 5832-1 — riportate come nella scheda originale, non verificate singolarmente in questa nota. + +Proprietà fisiche: densità relativa ≈99,9%; densità 7,90 g/cm³. + +Dati tecnici: accuratezza dimensionale tipica ±0,2/0,3 mm (quota <150 mm), ±0,05 mm ogni 25 mm (quota ≥150 mm); rugosità superficiale as-built Ra 5–9 µm, dopo lavorazione/lucidatura Ra <1,6 µm. + +Proprietà meccaniche as-built (metodo di prova ASTM E8/E8M, provino non lavorato, asse Z): resistenza a trazione Rm 640 ± 20 MPa; snervamento Rp0,2% 470 ± 20 MPa; allungamento a rottura 60 ± 10%; modulo di Young 170 ± 20 GPa; durezza (DIN EN ISO 6508-1) 18 HRC. + +Proprietà termiche: temperatura massima di esercizio a lungo termine ≈400 °C (752 °F); conducibilità termica ≈15 W/mK. + +Tutti i valori sono dati del produttore, non misure indipendenti: il disclaimer della scheda originale esclude l'uso per specifiche di progettazione o controllo qualità. + +## Esempio +Non applicabile (nota di dati di materiale, non caso applicativo documentato). + +## Fonti e collegamenti +[[SRC - ADDITIVA - Schede tecniche leghe metalliche per AM]] · [[Leghe Metalliche per AM (Alluminio, Rame, Titanio, Superleghe Inconel)]] · [[Powder Bed Fusion (SLS, SLM, DMLS, EBM)]] · [[Indice - Materiali]] diff --git a/03 Materiali/Titanium Ti6Al4V (Grado 23) per SLM-DMLS.md b/03 Materiali/Titanium Ti6Al4V (Grado 23) per SLM-DMLS.md new file mode 100644 index 0000000..9e46d72 --- /dev/null +++ b/03 Materiali/Titanium Ti6Al4V (Grado 23) per SLM-DMLS.md @@ -0,0 +1,53 @@ +--- +id: "am-titanium-ti6al4v-grado23-slm-dmls" +title: "Titanium Ti6Al4V (Grado 23) per SLM/DMLS" +type: "concetto" +status: "da_verificare" +created: "2026-09-10" +updated: "2026-09-10" +language: "it" +tags: ["am/concetto", "am/materiale"] +aliases: ["Ti6Al4V", "Ti-6Al-4V ELI", "Titanio Grado 23"] +sources: ["[[SRC - ADDITIVA - Schede tecniche leghe metalliche per AM]]"] +material: "lega di titanio Ti6Al4V, Grado 23 (ELI)" +process: "powder bed fusion (SLM/DMLS)" +--- + +# Titanium Ti6Al4V (Grado 23) per SLM/DMLS + +## In breve +Ti6Al4V è una lega di titanio leggera con elevate proprietà meccaniche (tenacità a frattura, resistenza a fatica, resistenza alla corrosione), bassa densità specifica e biocompatibilità, processabile per powder bed fusion metallica (SLM/DMLS). La scheda si riferisce al Grado 23 (variante ELI, extra-low interstitials). [Fonte: scheda tecnica produttore ADDITIVA; [[SRC - ADDITIVA - Schede tecniche leghe metalliche per AM]]] + +## Spiegazione +Il Grado 23 si differenzia dal Grado 5 principalmente per il tenore di ossigeno ridotto (massimo 0,13%), che migliora duttilità e tenacità a frattura a fronte di una lieve riduzione di resistenza. Applicazioni tipiche indicate: strutture aeronautiche critiche per frattura, componenti leggeri per motorsport e aerospaziale, impianti chirurgici e strumentazione medicale; il testo web complementare aggiunge: componenti a bassa/alta temperatura, fissaggi, dischi, mozzi, distanziali, tenute, pale di compressore, parti strutturali e componenti complessi di motori a turbina. Lavorabilità post-stampa dichiarata: lavorazione meccanica, saldatura, pallinatura, lucidatura, rivestimento. + +## Condizioni di applicazione +Dati riferiti al processo SLM/DMLS, stato "as-built" o trattato termicamente (ricottura sotto atmosfera di argon: 20→750 °C in 4 ore, mantenimento 750 °C per 1 ora, raffreddamento a 20 °C). Macchina, fornitore di polvere e parametri di processo non specificati: valori indicativi del produttore ADDITIVA, non generalizzabili. + +## Dati o formule +Composizione chimica (% in peso, dato produttore): Ti bilancio; Al 5,5–6,8%; V 3,5–4,5%; Fe ≤0,25%; O ≤0,13%; C ≤0,08%; N ≤0,05%; H ≤0,012%. + +Designazioni citate: UNS R56401; AMS 4956; ASTM B348 Grade 23; DIN EN 3.7164 – ISO 5832-3 — riportate come nella scheda originale, non verificate singolarmente in questa nota. + +Proprietà fisiche: densità relativa ≈99,9%; densità 4,43 g/cm³. + +Dati tecnici: accuratezza dimensionale tipica ±0,2/0,3 mm (quota <150 mm), ±0,05 mm ogni 25 mm (quota ≥150 mm); rugosità superficiale as-built Ra 5–9 µm, dopo lavorazione/lucidatura Ra <1,6 µm. + +Proprietà meccaniche (metodo di prova ASTM E8/E8M, provino non lavorato, asse Z): +| Proprietà | As-built | Trattato termicamente | +|---|---|---| +| Resistenza a trazione Rm | 1180 ± 30 MPa | 1100 ± 20 MPa | +| Snervamento Rp0,2% | 1080 ± 30 MPa | 1060 ± 20 MPa | +| Allungamento a rottura | 7 ± 1% | 12 ± 1% | +| Modulo di Young | 110 ± 3 GPa | 120 ± 5 GPa | +| Durezza (DIN EN ISO 6508-1) | 37 HRC | 37 HRC | + +Proprietà termiche: temperatura massima di esercizio a lungo termine ≈355 °C (670 °F); conducibilità termica 7 W/mK. + +Tutti i valori sono dati del produttore, non misure indipendenti: il disclaimer della scheda originale esclude l'uso per specifiche di progettazione o controllo qualità. + +## Esempio +Non applicabile (nota di dati di materiale, non caso applicativo documentato). + +## Fonti e collegamenti +[[SRC - ADDITIVA - Schede tecniche leghe metalliche per AM]] · [[Leghe Metalliche per AM (Alluminio, Rame, Titanio, Superleghe Inconel)]] · [[Powder Bed Fusion (SLS, SLM, DMLS, EBM)]] · [[Indice - Materiali]] diff --git a/10 Fonti/Catalogo fonti.md b/10 Fonti/Catalogo fonti.md index b142631..c370ddc 100644 --- a/10 Fonti/Catalogo fonti.md +++ b/10 Fonti/Catalogo fonti.md @@ -15,6 +15,8 @@ sources: [] - [[SRC - NIST - What is Additive Manufacturing]] - [[SRC - freeCodeCamp GaugeHow - 3D Printing and Additive Manufacturing Full Course]] +- [[SRC - Zhou et al. 2024 - Additive Manufacturing A Comprehensive Review]] +- [[SRC - ADDITIVA - Schede tecniche leghe metalliche per AM]] Aggiungi ogni nuova scheda fonte qui. Usa [[Modello - Fonte]]. diff --git a/10 Fonti/SRC - ADDITIVA - Schede tecniche leghe metalliche per AM.md b/10 Fonti/SRC - ADDITIVA - Schede tecniche leghe metalliche per AM.md new file mode 100644 index 0000000..fa58ea7 --- /dev/null +++ b/10 Fonti/SRC - ADDITIVA - Schede tecniche leghe metalliche per AM.md @@ -0,0 +1,46 @@ +--- +id: "am-src-additiva-schede-tecniche-leghe-metalliche" +title: "ADDITIVA — Schede tecniche leghe metalliche per manifattura additiva (SLM/DMLS)" +type: "fonte" +status: "da_verificare" +created: "2026-09-10" +updated: "2026-09-10" +language: "it" +tags: ["am/fonte"] +aliases: ["ADDITIVA datasheet", "ADDITIVA material data sheet"] +sources: [] +accessed: "2026-09-10" +--- + +# ADDITIVA — Schede tecniche leghe metalliche per manifattura additiva (SLM/DMLS) + +## Riferimento bibliografico +- Ente/produttore: ADDITIVA (servizio di manifattura additiva metallica; ragione sociale completa e sito web non acquisiti in questo clip — **da verificare**). +- Tipo di documento: schede tecniche materiale ("data sheet"), una per lega, in formato PDF (originariamente .docx secondo il nome file incorporato nel testo, es. `ADDITIVA_Aluminium AlSi10Mg_rev010.docx`), con numero di revisione. +- Documenti acquisiti (5 leghe, ciascuna con numero di revisione proprio e allegato conservato in `90 Allegati`, non modificare gli originali): + 1. Aluminium AlSi10Mg — rev. 010 — [[90 Allegati/ADDITIVA_Aluminium AlSi10Mg_rev010.pdf|ADDITIVA_Aluminium AlSi10Mg_rev010.pdf]] + [[90 Allegati/ADDITIVA_Aluminium AlSi10Mg_web|ADDITIVA_Aluminium AlSi10Mg_web]] (testo pagina web complementare) + 2. INCONEL 718 — rev. 006 — [[90 Allegati/ADDITIVA_INCONEL718_rev006.pdf|ADDITIVA_INCONEL718_rev006.pdf]] + [[90 Allegati/ADDITIVA_Inconel 718_web|ADDITIVA_Inconel 718_web]] + 3. Scalmalloy — rev. 005 — [[90 Allegati/ADDITIVA_Scalmalloy_rev005.pdf|ADDITIVA_Scalmalloy_rev005.pdf]] + [[90 Allegati/ADDITIVA_Scalmalloy_web|ADDITIVA_Scalmalloy_web]] + 4. Stainless Steel 316L — rev. 006 — [[90 Allegati/ADDITIVA_Stainless Steel 316L_rev006.pdf|ADDITIVA_Stainless Steel 316L_rev006.pdf]] + [[90 Allegati/ADDITIVA_Stainless Steel 316L_web|ADDITIVA_Stainless Steel 316L_web]] + 5. Titanium Ti6Al4V — rev. 009 — [[90 Allegati/ADDITIVA_Titanium Ti6Al4V_rev009.pdf|ADDITIVA_Titanium Ti6Al4V_rev009.pdf]] + [[90 Allegati/ADDITIVA_Titanium Ti6Al4V_web|ADDITIVA_Titanium Ti6Al4V_web]] +- Processo di riferimento dichiarato nelle schede: SLM/DMLS (selective laser melting / direct metal laser sintering), powder bed fusion metallica. +- Accesso: 2026-09-10, tramite Obsidian Web Clipper. **Il link di download presente in ciascun clip è un URL S3 firmato con scadenza (pochi minuti): non utilizzabile come riferimento stabile e già scaduto al momento della lettura.** Non è stata acquisita la URL pubblica del sito ADDITIVA né il PDF originale in locale — **da recuperare per una citazione stabile** (salvare il PDF in `90 Allegati` o annotare la URL pubblica della pagina/documento). +- Ogni scheda include, oltre ai dati del PDF ufficiale, un breve testo descrittivo aggiuntivo (probabilmente dalla pagina web del prodotto ADDITIVA, stesso materiale, nessuna URL propria acquisita), usato come fonte complementare per le applicazioni tipiche. + +## Ambito e qualità della fonte +Scheda tecnica di produttore/service bureau di manifattura additiva: fonte di parte (il produttore descrive i propri materiali/processi), non peer-reviewed né indipendente. Contiene però dati quantitativi con metodo di prova dichiarato (es. ASTM E8/E8M, ISO 6892-1, DIN EN ISO 6506-1/6508-1, ASTM E1461-13), quindi più utile di una fonte puramente divulgativa per proprietà meccaniche indicative — ma va trattata come dato del produttore, non come misura indipendente o valore di norma. Ogni scheda include un disclaimer esplicito del produttore: "This data sheet contains approximate values that may vary with build conditions [...] should not be used for design specifications or quality control" — vincolo da rispettare in ogni nota derivata. + +## Sezioni lette e localizzatori +Testo integrale di ciascuna scheda (1 pagina per materiale). Localizzatore usato nelle note derivate: nome del materiale (una sola pagina per scheda, non servono ulteriori riferimenti di pagina). + +## Risultati utili e limiti +Dati utili per ciascuna lega: composizione chimica (intervalli %), proprietà fisiche (densità, densità relativa), trattamento termico dichiarato (stress relief o tempra/invecchiamento secondo norma), accuratezza dimensionale tipica, rugosità superficiale (as-built e dopo lavorazione), proprietà meccaniche in stato as-built e trattato termicamente (resistenza a trazione, snervamento, allungamento a rottura, modulo di Young, durezza), conducibilità termica, temperatura massima di esercizio. + +Limiti: +- Nessuna informazione sulla macchina specifica, sui parametri di processo (potenza laser, velocità di scansione, spessore layer) né sul lotto di polvere: i valori vanno considerati indicativi del produttore, non generalizzabili ad altre macchine/fornitori di polvere. +- Il disclaimer del produttore esclude esplicitamente l'uso di questi dati per specifiche di progettazione o controllo qualità. +- Origine/identità legale di ADDITIVA non verificata in questa scheda. +- Le due fonti per materiale (PDF ufficiale + testo web complementare) potrebbero provenire da versioni/revisioni diverse del contenuto del produttore: eventuali discrepanze sono segnalate nelle note derivate. + +## Elaborazioni collegate +[[Aluminium AlSi10Mg per SLM-DMLS]] · [[Inconel 718 per SLM-DMLS]] · [[Scalmalloy per SLM-DMLS]] · [[Stainless Steel 316L per SLM-DMLS]] · [[Titanium Ti6Al4V (Grado 23) per SLM-DMLS]] diff --git a/10 Fonti/SRC - Zhou et al. 2024 - Additive Manufacturing A Comprehensive Review.md b/10 Fonti/SRC - Zhou et al. 2024 - Additive Manufacturing A Comprehensive Review.md new file mode 100644 index 0000000..6b8faa6 --- /dev/null +++ b/10 Fonti/SRC - Zhou et al. 2024 - Additive Manufacturing A Comprehensive Review.md @@ -0,0 +1,50 @@ +--- +id: "am-src-zhou-2024-comprehensive-review" +title: "Zhou et al. (2024) — Additive Manufacturing: A Comprehensive Review" +type: "fonte" +status: "da_verificare" +created: "2026-09-10" +updated: "2026-09-10" +language: "it" +tags: ["am/fonte"] +aliases: ["Zhou 2024", "Comprehensive Review Sensors 2024"] +sources: [] +doi: "10.3390/s24092668" +url: "https://doi.org/10.3390/s24092668" +accessed: "2026-09-10" +edition: "Sensors 2024, 24, 2668" +--- + +# Zhou et al. (2024) — Additive Manufacturing: A Comprehensive Review + +## Riferimento bibliografico +- Autori: Longfei Zhou, Jenna Miller, Jeremiah Vezza, Maksim Mayster, Muhammad Raffay, Quentin Justice, Zainab Al Tamimi, Gavyn Hansotte, Lavanya Devi Sunkara, Jessica Bernat. +- Affiliazione: Department of Biomedical, Industrial and Systems Engineering, School of Engineering and Computing, Gannon University, Erie, PA, USA. +- Titolo: "Additive Manufacturing: A Comprehensive Review". +- Rivista: *Sensors* 2024, 24(9), 2668. Articolo di tipo Review. +- DOI: https://doi.org/10.3390/s24092668 +- Editore: MDPI, Basel, Svizzera. Licenza: Creative Commons Attribution (CC BY 4.0), open access. +- Ricevuto: 1 marzo 2024; revisionato: 19 aprile 2024; accettato: 20 aprile 2024; pubblicato: 23 aprile 2024. +- Data di accesso: 2026-09-10, tramite ResearchGate (pagina articolo con testo integrale disponibile). +- Allegato: estratto testuale integrale (Obsidian Web Clipper dalla pagina ResearchGate) conservato in [[90 Allegati/(PDF) Additive Manufacturing_ A Comprehensive Review|(PDF) Additive Manufacturing_ A Comprehensive Review]]; non modificare l'originale. Non è il PDF impaginato originale, solo il testo estratto. **Il link di download presente nel clip è un URL firmato temporaneo (scaduto): non utilizzabile come riferimento stabile.** Riferimento stabile da usare: il DOI sopra indicato. + +## Ambito e qualità della fonte +Articolo di rassegna (review) peer-reviewed, pubblicato su rivista indicizzata (MDPI *Sensors*), con bibliografia numerata e affiliazione accademica verificabile. Qualità nettamente superiore rispetto a fonti divulgative (es. corsi video): utilizzabile come riferimento primario per definizioni, classificazioni di processo e confronti tecnologici, fermo restando che è comunque una fonte secondaria (sintesi della letteratura) e non riporta dati sperimentali originali degli autori. + +## Sezioni lette e localizzatori +Testo integrale (44 pagine, numerate "Sensors 2024, 24, 2668 X of 44" nel testo estratto). Struttura dell'articolo: +1. Introduzione (§1). +2. Processo di manifattura additiva — flusso di lavoro: design e modellazione (§2.1), conversione in STL (§2.2), slicing (§2.3), preparazione/stampa/post-processing (§2.4). +3. Tecnologie di manifattura additiva (§3), con tabella comparativa (Table 1) e sottosezioni dedicate: Material Extrusion (§3.1), VAT Polymerization (§3.2), Material Jetting (§3.3), Binder Jetting (§3.4), Selective Laser Sintering (§3.5), Selective Laser Melting (§3.6), Direct Metal Laser Sintering (§3.7), Electron Beam Melting (§3.8), Multi-Jet Fusion (§3.9), Direct Energy Deposition (§3.10), Carbon Fiber Reinforcement (§3.11), Laminated Object Manufacturing (§3.12). +4. Tendenze future e sfide (§4): 3D bioprinting (§4.1), 3D food printing (§4.2), stampa 3D su larga scala (§4.3), 4D printing (§4.4), AM basata su IA (§4.5), innovazioni in materiali/controllo qualità/post-processing (§4.6), standardizzazione e regolamentazione (§4.7), economia circolare e sostenibilità (§4.8). +5. Conclusioni (§5). + +Localizzatori usati nelle note derivate: `[§X.Y]` per la sezione, con eventuale numero di pagina "X of 44" quando disponibile. + +## Risultati utili e limiti +Fonte di alta qualità per: classificazione delle tecnologie AM (12 famiglie/varianti trattate, più dettagliata della classificazione ASTM a 7 famiglie usata nel corso video già presente nel vault), confronto sistematico vantaggi/limiti/materiali per tecnologia (Table 1, §3), flusso di lavoro CAD→STL→slicing→stampa→post-processing, e panoramica delle tendenze emergenti (bioprinting, food printing, stampa su larga scala, 4D printing, AM basata su IA) assente nella fonte video già processata. + +Limiti: è una review, quindi le affermazioni tecniche derivano da fonti terze citate con numero (es. `[3]`, `[124]`) che non sono state verificate singolarmente in questa scheda — i riferimenti numerici citati nelle note derivate vanno intesi come "citati da Zhou et al." e non come verifica diretta della fonte primaria originale. Non riporta dati sperimentali quantitativi propri (es. proprietà meccaniche misurate); per questi vedere le schede fonte dei produttori/datasheet (es. [[SRC - ADDITIVA - Schede tecniche leghe metalliche per AM]]). + +## Elaborazioni collegate +[[RIA - Zhou et al. 2024 - Additive Manufacturing A Comprehensive Review]] diff --git a/11 Riassunti/Indice riassunti.md b/11 Riassunti/Indice riassunti.md index d927fc5..ad7e4d1 100644 --- a/11 Riassunti/Indice riassunti.md +++ b/11 Riassunti/Indice riassunti.md @@ -14,6 +14,7 @@ sources: [] # Indice riassunti - [[RIA - freeCodeCamp GaugeHow - 3D Printing and Additive Manufacturing Full Course]] +- [[RIA - Zhou et al. 2024 - Additive Manufacturing A Comprehensive Review]] Usa [[Modello - Riassunto]] e collega la scheda fonte per ogni nuovo riassunto. diff --git a/11 Riassunti/RIA - Zhou et al. 2024 - Additive Manufacturing A Comprehensive Review.md b/11 Riassunti/RIA - Zhou et al. 2024 - Additive Manufacturing A Comprehensive Review.md new file mode 100644 index 0000000..5603c1f --- /dev/null +++ b/11 Riassunti/RIA - Zhou et al. 2024 - Additive Manufacturing A Comprehensive Review.md @@ -0,0 +1,43 @@ +--- +id: "am-ria-zhou-2024-comprehensive-review" +title: "Riassunto — Zhou et al. (2024), Additive Manufacturing: A Comprehensive Review" +type: "riassunto" +status: "da_verificare" +created: "2026-09-10" +updated: "2026-09-10" +language: "it" +tags: ["am/riassunto"] +aliases: [] +sources: ["[[SRC - Zhou et al. 2024 - Additive Manufacturing A Comprehensive Review]]"] +--- + +# Riassunto — Zhou et al. (2024), Additive Manufacturing: A Comprehensive Review + +## Fonte e copertura +[[SRC - Zhou et al. 2024 - Additive Manufacturing A Comprehensive Review]]. Articolo di rassegna peer-reviewed, testo integrale letto (44 pagine). + +## Sintesi +La rassegna definisce l'AM come tecnologia matura, passata da strumento di prototipazione rapida (anni '80) a metodo di produzione a pieno titolo, applicabile a polimeri, metalli, ceramiche e compositi. Descrive il flusso di lavoro generale (progettazione CAD → conversione STL → slicing/G-code → stampa e post-processing), poi tratta 12 tecnologie/varianti AM con principio di funzionamento, vantaggi, limiti, materiali tipici e applicazioni, per poi chiudere con una panoramica di tendenze emergenti e temi trasversali (bioprinting, food printing, stampa su larga scala, 4D printing, AM basata su IA, innovazioni di materiali/qualità/post-processing, standardizzazione, economia circolare). + +## Metodo e contesto +Rassegna della letteratura (review paper), non uno studio sperimentale: sintetizza e cita fonti terze numerate. Utile come riferimento strutturale e per la classificazione tecnologica, meno utile per dati quantitativi di proprietà dei materiali (per cui servono datasheet di produttore o norme). + +## Risultati principali +- **Flusso AM** in 5 fasi: design/modellazione CAD, conversione a STL (triangolazione, requisito di modello "watertight"/manifold), slicing (generazione G-code, parametri di stampa: altezza layer, densità di riempimento, supporti, velocità), stampa e post-processing (rimozione supporti, finitura superficiale, cura UV per resine, trattamenti termici per metalli). [§2.1–§2.4] +- **Confronto sistematico di 12 tecnologie AM** (Table 1, §3): FDM, VAT Polymerization (VP), Material Jetting (MJ), Binder Jetting (BJ), Selective Laser Sintering (SLS), Selective Laser Melting (SLM), Direct Metal Laser Sintering (DMLS), Electron Beam Melting (EBM), Multi-Jet Fusion (MJF), Direct Energy Deposition (DED), Carbon Fiber Reinforcement (CFR), Laminated Object Manufacturing (LOM) — ciascuna con vantaggi, limiti e materiali comuni sintetizzati in tabella. Classificazione più granulare (12 voci) di quella ASTM a 7 famiglie usata nella fonte video già presente nel vault ([[AM - Classificazione ASTM per i processi di stampa 3D]]); utile per un confronto incrociato. +- **Tendenze future** (§4): bioprinting 3D di tessuti/organi (bioinchiostri, vascolarizzazione), food printing 3D (sfide reologiche dei materiali alimentari), stampa su larga scala (edilizia, componenti aerospaziali di grandi dimensioni), 4D printing (materiali intelligenti, leghe a memoria di forma come nichel-titanio), AM basata su intelligenza artificiale (monitoraggio in tempo reale, digital twin, manutenzione predittiva), innovazioni di materiali/multimateriale/ibridazione con sottrattiva, standardizzazione e regolamentazione (assenza di standard universalmente accettati, criticità per settori regolamentati come aerospaziale/medicale), economia circolare e sostenibilità. +- **Considerazioni economiche** (§4.8): ROI dell'AM variabile per tecnologia e settore — FDM per prototipazione a basso costo, SLS/DMLS per componenti funzionali finali a più alto valore, SLA/MJ per parti ad alto dettaglio (es. dentale/medicale); ROI più marcato in aerospaziale e medicale, dove il costo del fallimento è alto e il valore della personalizzazione è significativo. + +## Limiti e questioni aperte +- Le affermazioni tecniche della rassegna derivano da fonti terze citate con numero (es. `[3]`, `[124]`), non verificate singolarmente in questa scheda: da trattare come "riportato da Zhou et al. (2024)", non come fatto verificato alla fonte primaria originale. +- Nessun dato quantitativo di proprietà meccaniche misurate: per questo servono datasheet di produttore (vedi [[SRC - ADDITIVA - Schede tecniche leghe metalliche per AM]]) o norme. +- Il link di accesso originale (ResearchGate, download firmato temporaneo) non è una URL stabile: usare il DOI per citazioni future. + +## Note da ricavare +La rassegna offre materiale sufficiente per arricchire con citazioni verificabili le note di concetto già presenti nel vault (derivate dalla fonte video, marcate `da_verificare`), in particolare: +- [[AM - Classificazione ASTM per i processi di stampa 3D]]: incrociare con la classificazione a 12 voci di Table 1 (§3). +- [[Flusso di lavoro e formati file per la stampa 3D]]: incrociare con §2.1–§2.4 (requisiti STL, ruolo dello slicing). +- Note tecnologiche in `02 Processi/`: aggiungere citazione a vantaggi/limiti/materiali di Table 1 per ciascuna famiglia di processo. +- Nuove note pianificate (non derivabili dalle fonti già presenti nel vault): 3D bioprinting, 4D printing e leghe a memoria di forma, AM basata su intelligenza artificiale/digital twin, stampa 3D su larga scala — da collocare rispettivamente in `01 Fondamenti` o in una futura sottosezione di `02 Processi`/`08 Applicazioni ed economia` a seconda dello sviluppo del vault. + +[[Indice riassunti]] diff --git a/90 Allegati/(PDF) Additive Manufacturing_ A Comprehensive Review.md b/90 Allegati/(PDF) Additive Manufacturing_ A Comprehensive Review.md new file mode 100644 index 0000000..6edc195 --- /dev/null +++ b/90 Allegati/(PDF) Additive Manufacturing_ A Comprehensive Review.md @@ -0,0 +1,5156 @@ +ArticlePDF Available + +## Additive Manufacturing: A Comprehensive Review[ + +Sensors + +](https://www.researchgate.net/journal/Sensors-1424-8220) + +Authors: + +[Longfei Zhou](https://www.researchgate.net/scientific-contributions/Longfei-Zhou-2279899135) + +[Longfei Zhou](https://www.researchgate.net/scientific-contributions/Longfei-Zhou-2279899135) + +- This person is not on ResearchGate, or hasn't claimed this research yet. + +[Jenna Miller](https://www.researchgate.net/scientific-contributions/Jenna-Miller-2276410348) + +[Jenna Miller](https://www.researchgate.net/scientific-contributions/Jenna-Miller-2276410348) + +- This person is not on ResearchGate, or hasn't claimed this research yet. + +[Jeremiah Vezza](https://www.researchgate.net/scientific-contributions/Jeremiah-Vezza-2279896547) + +[Jeremiah Vezza](https://www.researchgate.net/scientific-contributions/Jeremiah-Vezza-2279896547) + +- This person is not on ResearchGate, or hasn't claimed this research yet. + +[Maksim Mayster](https://www.researchgate.net/scientific-contributions/Maksim-Mayster-2279896982) + +[Maksim Mayster](https://www.researchgate.net/scientific-contributions/Maksim-Mayster-2279896982) + +- This person is not on ResearchGate, or hasn't claimed this research yet. + +Hide + +## Abstract and Figures + +Additive manufacturing has revolutionized manufacturing across a spectrum of industries by enabling the production of complex geometries with unparalleled customization and reduced waste. Beginning as a rapid prototyping tool, additive manufacturing has matured into a comprehensive manufacturing solution, embracing a wide range of materials, such as polymers, metals, ceramics, and composites. This paper delves into the workflow of additive manufacturing, encompassing design, modeling, slicing, printing, and post-processing. Various additive manufacturing technologies are explored, including material extrusion, VAT polymerization, material jetting, binder jetting, selective laser sintering, selective laser melting, direct metal laser sintering, electron beam melting, multi-jet fusion, direct energy deposition, carbon fiber reinforced, laminated object manufacturing, and more, discussing their principles, advantages, disadvantages, material compatibilities, applications, and developing trends. Additionally, the future of additive manufacturing is projected, highlighting potential advancements in 3D bioprinting, 3D food printing, large-scale 3D printing, 4D printing, and AI-based additive manufacturing. This comprehensive survey aims to underscore the transformative impact of additive manufacturing on global manufacturing, emphasizing ongoing challenges and the promising horizon of innovations that could further elevate its role in the manufacturing revolution. + +![](https://www.researchgate.net/images/icons/svgicons/researchgate-logo-white.svg) + +**Discover the world's research** + +- 25+ million members +- 160+ million publication pages +- 2.3+ billion citations + +Available via license: [CC BY 4.0](https://www.researchgate.net/deref/https%3A%2F%2Fcreativecommons.org%2Flicenses%2Fby%2F4.0%2F) + +Citation: Zhou, L.; Miller, J.; Vezza, J.; + +Mayster, M.; Raffay, M.; Justice, Q.; + +Al Tamimi, Z.; Hansotte, G.; Sunkara, + +L.D.; Bernat, J. Additive + +Manufacturing: A Comprehensive + +Review. Sensors 2024,24, 2668. + +https://doi.org/10.3390/s24092668 + +Academic Editor: Shah Nawaz + +Burokur + +Received: 1 March 2024 + +Revised: 19 April 2024 + +Accepted: 20 April 2024 + +Published: 23 April 2024 + +Licensee MDPI, Basel, Switzerland. + +This article is an open access article + +conditions of the Creative Commons + +Attribution (CC BY) license (https:// + +creativecommons.org/licenses/by/ + +4.0/). + +sensors + +Review + +Additive Manufacturing: A Comprehensive Review + +Longfei Zhou \*, Jenna Miller, Jeremiah Vezza, Maksim Mayster, Muhammad Raffay, Quentin Justice, + +Zainab Al Tamimi, Gavyn Hansotte, Lavanya Devi Sunkara and Jessica Bernat + +Department of Biomedical, Industrial and Systems Engineering, School of Engineering and Computing, + +College of