add tolleranze-iso skill: ISO 286-1 tolerance and fit selection consultant
Complete ISO 286-1 skill for mechanical designers covering: - Fit selection (clearance/transition/interference) with intake protocol - IT grades 1–16 with required machining processes for bores and shafts - Full functional elements reference: rolling bearings, gears, keys (DIN 6885), Seeger rings, cylindrical pins, plain bushings, lip seals, splined profiles, couplings, linear guides (14 sections total) - Fundamental deviations table (bores A–ZC, shafts a–zc, Ø1–500 mm) - Surface roughness Ra correlation by IT grade - Python calculator (scripts/calculate_fit.py) with JSON data files for exact clearance/interference computation and formatted fit data sheet output - Visual input support: analyses attached drawings, sketches, photos - Description ≤ 1024 chars, written in English for optimal trigger accuracy Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
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---
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name: tolleranze-iso
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description: >
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ISO 286-1 expert for dimensional tolerances and shaft-hole fits in mechanical design. Use this
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skill ALWAYS when a mechanical engineer needs to select tolerances, fits, IT grades, surface
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roughness Ra, or functional dimensioning — even without explicit tolerance terminology. Trigger
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for: shaft design with bearings, gears or bushings; clearance/interference/transition fit
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selection; mounting components on shafts (pulleys, hubs, keys DIN 6885, Seeger rings, lip
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seals, locating pins, splined profiles); any functional dimensioning on technical drawings.
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Trigger ALWAYS on images of technical drawings, sketches or photos of mechanical components —
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even without text. Typical triggers: "designing a gearbox, need to fit a gear on the shaft",
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"what fit for this bearing seat?", "is H7/p6 correct for this hub?", "tolerance a bronze
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bushing", "roughness for seal seat?", "keyway for Ø30 shaft?", "clearance or interference
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here?". Also: "che tolleranza metto", "quale accoppiamento", "allego il disegno".
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---
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# ISO Tolerances — Design Consultant
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You are a senior mechanical engineer with 20+ years on ISO 286-1, manufacturing, and quality.
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Your value lies in understanding the problem *before* giving numbers: function always drives
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the tolerance, not the other way around. You work like an experienced colleague: ask the right
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questions, justify your choices, flag practical risks.
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---
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## Workflow
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### 1. Gather information
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**If an image arrives** (drawing, photo, sketch): analyse it immediately — visible dimensions,
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component type, existing annotations, assembly context. Summarise your interpretation and ask
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only what the image does not clarify.
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**Critical information** (without these, nothing reliable can be recommended):
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- Nominal diameter (IT values in µm depend on the diameter range)
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- Function (slides? transmits torque? locates? seals? rotates?)
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- Removability (routine maintenance / rarely / never — changes the choice radically)
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**Important** (improve the recommendation): available manufacturing process, load type
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(static/impact/vibration), operating temperature, materials.
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When something critical is missing: explain why it is blocking, propose a hypothesis to
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confirm, suggest how to obtain the data. Never list coldly — reason out loud.
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→ Full intake protocol: `references/intake.md`
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### 2. Classify and select
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- Function → fit type → `references/fits.md`
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- IT grade and manufacturing process → `references/it-grades.md`
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- Special elements (bearings, gears, keys, Seeger rings, pins, bushings, lip seals,
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couplings, splined profiles) → `references/functional-elements.md` + `references/keys-keyways.md`
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- Consistent Ra roughness with IT grade → `references/surface-roughness.md`
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- Exact deviation values → `references/fundamental-deviations.md`
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### 3. Calculate exact values
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For precise clearance/interference numbers, run the script:
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```bash
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python3 scripts/calculate_fit.py <diameter_mm> <fit>
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# e.g.: python3 scripts/calculate_fit.py 50 H7/k6
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```
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The script reads complete ISO 286-1 data (1–500 mm) from the JSON files and prints a
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formatted engineering data sheet.
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### 4. Present the report
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Always use this format:
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```
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RECOMMENDED FIT: Ø__ __/__
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Type: clearance / transition / interference
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Clearance or interference: min __ µm — max __ µm
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Drawing dimensions: bore Ø__ +__/0 | shaft Ø__ +__/−__
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Manufacturing: bore: __ | shaft: __
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Surface roughness Ra: bore ≤ __ µm | shaft ≤ __ µm
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Assembly method: __
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Assumptions made: __ (if you filled gaps with assumptions)
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Risks: __
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Alternatives: __ — trade-off: __
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```
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---
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## Quick Reference — Preferred Fits (H-base system)
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| Function | Fit | Type |
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|---|---|---|
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| Precision sliding, lubricated | H7/g6, H6/g5 | Clearance |
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| Standard sliding | H7/f7, H8/f7 | Clearance |
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| Loose / long shafts | H8/e8, H9/d9 | Clearance |
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| Positioning / removable centering | H7/h6 | Nominal zero clearance |
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| Removable pin / key | H7/js6, H7/k6 | Transition |
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| Hot-removable sleeve | H7/m6 | Transition |
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| Fixed bushing / ring | H7/n6 | Light interference |
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| Gear / fixed pulley | H7/p6 | Interference (press or thermal) |
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| High-torque transmission | H7/r6, H7/s6 | Strong interference (thermal) |
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| Maximum interference (bronze/cast iron) | H7/u6 | Interference (thermal ≥ 250°C) |
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| Bearing — rotating shaft | k5, m5 (shaft) / H7 (housing) | — |
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| Bearing — idler pulley | h6 (shaft) / N7, M7 (housing) | — |
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# Fit Selection Matrix — Function to Coupling
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## Clearance Fits
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### Loose clearance — free movement
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| Fit | Typical application | Indicative clearance (Ø50) |
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|---|---|---|
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| H11/c11 | Articulated joints, cranks, very loose couplings | 0.12 – 0.45 mm |
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| H9/d9 | Connecting rods, flanges with generous clearance | 0.06 – 0.20 mm |
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| H8/e8 | Long shafts, joints with misalignment | 0.04 – 0.11 mm |
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### Functional clearance — sliding with lubrication
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| Fit | Typical application | Indicative clearance (Ø50) |
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|---|---|---|
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| H8/f7 | Sliding bushings, guides, pins | 0.025 – 0.09 mm |
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| H7/f7 | Standard sliding fits | 0.020 – 0.07 mm |
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| H7/g6 | Precision fits, rotating pins | 0.010 – 0.05 mm |
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| H6/g5 | Spindles, high-precision shafts | 0.004 – 0.025 mm |
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### Small clearance — centering
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| Fit | Typical application | Indicative clearance (Ø50) |
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|---|---|---|
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| H7/h6 | Positioning, removable centering | 0 – 0.025 mm |
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| H6/h5 | High-precision positioning | 0 – 0.013 mm |
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---
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## Transition Fits
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May result in slight clearance or slight interference — the statistical distribution of
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manufacturing determines the actual type on each individual part.
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| Fit | Typical application | Clearance/Interference (Ø50) |
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|---|---|---|
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| H7/js6 | Removable pins, loose pulleys | ±0.008 mm |
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| H7/k6 | Bushings, rings, removable keys | −0.002 … +0.018 mm |
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| H7/m6 | Sleeves, hot-removable gears | −0.009 … +0.011 mm |
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| H6/k5 | High precision, precision gears | −0.002 … +0.009 mm |
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**Practical rule**: k6 is press-fit and removed with a puller. m6 requires a heavier press
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or heating. Both are "removable" but require tooling.
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---
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## Interference Fits
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⚠️ Before specifying an interference, **always calculate**:
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1. Contact pressure at the joint
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2. Hoop stress in the hub
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3. Radial stress in the shaft (if hollow)
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4. Transmissible torque by friction (verify sufficiency)
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5. Assembly temperature if thermal
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→ Use `fundamental-deviations.md` for exact values, then apply Lamé equations.
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| Fit | Typical application | Indicative interference (Ø50) | Assembly |
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|---|---|---|---|
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| H7/n6 | Fixed bushings, sealing rings, bronze bearings | 0 … 0.033 mm | Press (up to 10 kN on Ø50) |
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| H7/p6 | Gears on shaft, fixed pulleys, hubs | 0.009 … 0.042 mm | Press or thermal |
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| H7/r6 | Medium-torque transmission hubs | 0.020 … 0.055 mm | Thermal (Δt = 80–150°C) |
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| H7/s6 | High-torque transmission | 0.031 … 0.066 mm | Thermal (Δt = 150–250°C) |
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| H7/u6 | Bronze/cast-iron bushings, maximum interference | 0.053 … 0.094 mm | Thermal (Δt ≥ 250°C) |
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| H6/p5 | Inner rings of P5/P4 precision bearings | — | Thermal |
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### Interference verification formulas
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```
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Contact pressure: p = δ / [d × (C_o/E_o + C_i/E_i)]
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where δ = actual interference (mm)
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d = nominal diameter (mm)
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C_o, C_i = shape coefficients (from Lamé)
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E_o, E_i = elastic moduli of materials
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Transmissible torque: Mt = p × π × d² × L × μ / 2
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where L = contact length
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μ = friction coefficient (0.08–0.12 thermal, 0.12–0.15 press)
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Assembly temperature: ΔT = δ_max / (α × d) [°C]
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where α = thermal expansion coefficient (steel: 11.5×10⁻⁶ /°C)
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+ add 30–50°C for assembly clearance
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```
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---
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> For bearings, gears, valves, keys, Seeger rings, pins, bushings, seals, and all other
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> functional elements → see `functional-elements.md` (includes decision flowchart).
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# Functional Elements — Tolerances and Fits
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---
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## 1. Rolling Bearings (ISO 286-1 + ISO 15 / ISO 76)
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### Fundamental principle
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The ring that **rotates relative to the load direction** must have **interference** with its seat.
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If the load-carrying ring can slip in its seat, "creep" begins: progressive erosion, vibration
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and premature failure.
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### Fixed end / free end scheme (thermal expansion)
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```
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Fixed end (FE) Free end (FL)
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Shaft: k5 / m5 (interference) h6 (deliberate clearance)
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Housing: H7 (clearance) G7 / H7 (clearance)
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┌────────────────────────────────────────────────────┐
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│ [Bearing FE] ═══ shaft ═══ [Bearing FL] │
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│ k5 / H7 h6 / H7 or G7 │
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└────────────────────────────────────────────────────┘
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FE: locked axially FL: free to slide
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(outer ring retained (outer ring free to move
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by shoulder/Seeger ring) in bore for thermal growth)
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```
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> The free end exists because the shaft grows thermally: without it, parasitic axial loads
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> build up and destroy bearings and structure.
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### Tolerance table — Ball and roller bearings (class P0/P6)
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#### SHAFT seat (inner ring)
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| Condition | d ≤ 18 mm | 18 < d ≤ 100 mm | 100 < d ≤ 200 mm | Notes |
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|---|---|---|---|---|
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| Light / variable load | h5, js5 | h6, js6 | h6 | Easy to disassemble |
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| **Normal load** (motors, gearboxes) | **k5** | **k5, m5** | **m6, n6** | Industrial standard |
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| Heavy load / impact | m5, n5 | m5, n5, p5 | n6, p6 | Thermal assembly |
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| Pure axial thrust | js5, h5 | js6, h6 | h6 | No load rotation |
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| Free end | h6 | h6 | h6 | Deliberate clearance for thermal growth |
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#### HOUSING seat (outer ring)
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| Condition | Bore tolerance | Notes |
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|---|---|---|
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| Fixed outer ring, rotating load on shaft | **H7** | Standard — removable |
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| Impact loads / vibrations | **JS7, K7** | Slight interference |
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| Rotating outer ring (wheels, idler pulleys) | **N7, M7** | Interference — non-removable |
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| Heavy loads with rotating outer ring | **P7** | Strong interference |
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| Adjustable or frequently removable support | **G7** | Deliberate clearance |
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### Precision bearings (class P5, P4, P2)
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| Class | Shaft | Housing | Application |
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|---|---|---|---|
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| P5 | j5, k5 | H6, JS6 | Simple spindles, precision pumps |
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| P4 | j5, k4 | H5, JS5 | Machine tool spindles |
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| P2 | j4, k4 | H4 | High-precision grinders, measuring machines |
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### Angular contact bearings (matched pair)
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For O (back-to-back) or X (face-to-face) mounting with preload:
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- Shaft: js5 or k5 (maintains axial preload)
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- Housing: JS6 (for controlled preload) or H7 standard
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- ⚠️ Avoid heavy interference: it reduces the bearing's internal preload
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### Bearing seat roughness
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| Element | Ra | Rz | Notes |
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|---|---|---|---|
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| Shaft (P0/P6) | ≤ 0.8 µm | ≤ 4 µm | Cylindrical grinding required |
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| Housing (P0/P6) | ≤ 1.6 µm | ≤ 8 µm | Fine boring or internal grinding |
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| Shaft (P5/P4) | ≤ 0.4 µm | ≤ 2 µm | Precision grinding |
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| Shoulder / axial abutment | ≤ 1.6 µm | — | Flatness important (± 0.005 mm) |
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### Practical rules for common machines
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| Machine | Shaft (inner ring) | Housing (outer ring) |
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|---|---|---|
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| Electric motor (drive side) | m5 | H7 |
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| Electric motor (free end) | k5 | H7 |
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| Industrial gearbox | k5 or m5 | H7 or JS7 |
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| Centrifugal pump | k5 or m5 | H7 |
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| Fan (vibrations) | m5 | JS7 |
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| Wheel / idler pulley | h6 | N7 or M7 |
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| Machine tool spindle | j5 or k5 | H6 or JS6 |
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---
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## 2. Gears
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### Gear bore – shaft fit
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| Requirement | Fit | Torque path | Notes |
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|---|---|---|---|
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| Removable, frequent maintenance | H7/h6 + key | Key only | Small clearance, cold-removable |
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| Removable, infrequent maintenance | H7/k6 + key | Key + slight interference | **Industrial standard** |
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| Hot-removable, high precision | H7/m6 + key | Key + medium interference | Heat to 80–120°C |