Engineering and Business, Gannon University, Erie, PA 16541, USA + +\*Correspondence: zhou009@gannon.edu; Tel.: +1-814-871-5491 + +Abstract: Additive manufacturing has revolutionized manufacturing across a spectrum of industries + +by enabling the production of complex geometries with unparalleled customization and reduced + +waste. Beginning as a rapid prototyping tool, additive manufacturing has matured into a compre- + +hensive manufacturing solution, embracing a wide range of materials, such as polymers, metals, + +ceramics, and composites. This paper delves into the workflow of additive manufacturing, encom- + +passing design, modeling, slicing, printing, and post-processing. Various additive manufacturing + +technologies are explored, including material extrusion, VAT polymerization, material jetting, binder + +jetting, selective laser sintering, selective laser melting, direct metal laser sintering, electron beam + +melting, multi-jet fusion, direct energy deposition, carbon fiber reinforced, laminated object manufac- + +turing, and more, discussing their principles, advantages, disadvantages, material compatibilities, + +applications, and developing trends. Additionally, the future of additive manufacturing is projected, + +highlighting potential advancements in 3D bioprinting, 3D food printing, large-scale 3D printing, + +4D printing, and AI-based additive manufacturing. This comprehensive survey aims to underscore + +the transformative impact of additive manufacturing on global manufacturing, emphasizing ongo- + +ing challenges and the promising horizon of innovations that could further elevate its role in the + +manufacturing revolution. + +Keywords: additive manufacturing; 3D printing; material extrusion; fused deposition modeling; VAT + +polymerization; binder jetting; material jetting; power bed fusion; CAD; review + +1\. Introduction + +Additive manufacturing (AM), widely recognized as 3D printing, has undergone a + +significant evolution since its inception in the 1980s, transitioning from a rapid prototyping + +tool to a viable manufacturing method for a broad spectrum of applications. The tech- + +nology’s advancement is marked by innovations in materials, technology, and software, + +propelling AM into industries such as aerospace, automotive, healthcare, and fashion \[ + +1 + +\]. + +Today, 3D printing is celebrated for its unparalleled customization capabilities, reduced + +waste, and the ability to fabricate complex geometries that are difficult or impossible to + +achieve with traditional manufacturing methods \[ + +2 + +\]. This evolution has transformed AM + +into a sophisticated array of processes that cater to a diverse range of materials, including + +polymers, metals, ceramics, and composites, driving innovations across numerous sectors. + +As AM continues to advance, it is set to revolutionize production processes, supply chains, + +and product design worldwide, marking its significance as a transformative technology in + +the manufacturing realm and outlining a future where on-demand customized production + +can become a reality across industries. + +AM distinguishes itself from traditional formative and subtractive methods through + +its capacity for complex geometries and customization with minimal waste, making it ideal + +for prototypes and small production runs. Figure 1shows the comparison of cost per part + +over different numbers of parts between AM and traditional manufacturing methods \[ + +3 + +\]. + +Sensors 2024,24, 2668. https://doi.org/10.3390/s24092668 https://www.mdpi.com/journal/sensors + +Sensors 2024,24, 2668 2 of 44 + +However, AM faces limitations in material variety, part size, and requires significant post- + +processing, potentially leading to anisotropic mechanical properties. In contrast, traditional + +manufacturing excels in mass production efficiency, offering superior mechanical strength, + +isotropy, and surface finish due to a wider range of materials and established processes. + +While AM can reduce initial costs by eliminating the need for molds or tooling, its cost + +advantages diminish with scale, unlike traditional methods that benefit from economies + +of scale. Thus, the choice between AM and traditional methods hinges on the project’s + +specific demands regarding complexity, volume, and cost efficiency. + +Figure 1. Cost comparison between formative, subtractive, and additive manufacturing \[3\]. + +deposition modeling (FDM), developed by Stratasys in the late 1980s, is one of the most + +widely used AM technologies. It works by extruding thermoplastic filaments through a + +heated nozzle, laying down material layer by layer to construct an object. Recent advance- + +ments have focused on enhancing the mechanical properties of FDM-printed parts through + +the incorporation of reinforced composite filaments and optimizing process parameters + +for better surface finish and dimensional accuracy \[ + +4 + +\]. Stereolithography (SLA), patented + +by 3D Systems in 1986, was the first commercial AM process. It uses an ultraviolet laser + +to cure photosensitive resins in a layer-by-layer fashion. Technological advancements + +in SLA have been directed towards improving the speed and resolution of the printing + +process, enabling the production of parts with high detail and smooth surface finishes \[ + +5 + +\]. + +Digital light processing (DLP) technology, similar to SLA, uses a digital light projector to + +cure photosensitive resins. It stands out for its high printing speed and ability to produce + +parts with fine details. Advances in DLP technology include the development of new + +resin formulations that expand the mechanical and thermal properties of printed objects, + +enabling their use in more demanding applications \[1\]. Selective laser sintering (SLS) and + +direct metal laser sintering (DMLS) are powder bed fusion technologies that use lasers to + +sinter powdered materials, binding them together to form a solid structure. These technolo- + +gies have seen significant development in the variety of materials that can be processed, + +including metals, polymers, and ceramics, allowing for the production of functional parts + +with complex geometries. Recent research has focused on optimizing process parameters + +and post-processing techniques to improve the mechanical properties and surface quality + +of printed parts \[ + +6 + +\]. Material jetting works similarly to inkjet printing, where droplets of + +material are selectively deposited and cured. Binder jetting involves depositing a liquid + +binding agent onto layers of powder material. Both technologies have advanced in terms + +of material diversity and printing resolution. Recent innovations aim at expanding the + +range of applications by developing new materials with enhanced properties and reducing + +production costs \[7\]. + +Sensors 2024,24, 2668 3 of 44 + +The future of AM is poised for growth along several vectors, including the develop- + +ment of new materials, process innovations, and the integration of AM technologies into + +traditional manufacturing lines. Significant research is focused on scalable AM techniques + +for large structures, bioprinting for medical applications, and the integration of artificial + +intelligence to optimize printing processes and material properties \[ + +8 + +\]. AM continues + +to push the boundaries of what is possible in manufacturing, driving towards a future + +where customized production on-demand can become a reality across industries. As the + +properties, its role in the next manufacturing revolution becomes increasingly significant. + +Despite the remarkable achievements of 3D printing technology, encompassing a wide + +range of industries from healthcare to aerospace with its innovative applications, it contin- + +ues to face significant limitations that highlight its future development potential. One of the + +primary challenges is the speed of printing, which, despite improvements, remains slow for + +mass production applications, limiting its utility to prototyping and small-scale manufactur- + +ing \[ + +9 + +\]. Material limitations also pose a significant barrier. The range of materials suitable + +for 3D printing is expanding, but still lacks the diversity and performance characteristics + +of those used in traditional manufacturing processes. Furthermore, the resolution and + +surface finish of printed objects often require extensive post-processing to meet industry + +standards, adding time and cost to the manufacturing process. Additionally, the cost of 3D + +printers and materials can be prohibitively high for widespread adoption, particularly in + +developing countries. There are also challenges related to intellectual property rights and + +10 + +\]. Look- + +ing forward, the evolution of 3D printing technology promises advancements in printing + +speed, material diversity, and cost efficiency. Innovations such as and enhanced precision + +are on the horizon, aiming to overcome current limitations and expand the technology’s + +applicability across more sectors, paving the way for a future where 3D printing plays a + +pivotal role in global manufacturing and beyond. + +In this paper, the main workflow of AM is first discussed, including design and + +modeling, conversion to STL, slicing, 3D printing, and post-processing. Then, different + +types of AM technologies are introduced, including material extrusion, VAT polymerization, + +material jetting, binder jetting, selective laser sintering, selective laser melting, direct + +metal laser sintering, electron beam melting, multi-jet fusion, direct energy deposition, + +carbon fiber reinforced, laminated object manufacturing, etc. The principle of operation, + +advantages and disadvantages, materials, main applications, and developing trends of + +each type of AM technology are discussed in detail. Finally, the challenges, development + +trends, and potential innovations of AM are analyzed, including important topics such + +as 3D bioprinting, 3D food printing, large-scale 3D printing, 4D printing, and AI-based + +AM technologies, as well as new materials, quality control, post-processing innovations, + +standardization, regulatory, circular economy, and sustainability. + +2\. Additive Manufacturing Process + +Additive manufacturing (AM), commonly known as 3D printing, has revolutionized + +the way objects are created, from simple models to complex structures used in various + +industries. The process involves adding material layer by layer to create objects from + +3D model data, contrary to traditional subtractive manufacturing methods. The overall + +pipeline of AM encompasses several critical steps, each contributing to the final product’s + +accuracy, quality, and functionality. Each step in the AM pipeline is vital for ensuring + +that the final product meets the desired specifications and quality standards. Advances + +in software, materials, and printing technologies continue to expand the possibilities of + +what can be achieved with 3D printing, making it an increasingly integral part of modern + +manufacturing processes Figure 2. The overall workflow of the additive manufacturing + +process is given below. + +Sensors 2024,24, 2668 4 of 44 + +3D Model STL File G-code Print + +Design & + +Modeling Convert to STL Slicing + +3D Printing + +& Post-processing + +Figure 2. Overall workflow of the additive manufacturing process. + +2.1. Design and Modeling + +The design phase marks the beginning of the AM process, where the creation of a 3D + +model is pivotal. Utilizing Computer-Aided Design (CAD) software tools, designers and + +engineers can craft detailed and complex digital representations of the desired object. This + +stage is characterized by meticulous planning of each aspect of the model, ensuring that + +every curve, edge, and dimension aligns perfectly with the final product’s requirements. + +A number of critical factors influence the design process. + +Design Complexity and Material Considerations: CAD software facilitates the creation + +of intricate designs that are often impossible to achieve through traditional manufacturing + +methods. This complexity enables the exploration of new design paradigms and function- + +alities. Concurrently, the choice of printing material plays a significant role, as different + +materials offer varying properties, such as durability, flexibility, and thermal resistance. + +These properties must be aligned with the object’s intended application, dictating specific + +design adjustments to cater to the chosen material’s strengths and weaknesses. + +Technology Limitations and Object Orientation: The capabilities and limitations of + +the selected 3D printing technology significantly impact the design process. Technologies + +such as fused deposition modeling (FDM), stereolithography (SLA), and selective laser + +sintering (SLS) each have unique specifications regarding resolution, accuracy, and the + +ability to create complex structures. Moreover, the size of the print bed limits the max- + +imum dimensions of the object, potentially necessitating the division of larger objects + +into smaller, assembleable parts. The orientation of the model during printing also re- + +quires careful consideration to optimize the print’s quality, strength, and the necessity for + +support structures. + +Optimization Strategies: Design optimization for AM can take several forms, including + +topology optimization for material efficiency and structural integrity, and strategic orienta- + +tion to reduce the need for support structures and improve surface finish. Techniques such + +as hollowing are employed to minimize material use and print time without compromising + +the object’s durability. + +The design stage, therefore, is not just about creativity but also about a deep under- + +standing of the chosen material, printing technology, and the practical applications of the + +final product. + +2.2. Conversion to STL + +Once the 3D model is complete, it is exported as an STL file. The conversion of 3D + +models into stereolithography (STL) files represents a crucial step in the pipeline of 3D + +printing, serving as the bridge between digital design and physical realization. This process + +involves transforming a 3D design into a format that 3D printers can interpret and use to + +build objects layer by layer. + +The STL format simplifies the model by breaking down its surface into a series of + +triangles, also known as tessellation. Each triangle is described by the coordinates of its + +Sensors 2024,24, 2668 5 of 44 + +vertices and the direction of its normal (an outward-facing vector perpendicular to the + +triangle’s surface). This simplification is crucial because it translates complex geometrical + +shapes into a uniform language of triangles that 3D printers can understand. + +STL files contain many important characteristics such as resolution and manifoldness. + +The resolution of an STL file depends on the size of the triangles. Smaller triangles result in + +higher resolution, producing more detailed prints, but at the cost of increasing the file size. + +Besides, the STL model must also be “watertight”, meaning it should not have any gaps or + +holes, and all normals should point outward. Non-manifold models can lead to printing + +errors. After exporting to STL, the file undergoes a slicing process, where specialized + +software further translates the STL file into G-code. Before slicing, users may adjust the + +model’s orientation, scale, and other parameters to optimize printing. + +There are some potential issues in the STL files. STL files can sometimes contain + +errors such as reversed normals or non-manifold edges. Many slicing programs include + +repair functions to automatically fix these issues. To reduce printing time and material + +use, designers might optimize their models for the STL format by minimizing overhangs + +and supports. + +Converting 3D models into STL files is a fundamental step that transforms intri- + +cate digital designs into a language that 3D printers can effectively interpret, setting the + +stage for the AM process. This conversion encapsulates the transition from conceptual + +design to physical object, embodying the core of what makes 3D printing a revolutionary + +manufacturing technique. + +2.3. Slicing + +Once the STL file is generated, the next essential step is slicing, which is a pivotal + +process where specialized software, often referred to as a slicer, transforms the STL file into + +a series of thin, horizontal layers. This conversion is critical because it breaks down the + +complex geometry of the model into a stack of manageable, printable layers, effectively + +translating the digital design into a physical object. The slicing software plays a multifaceted + +role in the 3D printing process. + +Generation of G-code: The primary output of the slicing process is the generation of + +G-code, a universally recognized programming language for Computer Numerical Control + +(CNC) machinery, including 3D printers. G-code is meticulous and detailed, containing + +precise instructions that direct the printer’s movements, such as the path it should follow, + +the speed of the extrusion head or laser, and where to start and stop extruding material. + +This code is what makes it possible for the 3D printer to materialize the digital model into + +a tangible form, layer by layer. + +Customization of Print Parameters: Slicing software offers users the ability to cus- + +tomize various print parameters, which significantly impact the quality, strength, and ap- + +pearance of the final print. These parameters include the layer height, which determines + +the print’s resolution; the fill density, affecting the object’s solidity and weight; and the + +necessity for support structures, which are crucial for printing overhangs and undercuts + +without deformation. Adjusting the print speed can also influence the print’s quality, + +with slower speeds generally resulting in higher-quality finishes. + +Optimization for Material and Printer: Different materials and printers have unique + +capabilities and limitations. The slicing stage allows for optimization tailored to the specific + +characteristics of the material (such as temperature sensitivity, shrinkage, and required + +post-processing) and the printer’s specifications (such as precision, maximum print size, + +and compatible materials). This optimization ensures the final print meets the desired + +criteria for functionality and aesthetics. + +Simulation and Troubleshooting: Many slicing programs provide simulation tools + +that preview the printing process, offering valuable insights into potential issues, such as + +insufficient supports, overly thin walls, or areas prone to warping. This preview enables + +users to make informed adjustments before committing to the actual print, saving time, + +materials, and effort by reducing the likelihood of print failures. + +Sensors 2024,24, 2668 6 of 44 + +After adjusting these parameters and settings, the slicer recompiles the model into + +an optimized G-code file, ready to be sent to the printer. This step marks the transition + +from a digital design to a set of actionable instructions tailored to the unique characteristics + +of the 3D printer and the material selected. The slicing process, therefore, is not merely + +a conversion but a critical phase of preparation that bridges digital modeling with the + +physical act of printing, ensuring that the envisioned design materializes accurately and + +efficiently in the real world. + +2.4. Preparation, Printing, and Post-Processing + +With the G-code prepared, the stage is set for the 3D printer to initiate the manufac- + +turing process. Preparing a 3D printer for operation involves a series of essential steps to + +ensure optimal performance and print quality. Initially, the material installation is carried + +out, which varies depending on the type of printer; FDM printers use a filament that must + +be loaded into the extruder, while SLA printers require the pouring of liquid resin into the + +resin tank. Following this, leveling the print bed is crucial to guarantee the proper adhesion + +of the first layer, a step that may involve manual adjustments or rely on auto-leveling fea- + +tures depending on the printer model. The final preparatory step is pre-heating the printer + +to the appropriate temperatures for both the print bed and the extruder in the case of FDM + +printers, ensuring materials are at the optimal temperature for printing. This pre-heating + +process aids in material adhesion and reduces issues such as warping, thus contributing + +to the overall quality of the print. These preparatory steps, from material installation to + +pre-heating, are critical for achieving successful printing outcomes and maintaining the + +printer’s longevity and safety. + +As the printing begins, the printer’s nozzle, or in some technologies, the laser or + +projector, precisely follows the paths dictated by the G-code. This path guides the deposition + +of material, constructing the object in a successive layering approach. The choice of material + +is crucial and is selected based on the object’s intended use, ranging from thermoplastics, + +photopolymers, and metals to more specialized materials, such as ceramics and composite + +filaments. Each layer solidifies upon deposition or through subsequent curing, gradually + +forming the final object with a high degree of accuracy and complexity. More details of + +different 3D printing technologies are discussed in Section 3. + +The completion of the printing phase marks the beginning of another essential phase: + +post-processing. This stage is vital for enhancing the physical properties and aesthetic quali- + +ties of the printed object. Common post-processing methods include the removal of support + +structures, which are often necessary to prevent the collapse of overhanging features during + +printing. Surface finishing techniques, such as sanding, polishing, or chemical bathing, + +are applied to improve smoothness and appearance. For resin-based prints, curing under + +UV light is a critical step to achieve full strength and stability. Additionally, objects may + +undergo secondary processes, such as painting, coating, or metal plating, to meet specific + +functional or aesthetic requirements. The necessity and complexity of post-processing vary + +significantly with the printing technology used and the end-use of the object. For instance, + +metal prints might require stress-relief heat treatments and machining to achieve precise + +tolerances, while plastic prints might need minimal finishing. Despite the advancements in + +3D printing technologies, post-processing remains an indispensable step in many cases, + +affecting the overall time and cost of production. The ongoing development in AM aims + +to reduce the dependency on extensive post-processing, striving for a future where prints + +emerge from the printer ready for immediate use, further streamlining the manufacturing + +process and expanding the applicability of 3D printing across industries. + +3\. Additive Manufacturing Technologies + +In this section, different types of AM technologies are discussed, including their + +principle of operation, advantages and limitations, common materials, main applications, + +and development trends. Table 1compares the advantages, limitations, and common + +Sensors 2024,24, 2668 7 of 44 + +materials between these different types of AM technologies. More details are discussed one + +by one later in this section. + +Table 1. AM technology comparison. + +AM Tech. Advantages Limitations Common Materials + +FDM + +Low price + +Speed efficiency + +Low maintenance + +Requires high temperatures + +Requires supports + +Inability for certain geometries + +PLA + +ABS + +PETG + +VP Exceptional details and surface + +Ideal for intricate features + +Limited build volume + +Shrinkage and warping + +Toxicity and environmental concerns + +Photocurable resins + +Waxes + +Ceramics + +MJ + +Exceptional resolution and details + +Multi-material and full-color + +Wide array of materials + +High costs + +Restricted build volume + +Low printing speed + +Photopolymers + +Thermoplastic polymers + +Metal powders + +BJ Full-color + +Various materials + +Low-density parts + +Labor-intensive + +Complex post-processing + +PVP + +PVA + +PAA + +SLS + +Support free + +Isotropic final products + +Complex geometries + +Porosity, shrinkage, and impurities + +Poor surface quality + +Post-processing for final appearance + +Plastics + +Composites + +Ceramics + +SLM + +Binder-free + +Often faster than SLS + +High powder recyclability + +High costs + +Less material flexibility + +Support structures and inert gas + +Titanium alloys + +Stainless steels + +Aluminum alloys + +DMLS + +Support-free + +Various materials of metal alloy + +High power recyclability + +High costs + +High porosity + +Limited build volume + +Stainless steels + +Aluminum + +Titanium + +EBM + +Excellent material properties + +Processing reactive metals + +Fast and efficient process + +High equipment costs + +Additional post-processing + +Limited selection of materials + +Titanium alloys + +Nickel-based superalloys + +Cobalt–chrome alloys + +MJF + +High speed and efficiency + +Less post-processing + +Multiple colors + +High ductility + +Material limitations + +Specific use cases + +Polyamides + +Thermoplastic Polyurethanes + +Polypropylene + +DED + +Minimizes waste + +Part repair and modification + +Efficiency for larger components + +Post-processing for a smooth finish + +Low precision + +Stainless steel + +Titanium alloys + +Nickel-based alloys + +CFR Strength and lightness + +Customizable fiber orientation High costs + +Limited material compatibility + +Nylon + Carbon fiber + +PEEK + Carbon fiber + +ABS + Carbon fiber + +LOM + +Cost-effectiveness and high speed + +Environmental friendliness + +Large part creation + +Low dimensional accuracy and strength + +Post-processing for surface finish + +Limited material range for composites + +Paper + +Metal foils + +Plastics + +Note: A list of abbreviations is in the Abbreviations section at the end of the manuscript. + +3.1. Material Extrusion + +Three-dimensional printing has become a more common way to produce materials + +at a reduced cost, time, and expense. One common type is Material Extrusion (ME), also + +known as fused deposition modeling (FDM). The main premise of FDM printers involves + +the creation of parts by extruding thermoplastics layer by layer as opposed to subtractive + +manufacturing \[11\]. + +Sensors 2024,24, 2668 8 of 44 + +3.1.1. Principle of Operation of FDM + +The production of each printer, in this case, FDM, is unique. Prior to each print, print + +orientation and the raster design angle must be selected to decrease the strain on the created + +object \[ + +12 + +\]. PLA is the typical material deposited to create each object. The structure of + +typical FDM printers is shown in Figure 3. As printing begins, two different materials are + +extruded through the extrusion head, i.e., one to create the desired part and the second to + +create supports for the part. The thermoplastics are heated through the extrusion heads at + +a temperature between 190 and 230 degrees Celsius and are then printed in strands layer + +by layer. As they are heated, they turn to liquid but are immediately cooled after being + +printed and fuse with the layer beneath them \[ + +13 + +\]. As the target part is made, the support + +material and part material are alternated between per layer. The initial layer begins on + +the base plate and is then built upon as the material deposited onto each layer \[ + +14 + +\]. Since + +the build is three-dimensional, the x, y, and z dimensions each have a motor to control + +movement on each axis. This leads to a bottom-up approach in FDM. The completed part + +can be removed from the printer by holding the part and twisting the tray. This will release + +the part and the supports can be broken or cut off. + +Figure 3. Schematic diagram of FDM 3D printing technology \[ + +15 + +\]. The picture on the left shows the + +whole structure of typical FDM printers where parts (1) to (7) are x-axis motor, z-axis motor, y-axis + +motor, hot nozzle, printing bad, controller display board, and filaments, respectively. The picture on + +the right shows more details of the printing nozzle where (7A) is the feed filament, and (4A), (4B), + +and (4C) are heating wires, Hotend, and extruded materials, respectively. + +3.1.2. Advantages and Limitations of FDM + +The main advantages of FDM printing are the low price, their ability to be reproduced, + +their speed efficiency, and low maintenance \[ + +16 + +\]. However, there are also many different + +limitations facing FDM printers. This type of printer typically requires a higher temperature + +and supports for angles greater than 45 degrees \[ + +17 + +\]. These supports lead to materials being + +wasted and an increased production time. One of the biggest limitations of FDM is its + +inability to produce a part regardless of the geometry. These limitations will be discussed + +in a later section of this review. + +3.1.3. Materials of FDM + +FDM primarily employs thermoplastics for their advantageous properties of being + +easily heated and reshaped, catering to a wide range of applications. Among the materials + +commonly utilized in FDM, polylactic acid (PLA) stands out for its unique combination of + +Sensors 2024,24, 2668 9 of 44 + +being a thermoplastic that is also biodegradable, making it an environmentally friendly + +option. This characteristic, coupled with its safety for use in sensitive environments + +such as hospitals and food packaging, underscores its popularity in FDM applications. + +Besides PLA, FDM technology often uses materials such as acrylonitrile butadiene styrene + +(ABS), polyethylene terephthalate glycol (PETG), and various polyolefins \[ + +18 + +\]. These + +materials are chosen for their robustness and flexibility, although they initially present + +more significant mechanical constraints compared to PLA. These limitations can affect the + +durability and functional applications of printed objects, necessitating careful consideration + +in material selection based on the specific requirements of the intended application. + +High-performance thermoplastics such as polyether ether ketone (PEEK) and polyether- + +imide (PEI) are valued for their exceptional mechanical properties and resistance to high + +temperatures. These materials are essential in applications demanding durability, chemical + +resistance, and thermal stability, such as in aerospace, automotive, and medical industries. + +However, their use in FDM requires specialized printing equipment capable of achiev- + +ing and maintaining high extrusion temperatures—typically above 350 °C for PEEK and + +around 340 °C to 360 °C for Ultem. Additionally, a heated print bed and chamber are + +crucial to ensure proper adhesion and minimize warping, as these materials are prone to + +contraction upon cooling. The high processing temperatures also necessitate advanced + +cooling systems and thermal management strategies to prevent material degradation and + +ensure dimensional accuracy. + +3.1.4. Applications of FDM + +FDM technology finds application across a broad spectrum of industries, significantly + +impacting fields from healthcare to automotive and even consumer goods. Within the med- + +ical sector, FDM plays a crucial role in enhancing surgical procedures and medical training + +by facilitating the creation of precise anatomical models. These models are invaluable + +for surgical preparation and educational purposes, offering a high degree of anatomical + +accuracy \[ + +19 + +\]. Furthermore, FDM’s versatility allows for its use in developing specialized + +medical devices, such as dialysis catheters, innovative drug delivery systems, and scaf- + +folds for tissue engineering, which are pivotal in regenerative medicine practices \[ + +20 + +– + +22 + +\]. + +In the automotive industry, FDM’s contribution extends to the production of durable and + +lightweight components such as window car holders, showcasing the technology’s ability + +to produce parts with complex geometries and tailored mechanical properties at a reduced + +cost and turnaround time \[23\]. Beyond professional applications, FDM’s accessibility and + +affordability have made it a favorite among hobbyists and educators. It serves as a tool + +for recreational projects, educational models, and prototype development, underlining its + +versatility and the broad appeal of 3D printing technologies. This wide-ranging utility of + +FDM underscores its transformative potential across various sectors, from revolutionizing + +medical practices to enhancing manufacturing processes and promoting innovation at the + +consumer level. + +3.1.5. Developing Trends of FDM + +As AM becomes more common, advancements are being made. Specifically, FDM + +has begun to implement five-axis 3D printers. This reduces overhanging structures and + +supports needed, which overall reduces the material and cost for each print. The two + +additional axes allow for a rotation during printing. This ensures a more detailed print + +with less required support \[ + +24 + +\]. Since AM is increasing in popularity advancements are + +needed to keep costs low and increase efficiency. Fused deposition modeling is a reliable + +method with a variety of uses and is a feasible solution to the production of a variety of + +products. Although there are many types of 3D printing, FDM should not be overlooked. + +The innovation of filament core reinforcement with glass, carbon, or basalt fibers + +in FDM significantly enhances the mechanical properties of printed parts. These fibers, + +embedded within the core of thermoplastic filaments, provide improved strength, stiff- + +ness, and thermal stability compared to standard thermoplastics. Carbon fiber-reinforced + +Sensors 2024,24, 2668 10 of 44 + +filaments, for instance, offer superior strength-to-weight ratios and dimensional stability, + +making them ideal for aerospace, automotive, and industrial applications. Glass fiber rein- + +forcement improves impact resistance and tensile strength, whereas basalt fibers contribute + +to excellent thermal and chemical resistance. + +Simultaneously, nanotechnology trends in FDM are pushing the boundaries of material + +performance further. The incorporation of nanoparticles into filaments, such as carbon + +nanotubes or graphene, enhances electrical conductivity, heat dissipation, and mechanical + +properties at the nanoscale, opening new avenues for functional and structural applications. + +These nanocomposites can be tailored for specific uses, ranging from wearable electronics + +with conductive properties to components requiring enhanced thermal management or + +mechanical performance. + +Both fiber reinforcement and nanotechnology trends in FDM represent a leap towards + +manufacturing more durable, functional, and customized 3D printed products, bridging + +the gap between prototyping and end-use manufacturing. + +3.2. VAT Polymerization + +Generally, the VAT polymerization (VP) technique uses a light source to cure a photopoly- + +mer resin contained within a reservoir \[ + +25 + +\]. There are three types of VP—stereolithography, + +digital light processing, and continuous digital light processing. + +3.2.1. Principal of Operation of VPs + +Of these three forms of VP, stereolithography (SLA) is distinct from the two similar + +techniques of regular DLP and continuous DLP (cDLP). Therefore, SLA will be discussed + +first, followed by both DLPs. Stereolithography utilizes a laser to cure a photopolymer resin + +onto a build plate in the desired geometry. The laser traces the resin within the reservoir + +as required per the guidance of a mirror. SLA printers are either top-down or bottom-up + +oriented. For top-down printers, the build plate starts at the top of the reservoir, the laser + +cures the layer as specified by the geometry code, and then the build plate moves down + +corresponding to one increment of layer thickness; thus, each successive layer is above the + +previous. On the other hand, the build plate of bottom-up printers starts at the bottom + +of the resin reservoir. Between each curing, the build plate moves up one thickness layer, + +resulting in each successive layer being below the prior \[ + +26 + +\]. Parameters that influence + +which printer orientation is used to print an object includes product size and complexity, + +time, reliability, etc. Digital light processing is similar to SLA in that a photopolymer resin + +is being cured; however, this method utilizes a digital light projector for curing. This digital + +light projector cures the complete layer simultaneously rather than tracing. Because the + +curer is a digital source, the print will exhibit square-like subunits composing each layer; + +these are square light pixels called “voxels” \[ + +27 + +\]. Despite these differences, DLP printers can + +also be oriented top-down or bottom-up with the same operation. The distinction between + +DLP and cDLP is the movement of the build plate along the z-axis. For DLP, the build plate + +moves one layer thickness per cure, while the cDLP build plate continuously moves along + +the z-axis to accommodate continuous curing, which results in shorter build times \[ + +28 + +\]. + +Figure 4shows the schematic of the SLA 3D printing process and a print sample. Note that + +a schematic for cDLP is not included because the difference in build plate motion is not + +visible in an image. Furthermore, two images are provided for SLA to display top-down + +versus bottom-up printer orientation, but this is applicable to DLP as well. Figure 5shows + +the different lighting technologies between SLA and DLP. The can be seen that a laser cures + +the resin by tracing a path in SLA while a voxel grid is illuminated to cure resin a full layer + +at a time. + +Sensors 2024,24, 2668 11 of 44 + +Figure 4. Schematic of the SLA 3D printing process and a print sample \[29\]. + +Figure 5. Different lighting technologies between SLA and DLP \[29\]. + +3.2.2. Advantages and Limitations of VP + +VAT polymerization, which encompasses technologies such as SLA and DLP, offers + +several significant advantages in the realm of AM. One of its primary benefits is the ability to + +produce parts with exceptional detail and surface finish, surpassing most other 3D printing + +technologies. This precision makes it an ideal choice for applications requiring intricate + +features, such as jewelry, dental applications, and highly detailed prototypes. Moreover, + +the variety of resins available for VAT polymerization technologies enables the creation of + +parts with specific mechanical, thermal, and optical properties. This versatility supports + +a wide range of applications, from functional prototypes to end-use parts in various + +industries. The technology also allows for relatively fast printing speeds, especially in the + +case of DLP, which can cure entire layers simultaneously \[ + +30 + +\]. Additionally, the support + +structures required for overhanging parts are generally less extensive than those needed + +for extrusion-based processes, simplifying post-processing steps. + +Despite its advantages, VAT polymerization also has several limitations that can affect + +its applicability for certain projects. One of the primary drawbacks is the limited build + +volume, which can restrict the size of parts that can be produced. This makes it less + +suitable for applications requiring large components or high-volume production runs. + +Additionally, the materials used in VAT polymerization, typically photopolymer resins, + +can be more expensive than those used in other forms of 3D printing, such as filament for + +FDM. The resins can also be brittle and may not possess the same strength or durability + +as materials used in other manufacturing processes, limiting their use in functional parts + +that require high mechanical strength \[ + +31 + +\]. Furthermore, the parts produced by VAT + +polymerization may suffer from shrinkage and warping due to the curing process, which + +can affect dimensional accuracy and require additional post-processing to achieve the + +desired tolerances. Lastly, working with photopolymer resins requires careful handling + +due to their potential toxicity and the need for proper disposal, posing environmental and + +safety concerns. + +Sensors 2024,24, 2668 12 of 44 + +3.2.3. Materials of VP + +Most commonly, VAT polymerization is used with a photocurable resin. These resins + +can range from standard resins with average mechanical properties for general prototyping, + +to structural, tough and durable, or elastic resins depending on usage or application. Due + +to the variability of polymers, resins come in many color options, as opposed to other + +printing materials, such as metals. More advanced materials that can also be used include + +ceramics or waxes, biocompatible resins, and bioinks; these are typically seen in biomedical + +applications \[ + +32 + +\]. Generally, as material quality/complexity increases, so does processing + +time and costs (both raw materials and equipment). + +3.2.4. Applications of VP + +Due to the versatility of 3D printing, there are endless applications in which VAT + +polymerization can be applied. Both SLA and DLP are utilized over a wide range of + +fields including manufacturing, research development, and medicine, to name a few. + +In research and development, these methods can quickly create products to test form, fit, + +and function or bring vision to a project through prototyping without a lot of time or + +financial investment \[ + +33 + +\]. Minimal time and financial obligations are also an incentive for + +manufacturers, particularly in areas of investment castings for metallurgy, because complex, + +dimensionally accurate molds and cores can be developed, which were otherwise made less + +accurately through hand carvings or FDM \[ + +34 + +\]. The revolution of 3D printing and market + +demand has also made utilizing this equipment for personal entertainment possible. + +3.2.5. Developing Trends of VP + +One of the greatest selling points to a solution in healthcare is its ability to impact a + +large range of patients. Because each human is unique, the more customizable a solution, + +the greater chances for success for a given patient. This makes VAT polymerization a great + +method for creating medical products. Recently, VAT (more specifically SLA) has been + +under development for its use and effectiveness with pharmaceuticals. Due to its high + +accuracy, resolution, speed, and materials, this method is thought to be up and coming for + +development of micro-scale, yet high concentration drug delivery systems in areas such as + +pain or disease management \[35\]. + +Besides, the biocompatibility of materials used in VP is a critical consideration, espe- + +cially for applications in the medical and dental fields, where direct or indirect contact with + +the human body is frequent. Biocompatible photopolymer resins have been developed to + +meet stringent regulatory standards for medical devices and implants. These materials + +undergo rigorous testing to ensure they do not elicit an adverse reaction from biological + +tissue. This includes assessments for cytotoxicity, irritation, sensitization, and, in some + +cases, longer-term biostability when intended for implantation \[ + +36 + +\]. The advantage of using + +VAT polymerization for producing biocompatible parts lies in its ability to create complex, + +high-resolution structures that can match the specific anatomical features of patients, es- + +sential for custom implants, dental restorations, and surgical guides. Furthermore, recent + +advancements have led to the development of resins that not only meet biocompatibility + +requirements but also possess properties such as improved mechanical strength, flexibility, + +and thermal stability, expanding their use in creating functional medical devices \[37\]. + +It is also worth noting that the biocompatibility of a printed part is not solely depen- + +dent on the material, but also on the printing process and post-processing steps. Proper + +cleaning and curing are essential to remove uncured resin and achieve the desired material + +properties, including biocompatibility. In some cases, additional sterilization is required + +before clinical use. As technology and materials evolve, the range of biocompatible resins + +and their applications in healthcare continues to expand, offering promising opportunities + +for personalized medicine and advanced medical treatments. + +Sensors 2024,24, 2668 13 of 44 + +3.3. Material Jetting + +Material Jetting (MJ) combines the precision of resin 3D printing with the speed of + +filament printing, producing parts with realistic colors and textures, primarily aimed at + +professionals in industries such as automaking, design, healthcare, and product manu- + +facturing. Two major brands, Stratasys and 3D Systems, dominate the production of MJ + +devices. This technology now extends to diverse applications, from biocompatible dental + +molds to high-speed manufacturing tooling. Three primary MJ types include PolyJet by + +Stratasys, Nano Functional Technology using solid nanoparticles, and Drop on Demand + +(DOD) for thick fluid materials, particularly useful in creating wax models for investment + +casting in jewelry manufacturing. + +3.3.1. Principle of Operation of MJ + +Material Jetting (MJ) operates akin to a two-dimensional inkjet printer, but instead of + +ink, it sprays material onto the construction platform using either a continuous or DOD + +approach. An illustration of how the Stratasys J55 (Stratasys, Ltd., Eden Prairie, MN, USA; + +Rehovot, Israel) dispenses print material is shown in Figure 6\[ + +38 + +\]. The process involves + +layer-by-layer construction as the material solidifies upon the substrate, and the print head, + +equipped with nozzles, moves horizontally across the build platform. The complexity of + +these machines varies, affecting the deposition methods and the materials used. The limited + +material options include polymers and waxes due to their viscosity and suitability for + +forming droplets. + +Figure 6. An illustration of how the Stratasys J55 dispenses print material \[38\]. + +The core components of an MJ system comprise the print head, responsible for precise + +material deposition; the build platform, where the object gradually forms layer by layer; + +and a UV or heat source to initiate material solidification. This layer-by-layer printing + +process allows for intricate shapes and structures. Support structures may be generated + +as needed and removed post-printing. After completion, post-processing steps might be + +necessary, including support removal, surface finishing, and additional curing for certain + +materials. MJ ensures high-resolution and precision in printing, often accompanied by + +quality control measures to validate the final product against specifications. + +In MJ’s operation, the material is heated to an optimal viscosity before tiny beads of + +photopolymer are deposited by the print head. UV light solidifies the material, forming + +each layer as the build platform gradually descends. Unlike many other 3D printing + +methods, MJ employs a line-wise material deposition system, enabling multiple heads + +to allocate different materials for multi-material printing or dispensing soluble support + +structures. Despite similarities to SLA in utilizing photo-polymerization, MJ-printed + +parts achieve desired properties without additional post-curing due to the minute layer + +thickness employed. + +Sensors 2024,24, 2668 14 of 44 + +3.3.2. Advantages and Limitations of MJ + +Material jetting stands out for its exceptional resolution and intricate detailing, apt + +for crafting complex geometric shapes with fine features. Capable of achieving layer + +thicknesses as minimal as 16 microns, it delivers remarkably accurate and smooth surfaces. + +Additionally, the technology enables multi-material printing, allowing simultaneous use of + +various materials, encompassing different colors, rigid and flexible materials, or materials + +with differing properties. This versatility facilitates the production of parts with diverse + +characteristics within a single print job. Certain material jetting systems excel in full- + +color printing, ideal for crafting vibrant prototypes, architectural models, and consumer + +products, enhancing realism in aesthetics. Known for its relatively high speed, particularly + +in producing small and intricate parts, material jetting serves as a favorable option for + +rapid prototyping and small-batch production. Moreover, it minimizes or eliminates the + +need for extensive support structures, as support materials can be easily removed during + +post-processing, reducing laborious support removal tasks. Embracing a wide array of + +compatible materials, from photopolymers to thermoplastics, ceramics, and even select + +metals, material jetting broadens its potential applications across various industries. + +Material Jetting encounters several limitations, starting with its high costs, encompass- + +ing substantial initial investments and ongoing operational expenses. Moreover, the ma- + +terials employed can be particularly pricey, especially for full-color printing applications. + +Another constraint lies in the restricted build volume of material jetting machines, render- + +ing them inadequate for large-scale production or crafting sizable parts. Post-processing + +becomes a requisite, involving the removal of support materials, surface refinement through + +sanding, and sometimes the application of additional coatings, consequently elongating + +production times. Material considerations pose a challenge as well, given the technology’s + +limitation to specific compatible materials, despite an expanding range, potentially falling + +short for certain applications. Additionally, the trade-off between resolution and speed + +presents a hurdle, as achieving high resolution often demands slower print speeds, posing + +a challenge in striking a balance between these parameters. Material waste emerges as + +another concern, particularly in discarding support materials, leading to increased expenses + +and environmental concerns. Lastly, the complexity involved in operating and maintaining + +material jetting machines necessitates skilled personnel and regular upkeep, adding to the + +operational intricacies. + +3.3.3. Materials of MJ + +In material jetting, a diverse range of materials have been utilized, including plastics, + +polymers, and, intriguingly, some metals. Each material boasts unique properties, signifi- + +cantly influencing both the printing process and the final attributes of the printed object. + +Typically, these materials exist in fluid or semi-fluid states, easily dispensed through a print + +head. Commonly used materials in material jetting can be categorized into several types, + +each demonstrating distinct impacts on the printing process \[39\]. + +Polymers represent a substantial portion of material choices in material jetting. Among + +them, photopolymers reign as the most prevalent. These liquid resins solidify upon expo- + +sure to ultraviolet (UV) light, recognized for their remarkable high resolution and capacity + +for intricate detailing, making them ideal for producing complex objects. Additionally, + +certain material jetting systems utilize thermoplastic polymers like PLA, ABS, and PETG. + +These materials, heated and extruded through the print head, enable layer-by-layer deposi- + +tion and solidification. + +Metal material jetting, while less common, stands as a more advanced process. It + +involves jetting metal powders encased in a polymer matrix or liquid binder. Subsequently, + +parts undergo sintering or debonding processes to eliminate the binder and fuse the metal + +particles, resulting in solid metal parts. This method serves applications necessitating high + +strength and metallic properties. + +Ceramic material jetting parallels metal material jetting in approach. Ceramic powders, + +mixed with a binder, create a printable slurry. Post-printing, the binder is removed, and the + +Sensors 2024,24, 2668 15 of 44 + +ceramic part is often sintered at elevated temperatures to attain desired mechanical and ther- + +mal properties. Such material jetting is employed in scenarios requiring high-temperature + +resistance and electrical insulation. + +Composite materials are also compatible with material jetting, involving the mixing + +of two or more materials during printing. For instance, carbon-fiber-reinforced polymers + +yield lightweight, robust parts with enhanced mechanical properties. + +The selection of materials impacts the printing process in multifaceted ways. First, + +diverse materials possess distinct optimal printing parameters—such as print speed, layer + +height, and curing times—necessitating printer configuration tailored to each material. Sec- + +ond, material choice affects the achievable resolution and detailing capabilities, with pho- + +topolymers excelling in intricate object production. Third, the mechanical properties, + +including strength and thermal resistance, vary among materials, requiring alignment with + +the desired final product properties. Furthermore, post-processing steps—such as sintering, + +curing, or debonding—may be material-dependent, impacting the complexity and cost of + +finalizing the product. Finally, specific application needs, such as electrical conductivity, + +mandate careful material selection tailored to meet these requirements. + +3.3.4. Applications of MJ + +Material jetting has become a versatile solution applied across various real-world + +domains due to its capacity for producing