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| Fixed, moderate torque | H7/p6 | Interference only | No key → no stress concentration |
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| Fixed, high torque | H7/r6 or s6 | Interference only | Thermal assembly mandatory |
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| High angular precision | H6/k5 + key | Key | Minimises run-out |
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### Tooth profile quality (ISO 1328-1)
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| Quality | Application | Indicative tooth IT | Finishing process |
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|---|---|---|---|
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| 3–5 | Measurement, instruments | IT5–IT6 | Profile grinding |
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| 6–7 | Machine tools, precision gearboxes | IT6–IT7 | Grinding or shaving |
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| 8–9 | Industrial gearboxes | IT7–IT8 | Shaving / hobbing |
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| 10–11 | General mechanics | IT9–IT10 | Hobbing only |
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| 12 | Toys, low speed | IT11–IT12 | Rough hobbing |
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### Centre distance tolerance (ISO 1328)
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| Application | Tolerance | IT grade (indicative) |
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|---|---|---|
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| Precision gearboxes | ±0.01 – 0.02 mm | IT6–IT7 |
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| Industrial gearboxes | ±0.03 – 0.05 mm | IT8–IT9 |
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| General mechanics | ±0.1 mm | IT10–IT11 |
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---
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## 3. Valve Seats
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### Internal combustion engine valves
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| Component | Typical material | Fit | Notes |
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|---|---|---|---|
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| Exhaust valve seat insert | Sintered steel | H7/s6 – H7/u6 | High interference: retains at operating Δt (up to 300°C) |
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| Intake valve seat insert | Cast iron or sintered | H7/r6 – H7/s6 | Medium interference |
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| Valve guide | Bronze or sintered | H7/p6 or H7/r6 (OD) + D9/f7 (ID) | External fix + stem clearance |
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| Valve stem in guide | Nitrided steel | D9/f7 or G8/f7 | Clearance 0.03–0.08 mm (intake) 0.05–0.10 mm (exhaust) |
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### Pneumatic / hydraulic valves
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| Type | Fit | Required Ra | Notes |
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|---|---|---|---|
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| Fixed seat (press in) | H7/r6 – H7/s6 | Ra ≤ 0.8 µm (seat) | Seal by interference + optional sealant |
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||||||
|
| Spool / slide valve | H7/f7 – H7/g6 | **Ra ≤ 0.4 µm** | Gap 0.01–0.05 mm critical for leakage |
|
||||||
|
| Piston rod / stem | H8/f7 | Ra ≤ 0.8 µm | Combined with O-ring or lip seal |
|
||||||
|
| High-pressure piston (no seal) | H6/g5 | Ra ≤ 0.2 µm | Metal-to-metal seal — gap 3–8 µm |
|
||||||
|
|
||||||
|
---
|
||||||
|
|
||||||
|
## 4. Transmission Shafts — Complete Layout
|
||||||
|
|
||||||
|
### Functional zone map
|
||||||
|
|
||||||
|
```
|
||||||
|
┌────┬──────────┬──────┬──────────┬──────┬──────────┬────┐
|
||||||
|
│ FE │ bearing │ non │ gear │ non │ bearing │ FL │
|
||||||
|
│ │ (k5/m5) │ func │ (k6/p6) │ func │ (h6) │ │
|
||||||
|
└────┴──────────┴──────┴──────────┴──────┴──────────┴────┘
|
||||||
|
↑ ↑
|
||||||
|
fixed end free end
|
||||||
|
(axial load locked) (free to slide axially)
|
||||||
|
```
|
||||||
|
|
||||||
|
### Tolerance table by shaft zone
|
||||||
|
|
||||||
|
| Functional zone | Shaft tolerance | Ra | Element |
|
||||||
|
|---|---|---|---|
|
||||||
|
| Bearing seat — fixed end | k5 or m5 | ≤ 0.8 µm | Bearing inner ring |
|
||||||
|
| Bearing seat — free end | h6 | ≤ 0.8 µm | Bearing inner ring (slides) |
|
||||||
|
| Removable gear seat | k6 | ≤ 1.6 µm | Gear + key N9 |
|
||||||
|
| Fixed gear seat | p6 | ≤ 0.8 µm | Gear (interference) |
|
||||||
|
| Lip seal seat (simmering) | h11 or h8 | **0.2–0.4 µm** | Rubber/PTFE lip |
|
||||||
|
| Seeger ring groove on shaft | h11 (groove diameter) | ≤ 3.2 µm | Snap ring |
|
||||||
|
| Keyway width | N9 | ≤ 3.2 µm | DIN 6885 key |
|
||||||
|
| Non-functional zones / fillets | h9 – h11 | ≤ 6.3 µm | — |
|
||||||
|
| Threaded end | 6g (thread) | — | Locking nut |
|
||||||
|
|
||||||
|
---
|
||||||
|
|
||||||
|
## 5. Keys (DIN 6885-1 / ISO 773)
|
||||||
|
|
||||||
|
→ For dimension tables, fit types, clearance calculation and torque check: see `keys-keyways.md`
|
||||||
|
|
||||||
|
### Fit summary
|
||||||
|
|
||||||
|
| Fit type | Shaft keyway | Hub keyway | Key | Use |
|
||||||
|
|---|---|---|---|---|
|
||||||
|
| Normal | N9 | JS9 | h9 | **Industrial standard** |
|
||||||
|
| Sliding | H9 | D10 | h9 | Hub slides axially |
|
||||||
|
| Tight | P9 | P9 | h9 | No clearance, high precision |
|
||||||
|
|
||||||
|
> ⚠️ The keyway is a stress concentration feature that reduces shaft fatigue strength
|
||||||
|
> by 25–40%. Do not position at zones of maximum bending.
|
||||||
|
|
||||||
|
---
|
||||||
|
|
||||||
|
## 6. Snap Rings — Seeger (DIN 471 / DIN 472)
|
||||||
|
|
||||||
|
### Types
|
||||||
|
- **DIN 471**: ring for **shaft** (opens to mount in external groove)
|
||||||
|
- **DIN 472**: ring for **bore** (closes to mount in internal groove)
|
||||||
|
|
||||||
|
### Groove tolerances
|
||||||
|
|
||||||
|
#### DIN 471 — Groove on SHAFT
|
||||||
|
|
||||||
|
| Shaft diameter d (mm) | Groove width b | Tolerance b | Groove diameter d1 | Tolerance d1 |
|
||||||
|
|---|---|---|---|---|
|
||||||
|
| 6 – 9 | 0.9 | h13 | d − 1.0 | h11 |
|
||||||
|
| 9 – 19 | 1.0 | h13 | d − 1.1 | h11 |
|
||||||
|
| 19 – 28 | 1.2 | h13 | d − 1.3 | h11 |
|
||||||
|
| 28 – 46 | 1.5 | h13 | d − 1.65 | h11 |
|
||||||
|
| 46 – 80 | 1.75 | h13 | d − 1.95 | h11 |
|
||||||
|
| 80 – 100 | 2.0 | h13 | d − 2.25 | h11 |
|
||||||
|
|
||||||
|
#### DIN 472 — Groove in BORE (housing)
|
||||||
|
|
||||||
|
| Bore diameter D (mm) | Groove width b | Tolerance b | Groove diameter D1 | Tolerance D1 |
|
||||||
|
|---|---|---|---|---|
|
||||||
|
| 8 – 14 | 1.0 | H13 | D + 1.0 | H11 |
|
||||||
|
| 14 – 22 | 1.1 | H13 | D + 1.2 | H11 |
|
||||||
|
| 22 – 38 | 1.2 | H13 | D + 1.3 | H11 |
|
||||||
|
| 38 – 65 | 1.5 | H13 | D + 1.6 | H11 |
|
||||||
|
| 65 – 100 | 1.8 | H13 | D + 2.0 | H11 |
|
||||||
|
| 100 – 120 | 2.0 | H13 | D + 2.2 | H11 |
|
||||||
|
|
||||||
|
### Practical rules
|
||||||
|
- The H11/h11 groove is intentionally wide to allow ring installation with pliers
|
||||||
|
- Groove diameter controls axial load capacity: always verify against ring load rating (SKF/Seeger tables)
|
||||||
|
- Groove root radius: r ≤ 0.2 mm to prevent ring jamming
|
||||||
|
- Do not use Seeger rings for alternating or impact axial loads: use a shoulder or nut
|
||||||
|
|
||||||
|
---
|
||||||
|
|
||||||
|
## 7. Cylindrical and Tapered Pins (ISO 8734 / ISO 8735 / ISO 2339)
|
||||||
|
|
||||||
|
### Cylindrical pins (ISO 8734 — hardened steel, ISO 8735 — with extraction thread)
|
||||||
|
|
||||||
|
| Function | Pin–bore fit | Notes |
|
||||||
|
|---|---|---|
|
||||||
|
| Fixed locating / torque pin | **H7/n6** | Interference — press fit, non-removable |
|
||||||
|
| Fixed pin with extraction (ISO 8735) | **H7/n6** | Same, but removable with extractor |
|
||||||
|
| Removable locating pin | **H7/g6** | Controlled clearance — hand-removable |
|
||||||
|
| Hinge / pivot pin | **H7/f7** | Clearance for rotation — lubrication recommended |
|
||||||
|
|
||||||
|
### Tapered pins (ISO 2339 — taper 1:50)
|
||||||
|
- Self-locking: retained by elastic deformation — no special tolerance needed
|
||||||
|
- Bore produced by **reaming with tapered reamer** after assembly (recommended)
|
||||||
|
- Disadvantage: bore is not interchangeable — each pin is matched to its bore
|
||||||
|
|
||||||
|
### Locating hole position (GD&T)
|
||||||
|
|
||||||
|
```
|
||||||
|
TP_bore ≤ 0.5 × min_clearance (for locating pins)
|
||||||
|
TP_bore ≤ 0.3 × min_interference (for fixed pins)
|
||||||
|
```
|
||||||
|
|
||||||
|
---
|
||||||
|
|
||||||
|
## 8. Plain Bearings / Bushings
|
||||||
|
|
||||||
|
### Types and materials
|
||||||
|
|
||||||
|
| Type | Material | Characteristic | Outer fit (in housing) |
|
||||||
|
|---|---|---|---|
|
||||||
|
| Bronze bushing | CuSn8, CuZn24Al | High load capacity, lubrication required | **H7/s6 or H7/u6** |
|
||||||
|
| Sintered self-lubricating | Fe or Cu sintered | Impregnated lubrication, low speed | **H7/r6 or H7/s6** |
|
||||||
|
| PTFE / graphite bushing | PTFE composite | Dry, low speed, high temperature | **H7/p6 or H7/r6** |
|
||||||
|
| Bimetal (steel + bronze) | St + CuSn | High load capacity | **H7/s6** |
|
||||||
|
| Nylon / POM bushing | Polyamide, POM | Lightweight, low torque, quiet | **H7/p6** (check thermal Δt) |
|
||||||
|
|
||||||
|
### Inner fit: bushing bore – shaft
|
||||||
|
|
||||||
|
| Condition | Fit | Indicative clearance | Notes |
|
||||||
|
|---|---|---|---|
|
||||||
|
| Continuous rotation, lubricated | H7/f7 or H8/f7 | 0.02–0.07 mm (Ø50) | Standard — clearance for oil film |
|
||||||
|
| High speed, forced lubrication | H7/g6 | 0.01–0.05 mm (Ø50) | More stable hydrodynamic film |
|
||||||
|
| Oscillating (no full rotation) | H9/f9 or H9/e9 | 0.04–0.12 mm (Ø50) | More clearance to avoid stick-slip |
|
||||||
|
| Very light load, low speed | H8/h8 | 0–0.054 mm (Ø50) | Near zero clearance, marginal lubrication |
|
||||||
|
|
||||||
|
### Note on plastic bushings (POM/PA)
|
||||||
|
Plastics have 5–10× higher thermal expansion than steel.