high-resolution, multi-material, and multi- + +color components. Its practical utilization spans diverse industries. For instance, in the + +domain of prototyping and product development, material jetting plays a pivotal role, + +especially within sectors like automotive, aerospace, and consumer electronics. Engineers + +and designers harness this technology for swift prototyping, enabling rapid iterations and + +efficient design testing before moving into large-scale production. Similarly, in the sphere + +of dental and medical devices, material jetting showcases its significance by crafting precise + +and tailored models, orthodontic devices, hearing aids, and surgical guides. Its ability to + +create intricate, patient-specific parts proves indispensable in these critical applications. + +The aerospace industry heavily relies on material jetting to fabricate lightweight, high- + +performance components such as air ducts, interior panels, and even small satellite parts. + +Architects and construction professionals leverage material jetting to develop intricate + +architectural models and prototypes, aiding in effective visualization and communication of + +design concepts. Additionally, the jewelry and fashion sectors benefit from the technology, + +utilizing its capabilities to produce finely detailed accessories and jewelry, often integrating + +a myriad of colors and materials. + +Moreover, high-end consumer electronics, including custom smartphone cases, tap + +into material jetting for its precision and capacity to amalgamate various materials within a + +single print. Educational institutions and research labs also find value in material jetting, + +employing it for both educational purposes and research exploration into 3D printing tech- + +nology and its expansive potential. Furthermore, the shoe and orthopedic industries deploy + +material jetting to manufacture custom insoles and orthotic inserts, precisely conforming to + +the wearer’s foot shape for superior comfort and support. + +An emerging frontier, 3D food printing recognizes the potential of material jetting in + +creating intricate and decorative food items or customizing food textures. This indicates its + +prospective utility in culinary and confectionery applications, potentially revolutionizing + +the way food is presented and experienced. + +3.3.5. Developing Trends of MJ + +Material jetting stands as an established 3D printing technology, continuously evolving + +through ongoing developments and applications. Its growth likely involves embracing + +new innovations and trends that further enhance its capabilities. Notable advancements + +within material jetting encompass a range of significant developments. + +Firstly, the exploration of hybrid systems integrates MJ with other 3D printing tech- + +nologies such as FDM and SLA. This approach aims to amalgamate the strengths of + +Sensors 2024,24, 2668 16 of 44 + +multiple technologies within a single print job, potentially unlocking new possibilities and + +diversifying the applications of material jetting. + +Secondly, the technology’s inherent strengths lie in its high resolution and precision. + +Material jetting excels in creating highly precise 3D-printed objects by jetting tiny droplets + +of photopolymer material, cured subsequently with UV light. Such precision makes it an + +ideal choice for applications requiring intricate details and fine surface finishes, particularly + +evident in industries such as healthcare and prototyping. + +Lastly, the influence of MJ expands into multi-material printing capabilities. This + +unique feature allows for the simultaneous use of diverse materials within a single print + +job, offering substantial value in crafting objects with varying properties, colors, and func- + +tionalities \[ + +40 + +\]. Industries such as automotive, aerospace, and healthcare benefit immensely + +from this versatile capacity, enabling the creation of complex, multi-functional components. + +Additionally, ongoing advancements in material properties, along with a focus on sustain- + +ability, further drive the technology’s evolution toward broader applications and more + +eco-friendly practices. + +3.4. Binder Jetting + +Binder jetting (BJ) was developed at MIT in the 1990s. The printing process of BJ + +consists of a binder being printed onto a bed of powder to form the cross sections of a print, + +similar to powder bed fusion printing \[41\]. + +3.4.1. Principle of Operation of BJ + +The BJ technology employs a precise and controlled process where a printer nozzle + +systematically traverses a powder bed, depositing a liquid binder to form the desired cross- + +sectional shape for each successive layer. Following the application of the binder, the system + +lays down an additional layer of powder. This ensures the freshly applied binder acts as + +an adhesive, effectively bonding the powder particles to form a solid layer \[ + +42 + +\]. The size + +of the liquid binder droplets is meticulously controlled, typically less than 100 microns in + +diameter, to ensure high precision and detail in the final product. After the binder is applied, + +the entire print bed undergoes a curing process, either under a heat lamp or within a furnace. + +This step is crucial for activating the binder and solidifying the powder, thereby imbuing + +the emerging object with the necessary mechanical strength \[ + +43 + +\]. Following this, the process + +of powder layering and binder application is repeated, layer by layer, until the object is + +fully formed. The interim product of this process, known as the "green body", signifies the + +nascent stage of the printed object. It has achieved its geometric specifications but requires + +further post-processing to enhance its structural integrity and surface finish. Through + +this intricate layer-by-layer approach, binder jetting technology facilitates the creation of + +complex parts with a high degree of accuracy and detail. One of the most common BJ + +technologies is ColorJet Printing (CJP). Figure 7shows the principle of operation of the BJ + +technology \[44\]. + +3.4.2. Advantages and Limitations of BJ + +The BJ technology offers several compelling advantages compared to alternative + +AM techniques, making it an attractive option for a range of applications. Notably, BJ + +is recognized for its cost-effectiveness, which stems from the efficient use of materials + +and the process’s scalability. Additionally, it minimizes the occurrence of heat-induced + +distortions and defects that are more common in methods involving high-temperature + +processes. A unique feature of BJ is its capability to produce parts in multiple colors + +by utilizing different colored binders, enhancing the aesthetic appeal and functionality + +of printed objects for applications such as prototypes and functional parts. Moreover, + +the versatility of BJ in printing with a diverse array of materials—from metals to ceramics + +and polymers—broadens its applicability across various industries \[45\]. + +Sensors 2024,24, 2668 17 of 44 + +Figure 7. Schematic diagram of binder jetting 3D printing technology: (a) the BJ system; (b) pow- + +der/binder interaction between adjacent layers \[44\]. + +However, the BJ technique is not without its limitations. One of the main challenges is + +achieving high-density parts, as the process tends to produce objects with lower density + +due to the use of larger particle sizes in the powder \[ + +46 + +\]. The post-processing stage of BJ is + +also more labor-intensive and complex, involving multiple steps that may include curing, + +infiltration, and sintering to enhance the mechanical properties and density of the printed + +objects. Additionally, printed parts are susceptible to deformation during the removal of + +supports or during post-processing. Manual intervention is often required to manage and + +finish the prints, adding to the labor cost and time \[ + +47 + +\]. Another concern is the residue left + +by the binders, which can affect the surface finish and may require further post-treatment + +to remove. Lastly, the initial mechanical properties of the green bodies—the objects in their + +nascent stage post-printing—tend to be poor, necessitating additional processes to achieve + +the desired strength and durability \[48\]. + +3.4.3. Materials of BJ + +The BJ technology exhibits versatility in working with a wide array of materials, + +including polymers, metals, and ceramics, underscoring its adaptability across various + +manufacturing domains \[ + +49 + +\]. The selection of binder agents, predominantly composed + +of organic polymer-based materials, is critical and is primarily influenced by the binder + +solution’s wettability and bindability characteristics. This selection process is vital, as each + +binding agent possesses unique properties tailored to the specific type of powder it aims + +to bind. Commonly used polymers in this context include polyvinyl pyrrolidone (PVP), + +Sensors 2024,24, 2668 18 of 44 + +polyvinyl alcohol (PVA), and polyacrylic acid (PAA), each offering distinct advantages and + +considerations depending on the application and material compatibility \[48\]. + +3.4.4. Applications of BJ + +The diverse material compatibility of BJ technology enables its application across a + +multitude of sectors, significantly broadening its utility beyond conventional manufac- + +turing paradigms. In the pharmaceutical domain, BJ technology is revolutionizing the + +production of oral medications, offering customized dosages and release profiles, which + +could lead to more personalized medicine practices \[ + +50 + +\]. Additionally, in dental medicine, + +the precision and adaptability of BJ facilitate the creation of ceramic dental prostheses, + +promising significant advancements in dental restoration and cosmetic dentistry \[ + +51 + +\]. Be- + +yond medical applications, BJ’s capacity to work with metals, including 316L stainless + +steel, opens new avenues in manufacturing complex, high-strength components with appli- + +cations ranging from aerospace to automotive industries, underscoring the technology’s + +versatility and potential to innovate across various manufacturing landscapes \[ + +52 + +\]. This + +breadth of application showcases the transformative potential of BJ technology in leading + +the next wave of manufacturing innovation, pushing the boundaries of what is possible in + +both medical and industrial applications. + +3.4.5. Developing Trends of BJ + +Currently, the main goal with binder jetting is to find a way to eliminate the porosity + +that comes with the prints to make it a more viable option. One of the more recent + +developments and applications would be printing an oral medicine using binder jetting. + +For example, BJ is being used to print Spritam, which is a medicine used to treat seizures \[ + +50 + +\]. + +This advancement is very important because to be able to mass produce medicines of + +all types makes medicines more available to more people and lowers the cost of those + +medications, making it very relevant in today’s world. + +3.5. Selective Laser Sintering + +Selective laser sintering (SLS) technology stands out in 3D printing due to its ability + +to utilize a variety of materials and produce complex, functional parts with high accuracy. + +Unlike traditional 3D printing methods that rely on layers of material being deposited or + +cured, SLS employs a laser to selectively fuse powdered materials, eliminating the need for + +support structures and allowing for greater design freedom. Its versatility in material use, + +lack of need for support structures, and capability to create intricate, fully functional parts + +set SLS apart from other conventional 3D printing technologies. + +3.5.1. Principle of Operation of SLS + +SLS technology utilizes lasers as the heat source and is a form of powder bed fusion. + +This technology is an effective method for rapid prototyping and forms a more solid layer + +of material with the high-density laser onto the bed of powder. This powder can be a + +variety of different materials and will be discussed further in the materials portion of this + +report. By printing parts one layer at a time and then building upon the previous layers, + +it is capable of rapidly producing 3D physical parts directly from a user-designed 3D + +model \[ + +53 + +\]. There are two classifications of SLS, including direct and indirect. These are + +based on the mechanism present in the specific SLS printer used \[ + +54 + +\]. A standard design + +for an SLS printer can be seen in a schematic form on Figure 8\[55\]. + +The process follows these steps: the powder is filled, and the feed container is con- + +nected to the build cylinder, next a protective gas is passed into the forming room to reduce + +oxygen content, then the roller moves a thin layer of the powder over the build plate, + +and finally the laser will scan the powder surface and form the appropriate layers \[53\]. + +Sensors 2024,24, 2668 19 of 44 + +Figure 8. Schematic of SLS 3D printers \[55\]. + +3.5.2. Advantages and Limitations of SLS + +The thermal and fluid behaviors of the layers during typical AM processes are essential + +to the proper adhesion between layers for the final product to be a strong and solid part. + +For SLS, this is a very good advantage, since the layer binding is very precise because of the + +use of a laser and results in the final product being almost isotropic \[ + +56 + +\]. This also allows + +SLS to be used for very complex component designs while having superior production + +time when compared with traditional manufacturing processes for the same designs, some + +of which would be unable to be used without AM. However, some disadvantages come + +from using powdered materials, which include porosity, shrinkage, impurities, and poor + +surface quality. Most parts will require post-processing for a clean final product \[54\]. + +3.5.3. Materials of SLS + +SLS is readily capable of producing 3D components utilizing a few materials, including + +plastics, composites, and ceramics \[ + +57 + +\]. Mainly, SLS is used for precise polymer production + +and is common in many industries for precise and rapid prototyping of more expensive + +components. The most commonly used polymer in SLS is nylon. In recent years, improve- + +ments to the post-processing of ceramic SLS components have made a viable final product. + +These improve some of the flaws originally found with the low density and strength of the + +original ceramic productions \[58\]. + +3.5.4. Applications of SLS + +With the rapid manufacturing time that SLS provides, it is a resourceful way to both + +prototype and produce fully functional polymer and ceramic parts that can be used in a + +variety of industrial applications. The first of which in this discussion involves the use + +of SLS in health fields. By using pharmaceutical powders, researchers have been able to + +create orally consumed medicines with different release times and could be an alternative + +in production in the short term \[ + +59 + +\]. The printing of pills is a very promising technique + +for the development of more patient-tailored medications to get the proper dosage rather + +than the standard sizes that currently exist \[ + +60 + +\]. SLS is also a beneficial technology with a + +variety of applications in aerospace as well. Mainly for the manufacturing of noncritical + +components as well as rapid prototyping of nonfunctional components. There are also + +instances where SLS is used as a functionally graded material due to the ability to produce + +SLS components with different crystallinities for different applications \[61\]. + +Sensors 2024,24, 2668 20 of 44 + +3.5.5. Developing Trends of SLS + +There have been recent developments in the creation of flexible electronics using SLS. + +The precise nature of the laser in the device allows it to be used in combination with metal + +nanoparticles for the creation of micropatterns, which can be used in small electrical devices + +as they take up minimal space \[62\]. + +In the SLS process, defects arise from the creation of gas bubbles due to overheating + +and trapped surrounding gasses. Artificial intelligence (AI) models are currently being + +developed to control the SLS device and decrease the amount of imperfections in the + +condition in which a defect would result from \[63\]. + +3.6. Selective Laser Melting + +Selective laser melting (SLM), also known as laser powder bed fusion (LPBF), is a + +type of powder bed fusion (PBF) printer that melts and fuses material powder together in + +layers \[ + +64 + +\]. Figure 9represents the general components in a schematic found in all types of + +PBF printers. A heat source, either a laser or an electron beam, is used to fuse the first layer, + +that is the first cross-section of the part, covering the build platform. Then, the printing bed + +lowers by a layer for new powder to be spread over the previous using a roller or blade, + +which is often vibrated to promote a more even powder distribution, and the cycle repeats + +until the part is completed \[65\]. + +Figure 9. Schematic of powder bed fusion \[65\]. + +3.6.1. Principle of Operation of SLM + +SLM follows the same process as PBF from beginning to end in layer-by-layer con- + +struction, but only takes metals, typically pure, and specifically uses a high powered laser + +to completely fuse the powder to print the part. The SLM process begins with a fresh layer + +of metallic powder deposited onto the print bed using a roller or blade provided by the + +powder reservoir and any excess is caught by the overflow container. The building platform + +or print bed is constrained to a translation in the + +z + +\-axis. The laser then activates. The beam + +is controlled by a scanner system, constrained to + +x + +– + +y + +rotation, which heats the powder + +bed to slightly above melting point to create a melt pool and draw the desired shape of + +the slicing plane. The molten metal then cools rapidly and solidifies, resulting in fused + +tracks. The stage starting when the laser interacts with the powder until the end of the + +molten metal’s solidification is called the Laser Powder Melt Pool (LPMP). After scanning + +the cross-section, the building platform lowers by an amount equal to the next layer’s + +thickness and the process repeats until the printed part is complete. After having fully + +Sensors 2024,24, 2668 21 of 44 + +cooled, the building platform is then raised to reveal the print and reduce lead time by + +freeing it from most of the powder \[ + +66 + +\]. During post-processing, the remaining unfused + +powder is retrieved and can be reused again and again \[ + +67 + +\]. Support structures of the + +recovered part are removed, and the part is cleaned with isopropyl alcohol or processed + +with CNC work to improve surface finish \[68\]. + +SLM parameters are controlled to minimize build time while conserving product + +quality. Scanning speed, hatch speed, layer thickness, and laser power are some of the + +most important to SLM \[ + +69 + +\]. The melting temperature the laser induces in the powder is + +controlled by laser parameters such as incident energy density (J/cm + +2 + +) and laser power. + +Powder characteristics, including morphology, size, and apparent density, are important + +considerations in micro-structure parts. The typical layer thickness of commercial SLM + +systems is 20–100 + +µ + +m, with particle size ranging from 20 to 50 + +µ + +m \[ + +70 + +\]. The typical + +tolerance is 0.2% with a lower limit of + +± + +0.1 ( + +± + +0.003 + +′′ + +). The best materials for SLM are single- + +component metals including titanium, aluminum, and steel \[ + +71 + +\]. Melting metal can require + +temperatures as high as 1600 °C, which creates destabilization in the microscopic level. + +Therefore, support structures are needed due to the high residual stress and to mitigate the + +distortion. SLM is also widely used with cobalt-chromium, titanium alloys, nickel alloys, + +iron-based alloys, aluminum alloys, niobium alloys, refractory alloys, amorphous alloys, + +and super alloys \[ + +72 + +\]. There is a reason why SLM favors homogenous, elemental metals. + +While SLM has been used with alloys such as cobalt chromium, it is more feasible with + +monometallic powders because of the singular melting point \[ + +73 + +\]. Complete melting results + +in full fusion of the particles but sintering, in comparison, does not result in fully fused parts + +since the material remains slightly under the melting point \[ + +74 + +\]. Therefore, the mechanical + +properties of an SLM print are better because of increased particle merging and fuller + +density. The surface finish of SLM is also better \[ + +75 + +\]. Overall, SLM works well with pure + +metals and certain alloys, but will struggle to combine and process a heterogenous metal + +powder mixture. + +3.6.2. Advantages and Limitations of SLM + +SLM, similar to other AM technologies, benefits from a shorter build time than tra- + +ditional machining process. This is especially powerful when coupled with the fact that + +the process results in a fully functional object because of its high forming accuracy, net- + +shape ability, and high tolerancing as well as its ability to fabricate complex shapes \[ + +76 + +\]. + +The advantages of SLM are highly attributed to its ability to melt and fully fuse powder + +that results in fully dense parts—up to 100% density which allows it to maximize tensile + +strength (unlike sintering) to its full potential and allowing it to create light, but strong parts + +using metals such as aluminum. SLM is also suitable for visual models and prototypes. + +There is no need for binders and fluxing agents in the metallic powder \[ + +77 + +\]. The SLM pro- + +cess is often faster than selective laser sintering (SLS). One boon of SLM is the recyclability + +of its unmelted powder, with up to 99% powder recovery, that can virtually always be + +reused. SLA can produce functional, complex, net-shaped, and fully dense parts, but still + +struggles with limitations. The extreme heat is, again, a culprit of many problems seen with + +the nature of having to fully melt metal such as warping. It is a high-energy process that + +relies on temperature gradients to fuse particles \[ + +68 + +\], which requires higher energy costs + +and has been found to be less energy efficient than SLS by upwards of 10–20%. One paper + +on the quality control of SLM gives an in-depth review of the major factors that contribute + +to the formation of internal defects in SLM printed objects during the LPMP stage. SLM + +fusion, gas pores and micro-cracks, which are promoted by the balling, spatter, and keyhole + +phenomena. Defect formation can be suppressed by adjusting process parameters to the + +knowledge of the formation mechanism of each problematic phenomenon. SLM’s material + +flexibility, as addressed, is minimal because of its bias for single-component metals. While + +powder can act as an integrated support material in PBF, this does not apply to SLM because + +of its need for support structures due to the problems that arise from high temperatures. + +Sensors 2024,24, 2668 22 of 44 + +Furthermore, the build chamber must be filled with inert gas \[ + +78 + +\]. There is also a size + +limitation to SLA, with a max part size of about 280 ×280 ×325 mm3. + +3.6.3. Materials of SLM + +The main materials utilized in SLM include titanium alloys (notably Ti6Al4V) for their + +exceptional strength-to-weight ratio and biocompatibility, making them ideal for aerospace + +and medical applications. Stainless steels (such as 316L and 304) are also widely used due to + +their corrosion resistance and mechanical properties, suitable for a wide range of industrial + +applications. Aluminum alloys, such as AlSi10Mg, offer advantages in automotive and + +aerospace parts because of their lightweight and good thermal properties. Cobalt–chrome + +alloys are chosen for high wear resistance in medical implants and aerospace components. + +Nickel-based superalloys, such as Inconel 625 and 718, are selected for their excellent + +strength and thermal resistance, crucial for applications in harsh environments. Finally, tool + +steels (e.g., H13, D2) are used for creating durable tooling components. Despite the broad + +utility of these materials, challenges such as controlling residual stresses, porosity, thermal + +crack, and ensuring material properties consistency remain key research and development + +focuses within the field. + +3.6.4. Applications of SLM + +SLM sees application in the jewelry, dental, aerospace, automobile, and medical + +industries \[ + +79 + +\]. Its demand in high-tech areas and industrial interest stems from its ability to + +manufacture fully functional parts with excellent mechanical properties and high geometric + +complexity. Recently, SLM has now been able to open its doors to ceramics, such as + +alumina and zirconia, and to gradient materials. In 2010, Hagedorn was able to develop + +technology that completely laser melts pure ceramic powder and manufactures net-shaped + +specimens with almost 100% densities without requiring post-processing to achieve it \[ + +76 + +\]. + +AM technologies have been used by surgeons and material scientists to create patient- + +specific medical devices of any geometry and sometimes within a day \[ + +80 + +\]. Furthermore, + +while an even more recent paper demonstrates the success of an SLA created hip implant, + +the reliability of these biomedical parts needs to be investigated, especially the powder + +materials themselves, the corrosion behavior, and fatigue properties \[81\]. + +3.6.5. Development Trends of SLM + +SLM technology has seen significant advancements and developing trends aimed + +at overcoming its initial limitations and broadening its application spectrum. One of + +the foremost trends is the exploration and development of new material systems, includ- + +ing high-entropy alloys and functionally graded materials, to exploit unique property + +combinations for tailored applications \[ + +82 + +\]. Concurrently, there is a focus on optimizing + +process parameters through machine learning and AI to enhance part quality, reduce de- + +fects, and improve material properties predictively. Multi-laser systems have emerged to + +increase build rates and improve the efficiency of the SLM process, addressing produc- + +tivity concerns for industrial-scale production. The integration of in situ monitoring and + +control systems using sensors and real-time data analysis aims to achieve consistent and + +reliable part quality by detecting and correcting process anomalies as they occur. Lastly, + +efforts towards achieving sustainability in SLM involve recycling of powder materials + +and energy efficiency improvements, crucial for minimizing the environmental impact of + +manufacturing processes. These trends underscore the dynamic evolution