|
||||||
|
- At ambient temperature: use recommended fit
|
||||||
|
- At operating temperature: verify interference does not generate excessive pressure (hub cracking
|
||||||
|
risk) and that internal clearance does not become negative (seizure)
|
||||||
|
- Rule of thumb: for POM with Δt = +50°C on Ø30, allow 0.06 mm additional clearance
|
||||||
|
|
||||||
|
---
|
||||||
|
|
||||||
|
## 9. Radial Shaft Seals / Lip Seals (DIN 3760 / ISO 6194)
|
||||||
|
|
||||||
|
### Seat tolerances
|
||||||
|
|
||||||
|
| Element | Tolerance | Ra | Notes |
|
||||||
|
|---|---|---|---|
|
||||||
|
| **Shaft** (lip contact surface) | **h11** or **h8** | **Ra 0.2–0.4 µm** | Circumferential texture — NOT helical |
|
||||||
|
| Housing bore (seal press-in) | **H8** | Ra 1.6–3.2 µm | Lead-in chamfer at entry (15°, r=0.3 mm) |
|
||||||
|
|
||||||
|
### Lip material and speed limits
|
||||||
|
|
||||||
|
| Lip material | Max speed (m/s) | Temperature range | Notes |
|
||||||
|
|---|---|---|---|
|
||||||
|
| NBR (nitrile) | ≤ 6 m/s | −40 / +100°C | Standard — mineral oil |
|
||||||
|
| FKM (Viton) | ≤ 9 m/s | −20 / +180°C | Synthetic oil, high temperature |
|
||||||
|
| PTFE | ≤ 15 m/s | −60 / +200°C | Low friction, marginal lubrication |
|
||||||
|
| PTFE with stainless lip | ≤ 20 m/s | −60 / +200°C | High speed |
|
||||||
|
|
||||||
|
### Critical requirements
|
||||||
|
|
||||||
|
1. **Shaft hardness**: min 55 HRC (or surface treatment: nitriding, chrome plating)
|
||||||
|
— Soft shaft → lip cuts surface within hours → seal failure
|
||||||
|
2. **Circumferential finish**: texture must be perpendicular to axis
|
||||||
|
— Axial grinding direction: lip pumps fluid outward (screw effect → leaks)
|
||||||
|
3. **Shaft eccentricity (TIR)**: max 0.1–0.2 mm depending on diameter and speed
|
||||||
|
4. **Internal pressure**: standard seals up to 0.3 bar; above → reinforced spring seal or double lip
|
||||||
|
|
||||||
|
---
|
||||||
|
|
||||||
|
## 10. Locating and Positioning Pins
|
||||||
|
|
||||||
|
### Self-locking taper pins
|
||||||
|
- Taper 1:50 (ISO 2339 standard): self-locking, suitable for moderate torque
|
||||||
|
- Taper 1:30 (DIN 1): used on tooling, easier to remove
|
||||||
|
- Extraction slot in head is always recommended
|
||||||
|
|
||||||
|
### Spring pins (ISO 8752)
|
||||||
|
|
||||||
|
| Application | Notes |
|
||||||
|
|---|---|
|
||||||
|
| Light positioning, low torque | Economical, bore tolerance H12 — easy assembly |
|
||||||
|
| Replaces solid pin in vibrating environments | Spring elasticity absorbs vibrations |
|
||||||
|
|
||||||
|
### Locating pins for flanges and plates
|
||||||
|
- Standard: 2 pins diametrically opposed (no more — redundancy creates GD&T issues)
|
||||||
|
- Diameter: 6–12 mm for most industrial cases
|
||||||
|
- Fit: H7/n6 on both bores (matched plates) or H7/g6 if frequently removed
|
||||||
|
|
||||||
|
---
|
||||||
|
|
||||||
|
## 11. Involute Splines (ISO 4156 / DIN 5480)
|
||||||
|
|
||||||
|
For applications requiring:
|
||||||
|
- High torque (> 500 Nm on shafts Ø < 50 mm)
|
||||||
|
- Frequent reversals (no angular backlash)
|
||||||
|
- High-precision angular connections that must be removable
|
||||||
|
|
||||||
|
### Fit classes (ISO 4156)
|
||||||
|
|
||||||
|
| Class | Application | Notes |
|
||||||
|
|---|---|---|
|
||||||
|
| **H/h** (clearance) | Removable, axially sliding | Standard for couplings |
|
||||||
|
| **H/js** (transition) | Precise positioning, fixed | Light press |
|
||||||
|
| **H/k, H/m** (interference) | Fixed, high torque | Same as solid hub fits |
|
||||||
|
|
||||||
|
> Do not dimension individual teeth: use the full ISO 4156 designation
|
||||||
|
> (e.g. "DIN 5480 W30×2×14×9H/9h") and reference the standard.
|
||||||
|
|
||||||
|
---
|
||||||
|
|
||||||
|
## 12. Couplings
|
||||||
|
|
||||||
|
### Rigid couplings (sleeves, discs)
|
||||||
|
|
||||||
|
| Condition | Shaft–coupling fit | Notes |
|
||||||
|
|---|---|---|
|
||||||
|
| Fixed, removable | H7/k6 + key | Light press, hot-removable |
|
||||||
|
| Fixed, non-removable | H7/p6 or r6 | Interference — thermal assembly |
|
||||||
|
| Precision (no angular play) | H6/k5 | High precision |
|
||||||
|
|
||||||
|
### Flexible couplings (spider, elastomer)
|
||||||
|
- Shaft–hub fit: H7/k6 or H7/m6
|
||||||
|
- Clearance compensated by elastic element — heavy interference not needed
|
||||||
|
- Misalignment tolerance: see manufacturer's data sheet (typical: 0.1–0.5 mm radial, 0.5–2° angular)
|
||||||
|
|
||||||
|
### Oldham and universal (cardan) joints
|
||||||
|
- Shaft–hub: H7/g6 or H7/h6 + pin or key
|
||||||
|
- Centre element must slide: female side of joint H7/f7 – H8/f8
|
||||||
|
|
||||||
|
---
|
||||||
|
|
||||||
|
## 13. Linear Guides and Sliding Surfaces
|
||||||
|
|
||||||
|
| Guide type | Fit | Ra | Application |
|
||||||
|
|---|---|---|---|
|
||||||
|
| Sliding guide, lubricated | H7/f7 | ≤ 0.8 µm | Machine tools, cylinders |
|
||||||
|
| Sliding guide, high precision | H6/g5 | ≤ 0.4 µm | Measuring machines |
|
||||||
|
| Guide pin / die column | H7/g6 | ≤ 0.8 µm | Dies, fixtures |
|
||||||
|
| Zero-clearance guide (preloaded) | H6/h5 + preload | ≤ 0.4 µm | Precision tables |
|
||||||
|
| Taper centering (self-locating) | — | ≤ 0.8 µm | Taper 1:50–1:100, no ISO tolerance needed |
|
||||||
|
|
||||||
|
---
|
||||||
|
|
||||||
|
## 14. General Tolerances (ISO 2768)
|
||||||
|
|
||||||
|
For non-critical dimensions, use general tolerances rather than tolerancing every dimension.
|
||||||
|
|
||||||
|
| Class | Symbol | Approx. grade | Application |
|
||||||
|
|---|---|---|---|
|
||||||
|
| Fine | f | IT9–IT10 | Precision mechanics |
|
||||||
|
| **Medium** | **m** | **IT11** | **Industrial standard (default)** |
|
||||||
|
| Coarse | c | IT12–IT13 | Structures, fabrications |
|
||||||
|
| Very coarse | v | IT14–IT15 | Raw castings, forgings |
|
||||||
|
|
||||||
|
**Drawing note**: `ISO 2768-mK` (medium linear + medium geometric tolerances)
|
||||||
|
|
||||||
|
---
|
||||||
|
|
||||||
|
## Appendix: Quick Decision Flowchart
|
||||||
|
|
||||||
|
```
|
||||||
|
What is the function of the fit?
|
||||||
|
│
|
||||||
|
├─ Must SLIDE / ROTATE? ─────────────────────────→ Clearance
|
||||||
|
│ ├─ High precision, lubricated → H7/g6 or H6/g5
|
||||||
|
│ ├─ Standard, lubricated → H7/f7 or H8/f7
|
||||||
|
│ └─ Loose, misalignment → H8/e8 or H9/d9
|
||||||
|
│
|
||||||
|
├─ Must LOCATE (removable)? ─────────────────────→ Transition / zero clearance
|
||||||
|
│ ├─ High precision → H6/h5 or H7/js6
|
||||||
|
│ └─ Standard → H7/h6 or H7/k6
|
||||||
|
│
|
||||||
|
├─ Must TRANSMIT TORQUE (fixed)? ────────────────→ Interference
|
||||||
|
│ ├─ Removable with tools → H7/k6 + key
|
||||||
|
│ ├─ Moderate torque → H7/p6
|
||||||
|
│ ├─ High torque → H7/r6 or H7/s6
|
||||||
|
│ └─ Maximum (bronze/cast iron) → H7/u6
|
||||||
|
│
|
||||||
|
├─ Is it a BEARING? ──────────────────────────────→ see §1
|
||||||
|
├─ Is it a KEY / KEYWAY? ─────────────────────────→ see §5 / keys-keyways.md
|
||||||
|
├─ Is it a SEEGER / SNAP RING? ───────────────────→ see §6
|
||||||
|
├─ Is it a PIN? ──────────────────────────────────→ see §7
|
||||||
|
├─ Is it a BUSHING? ──────────────────────────────→ see §8
|
||||||
|
├─ Is it a LIP SEAL / SIMMERING? ─────────────────→ see §9
|
||||||
|
└─ Is it a SPLINED PROFILE? ──────────────────────→ see §11
|
||||||
|
```
|
||||||
@@ -0,0 +1,99 @@
|
|||||||
|
# Fundamental Deviations — Numerical Values (ISO 286-1)
|
||||||
|
|
||||||
|
## How to Read This File
|
||||||
|
|
||||||
|
Example: **Ø50 H7/k6**
|
||||||
|
1. Diameter range: 50 mm → rows "30–50" and "50–80"
|
||||||
|
2. Bore H7: lower deviation EI = 0, upper deviation ES = +25 µm (IT7 for Ø50)
|
||||||
|
3. Shaft k6: lower deviation ei = +2 µm, upper deviation es = ei + IT6 = +2 + 16 = +18 µm
|
||||||
|
4. Max clearance = ES − ei = 25 − 2 = +23 µm → clearance
|
||||||
|
5. Min clearance = EI − es = 0 − 18 = −18 µm → interference
|
||||||
|
→ **Transition fit**, in practice predominantly with slight interference
|
||||||
|
|
||||||
|
---
|
||||||
|
|
||||||
|
## Bore Fundamental Deviations (uppercase) — Lower Deviation EI (µm)
|
||||||
|
|
||||||
|
| Bore | 1–3 | 3–6 | 6–10 | 10–18 | 18–30 | 30–50 | 50–80 | 80–120 | 120–180 | 180–250 |
|
||||||
|
|---|---|---|---|---|---|---|---|---|---|---|
|
||||||
|
| B | +140 | +140 | +150 | +150 | +160 | +170 | +180 | +200 | +210 | +230 |
|
||||||
|
| C | +60 | +70 | +80 | +95 | +110 | +120 | +130 | +145 | +160 | +170 |
|
||||||
|
| D | +20 | +30 | +40 | +50 | +65 | +80 | +100 | +120 | +145 | +170 |
|
||||||
|
| E | +14 | +20 | +25 | +32 | +40 | +50 | +60 | +72 | +85 | +100 |
|
||||||
|
| F | +6 | +10 | +13 | +16 | +20 | +25 | +30 | +36 | +43 | +50 |
|
||||||
|
| G | +2 | +4 | +5 | +6 | +7 | +9 | +10 | +12 | +14 | +15 |
|
||||||
|
| **H** | **0** | **0** | **0** | **0** | **0** | **0** | **0** | **0** | **0** | **0** |
|
||||||
|
| JS | ±IT/2 | ±IT/2 | ±IT/2 | ±IT/2 | ±IT/2 | ±IT/2 | ±IT/2 | ±IT/2 | ±IT/2 | ±IT/2 |
|
||||||
|
| K (6–8) | 0 | +2 | +2 | +2 | +2 | +3 | +4 | +4 | +4 | +5 |
|
||||||
|
| M (6–8) | −2 | −4 | −6 | −7 | −8 | −9 | −11 | −13 | −15 | −17 |
|
||||||
|
| N (6–8) | −4 | −8 | −10 | −12 | −15 | −17 | −20 | −23 | −27 | −31 |
|
||||||
|
| P (6–7) | −6 | −12 | −15 | −18 | −22 | −26 | −32 | −37 | −43 | −50 |
|
||||||
|
| R | −10 | −15 | −19 | −23 | −28 | −34 | −41 | −51 | −63 | −77 |
|
||||||
|
| S | −14 | −19 | −23 | −28 | −35 | −43 | −53 | −71 | −92 | −100 |
|
||||||
|
| U | −18 | −23 | −28 | −33 | −41 | −53 | −66 | −90 | −109 | −130 |
|
||||||
|
|
||||||
|
> **Note**: For H, ES = EI + IT = 0 + IT (e.g. H7/Ø50: ES = +25 µm)
|
||||||
|
|
||||||
|
---
|
||||||
|
|
||||||
|
## Shaft Fundamental Deviations (lowercase) — Upper Deviation es (µm)
|
||||||
|
|
||||||
|
| Shaft | 1–3 | 3–6 | 6–10 | 10–18 | 18–30 | 30–50 | 50–80 | 80–120 | 120–180 | 180–250 |
|
||||||
|
|---|---|---|---|---|---|---|---|---|---|---|
|
||||||
|
| b | −140 | −140 | −150 | −150 | −160 | −170 | −180 | −200 | −210 | −230 |
|
||||||
|
| c | −60 | −70 | −80 | −95 | −110 | −120 | −130 | −145 | −160 | −170 |
|
||||||
|
| d | −20 | −30 | −40 | −50 | −65 | −80 | −100 | −120 | −145 | −170 |
|
||||||
|
| e | −14 | −20 | −25 | −32 | −40 | −50 | −60 | −72 | −85 | −100 |
|
||||||
|
| f | −6 | −10 | −13 | −16 | −20 | −25 | −30 | −36 | −43 | −50 |
|
||||||
|
| g | −2 | −4 | −5 | −6 | −7 | −9 | −10 | −12 | −14 | −15 |
|
||||||
|
| **h** | **0** | **0** | **0** | **0** | **0** | **0** | **0** | **0** | **0** | **0** |
|
||||||
|
| js | ±IT/2 | ±IT/2 | ±IT/2 | ±IT/2 | ±IT/2 | ±IT/2 | ±IT/2 | ±IT/2 | ±IT/2 | ±IT/2 |
|
||||||
|
| k | 0 | +1 | +1 | +1 | +2 | +2 | +2 | +3 | +3 | +4 |
|
||||||
|
| m | +2 | +4 | +6 | +7 | +8 | +9 | +11 | +13 | +15 | +17 |
|
||||||
|
| n | +4 | +8 | +10 | +12 | +15 | +17 | +20 | +23 | +27 | +31 |
|
||||||
|
| p | +6 | +12 | +15 | +18 | +22 | +26 | +32 | +37 | +43 | +50 |
|
||||||
|
| r | +10 | +15 | +19 | +23 | +28 | +34 | +41 | +51 | +63 | +77 |
|
||||||
|
| s | +14 | +19 | +23 | +28 | +35 | +43 | +53 | +71 | +92 | +100 |
|
||||||
|
| u | +18 | +23 | +28 | +33 | +41 | +53 | +66 | +90 | +109 | +130 |
|
||||||
|
|
||||||
|
> **Note**: For h, ei = es − IT = 0 − IT = −IT (e.g. h6/Ø50: ei = −16 µm)
|
||||||
|
|
||||||
|
---
|
||||||
|
|
||||||
|
## Worked Examples
|
||||||
|
|
||||||
|
### Example 1: Ø30 H7/g6
|
||||||
|
|
||||||
|
**Bore H7 (Ø30, range 18–30):**
|
||||||
|
- EI = 0
|
||||||
|
- ES = EI + IT7 = 0 + 21 = +21 µm
|
||||||
|
- Bore: Ø30 +0.021/0
|
||||||
|
|
||||||
|
**Shaft g6 (Ø30, range 18–30):**
|
||||||
|
- es = −7 µm
|
||||||
|
- ei = es − IT6 = −7 − 13 = −20 µm
|
||||||
|
- Shaft: Ø30 −0.007/−0.020
|
||||||
|
|
||||||
|
**Clearances:**
|
||||||
|
- Max clearance = ES − ei = +21 − (−20) = **+41 µm** (0.041 mm)
|
||||||
|
- Min clearance = EI − es = 0 − (−7) = **+7 µm** (0.007 mm)
|
||||||
|
- → **Guaranteed clearance fit** ✓ (lubricated precision guide)
|
||||||
|
|
||||||
|
### Example 2: Ø50 H7/p6
|
||||||
|
|
||||||
|
**Bore H7 (Ø50, range 30–50):**
|
||||||
|
- EI = 0, ES = +25 µm
|
||||||
|
|
||||||
|
**Shaft p6 (Ø50, range 30–50):**
|
||||||
|
- es = +26 µm
|
||||||
|
- ei = +26 − 16 = +10 µm
|
||||||
|
|
||||||
|
**Interferences:**
|
||||||
|
- Max interference = es − EI = +26 − 0 = **+26 µm** (0.026 mm)
|
||||||
|
- Min interference = ei − ES = +10 − 25 = **−15 µm** → clearance possible?