of SLM, pushing + +towards broader industrial adoption and the creation of more complex, high-performance + +components across sectors. + +3.7. Direct Metal Laser Sintering + +Direct metal laser sintering (DMLS) is another PBF process that is similar to SLM but + +only takes metal alloys or combined powder metals. DMLS was evolved from SLS and uses + +a laser beam to condense metal powder without binders, creating a high-density product. + +Sensors 2024,24, 2668 23 of 44 + +It can produce sophisticated components with complex geometries that casting, machining, + +and forming cannot because to their limitations \[83\]. + +3.7.1. Principle of Operation of DMLS + +DMLS feeds and deposits metallic powders using a core concept. It uses lasers + +to overlay metallic powders to make functioning parts. This method has three phases + +including powder delivery, deposition, and waste storage. In the powder delivery stage, + +a feeder with a roller and rake precisely applies material with the proper thickness to + +the preceding layer, as shown in Figure 10 during deposition. The deposition stage fuses + +metallic powder with the underlying layer by precisely moving the laser source \[ + +84 + +\]. + +Overhanging structures in fused layers are supported by powder not fused by high-energy + +sources \[85\]. In the waste storage stage, powder not used in deposition is stored for reuse. + +Looping through these phases creates a 3D component. The sintering mechanism uses heat + +to fuse powder particles into a dense component \[86\]. + +Figure 10. Schematic of direct metal laser sintering \[87\]. + +3.7.2. Advantages and Limitations of DMLS + +AM through DMLS stands out as a support-free technique that enhances its capacity + +to craft intricate pieces with precise dimensions \[ + +88 + +\]. This process facilitates the direct + +printing of metal components or prototypes using a diverse range of metal alloys while up- + +holding their inherent qualities \[ + +89 + +\]. Moreover, the innovative feature of recycling unused + +metal powder post-printing elevates productivity in creating prototypes and components, + +concurrently curbing material costs and waste \[90\]. + +However, the utilization of DMLS in 3D projects entails considerable expenses, con- + +stituting one of the pricier avenues within AM due to machine and material costs \[ + +91 + +\]. + +Additionally, the nature of DMLS tends to produce components with higher porosity com- + +pared to traditional metal AM methods, albeit engineers have a degree of control over + +porosity during the printing process. Furthermore, when considering 3D printing projects + +constrained by build volume, engineers opt for the most suitable technology, recognizing + +DMLS as a choice for low-volume metal additive applications \[92\]. + +3.7.3. Materials of DMLS + +DMLS technology has applications in the construction of components utilizing a + +range of materials \[ + +93 + +\]. The materials that can be used in this technique are ABS nylon + +filled with glass and polymers of polycarbonate. In addition, DMLS is capable of working + +with a variety of metallic materials, such as copper, low-carbon steels, superalloys, and + +stainless steels. DMLS makes it easier to manufacture additive metal parts by providing + +Sensors 2024,24, 2668 24 of 44 + +compatibility with a wide variety of metals, including aluminum, titanium, steel, stainless + +steel, cobalt chrome, nickel alloys, and precious metals. + +3.7.4. Applications of DMLS + +The manufacture of high-performance components is one of the primary applications + +for DMLS, which has seen widespread adoption in the aerospace and automotive industries. + +Additionally, it has applications in a wide variety of other industries, such as functional + +prototypes, tooling, and medical prostheses, to name a few. In addition, the use of DMLS + +in the process of manufacturing orthopedic implants for dogs is quickly becoming more + +commonplace. This broadens its uses beyond the realm of traditional implants to include + +individualized prostheses and bone replacements in veterinary medicine as well as other + +fields \[94\]. + +3.7.5. Developing Trends of DMLS + +In order to overcome the surface accuracy issues, a technique of optimization that is + +based on two criteria is presented. This strategy places an emphasis on optimizing certain + +subprocesses, such as the orientation of the component, the determination of the layer + +thickness, and the directions of the laser scanning, with the twin goals of achieving: (a) the + +shortest possible production time and (b) the fewest possible surface flaws. In addition + +to this, when it comes to the optimization process, the model takes into consideration the + +impacts that are caused by the shrinking of the material \[95\]. + +3.8. Electron Beam Melting + +Electron beam melting (EBM) is an AM technique that uses a high-energy electron + +beam to fuse metal powder particles layer by layer to build complex parts. + +3.8.1. Principle of Operation of EBM + +The process occurs inside a vacuum chamber to prevent oxidation of the materials and + +to maintain the integrity of the electron beam. A high-voltage electron beam is generated + +and focused onto a thin layer of metal powder, selectively melting the powder according to + +the digital design of the part. After one layer is melted and solidified, the build platform + +is lowered, and a new layer of powder is applied. This process repeats until the part is + +fully constructed \[ + +96 + +\]. The energy source, an electron beam, allows for rapid melting and + +solidification, making EBM distinct in its speed and the quality of the parts produced. + +3.8.2. Advantages and Limitations of EBM + +EBM technology offers several benefits, including the ability to produce parts with + +complex geometries that are difficult or impossible to achieve with traditional manufactur- + +ing methods. It provides excellent material properties, comparable to wrought metals, due + +to the rapid cooling rates and high-temperature processing, which results in fine microstruc- + +tures. EBM can process reactive metals such as titanium and its alloys in a vacuum, which + +is essential for aerospace and medical applications. Moreover, the process is relatively fast + +and efficient, with minimal material waste. + +EBM also has its drawbacks. The requirement for a vacuum environment and the use + +of electron beam technology contribute to high equipment costs. The surface finish of EBM- + +produced parts is often rougher compared to other AM technologies, which may require + +additional post-processing. The selection of materials compatible with EBM is currently + +more limited than for other AM methods. Additionally, the layer-by-layer construction can + +introduce residual stresses, requiring heat treatment or other stress-relief processes. + +3.8.3. Materials of EBM + +EBM technology primarily processes metals, with a focus on high-value, high-performance + +materials. Titanium alloys, such as Ti6Al4V, are among the most commonly used materials + +due to their strength, lightweight, and biocompatibility, making them ideal for aerospace + +Sensors 2024,24, 2668 25 of 44 + +and medical implants \[ + +97 + +\]. Nickel-based superalloys, such as Inconel 718, are used for + +applications requiring high strength and corrosion resistance at elevated temperatures. + +Cobalt–chrome alloys are also processed for their wear resistance and biocompatibility + +in medical prostheses. The general requirement for EBM precursor powder is stringent, + +emphasizing the need for high purity and uniform particle size to ensure consistent melting + +and solidification properties. This is crucial in metallic 3D printing, where the choice + +and quality of the powder significantly affect the final product’s mechanical properties + +and surface finish. Recent research is expanding the range of materials suitable for EBM, + +including refractory metals and high-entropy alloys, to broaden its application base \[98\]. + +3.8.4. Applications of EBM + +EBM has found applications in industries where the properties of metal parts are + +critical, and complexity is valued. In aerospace, EBM is used to manufacture lightweight + +structural components and complex engine parts that benefit from the weight reduction + +without compromising strength. The medical field uses EBM to create custom implants + +and prosthetic devices, taking advantage of the ability to produce porous structures that + +encourage bone ingrowth. The energy sector benefits from the production of durable parts + +for high-temperature applications. As the technology matures, its applications continue + +to expand into areas such as automotive and tooling, where customization and material + +properties are key considerations. + +3.8.5. Developing Trends of EBM + +The future of EBM technology is focused on overcoming its current limitations while + +expanding its capabilities and applications. Research is underway to improve surface finish + +and reduce residual stresses, potentially broadening the range of materials that can be + +effectively processed. Advances in machine learning and artificial intelligence are being + +applied to optimize process parameters and predict outcomes, enhancing efficiency and + +part quality. There is also a trend towards multi-material processing, allowing for parts + +with graded properties or complex material systems. Sustainability efforts are focusing on + +reducing energy consumption and increasing material utilization rates. As the technology + +progresses, EBM is poised to play a significant role in the future of AM, with ongoing + +developments aimed at increasing its accessibility, versatility, and efficiency. + +3.9. Multi-Jet Fusion + +Multi-jet fusion (MJF) is a very innovative AM method created by the company + +Hewlett-Packard \[ + +99 + +\]. This type of AM method falls into the powder bed fusion family of + +printers alongside technologies such as SLS, DMLS/SLM, and EBM \[100\]. + +3.9.1. Principle of Operation of MJF + +MJF printers’ function in ways similar to most other 3D printing technologies but + +also has its own unique functions. MJF uses an array of inkjets to lay a layer of detailing + +agents one layer at a time to be fused in a bed of powdered material. These layers of + +detailing agents fuse together by use of a heating element \[ + +101 + +\]. This heating element + +functions by using an infrared lab that fuses materials in the same vein as the feed material. + +These various materials are thermoplastic polymers and are commonly used in such + +applications \[ + +102 + +\]. The step-by-step process of how a MJF printer operates is shown in + +Figure 11 \[ + +103 + +\]. Here, a material coating is applied that acts as the base layer for printing. + +Next, an agent is applied to the desired places in the print. Energy is then applied using + +the infrared heating element mentioned above, then the final fusion takes place, and the + +print is ready. + +Sensors 2024,24, 2668 26 of 44 + +Figure 11. Schematic diagram of multi-jet fusion (MJF) \[103\]. + +3.9.2. Advantages and Limitations of MJF + +When it comes to the MJF technology, it offers relatively low machining time with + +similar part properties with minimal post processing required after the fact \[ + +101 + +\]. Some + +studies, such as the AAPM study below, have reported MJF to be up to about 10 times faster + +than standard FDM printing for mass production of various parts \[ + +104 + +\]. When it comes to + +how the materials perform, MJF-printed designs often have a more ductile nature to them, + +which could be a desired material property for some applications but also a limitation in + +other applications depending on needs \[ + +105 + +\]. An MDPI study even found MJF printing to + +have an average printing cost of about half of other similar products. A wonderful photo + +can be seen below in Figure 12 of the various colors that MJF can print as well as the types + +of projects that can be printed out of MJF \[ + +106 + +\]. One of the MJF’s main limitations is its + +material limitations, because the ductility of MJF parts, while beneficial in some cases, may + +not be suitable for applications requiring higher material stiffness or strength. Besides, + +the advantages of MJF, such as its speed and cost-effectiveness, are maximized in particular + +scenarios, such as mass production, which may not apply to all projects. + +Figure 12. Sample 3D-printed part through the MJF technology by HP \[106\]. + +3.9.3. Materials of MJF + +MJF technology employs an extensive selection of powdered materials as the founda- + +tion for its printing process. These materials are meticulously fused by the application of + +two distinct types of binder fluids: a fusing agent and a detailing agent. The detailing agent, + +often incorporating a cyan, magenta, yellow, and key (CMYK) color scheme, plays a crucial + +role in enabling the production of parts in a vast spectrum of colors, adding to the versatility + +and aesthetic appeal of the printed objects. This capability was exemplified in Figure 12, + +showcasing the technology’s ability to achieve detailed and vibrant colorations in printed + +parts. The fusion of these agents with the base materials under precise conditions not only + +ensures the structural integrity of the components but also opens up new possibilities for + +customization and design innovation in AM \[107\]. + +3.9.4. Applications of MJF + +The potential applications of MJF go far and wide, but in part to being a bit more + +energy and resource efficient than SLS, MJF can be more attractive to industries that require + +Sensors 2024,24, 2668 27 of 44 + +more energy and resource efficiency \[ + +108 + +\]. MJF printed parts are said to have significant + +vibration isolation characteristics, especially between the ranges of 10–30 Hz, which means + +that MJF parts could be desired for various applications that require that specific kind of + +isolation within that range \[109\]. + +3.9.5. Developing Trends of MJF + +Some common developing trends in the world of MJD 3D manufacturing would be + +to use MJF parts in mechanical parts/devices along with biometrical lattices, structures, + +and other medical and orthotics applications such as prosthetics. The MJF technology was + +also found to have a potential in creating mechanical tools and well as in devices that are + +required to be fluid-tight \[ + +110 + +\]. These applications are only scratching the surface as to + +what this technology has to offer. The future of MJF is bright and shows potential to take + +a significant part of certain industries in the future with its abilities to print efficiently as + +well as print parts with certain desirable material properties. MJF, as most 3D printing + +technologies, is still more or less in its infant stage and could see some major growth in the + +coming years. + +3.10. Direct Energy Deposition + +Direct energy deposition (DED) is an advanced AM technology that involves the use + +of focused thermal energy—such as a laser, electron beam, or plasma arc—to fuse materials + +by melting as they are being deposited. DED is distinguished by its ability to create high- + +of material efficiency, design flexibility, and the ability to repair or add material to existing + +components. This report explores the principle of operation, advantages and limitations, + +materials, applications, and developing trends of DED technology. + +3.10.1. Principle of Operation of DED + +DED technology operates by focusing thermal energy to melt a material—typically + +metal powder or wire—as it is being deposited onto a substrate or part surface. The material + +is delivered through a nozzle that moves in multiple axes, allowing for the construction of + +complex geometries. Figure 13 shows the principle of operation of two different types of + +DED technologies \[111\]. + +Figure 13. Schematic of directed energy deposition (DED): (a) Powder DED (laser source); (b) Wire + +DED (E-beam source) \[111\]. + +The process is typically controlled by a CAD file, which guides the nozzle’s path to + +create the desired shape layer by layer. The precise application of energy and material + +results in parts that are fully dense and strongly bonded to the substrate \[112\]. + +Sensors 2024,24, 2668 28 of 44 + +3.10.2. Advantages and Limitations of DED + +There are several advantages of DED. DED minimizes waste by depositing material + +only where needed. DED also enables the creation of complex geometries that are difficult + +or impossible to achieve with traditional manufacturing methods. DED can be used to + +add material to existing parts, allowing for the repair of worn or damaged components, + +or the modification of parts to improve performance. DED is capable of processing a wide + +range of materials, including difficult-to-process alloys \[ + +113 + +\]. For certain applications, DED + +can be faster than other AM technologies, especially when producing large or medium- + +sized components. + +DED has some limitations, such as rough surface finish and low precision. DED often + +requires post-processing to achieve a smooth surface finish, as the parts may have a rough + +texture directly after manufacture. While suitable for many applications, DED may not + +achieve the fine detail or dimensional accuracy of some other AM processes. + +3.10.3. Materials of DED + +DED technology boasts a remarkable capacity to handle an expansive range of ma- + +terials, making it a versatile tool in the AM landscape. This technology is proficient in + +processing a wide spectrum of metals, such as stainless steel, titanium alloys, nickel-based + +alloys, aluminum, and cobalt–chrome, catering to the demands of various industrial ap- + +plications. Beyond metals, DED also extends its capabilities to ceramics and composite + +materials, although these applications are less widespread \[ + +114 + +\]. For DED technology, + +flowability, and purity to ensure efficient deposition and optimal material properties in + +the final product. The precision in powder characteristics is vital to achieving the desired + +material behavior during the melting and solidification processes, which is instrumental in + +extending DED’s application in manufacturing complex and custom fabrications across + +various industries. Recent advancements in DED technology are continually broadening + +the scope of its material compatibility, paving the way for its application in more specialized + +fields. These developments not only enhance the utility of DED, but also underscore its + +potential to revolutionize manufacturing processes by accommodating a diverse array of + +materials for custom and complex fabrications \[115\]. + +3.10.4. Applications of DED + +DED technology is widely applied in several key industries, demonstrating its versatil- + +ity and effectiveness. In the aerospace sector, it is utilized for manufacturing and repairing + +vital components such as turbine blades and structural parts, underscoring its importance + +in maintaining the reliability and performance of aircraft. The energy industry benefits + +from DED through the repair of parts used in oil and gas exploration as well as in power + +generation equipment, highlighting its role in sustaining critical infrastructure. In the + +medical field, DED’s ability to produce customized implants and prosthetics showcases its + +potential in personalized medicine, offering solutions tailored to individual patient needs. + +The tooling industry uses DED to add features or coatings to tools, dies, and molds, en- + +hancing their functionality and lifespan. Additionally, its flexibility in processing different + +materials makes DED invaluable for research and development purposes, particularly for + +prototyping and material development, thereby fueling innovation across various sectors. + +3.10.5. Developing Trends of DED + +The evolving landscape of DED technology is marked by several promising develop- + +ments that are set to enhance its capabilities and broaden its applications across industries. + +Hybrid manufacturing emerges as a notable trend, integrating DED with traditional sub- + +tractive manufacturing within a single setup to harness the combined strengths of both + +methods, optimizing the production process for efficiency and precision. Concurrently, + +advancements in DED are paving the way for multi-material printing, enabling the cre- + +ation of components with multiple materials in a single build. This innovation introduces + +Sensors 2024,24, 2668 29 of 44 + +the potential for parts with functionally graded materials and localized property varia- + +tions, expanding the design possibilities and functional capabilities of manufactured parts. + +Furthermore, the integration of real-time monitoring and adaptive control systems is revo- + +lutionizing the DED process, significantly improving part quality and process reliability + +through precise control and adjustments during fabrication. Complementing these techno- + +logical strides, the development of sophisticated software and simulation tools is crucial, + +offering predictive insights and optimization strategies for material properties and process + +parameters, thereby minimizing the reliance on trial and error and enhancing the overall + +quality of the final products. Collectively, these developments signify a significant leap + +forward for DED technology, showcasing its growing importance in the AM domain and + +its potential to revolutionize manufacturing practices across a diverse array of sectors by + +offering unmatched material efficiency, design flexibility, and the capability to repair or + +augment existing components. + +3.11. Carbon Fiber Reinforcement + +Carbon fiber reinforcement (CFR) technology combines carbon fiber with polymer + +matrixes to produce composite materials that are exceptionally strong and lightweight. + +3.11.1. Principle of Operation of CFR + +The principle of operation involves the selective layer-by-layer deposition of carbon + +fiber-infused filaments, which are then melted and fused together using a heated nozzle + +in a process similar to FDM. This technique allows for the precise alignment of carbon + +fibers, optimizing the strength-to-weight ratio of the final product \[ + +116 + +\]. Advanced variants + +of this technology can also embed continuous carbon fiber strands into a base material, + +significantly enhancing the mechanical properties of the printed object. Figure 14 shows + +3D-printed bicycle lugs reinforced with continuous carbon fiber \[117\]. + +Figure 14. Three-dimensionally-printed bicycle lugs reinforced with continuous carbon fiber \[117\]. + +3.11.2. Advantages and Limitations of CFR + +CFR offers several compelling advantages, including the production of parts that are + +significantly stronger and lighter than those made from conventional materials, making it + +ideal for high-performance applications. The technology allows for complex geometries that + +are difficult to achieve with traditional composite manufacturing techniques, along with + +reduced waste and shorter production cycles \[ + +118 + +\]. Additionally, the ability to customize + +the fiber orientation provides unparalleled control over the mechanical properties of the + +final part. + +Despite its benefits, CFR technology faces limitations such as higher material and + +operational costs compared to standard AM processes. The range of materials compatible + +with carbon fibers is also limited, primarily to certain thermoplastics and thermosetting + +polymers. Moreover, the technology requires specialized equipment and expertise to ensure + +the optimal placement of fibers and to manage the thermal stresses during printing, which + +can affect the dimensional accuracy and surface finish of the parts. + +Sensors 2024,24, 2668 30 of 44 + +3.11.3. Materials of CFR + +In CFR, the choice of materials plays a pivotal role in achieving the desired mechanical + +and thermal properties of the final product. The base matrix typically involves high- + +performance thermoplastic polymers such as nylon, PEEK, and ABS. These polymers are + +chosen for their excellent balance of strength, durability, and ease of processing. The re- + +inforcement comes in the form of short or continuous strands of carbon fiber, which are + +embedded into the polymer matrix to enhance the composite material’s overall proper- + +ties \[ + +119 + +\]. The inclusion of carbon fiber, particularly in a continuous form, significantly ele- + +vates the mechanical performance of the composite. Continuous carbon fiber reinforcement + +leads to a marked increase in tensile strength and rigidity, which are critical for components + +subjected to high stress or load. Moreover, these carbon fiber-reinforced materials exhibit + +superior thermal stability, maintaining their integrity and performance over a wide tem- + +perature range. This combination of high strength, stiffness, and thermal resistance makes + +CFR composites ideal for use in advanced engineering applications, including aerospace, + +automotive, and high-performance sporting equipment, where materials must withstand + +rigorous operational conditions while minimizing weight and maximizing performance. + +3.11.4. Applications of CFR + +CFR is increasingly employed in industries where strength-to-weight ratio is critical, + +such as aerospace, automotive, and sporting goods. In aerospace, it is used for producing + +lightweight structural components and fixtures. Automotive applications include the + +fabrication of high-performance parts such as gears, brackets, and structural components + +that benefit from the reduced weight without sacrificing strength. In the sporting goods + +industry, CFR technology is used to create equipment such as bicycles, racquets, and drones, + +offering enhanced performance characteristics. + +3.11.5. Developing Trends of CFR + +The future of CFR is driven by ongoing innovations aimed at expanding its applica- + +tions and improving performance. One key trend is the development of new composite + +materials that offer higher thermal and chemical resistance, opening up new industrial + +applications. Another area of focus is the improvement in printing technologies to enable + +the use of continuous carbon fiber reinforcement over larger areas and more complex + +geometries, further enhancing the mechanical properties of printed parts. Additionally, + +advancements in simulation and modeling software are improving the predictability and + +optimization of fiber orientations, reducing the need for physical prototypes and accelerat- + +ing the design-to-production cycle. As these trends progress, CFR is set to revolutionize + +industries by providing lighter, stronger, and more customizable components. + +3.12. Laminated Object Manufacturing + +Laminated Object Manufacturing (LOM) involves the layer-by-layer bonding of sheet + +materials, which are precisely cut to shape and then bonded together to form a three- + +dimensional object. + +3.12.1. Principle of Operation of LOM + +The process of LOM starts with a roll or a stack of sheets made of metal, paper, + +or plastic. Each sheet is affixed to the layer beneath using an adhesive, welding, or another + +bonding technique. A laser or knife then precisely cuts the outline and internal features of + +the current layer based on the digital model. This process repeats, stacking and shaping + +layers until the desired 3D object is fully formed. Excess material from each layer acts as + +support for the object during the build and can be removed afterward \[120\]. + +3.12.2. Advantages and Limitations of LOM + +LOM offers several advantages, including the ability to use a wide range of materials, + +from paper and polymers to metals, making it versatile across various applications. It is + +Sensors 2024,24, 2668 31 of 44 + +cost-effective, especially when using inexpensive materials such as paper, and the process + +can be faster than other AM techniques for certain geometries and materials. Additionally, + +the waste material can often be recycled, especially when paper is used, making it an + +environmentally friendly option. The technology is also beneficial for creating large parts + +and offers unique aesthetic finishes, particularly with paper-based laminates \[121\]. + +However, the technology faces limitations, including lower dimensional accuracy + +and part strength compared to other AM methods, due to the layer bonding mechanism. + +posite or functionally graded materials. Furthermore, the post-processing required to + +remove excess material and achieve the final part geometry can be labor-intensive and time- + +consuming. The surface finish may also be rough, requiring additional post-processing to + +smooth out. + +3.12.3. Materials of LOM + +LOM can process a diverse array of materials, including paper, metal foils, various + +plastics, ceramic-based materials \[ + +122 + +\], and composite materials \[ + +123 + +\]. Paper is commonly + +used for conceptual models and visual prototypes due to its low cost and ease of handling. + +Metal foils allow for the creation of more durable and functional prototypes or parts, + +though they require stronger bonding techniques such as ultrasonic welding. Plastics + +offer a balance between durability and ease of processing, suitable for both prototypes + +and functional parts. The choice of material significantly influences the application and + +performance of the finished product. + +3.12.4. Applications of LOM + +The applications of LOM are varied and span several industries. In prototyping, + +cost-effectiveness and rapid turnaround. Metal and plastic laminates are used in the + +automotive, aerospace, and electronics industries for creating functional prototypes, tooling, + +and even end-use parts that benefit from the layered aesthetic or specific material properties. + +Additionally, the education and architectural sectors utilize LOM for creating detailed scale + +models and teaching aids, capitalizing on its ability to produce large objects at relatively + +low costs. + +3.12.5. Developing Trends of LOM + +The field of LOM is witnessing several developing trends aimed at overcoming its + +limitations and broadening its application scope. One significant trend is the integration of + +advanced materials, including composites and functionally graded materials, to enhance + +part strength and functionality. There is also a growing focus on improving bonding tech- + +niques to increase durability and dimensional accuracy. Innovations in cutting technology, + +such as more precise lasers and knives, are enabling finer details and better surface finishes. + +Additionally, the development of automated post-processing solutions is aiming to reduce + +the time and labor associated with removing excess material. As these trends evolve, LOM + +is expected to become more competitive with other AM technologies, offering unique + +advantages in cost, speed, and material diversity. + +4\. Developing Trends of Additive Manufacturing + +AM is evolving rapidly, with key trends shaping its future. Figure 15 shows the devel- + +oping trends of AM technologies. 3D bioprinting is advancing the fabrication of complex + +biological structures, promising revolutionary healthcare solutions. Three-dimensional + +food printing is transforming culinary arts, allowing for customized nutrition and intricate + +food designs, merging gastronomy with technology for personalized eating experiences. + +Meanwhile, large-scale 3D printing is pushing the boundaries of construction and industrial + +production, enabling the creation of large structures and components with unprecedented + +speed and efficiency. 4D printing introduces time as a dimension, enabling printed objects + +Sensors 2024,24, 2668 32 of 44 + +to change shape or function in response to stimuli, offering innovative applications in smart + +materials and structures. AI-based 3D printing is optimizing the manufacturing process, + +enhancing design, predicting material behavior, and improving the quality and efficiency of + +printed objects, marking a significant leap toward intelligent and autonomous production + +systems. There are also other directions, such as multi-material and new materials. + +(a) 3D bioprinting (b) 3D food printing + +(c) Large-scale 3D printing (d) 4D printing + +Figure 15. Developing trends of additive manufacturing technologies: (a) a 3D-bioprinted human + +tissue (an ear) with biodegradable plastic scaffolding using an integrated tissue and organ printing + +system (ITOP) by the Wake Forest Institute for Regenerative Medicine \[ + +124 + +\]; (b) a 3D-printed pizza + +by Beehex through a fund from NASA \[ + +125 + +\]; (c) the Crane Wasp 3D printer, created to print homes + +using local materials \[ + +126 + +\]; (d) a ‘smart’ self-folding material that can transform shape, printed by + +MIT’s Self-Assembly Lab \[127\]. + +4.1. 3D Bioprinting + +Biological additive manufacturing, also known as biological fabrication, integrates + +principles of biology, chemistry, and engineering to fabricate biological structures and + +materials via AM techniques \[ + +128 + +\]. This innovative field leverages the precision and + +versatility of 3D printing technologies to create complex biological constructs, such as + +tissues, organs, and biocompatible materials, layer by layer \[ + +129 + +, + +130 + +\]. State-of-the-art + +advancements include the development of sophisticated bioprinting methods capable of + +handling living cells, bioinks composed of natural or synthetic biomaterials that support + +cell growth and differentiation, and the creation of vascularized tissues that mimic natural + +blood vessels for improved survival and function of fabricated tissues. Challenges remain, + +including the replication of the complex microarchitecture of native tissues, ensuring long- + +Sensors 2024,24, 2668 33 of 44 + +term viability and integration of printed constructs within the body, and scaling up the + +technology for widespread clinical application \[131\]. + +Significant efforts are underway to overcome these hurdles, with ongoing research + +focusing on improving the resolution and fidelity of bioprinted structures, developing new + +bioink formulations, and enhancing the mechanical and functional properties of printed + +tissues. Figure 15a shows a 3D-bioprinted human tissue (an ear) with biodegradable plastic + +scaffolding using an integrated tissue and organ printing system (ITOP) by the Wake + +Forest Institute for Regenerative Medicine \[ + +124 + +\]. Besides, bioinspired AM is a cutting- + +edge convergence of biology, material science, and advanced manufacturing techniques. + +This innovative approach draws inspiration from the natural world, aiming to mimic + +the complex structures and functionalities observed in biological systems through AM + +processes \[132\]. + +4.2. 3D Food Printing + +Three-dimensional food printing represents a pioneering intersection of technology + +and gastronomy, offering personalized nutrition, intricate edible designs, and the potential + +for sustainable food production. State-of-the-art trends in this domain involve the use + +of a variety of edible materials, including proteins, carbohydrates, and fats, which are + +extruded layer by layer to create complex and customized food items. This technology + +not only allows for the customization of nutritional content to meet individual dietary + +needs, but also introduces novel textures and forms in culinary arts, potentially reducing + +food waste by utilizing ingredients more efficiently. Despite its innovative prospects, 3D + +food printing faces significant challenges, such as the limited range of printable food + +materials, slow printing speeds compared to conventional cooking methods, and the need + +for stringent food safety standards. Additionally, the acceptance of 3D-printed foods by + +consumers and the integration of such technologies into commercial kitchens pose further + +hurdles. Ongoing research and development aim to overcome these obstacles by enhancing + +printer technology, expanding the variety of printable food materials, and improving the + +scalability of 3D food printing processes \[ + +125 + +\]. Figure 15b shows a 3D-printed pizza by + +Beehex through a fund from NASA \[125\]. + +Optimizing the rheological properties of 3D printing food products presents unique + +challenges, as these properties are crucial for both the printability of food pastes and + +the quality of the final product. Rheological properties, including viscosity, yield stress, + +and thixotropy, must be carefully balanced to ensure that food materials can be extruded + +smoothly through the printing nozzle and maintain their shape once deposited. Some + +challenges in optimizing these properties are discussed as follows. + +• + +Complexity of Food Materials: Food materials are inherently complex and can exhibit + +non-Newtonian behavior, making it challenging to predict how they will behave under + +the shear rates applied during 3D printing. Ingredients can interact in unpredictable + +ways, affecting their rheological properties. + +• + +Variability of Ingredients: Natural variability in food ingredients due to factors such + +as origin, season, and processing can lead to fluctuations in the rheological properties + +of the food paste, affecting consistency and printability. + +• + +Sensitivity to Processing Conditions: The rheological properties of food materials can + +be highly sensitive to temperature, pH, and the presence of air bubbles, among other + +factors. Maintaining optimal conditions throughout the printing process to ensure + +consistent properties is challenging. + +• + +Balancing Printability with Nutritional and Sensory Qualities: Achieving the right + +rheological properties for printing often requires the addition of modifiers such as + +hydrocolloids or emulsifiers. However, these adjustments can impact the nutritional + +value, taste, and texture of the final product, potentially compromising consumer + +acceptance. + +Sensors 2024,24, 2668 34 of 44 + +• + +Post-Processing Changes: Foods can undergo changes in structure and rheology after + +printing or during cooking or cooling processes. Predicting and controlling these + +changes to ensure the final product meets desired quality standards is difficult. + +• + +Equipment Limitations: The performance and characteristics of 3D food printers, + +especially the extrusion system, can limit the range of rheological properties that + +can be effectively printed. Printers with enhanced capabilities can be expensive and + +less accessible. + +Addressing these limitations requires a multidisciplinary approach, combining food + +science, material science, and engineering. Advances in ingredient technology, precise + +control systems for 3D printers, and a deeper understanding of the rheology of complex + +food systems are essential for overcoming these challenges and unlocking the full potential + +of 3D food printing. + +4.3. Large-Scale 3D Printing + +Large-scale additive manufacturing has emerged as a groundbreaking technology, sig- + +nificantly impacting the construction, aerospace, and manufacturing sectors by enabling the + +direct fabrication of large structures, components, and parts. State-of-the-art advancements + +include the development of large-format 3D printers capable of printing entire buildings or + +large aerospace components from specialized materials, ranging from concrete and metals + +to composite polymers. This technology offers the potential for increased customization, + +reduced waste, and accelerated construction times \[ + +133 + +\]. However, challenges persist, + +including the need for improved mechanical properties of printed materials, the scaling + +up of printing processes without compromising precision or material properties, and the + +integration of large-scale 3D printing into existing manufacturing and construction ecosys- + +tems. Additionally, there are logistical challenges in transporting and operating large-scale + +ability of the materials used \[ + +134 + +\]. Ongoing research and development aim to address these + +issues by enhancing material formulations, printing technologies, and process efficiencies, + +paving the way for broader adoption and innovation in large-scale AM. Figure 15c shows + +the Crane Wasp 3D printer, created to print homes using local materials \[126\]. + +Integrating structural reinforcement into large-scale 3D printed components presents + +significant challenges that necessitate meticulous attention to the material and process intri- + +cacies. The mechanical strength and durability of printed structures, especially in sectors + +demanding high reliability such as aerospace and construction, require advancements in + +reinforcement techniques and materials. Moreover, the absence of standardized guidelines + +and regulations specifically tailored to large-scale AM poses a hurdle to ensuring uniform + +quality, safety, and performance across the industry. Establishing comprehensive standards + +and regulatory frameworks is essential for fostering innovation, ensuring structural in- + +tegrity, and promoting widespread acceptance and integration of large-scale 3D printing + +technologies into traditional manufacturing and construction practices. + +4.4. 4D Printing + +Four-dimensional printing, an innovation extending beyond traditional 3D printing, + +incorporates the dimension of time to create objects that can change shape, properties, + +or functionality in response to external stimuli such as temperature, light, moisture, or mag- + +netic fields. This dynamic technology leverages smart materials, including shape-memory + +polymers and responsive hydrogels, to fabricate objects with pre-programmed transforma- + +tions \[ + +135 + +\]. Shape memory alloys (SMAs) represent a pioneering class of smart materials + +in 4D printing, offering distinct advantages due to their ability to return to a pre-defined + +shape when subjected to an appropriate thermal stimulus. These materials, including + +nickel–titanium alloys, can undergo phase transitions that enable them to remember and + +revert to their original shapes upon heating \[ + +136 + +\]. Their integration into 4D printing opens + +avenues for creating complex, self-adjusting structures and devices that can react to tem- + +perature changes with high precision. The exploration of SMAs in 4D printing highlights + +Sensors 2024,24, 2668 35 of 44 + +the potential for advanced applications in fields requiring adaptive materials, such as + +responsive aerospace components and medical devices that can conform to anatomical + +changes, further pushing the boundaries of what is achievable with AM technologies. + +State-of-the-art developments in 4D printing have led to potential applications in + +various fields, including biomedical devices that adapt to bodily changes, self-assembling + +structures for aerospace and construction, and smart textiles that adjust to environmental + +conditions \[ + +137 + +\]. Despite its promise, 4D printing faces challenges, including the limited + +range of smart materials available, the need for precise control over material properties to + +perform intended functions under real-world conditions. Ongoing research aims to address + +these challenges by developing new materials, refining AM techniques, and enhancing + +computational design tools to accurately predict and program the dynamic behavior of + +printed objects. Figure 15d shows a ‘smart’ self-folding material that can transform shape, + +printed by MIT’s Self-Assembly Lab \[127\]. + +4.5. AI-Based Additive Manufacturing + +AI-based additive manufacturing integrates advanced technologies such as AI, ma- + +chine learning, and the Internet of Things (IoT) with traditional 3D printing processes to + +enhance efficiency, quality, and customization. This intelligent approach enables real-time + +monitoring and control of the printing process, predictive maintenance of equipment, + +and dynamic adjustment of printing parameters for optimal results \[ + +138 + +\]. State-of-the-art + +trends in AI-based AM involve the use of AI algorithms to predict material properties and + +outcomes, IoT for seamless integration of AM systems into broader production networks, + +and digital twin technologies for virtual simulation and optimization of the manufactur- + +ing process \[ + +139 + +\]. Challenges facing AI-based AM include ensuring data security and + +the resistance to adopting new manufacturing paradigms within established industries. + +Furthermore, there is a continuous need for skilled workers capable of operating these + +advanced systems and for ongoing development to reduce costs and improve the scalability + +of smart AM solutions. Research and development efforts are focused on addressing these + +challenges, aiming to unlock the full potential of AI-based AM across various sectors. AI + +and machine learning algorithms optimize printing parameters in real time, enhancing + +quality, reducing material waste, and improving the mechanical properties of printed + +parts. Simulation software allows for the predictive modeling of material behavior and the + +optimization of designs before printing, saving time and resources. + +4.6. Innovations in Materials, Quality Control, and Post-Processing + +The ability to print with multiple materials simultaneously or to combine different AM + +processes in a single machine (hybrid printing) is a significant area of development. This + +advancement enables the creation of parts with varied properties (e.g., rigid and flexible, + +conductive and insulative) within a single build process, expanding the functional capabili- + +ties of AM parts. Hybrid systems that integrate subtractive processes (e.g., CNC milling) + +with additive processes improve surface finishes and dimensional accuracy. The exploration + +and development of new materials specifically designed for AM processes are expanding + +the capabilities and applications of AM. This includes the creation of high-performance + +polymers, metals, ceramics, and composite materials. Material innovation also focuses on + +sustainability, with an increasing emphasis on recyclable and biobased materials. + +Improvements in build size and printing speed are crucial for the broader adoption + +of AM across industries. Developments in this area include the creation of larger print + +beds, faster printing techniques, and more efficient post-processing methods. These im- + +provements aim to make AM viable for mass production and large-scale applications, + +moving beyond prototyping and small-batch production. Enhancements in the precision + +and repeatability of AM processes are vital for meeting industrial quality standards. This + +involves the development of more sophisticated monitoring and control systems that can + +Sensors 2024,24, 2668 36 of 44 + +detect and correct errors in real time during the printing process. Such systems rely on + +sensors and machine vision technologies to ensure parts are built to specification, reducing + +failure rates and improving reliability. + +Advancements in post-processing are crucial for advancing AM from a specialized + +to a mainstream production technique, especially important in sectors such as aerospace + +and healthcare. Automated support removal, using mechanical, chemical, or thermal + +methods, now allows for efficient and precise part cleaning. Surface finishing technologies, + +such as chemical vapor smoothing and electro-polishing, are reducing manual work and + +improving both the looks and function of 3D printed parts by minimizing surface roughness. + +Furthermore, techniques such as hot isostatic pressing (HIP) and annealing are being + +automated to enhance the mechanical properties of 3D printed parts, addressing common + +issues such as stress and porosity, thereby making AM more viable for a wide range + +of applications. + +4.7. Standardization and Regulatory + +Addressing standardization and regulatory challenges in AM is crucial for unlocking + +its full potential across various industries. The absence of universally accepted standards + +and clear regulatory guidelines currently presents significant obstacles to the widespread + +adoption of AM technologies. These challenges stem from the innovative nature of AM, + +production techniques, and product properties. Standardization efforts are essential for + +ensuring consistency, safety, and quality in AM-produced goods. Without standardized + +protocols, comparing and validating the performance of products made through AM + +across different sectors becomes problematic. This lack of standardization also hampers + +material development, process optimization, and the sharing of knowledge within the AM + +community, ultimately slowing down innovation. On the regulatory front, establishing + +clear guidelines is necessary to address safety concerns and intellectual property issues, + +which are paramount for consumer and industry confidence. For instance, in highly + +regulated sectors such as aerospace, automotive, and medical devices, manufacturers must + +navigate complex certification processes that are not yet fully adapted to the specifics of + +AM technologies. This adaptation is essential for ensuring that AM products meet stringent + +safety and performance requirements. + +Moreover, there is a pressing need for regulations that encompass the entire lifecycle + +of AM products, from design and production to use and end-of-life disposal. Such compre- + +hensive regulatory frameworks could address environmental concerns, including energy + +consumption and material waste, promoting sustainability in AM practices. Progress + +in overcoming these standardization and regulatory hurdles is being made through the + +collaboration of industry stakeholders, research institutions, and regulatory bodies. These + +efforts include the development of industry-specific standards, the creation of certifica- + +tion pathways for AM materials and processes, and the initiation of dialogue on ethical + +considerations and intellectual property rights in the context of AM. + +In conclusion, tackling the challenges of standardization and regulation is key to + +facilitating the broader adoption of AM technologies. By establishing clear, universally + +accepted standards and regulatory frameworks, the AM industry can ensure product safety + +and quality, foster innovation, and build the trust of consumers and industries alike, paving + +the way for a new era of manufacturing. + +4.8. Circular Economy and Sustainability + +The economic analysis of AM processes reveals a complex landscape of costs, benefits, + +production efficiencies, and return on investment (ROI), varying significantly across differ- + +ent AM technologies and application contexts. Understanding these financial implications + +is crucial for businesses considering adopting AM processes. + +Initial costs for AM include the purchase of printers, materials, and software, alongside + +operational costs such as energy consumption, maintenance, and labor. Advanced AM + +Sensors 2024,24, 2668 37 of 44 + +systems, especially those capable of metal printing, can require substantial initial invest- + +ment. Material costs can also be high, particularly for specialized or high-quality inputs. + +Training and integrating AM into existing production workflows can add to the initial + +expenses. AM offers several financial benefits, including reduced material waste, lower in- + +ventory and storage costs, and the ability to produce complex designs without a significant + +increase in cost. For customized or low-volume production, AM can significantly reduce + +the cost per unit compared to traditional manufacturing methods. Technology also enables + +faster product development cycles, reducing time to market and potentially increasing + +competitive advantage. AM can enhance production efficiency by consolidating parts, + +thereby reducing assembly time and costs. It allows for just-in-time production, minimizing + +inventory levels and associated costs. However, the production speed of AM may be slower + +compared to traditional manufacturing methods for high-volume production, potentially + +offsetting some efficiency gains unless combined with other manufacturing processes in a + +hybrid approach. + +The return on investment (ROI) from different AM technologies can vary. FDM is often + +used for prototyping due to its lower cost, FDM can offer a quick ROI in environments + +where design flexibility and rapid prototyping are valued. SLS and DMLS are more expen- + +sive but can produce functional parts with properties close to traditionally manufactured + +items. They are more likely to be used in final product manufacturing, potentially offering a + +higher ROI by enabling the production of complex, high-value items. SLA and MJ are ideal + +for producing high-detail parts with smooth surface finishes, SLA can be cost-effective for + +applications requiring precise geometries and aesthetics, such as dental or medical models. + +The ROI also depends on the industry. In aerospace and medical sectors, where the cost + +of failure is high, and the value of customized, complex parts is significant, the ROI can + +be substantial. In contrast, for industries focused on high-volume, low-margin products, + +integrating AM may require a more strategic approach to realize a positive ROI. + +The financial implications of adopting AM are influenced by a myriad of factors, + +including the type of AM technology, the scale of adoption, the specific application, and the + +industry. While the initial costs can be high, the benefits of customization, reduced lead + +times, and efficiency improvements present a compelling case for AM in many scenarios. + +A thorough cost–benefit analysis, considering both direct and indirect financial impacts, is + +essential