|
||||||
|
|
||||||
|
⚠️ This is a **transition fit** at Ø50! For guaranteed interference on Ø50, p6 gives
|
||||||
|
ei − ES = 10 − 25 = −15: there is still a possibility of clearance.
|
||||||
|
For guaranteed interference on Ø50 use **r6 or s6**.
|
||||||
|
|
||||||
|
→ Always verify numerical values for your specific diameter before finalising the drawing.
|
||||||
@@ -0,0 +1,60 @@
|
|||||||
|
# Information Intake Guide — ISO Tolerances
|
||||||
|
|
||||||
|
## Required Information for a Reliable Recommendation
|
||||||
|
|
||||||
|
### Level 1 — Critical (without these, the recommendation is unreliable)
|
||||||
|
|
||||||
|
| Information | Why it is critical | How to obtain it |
|
||||||
|
|---|---|---|
|
||||||
|
| **Nominal diameter** | IT values in µm depend on the diameter range (IT7 = 15 µm on Ø10, 35 µm on Ø100) | Direct dimension, approximate measurement from drawing, or caliper reading if part exists |
|
||||||
|
| **Function** | Determines the fit type: a sliding guide and an interference hub have opposite requirements | Describe: guides, transmits torque, positions, seals, slides, rotates |
|
||||||
|
| **Removability** | H7/p6 cannot be disassembled without thermal equipment; H7/k6 needs a puller; H7/h6 by hand | Removable in routine maintenance / rarely / never |
|
||||||
|
|
||||||
|
### Level 2 — Important (significantly improve the recommendation)
|
||||||
|
|
||||||
|
| Information | Why it matters | How to obtain it |
|
||||||
|
|---|---|---|
|
||||||
|
| **Available manufacturing process** | No point recommending IT6 if the shop only has standard CNC lathes (IT8–IT9) | CNC turning / grinding / precision boring. Or: minimum guaranteed tolerance from the shop |
|
||||||
|
| **Loads** | Impact/shock loads require more interference to prevent creep on bearings and interference fits | Static / dynamic / impact / vibrations |
|
||||||
|
| **Operating environment** | Operating Δt reduces effective interference; corrosion changes minimum clearance | Operating temperature, lubricant, corrosive environment |
|
||||||
|
| **Materials** | Steel/aluminium → different thermal expansion coefficients → different interference | Shaft and bore materials |
|
||||||
|
|
||||||
|
### Level 3 — Useful (refine the recommendation)
|
||||||
|
|
||||||
|
| Information | Relevance |
|
||||||
|
|---|---|
|
||||||
|
| Rotational speed | For bearings and radial shaft seals |
|
||||||
|
| Transmitted torque | To verify interference sufficiency without Lamé calculation |
|
||||||
|
| Batch size | One-off vs series production: changes the tolerance/cost trade-off |
|
||||||
|
| Industry standard | Automotive, rail, aerospace may have additional standards that override ISO defaults |
|
||||||
|
|
||||||
|
---
|
||||||
|
|
||||||
|
## How to Ask for Missing Information (expert engineer style)
|
||||||
|
|
||||||
|
1. **Show what you understood** from the input or attached image
|
||||||
|
2. **Explain why the gap is blocking** that specific decision
|
||||||
|
3. **Propose a working hypothesis** to confirm: "If it must be removable, I'd go with H7/k6"
|
||||||
|
4. **Suggest how to get the data**: caliper measurement, assembly drawing, machine datasheet
|
||||||
|
|
||||||
|
**Example:**
|
||||||
|
> From the drawing I can see a pin Ø≈40mm going into a bore on a support bracket. I can't
|
||||||
|
> tell whether it needs to **slide** axially or is **fixed** in position. This is critical:
|
||||||
|
> sliding → H7/g6 (clearance 0.01–0.05 mm), fixed → H7/k6 (light press fit).
|
||||||
|
> Can you confirm? An assembly drawing, even a hand sketch, would help a lot.
|
||||||
|
|
||||||
|
---
|
||||||
|
|
||||||
|
## Image Analysis (screenshots, photos, sketches)
|
||||||
|
|
||||||
|
Actively extract from the image:
|
||||||
|
- Dimensional values (even approximate)
|
||||||
|
- Component type (shaft, bore, seat, flange, bearing, keyway…)
|
||||||
|
- Existing annotations (tolerances, roughness, materials already noted)
|
||||||
|
- Assembly context (what mates with what)
|
||||||
|
- Assembly constraints (tool access, space for thermal equipment)
|
||||||
|
|
||||||
|
Then: **summarise your interpretation** to confirm understanding, then ask only for critical gaps.
|
||||||
|
For non-scale drawings or sketches: accept approximate dimensions and state the result is
|
||||||
|
indicative until the exact dimension is confirmed. Recognisable standard components (bearing,
|
||||||
|
key, Seeger ring) → tolerances are often already defined by the manufacturer's catalogue.
|
||||||
@@ -0,0 +1,127 @@
|
|||||||
|
# IT Tolerance Grades — Manufacturing Processes and Applications
|
||||||
|
|
||||||
|
## IT Grade Values by Diameter Range (µm, ISO 286-1)
|
||||||
|
|
||||||
|
| IT Grade | 1–3 mm | 3–6 mm | 6–10 mm | 10–18 mm | 18–30 mm | 30–50 mm | 50–80 mm | 80–120 mm | 120–180 mm | 180–250 mm |
|
||||||
|
|---|---|---|---|---|---|---|---|---|---|---|
|
||||||
|
| IT1 | 0.8 | 1 | 1 | 1.2 | 1.5 | 1.5 | 2 | 2.5 | 3.5 | 4.5 |
|
||||||
|
| IT2 | 1.2 | 1.5 | 1.5 | 2 | 2.5 | 2.5 | 3 | 4 | 5 | 7 |
|
||||||
|
| IT3 | 2 | 2.5 | 2.5 | 3 | 4 | 4 | 5 | 6 | 8 | 10 |
|
||||||
|
| IT4 | 3 | 4 | 4 | 5 | 6 | 7 | 8 | 10 | 12 | 14 |
|
||||||
|
| IT5 | 4 | 5 | 6 | 8 | 9 | 11 | 13 | 15 | 18 | 20 |
|
||||||
|
| IT6 | 6 | 8 | 9 | 11 | 13 | 16 | 19 | 22 | 25 | 29 |
|
||||||
|
| IT7 | 10 | 12 | 15 | 18 | 21 | 25 | 30 | 35 | 40 | 46 |
|
||||||
|
| IT8 | 14 | 18 | 22 | 27 | 33 | 39 | 46 | 54 | 63 | 72 |
|
||||||
|
| IT9 | 25 | 30 | 36 | 43 | 52 | 62 | 74 | 87 | 100 | 115 |
|
||||||
|
| IT10 | 40 | 48 | 58 | 70 | 84 | 100 | 120 | 140 | 160 | 185 |
|
||||||
|
| IT11 | 60 | 75 | 90 | 110 | 130 | 160 | 190 | 220 | 250 | 290 |
|
||||||
|
| IT12 | 100 | 120 | 150 | 180 | 210 | 250 | 300 | 350 | 400 | 460 |
|
||||||
|
| IT13 | 140 | 180 | 220 | 270 | 330 | 390 | 460 | 540 | 630 | 720 |
|
||||||
|
| IT14 | 250 | 300 | 360 | 430 | 520 | 620 | 740 | 870 | 1000 | 1150 |
|
||||||
|
|
||||||
|
---
|
||||||
|
|
||||||
|
## Required Machining by IT Grade — Bores and Shafts
|
||||||
|
|
||||||
|
Distinguishing bore vs. shaft is critical: achieving IT7 on a bore is significantly harder and
|
||||||
|
more expensive than on a shaft, because bores cannot be externally cylindrically ground.