for businesses to make informed decisions about investing in AM technologies. + +The strategic integration of AM can offer competitive advantages, ultimately leading to a + +positive return on investment. + +The development of AM technologies is increasingly aligned with the principles of + +the circular economy. This includes the use of recycled materials in the printing process, + +the development of recyclable or biodegradable materials, and the potential for AM to + +reduce waste through optimized design and on-demand production. The direction of + +development in AM technologies and processes reflects a push towards greater integration + +with digital technologies, enhanced material capabilities, and a focus on sustainability. + +These trends aim to solidify AM’s role in the future of manufacturing, offering unparalleled + +flexibility, efficiency, and innovation across industries. + +5\. Conclusions + +This study has provided an extensive overview of the AM landscape, reflecting on its + +historical evolution, current state, and future prospects. AM technologies, characterized + +by their versatility and innovation, offer significant advantages across various sectors, + +including aerospace, healthcare, automotive, and fashion. The exploration of different AM + +technologies reveals a nuanced understanding of their operational mechanisms, material + +requirements, and application potentials. Despite the transformative impacts of AM, chal- + +lenges such as printing speed, material diversity, cost, and post-processing requirements + +persist, indicating areas for future improvement and research. + +Future developments in AM are poised to address these challenges through advance- + +ments in material science, printing technologies, and process optimization. The integration + +Sensors 2024,24, 2668 38 of 44 + +of artificial intelligence and the exploration of new domains such as 3D bioprinting, 3D + +food printing, and large-scale 3D printing are expected to further enhance the efficiency, + +accessibility, and applicability of 3D printing technologies. Moreover, the potential for multi- + +material printing and improved precision offers a glimpse into a future where 3D printing + +could seamlessly blend into traditional manufacturing processes, offering customized and + +on-demand production capabilities that were previously unattainable. Standardization, + +regulation, circular economy, and sustainability also need future efforts and studies. + +In conclusion, AM stands at the cusp of a new era in manufacturing, with the potential + +to fundamentally alter how products are designed, produced, and distributed. As the + +technology continues to evolve, overcoming its current limitations, its integration into + +the broader manufacturing ecosystem will likely accelerate, heralding a future where + +AM plays a central role in the next manufacturing revolution. The ongoing research and + +development within this field are critical, not only for advancing the technology itself but + +also for realizing the full spectrum of its applications across industries worldwide. + +Author Contributions: Conceptualization, L.Z.; methodology, L.Z.; formal analysis, L.Z.; investiga- + +tion, L.Z., J.M., J.V., M.M., Z.A.T., J.B., Q.J., G.H., M.R. and L.D.S.; writing—original draft preparation, + +L.Z.; writing—review and editing, L.Z.; visualization, L.Z.; supervision, L.Z.; project administration, + +L.Z. All authors have read and agreed to the published version of the manuscript. + +Funding: This research was funded by the Partnerships for Opportunity and Workforce and Eco- + +nomic Revitalization (POWER) Initiative grant (grant number: PW-20426-IM-21) awarded by the + +Appalachian Regional Commission (ARC), USA. + +Conflicts of Interest: The authors declare no conflicts of interest. + +Abbreviations + +The following abbreviations are used in this manuscript: + +AM Additive manufacturing + +ME Material extrusion + +FDM Fused deposition modeling + +PEEK Polyether ether ketone + +PEI Polyetherimide + +VP VAT polymerization + +SLA Stereolithography + +DLP Digital light processing + +cDLP Continuous digital light processing + +SLS Selective laser sintering + +DMLS Direct metal laser sintering + +CAD Computer-aided design + +STL Stereolithography + +CNC Computer numerical control + +PLA Polylactic acid + +ABS Acrylonitrile butadiene styrene + +MJ Material jetting + +DOD Drop-on-demand + +UV Ultraviolet + +PETG Polyethylene terephthalate glycol + +FFF Fused filament fabrication + +BJ Binder jetting + +CJP Color jet printing + +PVP Polyvinyl pyrrolidone + +PVA Polyvinyl alcohol + +PAA Polyacrylic acid + +SMA Shape memory alloy + +AI Artificial intelligence + +Sensors 2024,24, 2668 39 of 44 + +SLM Selective laser melting + +LPBF Laser powder bed fusion + +PBF Powder bed fusion + +LPMP Laser powder melt pool + +EBM Electron beam melting + +MJF Multi-jet fusion + +CMYK Cyan, magenta, yellow, and key + +DED Direct energy deposition + +CFR Carbon fiber reinforcement + +LOM Laminated object manufacturing + +ITOP Integrated tissue and organ printing system + +IoT Internet of things + +HIP Hot isostatic pressing + +ROI Return on investment + +References + +1. + +Prashar, G.; Vasudev, H.; Bhuddhi, D. 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Additive manufacturing (AM) which also includes selective laser melting (SLM), fused deposition modelling (FDM), directed energy deposition (DED) and binder jetting has become one of the most radical technologies of production in the modern age \[5,==6\]==. Its inherent benefits of geometric freedom, material efficiency, and close to zero tooling overhead make it especially subject to optimization by AI.... + +[Artificial intelligence in additive and smart manufacturing: a critical review of design, process optimization, and quality control](https://www.researchgate.net/publication/414028935_Artificial_intelligence_in_additive_and_smart_manufacturing_a_critical_review_of_design_process_optimization_and_quality_control) + +Article + +Full-text available + +- Sep 2026 + +The rapid adoption of artificial intelligence (AI) in the production sector has triggered a revolutionary change in the design, manufacturing, monitoring, and optimization. The paper is a critical analysis of AI-based additive manufacturing (AM) and smart manufacturing systems with an emphasis on design intelligence and process optimization, real-time quality control, and sustainable production. Based on recent literature, this paper considers the major AI methods, such as machine learning (ML), deep learning (DL), reinforcement learning (RL), and physics-informed neural networks (PINNs) throughout the manufacturing lifecycle. The results show that AI can greatly decrease the time spent on design iterations, increase the accuracy of predictions of process parameters, and allow in-situ defect detection with high accuracy. Moreover, AI helps to ensure predictive maintenance strategies, reduce the number of unforeseen failures and enhance operational efficiency. The interplay of AI and digital twin technology, Industrial Internet of Things (IIoT), edge computing, and big data analytics is cited as a pillar of Industry 4.0 and the future Industry 5.0 paradigm. Regardless of these developments, the issues of data sparsity, the applicability of the model, computational expense, and interpretability are the key obstacles to large-scale industrial adoption. The value of human-AI cooperation and the necessity to have explainable and reliable AI systems in critical safety areas are also emphasized in the study. Lastly, the review provides future research directions, which focus on multi-modal AI, large-scale manufacturing models, and sustainability-based optimization frameworks. In general, the article is a thorough synthesis of the recent developments and realistic directions of introducing AI-enabled smart manufacturing. + +... Combining digital methods with new materials is changing how personal and vehicle armor is developed, making the process faster and smarter. ==115== In summary, ballistic materials are evolving quickly thanks to advances in smart technologies, new materials, and sustainable design. Innovations now include nanotech composites, shearthickening fluids, 3D textiles, and sensor-enabled fabrics.... + +[ADVANCED BALLISTIC MATERIALS: A COMPREHENSIVE REVIEW OF NATURAL AND SYNTHETIC FIBER COMPOSITES FOR BODY ARMOR APPLICATIONS](https://www.researchgate.net/publication/413907380_ADVANCED_BALLISTIC_MATERIALS_A_COMPREHENSIVE_REVIEW_OF_NATURAL_AND_SYNTHETIC_FIBER_COMPOSITES_FOR_BODY_ARMOR_APPLICATIONS) + +Article + +- Aug 2026 +- CELL CHEM TECHNOL + +Body armor plays a crucial role in modern defense and law enforcement, offering lifesaving protection against ballistic threats. With the growing complexity of threats and the demand for improved wearer mobility, research has shifted toward optimizing materials for higher strength-to-weight ratios, enhanced energy absorption, and flexibility. This review comprehensively examines advancements in both natural and synthetic fibers used in soft and hard ballistic armor systems. Focus is given to their mechanical properties, structural configurations, and the incorporation of novel technologies, such as hybrid composites. The role of fabric architecture, surface treatments, and fiber-matrix adhesion in enhancing energy absorption is also discussed. The article concludes with future directions for the development of multifunctional, lightweight, and eco-friendly ballistic protection systems using emerging material technologies. + +[Fused deposition modeling–subtractive hybrid manufacturing: process integration, system configurations, and performance trade-offs](https://www.researchgate.net/publication/414156746_Fused_deposition_modeling-subtractive_hybrid_manufacturing_process_integration_system_configurations_and_performance_trade-offs) + +Article + +Full-text available + +- Sep 2026 +- INT J ADV MANUF TECH + +The introduction of Fused Deposition Modeling (FDM)-subtractive manufacturing hybrid techniques represents one possible avenue toward sustainability through manufacturing systems. The advantage offered by the use of FDM is the capability of fabricating complex geometries; however, components manufactured via the use of FDM present poor surface finish and have anisotropic characteristics. On the other hand, the advantage provided by subtractive machining is the high precision in terms of dimensional accuracy and surface finish. Unfortunately, this technology suffers from the drawback of wasting material. As such, the present study will provide an overview of the current status of FDM-subtractive hybrid manufacturing systems along with the advantages and disadvantages of these manufacturing processes. The comparison presented shows the improvement offered by the hybridization of the two processes in terms of dimensional accuracy and functional performance, along with surface finish of manufactured parts. In addition, it was found that these systems can overcome limitations concerning material utilization efficiency and process efficiencies. However, the degree of improvement heavily depends on process sequencing, machine arrangement and material compatibility. The current limitations observed include the lack of multi-material platform for both FDM and subtractive technologies, the limitation in the use of hybrid capabilities of machines within CAM software packages, and the inadequate application of integrated process planning and adaptive controls. Such limitations need to be overcome for further development of hybrid manufacturing systems. + +[Effect of Immediate Thermal Exposure on the Surface Mechanical Performance of Polyurethane-Coated Oak Wood and Visible 3D-Printed Furniture Components](https://www.researchgate.net/publication/413995443_Effect_of_Immediate_Thermal_Exposure_on_the_Surface_Mechanical_Performance_of_Polyurethane-Coated_Oak_Wood_and_Visible_3D-Printed_Furniture_Components) + +Article + +- Sep 2026 + +A polyurethane coating represents the conventional solution for protecting and finishing visible wooden furniture surfaces. However, the increasing use of additive manufacturing has introduced visible 3D-printed polymer components whose surface mechanical performance is relevant to their application in furniture. This study investigated the effect of short-term exposure to 60 °C for 1 h on the surface mechanical properties of a pigmented polyurethane coating applied to oak wood and 3D-printed PLA, ABS-T and PET-G components. Specimens were evaluated under laboratory conditions (20 °C) and immediately after exposure to 60 °C, while their surfaces remained at an elevated temperature. Impact resistance, abrasion resistance, and scratch resistance using a tungsten carbide tip were determined according to the relevant standards, and the surface damage was assessed by visual inspection and digital microscopy. The polyurethane coating exhibited the smallest impact indentation diameter but showed earlier crack initiation and lower abrasion resistance than the 3D-printed polymers. Among the investigated polymers, ABS-T provided the most balanced combination of impact resistance, abrasion resistance and surface hardness, whereas PLA exhibited the greatest dimensional changes after exposure to 60 °C. Microscopic analysis revealed surface defects that were not detectable by visual inspection, demonstrating the value of digital microscopy for detecting subtle surface damage. The results indicate that ABS-T is a promising material for visible furniture components exposed to short-term elevated temperatures, while PET-G should be used with caution in applications exposed to radiant heat or direct sunlight. + +[Caracterização microestrutural em pré-formas de aço inoxidável 316L-Si obtidas através de manufatura aditiva por deposição a arco via GMAW-pulsado](https://www.researchgate.net/publication/413952041_Caracterizacao_microestrutural_em_pre-formas_de_aco_inoxidavel_316L-Si_obtidas_atraves_de_manufatura_aditiva_por_deposicao_a_arco_via_GMAW-pulsado) + +Conference Paper + +Full-text available + +- Sep 2026 + +Entre as tecnologias de manufatura para metais, a manufatura aditiva por deposição a arco (WAAM) tem ganhado destaque por permitir a fabricação de geometrias complexas, pelas altas taxas de deposição, pela facilidade em fabricar peças de grandes dimensões e pelo baixo custo dos equipamentos. O aço inoxidável 316L é um dos materiais mais empregados na WAAM, devido à sua boa soldabilidade, resistência à corrosão, ductilidade e tenacidade. Contudo, diversos desafios associados a esse método de fabricação ainda limitam a difusão da WAAM na indústria, entre eles: a concentração da transferência de calor ao longo da direção de construção; a formação de porosidade; as tensões residuais causadas pela oscilação térmica; e a anisotropia induzida por gradientes térmicos. Os efeitos dos parâmetros de soldagem na microestrutura do aço 316L têm sido amplamente estudados nos últimos anos, destacando-se a formação da fase metaestável ferrita-δ e a influência da taxa de resfriamento em sua morfologia. Embora alguns estudos tenham demonstrado a inflência dos aspectos térmicos da WAAM na microestrurura de aços inoxidáveis 316L, ainda há uma lacuna na compreensão da heterogeneidade microestrurural ao longo das camadas em processos baseados em soldagem a arco pulsado com eletrodo consumível (GMAW-P). Motivado por essas lacunas na literatura, este estudo tem como objetivo investigar o impacto das variações térmicas na evolução microestrutural e dureza ao longo das camadas de pré-formas de aço inoxidável 316L-Si manufaturadas por WAAM, especificamente pelo processo de soldagem GMAWpulsado. Foram retiradas amostras para análise metalográfica por microscopia óptica, para medição do teor de ferrita- δ e espaçamento dos braços dendríticos secundários (SDAS) através do software ImageJ® e para ensaio de microdureza Vickers. As análises microestruturais revelaram teores de ferrita-δ menores nas primeiras camadas depositadas em razão do histórico térmico, bem como espaçamentos de braços dendríticos secundários maiores e taxas de resfriamento menores nas camadas superiores. Os ensaios de microdureza Vickers revelaram uma diminuição da dureza nas camadas superiores em função da microestrutura grosseira formada sob menores taxas de resfriamento. + +[Natural Fiber-Reinforced Polylactic Acid Composites: 3D Printing, Life Cycle Assessment, and Applications](https://www.researchgate.net/publication/413949713_Natural_Fiber-Reinforced_Polylactic_Acid_Composites_3D_Printing_Life_Cycle_Assessment_and_Applications) + +Article + +- Sep 2026 + +Natural fiber-reinforced biopolymer composites are an attractive class of materials owing to their renewability, sustainability, and eco-friendliness. Meanwhile, fused deposition modeling (FDM) is transforming the manufacturing industry and gaining popularity for fabricating intricate and customized geometries that are difficult to produce with traditional techniques. Recently, FDM printing of natural fiber-reinforced PLA composites (NFRPCs) has emerged as a promising approach for developing sustainable green composites with potential application across diverse fields. This review comprehensively examines recent advances in the development of FDM-printed NFRPCs, with particular emphasis on mechanical and tribological properties. In addition, the review examines life cycle assessment (LCA) studies to evaluate the environmental sustainability of FDM-printed NFRPCs and identifies important gaps that require further investigation. Challenges associated with the processing of NFRPCs, including printability, interfacial adhesion, and optimal printing parameters, are also highlighted. Finally, future research directions are proposed to facilitate the development of high-performance, printable, and environmentally sustainable NFRPCs. + +[WLAM of inconel 625 and stainless steel 316 bimetallic structures: an investigation on microstructure, mechanical properties, environment stability and corrosion performance](https://www.researchgate.net/publication/413945736_WLAM_of_inconel_625_and_stainless_steel_316_bimetallic_structures_an_investigation_on_microstructure_mechanical_properties_environment_stability_and_corrosion_performance) + +Article + +Full-text available + +- Sep 2026 +- INT J ADV MANUF TECH + +Wire-feed laser additive manufacturing (WLAM) offers significant potential for producing bimetallic structures (BMs) by combining the unique properties of dissimilar alloys. This study investigates the microstructural evolution, mechanical properties, and environmental performance of a BM composed of Inconel 625 (IN625) and Stainless Steel 316 (SS316) fabricated using a WLAM system. Monolithic IN625, monolithic SS316, and a 50/50 IN625-SS316 BM were characterized using optical microscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), and mechanical testing. Microstructural analysis revealed a smooth transition zone with good metallurgical bonding, exhibiting epitaxial grain growth in the form of columnar dendrites and equiaxed grains with effective elemental mixing and no sharp discontinuities. XRD confirmed the stability of face-centered cubic (FCC) phases throughout the bimetallic structure, with no detectable peaks corresponding to brittle secondary phases. Mechanical testing showed that the BM exhibited intermediate properties, with a UTS of ~ 506 MPa and an average hardness of ~ 145 HV, corresponding to 27.5% lower strength and 18.5% lower hardness than IN625, but 4.3% higher strength and 10.7% higher hardness than SS316. High-temperature oxidation tests at 400 °C, 600 °C, and 900 °C showed intermediate oxidation resistance in the BM, associated with the formation of Cr and Fe-rich oxides. Electrochemical testing in 3.5 wt% NaCl showed corrosion rates of ~ 0.178, ~ 0.879, and ~ 0.353 mils per year (mpy) for IN625, SS316, and the 50/50 BM, respectively. The BM exhibited intermediate corrosion resistance, with a corrosion rate approximately 59.8% lower than SS316 but 98.3% higher than IN625.This intermediate behavior is attributed to the combined electrochemical response of the corrosion resistant IN625 region and the comparatively more susceptible SS316 region in the bimetallic structure. + +[Measurement of Optimum Laser Energy Required to 3d Print Continuous Fiber Reinforced Composites Using Photo-Curable Thermoset Resin](https://www.researchgate.net/publication/378002937_Measurement_of_Optimum_Laser_Energy_Required_to_3d_Print_Continuous_Fiber_Reinforced_Composites_Using_Photo-Curable_Thermoset_Resin) + +Conference Paper + +Full-text available + +- Feb 2024 + +Continuous carbon fiber (CCF) reinforcement has garnered significant attention in 3D printing due to its ability to impart exceptional mechanical performance characteristics to polymer composites. Light-assisted 3D printing of thermoset resin with CCF reinforcement enables the scalable production of complex structures using additive manufacturing. However, the opaqueness of carbon fiber poses challenges to the curing process of thermoset resins during printing with CCF reinforcement. Therefore, knowledge on the minimum light energy required to continue printing while retaining the desired print shape is crucial for designing energy-efficient and successful manufacturing systems. The primary objective of this study was to measure and compare the minimum energy required to continue light-assisted 3D printing of thermoset resin with CCF reinforcement. The study specifically investigated the minimum light energy needed for printing with both an acrylate-based thermoset resin and an epoxy-acrylate resin. Optimized laser irradiation with the appropriate light energy is imperative for achieving scalable production of CCF reinforced composites with minimum energy consumption. + +[A Review of the Metal Additive Manufacturing Processes](https://www.researchgate.net/publication/376227759_A_Review_of_the_Metal_Additive_Manufacturing_Processes) + +Article + +Full-text available + +- Dec 2023 + +Metal additive manufacturing (AM) is a layer-by-layer process that makes the direct manufacturing of various industrial parts possible. This method facilitates the design and fabrication of complex industrial, advanced, and fine parts that are used in different industry sectors, such as aerospace, medicine, turbines, and jewelry, where the utilization of other fabrication techniques is difficult or impossible. This method is advantageous in terms of dimensional accuracy and fabrication speed. However, the parts fabricated by this method may suffer from faults such as anisotropy, micro-porosity, and defective joints. Metals like titanium, aluminum, stainless steels, superalloys, etc., have been used—in the form of powder or wire—as feed materials in the additive manufacturing of various parts. The main criterion that distinguishes different additive manufacturing processes from each other is the deposition method. With regard to this criterion, AM processes can be divided into four classes: local melting, sintering, sheet forming, and electrochemical methods. Parameters affecting the properties of the additive-manufactured part and the defects associated with an AM process determine the method by which a certain part should be manufactured. This study is a survey of different additive manufacturing processes, their mechanisms, capabilities, shortcomings, and the general properties of the parts manufactured by them. + +[4D printing of recoverable buckling-induced architected iron-based shape memory alloys](https://www.researchgate.net/publication/373256030_4D_printing_of_recoverable_buckling-induced_architected_iron-based_shape_memory_alloys) + +Article + +Full-text available + +- Aug 2023 + +A R T I C L E I N F O Keywords: Architected materials Fe-based shape memory alloys Energy absorption Shape recovery Energy dissipation Snap-through Laser powder bed fusion 3D and 4D metal printing A B S T R A C T Architected materials exhibit extraordinary properties in comparison with conventional materials and structures, resulting in additional functionality and efficiency by engineering the geometry in harmony with the base material. Buckling-induced architected materials (BIAMs) are a class of architected materials that exhibit a significant potential to absorb and dissipate energy owing to their local instabilities. Previous studies have shown a trade-off between energy dissipation and geometrical recoverability in metallic BIAM, which limits their use in applications that require both of these features. This study, for the first time, presents 4D printing of buckling-induced architected iron-based shape memory alloys (BIA Fe-SMAs) using laser powder bed fusion (LPBF). The results show that 4D printing of BIA Fe-SMAs can offer both energy dissipation and geometrical recoverability (i. e., recentring). The study was conducted on two different alloy compositions of Fe-17Mn-5Si-10Cr-4Ni. Quasi-static cyclic tests were performed on the two BIA Fe-SMAs, and the samples were subsequently heated to 200 • C to activate the shape memory effect (SME) of the base material. The samples could recover the residual deformations accumulated during the cyclic load owing to the SME of the base material, which led to shape-recovery ratios of 96.8 and 98.7% for the studied BIA Fe-SMAs. The results of this study demonstrate that 4D printing of BIA Fe-SMAs can yield an enhanced multi-functional behavior by combining the material's inherent functional behavior with the functionalities of the architected structure. Notably, BIA Fe-SMA samples could reconfigure their initial shape without damage after densification, which sets them apart from conventional crushable lattices. + +[A Review on the Metal Additive Manufacturing Processes](https://www.researchgate.net/publication/372864464_A_Review_on_the_Metal_Additive_Manufacturing_Processes) + +Preprint + +Full-text available + +- Aug 2023 + +In this article, metallic additive manufacturing (AM) processes were classified and demonstrated. AM technology can be applied to a wide range of industrial areas because of its great feasibility in the design and manufacturing of various complex parts. The main factor that distinguishes various metallic AM processes from each other is the deposition method. Deposited metal can be imported in the form of melt or semi-solid. AM technology also covers a wide range of materials like aluminum, titanium, and many other alloys. Some of the common applications of metallic AM processes are the quick manufacturing of the parts which utilized in various industries like medical, automotive, aerospace, and jewelry industries. AM can help to fabricate parts that are impossible to be manufactured by other processes. + +[New Trends in 4D Printing: A Critical Review](https://www.researchgate.net/publication/372419577_New_Trends_in_4D_Printing_A_Critical_Review) + +Article + +Full-text available + +- Jun 2023 + +In a variety of industries, Additive Manufacturing has revolutionized the whole design–fabrication cycle. Traditional 3D printing is typically employed to produce static components, which are not able to fulfill dynamic structural requirements and are inappropriate for applications such as soft grippers, self-assembly systems, and smart actuators. To address this limitation, an innovative technology has emerged, known as “4D printing”. It processes smart materials by using 3D printing for fabricating smart structures that can be reconfigured by applying different inputs, such as heat, humidity, magnetism, electricity, light, etc. At present, 4D printing is still a growing technology, and it presents numerous challenges regarding materials, design, simulation, fabrication processes, applied strategies, and reversibility. In this work a critical review of 4D printing technologies, materials, and applications is provided. + +[Bio-Inspired Additive Manufacturing of Hierarchical Materials: From Bio-Structures to Functions](https://www.researchgate.net/publication/370890625_Bio-Inspired_Additive_Manufacturing_of_Hierarchical_Materials_From_Bio-Structures_to_Functions) + +Article + +Full-text available + +- Jun 2023 + +Throughout billions of years, biological systems have evolved sophisticated, multiscale hierarchical structures to adapt to changing environments. Biomaterials are synthesized under mild conditions through a bottom-up self-assembly process, utilizing substances from the surrounding environment, and meanwhile are regulated by genes and proteins. Additive manufacturing, which mimics this natural process, provides a promising approach to developing new materials with advantageous properties similar to natural biological materials. This review presents an overview of natural biomaterials, emphasizing their chemical and structural compositions at various scales, from the nanoscale to the macroscale, and the key mechanisms underlying their properties. Additionally, this review describes the designs, preparations, and applications of bio-inspired multifunctional materials produced through additive manufacturing at different scales, including nano, micro, micro-macro, and macro levels. The review highlights the potential of bio-inspired additive manufacturing to develop new functional materials and insights into future directions and prospects in this field. By summarizing the characteristics of natural biomaterials and their synthetic counterparts, this review inspires the development of new materials that can be utilized in various applications. \ No newline at end of file diff --git a/90 Allegati/ADDITIVA_Aluminium AlSi10Mg_rev010.pdf.md b/90 Allegati/ADDITIVA_Aluminium AlSi10Mg_rev010.pdf.md new file mode 100644 index 0000000..f5d64ec --- /dev/null +++ b/90 Allegati/ADDITIVA_Aluminium AlSi10Mg_rev010.pdf.md @@ -0,0 +1,51 @@ +[Download](https://presentations-decks-uploads-prod.s3.amazonaws.com/7403838/3888537/5e2dce5faba1a8500f30c5dafc639e14e28d093eade06720d37f6c08e055c4c5.pdf?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Date=20260910T072618Z&X-Amz-SignedHeaders=host&X-Amz-Expires=60&X-Amz-Credential=AKIAZ32RUKUMSNCVYAKB%2F20260910%2Fus-east-1%2Fs3%2Faws4_request&X-Amz-Signature=9cd4cf230f73e325ba058cf47282725825a2fb61c4faea6f24ad0f75d6315ae8) + +This data sheet contains approximate values that may vary with build conditions and is intended for reference and comparison purposes only. It should not be used for +design specifications or quality control. The performance characteristics of the material can be affected (±) by, but not limited to, part design, part geometries, +application and operating conditions. Each user is responsible for determining that the material is safe, lawful and technica lly suitable for the intended laws and +regulations. ADDIT IVA makes no warranties of any kind, express or implied, including, but not limited to, the warranties of merchantability, fi tness for a particular use, or +warranty against patent infringement. ADDITIVA excludes liability, however arising, for any inaccura cies in this document. +ADDITIVA\_Aluminium AlSi10Mg\_rev010.docx 9 +Aluminium AlSi10Mg is a common casting alloy with good castability. It is typically used for thin \- walled, complex +components and applications requiring a combination of good thermal properties and low weight. It offers excellent +strength, hardness, and dyn amic performance, making it suitable for parts subjected to high loads. Traditionally, cast +parts made from this aluminium alloy are heat \- treated to enhance mechanical properties, typically via the T6 cycle of +solution annealing, quenching, and age hardeni ng. +The SLM/DMLS process is notable for its extremely rapid melting and re \- solidification, allowing mechanical properties +in the as \- built condition to be comparable to those of T6 heat \- treated cast parts. Thanks to its high strength \- to \- weight +ratio, AlSi10Mg i s an excellent choice for automotive and aerospace applications, especially gearboxes, housings, and +brackets that endure significant loading. Components can be machined, spark \- eroded, welded, shot \- peened, polished, +and coated. +USA UNS European Union / EN ASTM DIN +A0 3600 – A13600 EN AC \- 430 00 B 85 A360.0 (F3318) Al 4046 \- 3.2381 +Chemical composition Physical properties +Al – Aluminium balance Relative density Approx. 99.9% +Si – Silicon 9.0÷11.0% Density 2.67 g/cm 3 +Mg – Magnesium 0.20÷0.45% +Fe – Iron ≤ 0.55% Heat Treatment (stress relief) +Mn – Manganese ≤ 0.45% 20°C → 300 °C 1 hour +Ti – Titanium ≤ 0.15% 300 °C 2 hours +Cu – Copper ≤ 0.10% 300 °C → 20°C \- +Zn – Zinc ≤ 0.10% +Ni – Nickel ≤ 0.05% +C – Carbon ≤ 0.05% +Technical data +Typical part accuracy (quote < 150 mm) ± 0.2/0.3 mm +Typical part accuracy (quote ≥ 150 mm) ± 0.05mm each 25mm +Surface roughness (as built) Ra: 5 ÷ 9 µm +Surface roughness (after machining / polishing) Ra < 1.6 µm +Mechanical properties +Mechanical data Test method As Built Stress relieved +Tensile strenght (Rm) +ASTM E8 / E8M +(unmachined specimen, Z \- axis) +4 0 0 ± 5 MPa 2 70 ± 5 MPa +Yield strenght (Rp 0.2%) 2 55 ± 5 MPa 1 60 ± 5 MPa +Elongation at break 4,5 ± 1 % 11 ± 1 % +Young’s modulus 70 ± 3 GPa 70 ± 3 GPa +Hardness Brinell DIN EN ISO 6506 \- 1 120 ± 5 HBW +Thermal conductivity ASTM E1461 \- 13 110 ± 5 W/m°C 170 ± 10 W/m°C + +Pagina 1 di 1 + +![](https://presentations-slides-prod.s3.amazonaws.com/7403838/3888537/2026/05/26/234a832ff0be7f2ed30a98cbbdc6118c.thumb.jpg) \ No newline at end of file diff --git a/90 Allegati/ADDITIVA_Aluminium AlSi10Mg_web.md b/90 Allegati/ADDITIVA_Aluminium AlSi10Mg_web.md new file mode 100644 index 0000000..6f90e77 --- /dev/null +++ b/90 Allegati/ADDITIVA_Aluminium AlSi10Mg_web.md @@ -0,0 +1,7 @@ +AlSi10Mg is an aluminium-based alloy widely used for functional parts as well as prototypes. It offers good corrosion resistance, good electrical conductivity, high dynamic toughness, excellent thermal conductivity. + +Conventionally cast parts in this type of aluminium alloy are often heat-treated to improve the mechanical properties, for example, applying the T6 cycle of solution annealing, quenching and age hardening. The SLM / DMLS process is characterised by extremely rapid melting and solidification: this enables mechanical properties in the as-built condition similar to T6 heat-treated cast parts. + +Due to its high strength-to-weight ratio, AlSi10Mg is a good choice for automotive, aerospace and automation applications, notably gearboxes, engine parts, ductwork, heat exchangers, high-pressure pipes, manifolds, housings and brackets subject to high loading. + +Parts can be machined, spark-eroded, welded, micro shot-peened, polished and coated. \ No newline at end of file diff --git a/90 Allegati/ADDITIVA_INCONEL718_rev006.pdf.md b/90 Allegati/ADDITIVA_INCONEL718_rev006.pdf.md new file mode 100644 index 0000000..d415e06 --- /dev/null +++ b/90 Allegati/ADDITIVA_INCONEL718_rev006.pdf.md @@ -0,0 +1,53 @@ +[Download](https://presentations-decks-uploads-prod.s3.amazonaws.com/7403838/3888537/12414a9d77c0e8922332cee99c8836e36d7746ccda751d87f542742c6a6e80bf.pdf?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Date=20260910T074626Z&X-Amz-SignedHeaders=host&X-Amz-Expires=60&X-Amz-Credential=AKIAZ32RUKUMSNCVYAKB%2F20260910%2Fus-east-1%2Fs3%2Faws4_request&X-Amz-Signature=d38ee3ee79ae440a58c93667816572b64134f9419059e2abe0f290894ab91842) + +This data sheet contains approximate values that may vary with build conditions and is intended for reference and comparison purposes only. It should not be used for +design specifications or quality control. The performance characteristics of the material can be affected (±) by, but are not limited to, part design, part geometries, +application and operating conditions. Each user is responsible for determining that the material is safe, lawful and technica lly suitable for the intended laws and +regulations. A DDITIVA makes no warranties of any kind, express or implied, including, but not limited to, the warranties of merchantability, fitness for a particular use, or +warranty against patent infringement. ADDITIVA excludes liability, however arising, for any inac curacies in this document. +ADDITIVA\_INCONEL718\_rev006.docx +INCONEL® alloy 718 is a high \- strength, corrosion \- resistant nickel \- chromium material. Similar to its sister alloy 625, +Inconel 718 is an age \- hardened version of alloy 625. Ageing (or precipitation hardening) produces precipitates within +the microstructure t hat pin the metal's grains in place. As a result, the material typically becomes significantly +stronger. Service temperatures range from \- 196°C to 700°C (\- 321°F to 1.300°F). Its welding characteristics, especially +its resistance to post \- weld cracking, are outstanding. Good tensile, fatigue, creep, and rupture strengths have led to its +use in a wide range of applications. The alloy is utilised in jet engines, liquid \- fuelled rockets, rings, casings, and metal +parts for aircraft and land \- based gas turbine engi nes, cryogenic tankage, and high \- temperature fasteners. INCONEL +718 is also employed in the oil and gas drilling and production industries due to its high strength and resistance to +chlorides, stress corrosion, and sulphide stress cracking. Parts can be ma chined, welded, shot \- peened, polished, and +coated. +UNS AMS ASTM DIN +N07718 5596 \- 5832 B670 – F3055 2.4668 +Chemical composition Physical properties +Ni – Nickel 50.0÷55.0% Relative density Approx. 99.9% +Cr – Chromium 17.0÷21.0% Density 8.15 g/cm 3 +Nb – Niobium 4.7÷5.5% Heat Treatment (AMS 5662) +Mo – Molybdenum 2.8÷3.3% STEP 1 – Annealing +Ti – Titanium 0.6÷1.2% 20°C → 980°C \- +Al – Aluminium 0.2÷0.8% 980°C 1 hour +Co – Cobalt ≤ 1.0% 980°C → 20°C \- +Cu – Copper ≤ 0.3% STEP 2 – Ageing +C – Carbon ≤ 0.08% 20°C → 720°C \- +Mn – Manganese ≤ 0.35% 720°C 8 hours +Si – Silicon ≤ 0.35% 720°C → 620°C 2 hours +P – Phosphorus ≤ 0.015% 620°C 10 hours +S – Sulfur ≤ 0.015% 620°C → 20°C \- +Technical data +Typical part accuracy (quote < 150 mm) ± 0.2/0.3 mm +Typical part accuracy (quote ≥ 150 mm) ± 0.05mm each 25mm +Surface roughness (as built) Ra: 5 ÷ 9 µm +Surface roughness (after machining / polishing) Ra < 1.6 µm +Mechanical properties +Mechanical data Test method As Built Heat Treated AMS 5662 +Tensile strenght ISO 6892 \- 1:2009(B) Annex D 1020 ± 15 MPa 1.400 ± 15 MPa +Yield strenght (Rp 0.2%) ISO 6892 \- 1:2009(B) Annex D 630 ± 15 MPa 1.1 4 0 ± 15 MPa +Elongation at break ISO 6892 \- 1:2009(B) Annex D 30 ± 5 % 10 ± 2% +Young’s modulus 1 85 ± 1 0 GPa 210 ± 1 0 GPa +Hardness DIN EN ISO 6508 \- 1 30 HRC 46 HRC +Thermal properties +Maximum long \- term operating temperature Approx. 700°C / 1.300 °F +Thermal conductivity 6 ÷ 12 W/mK + +Pagina 1 di 1 + +![](https://presentations-slides-prod.s3.amazonaws.com/7403838/3888537/2026/05/26/ac2e8eefcbbf8692e4c7f51584321ed5.thumb.jpg) \ No newline at end of file diff --git a/90 Allegati/ADDITIVA_Inconel 718_web.md b/90 Allegati/ADDITIVA_Inconel 718_web.md new file mode 100644 index 0000000..54df6d2 --- /dev/null +++ b/90 Allegati/ADDITIVA_Inconel 718_web.md @@ -0,0 +1,3 @@ +INCONEL® alloy 718 is a high-strength, corrosion-resistant Nickel-Chromium material. Service temperatures range from -196°C to 700°C (-321°F÷1.300°F). + +Its welding characteristics, especially its resistance to post-weld cracking, are outstanding. Good tensile, fatigue, creep and rupture strengths enable its use in a wide range of applications. The alloy is used in jet engines, liquid-fueled rockets, rings, casings and metal parts for aircraft and land-based gas turbine engines, cryogenic tankage, high-temperature fasteners. Inconel 718 is also used in the oil and gas drilling and production industries due to its high strength and resistance to chlorides, stress corrosion and sulfide stress cracking. Parts can be machined, welded, shot-peened, polished and coated. \ No newline at end of file diff --git a/90 Allegati/ADDITIVA_Scalmalloy_rev005.pdf.md b/90 Allegati/ADDITIVA_Scalmalloy_rev005.pdf.md new file mode 100644 index 0000000..3b5b5e5 --- /dev/null +++ b/90 Allegati/ADDITIVA_Scalmalloy_rev005.pdf.md @@ -0,0 +1,51 @@ +[Download](https://presentations-decks-uploads-prod.s3.amazonaws.com/7403838/3888537/015f9cccb16a040bbe73d9165683ae703829853f3adb06aa6caa84933942c279.pdf?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Date=20260910T074528Z&X-Amz-SignedHeaders=host&X-Amz-Expires=60&X-Amz-Credential=AKIAZ32RUKUMSNCVYAKB%2F20260910%2Fus-east-1%2Fs3%2Faws4_request&X-Amz-Signature=b5380a5416d932e91fed1229d5d9c2b262541eb248cfcdcc0aa8e78640e3a799) + +This data sheet contains approximate values that may vary with build conditions and is intended for reference and comparison purposes only. It should not be used for +design specifications or quality control. The performance characteristics of the material can be affected (±) by, but not limited to, part design, part geometries, +application and operating conditions. Each user is responsible for determining that the material is safe, lawful and technica lly suitable for the intended laws and +regulations. ADDIT IVA makes no warranties of any kind, express or implied, including, but not limited to, the warranties of merchantability, fi tness for a particular use, or +warranty against patent infringement. ADDITIVA excludes liability, however arising, for any inaccura cies in this document. +ADDITIVA\_Scalmalloy\_rev005.docx +Scalmalloy is an aluminium \- magnesium \- scandium alloy that offers excellent stiffness, an exceptionally high strength \- +to \- weight ratio, superb weldability and ductility, and low density to reduce parasitic mass from non \- structural +features. It can effectively replace high \- strength 7000 series aluminium alloys in plate or forging form. Thanks to its +low density, Scalmalloy provides density \- specific properties that are highly competitive, even when compared with +the strongest alternatives. Compared with other al uminium alloys used in additive manufacturing, Scalmalloy delivers +a unique level of corrosion resistance and maintains a highly stable microstructure up to 250°C, making it suitable for +a broad range of high \- performance applications. +Combining high strength with excellent ductility and processability, it is the ideal material for heavily loaded +components, which is why it is already employed in many critical applications. Scalmalloy has an established track +record across a wide range o f fields, including a erospace, robotics, marine, and motorsport, and is an approved +material under FIA regulations. +Chemical composition Physical properties +Al – Aluminium balance Relative density Approx. 99.5 % +Mg – Magnesium 4.0÷4.9 % Density 2.67 g/cm 3 +Sc \- Scandium 0.6 ÷0.8% +Mn – Manganese 0.3 ÷0.8% +Zr – Zirconium 0.2÷0.5 % +Fe – Iron ≤ 0.4 % +Si – Silicon ≤ 0.4 % +Zn – Zinc ≤ 0.25 % Heat Treatment (stress relief) +Ti – Titanium ≤ 0.15 % 20°C → 325 °C 1 hour +Cu – Copper ≤ 0.10 % 325 °C 4 hours +325 °C → 20°C \- +Technical data +Typical part accuracy (quote < 150 mm) ± 0.2/0.3 mm +Typical part accuracy (quote ≥ 150 mm) ± 0.05mm each 25mm +Surface roughness (as \- built) Ra: 5 ÷ 9 µm +Surface roughness (after machining / polishing) Ra < 1.6 µm +Mechanical properties +Mechanical data Test method As \- Built Heat Treated +Tensile streng th (Rm) +ASTM E8 / E8M +(unmachined specimen, Z \- axis) +330 ± 5 MPa 5 5 5 ± 10 MPa +Yield strength (Rp 0.2%) 260 ± 5 MPa 51 5 ± 10 MPa +Elongation at break 19 ± 2 % 1 4 ± 2 % +Young’s modulus na 72 ± 3 GPa +Hardness Hv10 na 160 +Thermal conductivity ASTM E1461 \- 13 na 95 W/m·K + +Pagina 1 di 1 + +![](https://presentations-slides-prod.s3.amazonaws.com/7403838/3888537/2026/05/26/ae13e21defcfa984cdb5e352835c9b8c.thumb.jpg) \ No newline at end of file diff --git a/90 Allegati/ADDITIVA_Scalmalloy_web.md b/90 Allegati/ADDITIVA_Scalmalloy_web.md new file mode 100644 index 0000000..fe4fca3 --- /dev/null +++ b/90 Allegati/ADDITIVA_Scalmalloy_web.md @@ -0,0 +1,4 @@ +At room temperature, Scalmalloy has significantly higher strength than aluminium AlSi10Mg. Compared to other aluminium alloys for Additive Manufacturing, Scalmalloy offers a unique corrosion resistance level and a highly stable microstructure up to 250°C, which makes it well-suited for a wide range of high-performance applications. + +Scalmalloy is particularly suited to applications within motorsport, aerospace, aircraft construction, and advanced engineering with high strength and low density. +Parts can be machined, welded, shot-peened, polished and coated. \ No newline at end of file diff --git a/90 Allegati/ADDITIVA_Stainless Steel 316L_rev006.pdf.md b/90 Allegati/ADDITIVA_Stainless Steel 316L_rev006.pdf.md new file mode 100644 index 0000000..4a2701e --- /dev/null +++ b/90 Allegati/ADDITIVA_Stainless Steel 316L_rev006.pdf.md @@ -0,0 +1,53 @@ +[Download](https://presentations-decks-uploads-prod.s3.amazonaws.com/7403838/3888537/d7d22c9c3f0b5ebadec559f8674a1cc0830ef7ceed32211f489adeefce60aefe.pdf?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Date=20260910T074648Z&X-Amz-SignedHeaders=host&X-Amz-Expires=60&X-Amz-Credential=AKIAZ32RUKUMSNCVYAKB%2F20260910%2Fus-east-1%2Fs3%2Faws4_request&X-Amz-Signature=9af994d3996464c9abb7aa76139830a4591bb294404a2ad9757ebc9e7cc99f68) + +This data sheet contains approximate values that may vary with build conditions and is intended for reference and comparison purposes only. It should not be used for +design specifications or quality control. The performance characteristics of the material may be affected (±) by, but are not limited to, part design, part geometries, +application and operating conditions. Each user is responsible for determining that the material is safe, lawful and technica lly suitable for the intended laws and +regulations. A DDITIVA makes no warranties of any kind, express or implied, including, but not limited to, the warranties of merchantability, fitness for a particular use, or +warranty against patent infringement. ADDITIVA excludes liability, however arising, for any inac curacies in this document. +ADDITIVA\_Stainless Steel 316L\_rev006.docx +Stainless Steel 316L is a fully austenitic chromium \- nickel \- molybdenum steel. Molybdenum provides high corrosion +resistance. Its very low carbon content also improves resistance to intergranular corrosion and enhances weldability. +Post \- weld heat treatment i s generally unnecessary. Stainless Steel 316L is not susceptible to pitting or crevice corrosion +in chloride \- rich solutions. +Stainless Steel 316L is used to manufacture acid \- and corrosion \- resistant prototypes, as well as unique or series \- +production parts,in sectors such as automotive, shipbuilding, aerospace, food and beverage (including corrosion \- +resistant pipes and containers), chemical, pharmaceutical, oil, and gas. +Parts made from stainless steel 316L can be machined, welded, shot \- peened, polished, and coated. +UNS AMS ASTM DIN +S31603 5507 \- 5653 A240 DIN 1.4404 – ISO 5832 \- 1 +Chemical composition Physical properties +Fe – Iron balance Relative density Approx. 99.9% +Cr – Chromium 16÷18% Density 7.90 g/cm 3 +Ni – Nickel 11÷13% +Mo – Molybdenum 2.0÷3.0% Heat Treatment (stress relief) +Mn – Manganese ≤ 2.00% optional for parts sensitive to warpage +Si – Silicon ≤ 0.75% 20°C → 550°C 3 hours +Cu – Copper ≤ 0.50% 550°C 6 hours +P – Phosphorus ≤ 0.25% 550°C → 20°C \- +N – Nitrogen ≤ 0.10% +S – Sulfur ≤ 0.10% +O – Oxygen ≤ 0.10% +C – Carbon ≤ 0.03% +Technical data +Typical part accuracy (quote < 150 mm) ± 0.2/0.3 mm +Typical part accuracy (quote ≥ 150 mm) ± 0.05mm each 25mm +Surface roughness (as built) Ra: 5 ÷ 9 µm +Surface roughness (after machining / polishing) Ra < 1.6 µm +Mechanical properties +Mechanical data Test method As Built Heat Treated +Tensile strenght (Rm) +ASTM E8 / E8M +(unmachined specimen, Z \- axis) +6 4 0 ± 2 0 MPa +Yield strength (Rp 0.2%) 4 7 0 ± 2 0 MPa +Elongation at break 6 0 ± 10 % +Young’s modulus 17 0 ± 2 0 GPa +Hardness DIN EN ISO 6508 \- 1 18 HRC +Thermal properties +Maximum long \- term operating temperature Approx. 400°C / 752 °F +Thermal conductivity Approx.15 W/mK + +Pagina 1 di 1 + +![](https://presentations-slides-prod.s3.amazonaws.com/7403838/3888537/2026/05/26/a811995d0c5ab7b45074402a0669860e.thumb.jpg) \ No newline at end of file diff --git a/90 Allegati/ADDITIVA_Stainless Steel 316L_web.md b/90 Allegati/ADDITIVA_Stainless Steel 316L_web.md new file mode 100644 index 0000000..59931ee --- /dev/null +++ b/90 Allegati/ADDITIVA_Stainless Steel 316L_web.md @@ -0,0 +1,5 @@ +Stainless Steel 316L is a fully austenitic, corrosion-resistant Chromium-Nickel-Molybdenum steel. The molybdenum gives the material a high corrosion resistance. + +The low carbon content also improves resistance to inter-granular corrosion and weldability. Heat treatment after laser melting is normally not necessary. Stainless Steel 316L is not susceptible to pitting in chloride-containing solutions. Stainless Steel 316L is used for manufacturing acid and corrosion resistant prototypes, unique or series production parts in the following fields: automotive, shipbuilding, aerospace, food and beverage (i.e. corrosion-resistant pipes and containers), chemical, pharmaceutical, oil and gas industries. Typical applications are exhaust manifolds, furnace parts, heat exchangers, jet engine parts, pharmaceutical and photographic equipment, valve and pump parts, chemical processing equipment, tanks, evaporators. It also is used in pulp, paper, and textile processing equipment and for any parts exposed to marine environments. + +Parts can be machined, welded, shot-peened, polished and coated. \ No newline at end of file diff --git a/90 Allegati/ADDITIVA_Titanium Ti6Al4V_rev009.pdf.md b/90 Allegati/ADDITIVA_Titanium Ti6Al4V_rev009.pdf.md new file mode 100644 index 0000000..3c055a5 --- /dev/null +++ b/90 Allegati/ADDITIVA_Titanium Ti6Al4V_rev009.pdf.md @@ -0,0 +1,46 @@ +[Download](https://presentations-decks-uploads-prod.s3.amazonaws.com/7403838/3888537/b21445edf69ed40915ebe94e04aa1abba12ed7a762bba4c4de6051a539f246c2.pdf?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Date=20260910T073256Z&X-Amz-SignedHeaders=host&X-Amz-Expires=60&X-Amz-Credential=AKIAZ32RUKUMSNCVYAKB%2F20260910%2Fus-east-1%2Fs3%2Faws4_request&X-Amz-Signature=72fa95bd59f9e1e43ac334dc465810fca266e953ab393c3fa20b00f2108696ac) + +This data sheet contains approximate values that may vary with build conditions and is intended for reference and comparison purposes only. It should not be used for +design specifications or quality control. The performance characteristics of the material can be affected (±) by, but not limited to, part design, part geometries, +application and operating conditions. Each user is responsible for determining that the material is safe, lawful and technica lly suitable for the intended laws and +regulations. ADDIT IVA makes no warranties of any kind, express or implied, including, but not limited to, the warranties of merchantability, fi tness for a particular use, or +warranty against patent infringement. ADDITIVA excludes liability, however arising, for any inaccura cies in this document. +ADDITIVA\_Titanium Ti6Al4V\_rev009.docx +Titanium Ti6Al4V is a lightweight alloy renowned for its excellent mechanical properties, including fracture toughness, +fatigue strength, and corrosion resistance, together with low specific weight and biocompatibility. Grade 23 differs from +Grade 5 primar ily in its reduced oxygen content (maximum 0.13% in Grade 23), which enhances ductility and fracture +toughness, although it slightly reduces strength. Grade 23 is widely used in fracture \- critical airframe structures, +lightweight components for the motorspo rts and aerospace sectors, and surgical implants and medical instruments. +UNS AMS ASTM DIN +R 56401 4956 B 348 Grade 23 EN 3.7164 ISO 5832 \- 3 +Chemical composition Physical properties +Ti – Titanium b alance Relative density Approx. 99.9% +Al – Aluminium 5.5÷6.8% Density 4.43 g/cm 3 +V – Vanadium 3.5÷4.5% +Fe – Iron ≤ 0.25% Heat Treatment (Annealing) +O – Oxygen ≤ 0.13% under Argon atmosphere +C – Carbon ≤ 0.08% 20°C → 7 50 °C 4 hours +N – Nitrogen ≤ 0.05% 7 50 °C 1 hours +H – Hydrogen ≤ 0.012% 7 50 °C → 20°C \- +Technical data +Typical part accuracy (quote < 150 mm) ± 0.2/0.3 mm +Typical part accuracy (quote ≥ 150 mm) ± 0.05mm each 25mm +Surface roughness (as built) Ra: 5 ÷ 9 µm +Surface roughness (after machining / polishing) Ra < 1.6 µm +Mechanical properties +Mechanical data Test method As \- Built Heat Treated +Tensile streng th (Rm) +ASTM E8 / E8M +(unmachined specimen, Z \- axis) +1.1 8 0 ± 3 0 MPa 1.100 ± 20 MPa +Yield strength (Rp 0.2%) 1.0 8 0 ± 3 0 MPa 1.0 6 0 ± 20 MPa +Elongation at break 7 ± 1 % 1 2 ± 1 % +Young’s modulus 11 0 ± 3 GPa 1 20 ± 5 GPa +Hardness DIN EN ISO 6508 \- 1 3 7 HRC 3 7 HRC +Thermal properties +Maximum long \- term operating temperature Approx 355°C / 67 0°F +Thermal conductivity 7 W/mK + +Pagina 1 di 1 + +![](https://presentations-slides-prod.s3.amazonaws.com/7403838/3888537/2026/05/26/6e4f66ea679a4c2d728bf650d0404c84.thumb.jpg) \ No newline at end of file diff --git a/90 Allegati/ADDITIVA_Titanium Ti6Al4V_web.md b/90 Allegati/ADDITIVA_Titanium Ti6Al4V_web.md new file mode 100644 index 0000000..6f9ad30 --- /dev/null +++ b/90 Allegati/ADDITIVA_Titanium Ti6Al4V_web.md @@ -0,0 +1,7 @@ +Titanium Ti6Al4V is a light alloy with excellent mechanical properties, fracture toughness, fatigue strength and corrosion resistance combined with low specific weight and biocompatibility. + +Grade 23 differs from Grade 5 by the reduced oxygen content (max 0.13% in Grade 23): this ensures improved ductility and fracture toughness, with a slight reduction in strength. + +Typical applications can be fracture-critical parts, low and high-temperature components and structures, such as fasteners, discs, hubs, spacers, seals, compressor blades, structural parts and complex turbine engine components. Ti6Al4V is ideal for many high-performance engineering applications in aerospace and motorsport and the production of biomedical implants due to its higher strength, low modulus, and fatigue resistance. + +Parts can be machined, welded, shot-peened, polished and coated. \ No newline at end of file