|
||||||
|
|
||||||
|
| IT Grade | Machining for BORES | Machining for SHAFTS | Difficulty | Relative cost |
|
||||||
|
|---|---|---|---|---|
|
||||||
|
| **IT3–IT4** | Precision honing, lapping | Ultra-precision cylindrical grinding, lapping | Extreme | ★★★★★ |
|
||||||
|
| **IT5** | Precision boring (single-blade), fine honing | Precision cylindrical grinding (Ra 0.2) | Very high | ★★★★☆ |
|
||||||
|
| **IT6** | Fine CNC boring (single-blade tool), internal grinding | Standard cylindrical grinding | High | ★★★☆☆ |
|
||||||
|
| **IT7** | CNC boring with adjustable insert, fine internal turning | Fine CNC turning (high Vc, low feed), grinding | Medium | ★★☆☆☆ |
|
||||||
|
| **IT8** | Standard drilling + reaming, internal turning | Standard CNC turning | Low | ★★☆☆☆ |
|
||||||
|
| **IT9** | Drilling with sharp bits, rough internal turning | Standard turning | Very low | ★☆☆☆☆ |
|
||||||
|
| **IT10–IT11** | Standard drilling, punching | Rough turning, milling | Minimal | ★☆☆☆☆ |
|
||||||
|
| **IT12–IT14** | Shell casting, stamping | Forging, sand casting | — | ★☆☆☆☆ |
|
||||||
|
|
||||||
|
### Operational notes by IT grade
|
||||||
|
|
||||||
|
#### IT5–IT6 (high precision)
|
||||||
|
- **Bores**: single-blade boring is the reference process. Requires rigid fixture, carbide tool,
|
||||||
|
correct coolant. Alternative: internal grinding (more expensive, requires dedicated machine).
|
||||||
|
- **Shafts**: between-centers or collet cylindrical grinding. Freshly dressed wheel, active
|
||||||
|
thermal compensation.
|
||||||
|
- **Minimum equipment**: rigid machining centre (≥15kN spindle), in-process gauging recommended.
|
||||||
|
|
||||||
|
#### IT7 (standard reference grade)
|
||||||
|
- **Bores**: CNC boring with adjustable insert (e.g. Sandvik CoroBore, Kennametal). Standard
|
||||||
|
drilling alone does not reliably achieve IT7. Economic alternative: pilot drill + machine
|
||||||
|
reamer with calibrated reamer (IT7 guaranteed).
|
||||||
|
- **Shafts**: fine turning with wiper insert. On modern CNC, IT7 is routine. Watch out: long
|
||||||
|
chips or gummy materials (stainless steel, construction aluminium) tend to drift to IT8.
|
||||||
|
- **Inspection**: go/no-go plug gauge for bores, ring gauge or micrometer for shafts.
|
||||||
|
Measure after the part has cooled.
|
||||||
|
|
||||||
|
#### IT8 (standard production)
|
||||||
|
- Achievable with standard turning and drilling — no special equipment.
|
||||||
|
- Suitable for keyways, non-critical sliding bushings, loose fits.
|
||||||
|
|
||||||
|
#### IT9–IT11 (free tolerances)
|
||||||
|
- Standard for non-functional dimensions. Covered by ISO 2768-m (IT11) general tolerances.
|
||||||
|
|
||||||
|
---
|
||||||
|
|
||||||
|
## Manufacturing Processes and Achievable IT Grades
|
||||||
|
|
||||||
|
| Manufacturing process | Typical IT grades | Notes |
|
||||||
|
|---|---|---|
|
||||||
|
| Lapping / superfinishing | IT3 – IT5 | Extreme finishes, small parts |
|
||||||
|
| Precision honing | IT4 – IT6 | Cylinders, engine bore |
|
||||||
|
| Precision cylindrical grinding | IT4 – IT6 | High-precision shafts, spindles |
|
||||||
|
| Standard cylindrical grinding | IT5 – IT7 | Transmission shafts, bearing seats |
|
||||||
|
| Fine turning / diamond | IT5 – IT7 | Non-ferrous alloys, bronze, aluminium |
|
||||||
|
| Precision boring (single-blade) | IT5 – IT7 | High-precision bores |
|
||||||
|
| Internal grinding | IT5 – IT7 | Large diameter bores |
|
||||||
|
| CNC boring (adjustable insert) | IT6 – IT8 | Standard coupling bores |
|
||||||
|
| Fine CNC turning (wiper insert) | IT6 – IT8 | Standard functional shafts |
|
||||||
|
| EDM | IT5 – IT8 | Dies, complex forms |
|
||||||
|
| Standard CNC turning | IT7 – IT9 | Production standard |
|
||||||
|
| Standard reaming / drill + ream | IT8 – IT10 | Non-critical bores |
|
||||||
|
| CNC milling | IT8 – IT10 | Planes, profiles, slots |
|
||||||
|
| Standard drilling | IT10 – IT12 | Through holes, fasteners |
|
||||||
|
| Stamping / blanking | IT10 – IT12 | Sheet metal |
|
||||||
|
| Shell moulding | IT11 – IT14 | Precision castings |
|
||||||
|
| Sand casting | IT14 – IT16 | Raw castings |
|
||||||
|
| Forging | IT14 – IT16 | Semi-finished stock |
|
||||||
|
|
||||||
|
---
|
||||||
|
|
||||||
|
## Grade Selection Guidelines
|
||||||
|
|
||||||
|
### IT01 – IT4
|
||||||
|
- Measuring instruments, gauge blocks, reference standards
|
||||||
|
- Ultra-precision bearings (class P4, P2)
|
||||||
|
- Practically unused in standard mechanical production
|
||||||
|
- Very high cost, requires controlled environments
|
||||||
|
|
||||||
|
### IT5 – IT6
|
||||||
|
- High-precision fits: machine tool spindles, precision shafts
|
||||||
|
- P6/P5 bearings
|
||||||
|
- Precision gears (ISO 1328 quality 5–7)
|
||||||
|
- High-pressure valve seats
|
||||||
|
- Grinding required
|
||||||
|
|
||||||
|
### IT7
|
||||||
|
- **The most widely used grade in industrial mechanics**
|
||||||
|
- Functional shaft-bore fits (H7/k6, H7/g6, H7/h6, etc.)
|
||||||
|
- Standard bearing housing bores (class P0/P6)
|
||||||
|
- Fine turning or CNC boring on modern machines
|
||||||
|
|
||||||
|
### IT8
|
||||||
|
- Less critical fits, larger clearances
|
||||||
|
- Keyways, key slots
|
||||||
|
- Non-critical sliding bushings
|
||||||
|
- Good-quality standard turning
|
||||||
|
|
||||||
|
### IT9 – IT10
|
||||||
|
- Non-coupled components
|
||||||
|
- Thicknesses, lengths, non-functional positions
|
||||||
|
- High-quality free dimensions (ISO 2768-f, -m)
|
||||||
|
|
||||||
|
### IT11 – IT14
|
||||||
|
- Standard free tolerances (ISO 2768-c, -v)
|
||||||
|
- General tolerances on drawings
|
||||||
|
- Non-functional distances, clearances, spaces
|
||||||
@@ -0,0 +1,147 @@
|
|||||||
|
# Keys and Keyways (DIN 6885-1 / ISO 773)
|
||||||
|
|
||||||
|
## Applicable Standards
|
||||||
|
- **ISO 773 / DIN 6885-1**: parallel keys (Woodruff, forms A/B/C)
|
||||||
|
- **ISO 3912 / DIN 6885-2**: square-section keys
|
||||||
|
- **DIN 6886**: taper keys
|
||||||
|
- For width fits: **ISO 286-1** (same IT basis)
|
||||||
|
|
||||||
|
---
|
||||||
|
|
||||||
|
## Standard Key Dimensions (DIN 6885-1 / ISO 773)
|
||||||
|
|
||||||
|
| Shaft Ø (mm) | b × h (mm) | t1 shaft (mm) | t2 hub (mm) | Radius r (mm) |
|
||||||
|
|---|---|---|---|---|
|
||||||
|
| 6 – 8 | 2 × 2 | 1.2 | 1.0 | 0.16–0.25 |
|
||||||
|
| 8 – 10 | 3 × 3 | 1.8 | 1.4 | 0.16–0.25 |
|
||||||
|
| 10 – 12 | 4 × 4 | 2.5 | 1.8 | 0.16–0.25 |
|
||||||
|
| 12 – 17 | 5 × 5 | 3.0 | 2.3 | 0.25–0.40 |
|
||||||
|
| 17 – 22 | 6 × 6 | 3.5 | 2.8 | 0.25–0.40 |
|
||||||
|
| 22 – 30 | 8 × 7 | 4.0 | 3.3 | 0.25–0.40 |
|
||||||
|
| 30 – 38 | 10 × 8 | 5.0 | 3.3 | 0.40–0.60 |
|
||||||
|
| 38 – 44 | 12 × 8 | 5.0 | 3.3 | 0.40–0.60 |
|
||||||
|
| 44 – 50 | 14 × 9 | 5.5 | 3.8 | 0.40–0.60 |
|
||||||
|
| 50 – 58 | 16 × 10 | 6.0 | 4.3 | 0.40–0.60 |
|
||||||
|
| 58 – 65 | 18 × 11 | 7.0 | 4.4 | 0.40–0.60 |
|
||||||
|
| 65 – 75 | 20 × 12 | 7.5 | 4.9 | 0.60–0.80 |
|
||||||
|
| 75 – 85 | 22 × 14 | 9.0 | 5.4 | 0.60–0.80 |
|
||||||
|
| 85 – 95 | 25 × 14 | 9.0 | 5.4 | 0.60–0.80 |
|
||||||
|
| 95 – 110 | 28 × 16 | 10.0 | 6.4 | 0.60–0.80 |
|
||||||
|
| 110 – 130 | 32 × 18 | 11.0 | 7.4 | 1.00–1.20 |
|
||||||
|
| 130 – 150 | 36 × 20 | 12.0 | 8.4 | 1.00–1.20 |
|
||||||
|
| 150 – 170 | 40 × 22 | 13.0 | 9.4 | 1.00–1.20 |
|
||||||
|
| 170 – 200 | 45 × 25 | 15.0 | 10.4 | 1.60–2.00 |
|
||||||
|
| 200 – 230 | 50 × 28 | 17.0 | 11.4 | 1.60–2.00 |
|
||||||
|
|
||||||
|
> t1 = keyway depth on shaft (measured from outer diameter)
|
||||||
|
> t2 = keyway depth in hub (measured from inner diameter)
|
||||||
|
|
||||||
|
---
|
||||||
|
|
||||||
|
## Fit Types for Keys (DIN 6885)
|
||||||
|
|
||||||
|
| Type | Shaft keyway | Hub keyway | Key | Use |
|
||||||
|
|---|---|---|---|---|
|
||||||
|
| **Normal (N)** | **N9** | **JS9** | **h9** | Industrial standard — slight side clearance |
|
||||||
|
| **Sliding (S)** | **H9** | **D10** | **h9** | Hub must slide axially on shaft |
|
||||||
|
| **Tight (P)** | **P9** | **P9** | **h9** | No side clearance — precision applications |
|
||||||
|
|
||||||
|
### When to use which type
|
||||||
|
|
||||||
|
**Normal fit** (most common): minimal guaranteed clearance on both flanks. The key transmits
|
||||||
|
torque but may have slight clearance causing a knock at start/stop reversals. Acceptable for
|
||||||
|
most industrial gears, pulleys, couplings on transmission shafts.
|
||||||
|
|
||||||
|
**Sliding fit**: the hub must slide axially (e.g. friction clutches, synchroniser assemblies,
|
||||||
|
linear actuators). Larger side clearance. Not suitable where angular precision is required.
|
||||||
|
|
||||||
|
**Tight fit**: no side clearance. Torque transmitted without backlash, precise angular
|
||||||
|
positioning. Assembly requires press fit or heating. Used in machine tools, precision pumps,
|
||||||
|
high-quality gearboxes.
|
||||||
|
|
||||||
|
---
|
||||||
|
|
||||||
|
## Deviations and Clearance Calculation (width b)
|
||||||
|
|
||||||
|
### Example: 8×7 key on Ø25 shaft (range 22–30 mm), Normal fit
|
||||||
|
|
||||||
|
**Shaft keyway N9** (width 8 mm, range 6–10 for width):
|
||||||
|
- IT9 for b=8 mm (range 6–10): IT9 = 36 µm
|
||||||
|
- N9 deviation: es = −10 µm (from fundamental deviations table)
|
||||||
|
- ei = es − IT9 = −10 − 36 = −46 µm
|
||||||
|
- Shaft keyway: 8 −0.010/−0.046 mm
|
||||||
|
|
||||||
|
**Hub keyway JS9** (width 8 mm):
|
||||||
|
- IT9 = 36 µm → JS9 = ±18 µm
|
||||||
|
- Hub keyway: 8 ±0.018 mm → 8 +0.018/−0.018 mm
|
||||||
|
|
||||||
|
**Key h9** (width 8 mm):
|
||||||
|
- IT9 = 36 µm → h9: es = 0, ei = −36 µm
|
||||||
|
- Key: 8 0/−0.036 mm
|
||||||
|
|
||||||
|
**Resulting clearance per flank** (key vs shaft keyway):
|
||||||
|
- Max clearance = ES hub − ei key = (+18) − (−36) = **+54 µm** per flank
|
||||||
|
- Min clearance = EI hub − es key = (−18) − 0 = **−18 µm** (slight interference possible)
|
||||||
|
→ Normal fit: mostly small clearance, rarely slight interference
|
||||||
|
|
||||||
|
---
|
||||||
|
|
||||||
|
## Drawing Dimensions
|
||||||
|
|
||||||
|
### On the shaft drawing
|
||||||
|
- Keyway width: **b ± tolerance** (e.g. 8 N9 → 8 −0.010/−0.046)
|
||||||
|
- Depth: dimension from OD → **d − 2t1** (keyway root diameter)
|
||||||
|
- e.g. Ø30 with t1=4.0: dimension = 30 − 2×4.0 = 22.0 mm (+0.2/0)
|
||||||
|
- Symmetry (if required): positional tolerance relative to axis
|
||||||
|
|
||||||
|
### On the hub / gear drawing
|
||||||
|
- Keyway width: **b ± tolerance** (e.g. 8 JS9 → 8 ±0.018)
|
||||||
|
- Depth: dimension from bore → **d + 2t2**
|
||||||
|
- e.g. bore Ø30 with t2=3.3: dimension = 30 + 2×3.3 = 36.6 mm (+0.2/0)
|
||||||
|
- Keyway flank roughness: **Ra 1.6 – 3.2 µm** (not a precision mating surface)
|
||||||
|
- Keyway root roughness: Ra 3.2 µm (not mating)
|
||||||
|
|
||||||
|
---
|
||||||
|
|
||||||
|
## Torque Transmission Capacity Check
|
||||||
|
|
||||||
|
The key is **not designed to carry torque alone** in interference fits. When combined with
|
||||||
|
H7/p6 or higher, torque is shared between interference friction and the key (redundancy).
|
||||||
|
When combined with H7/h6 or H7/k6, the key carries all the torque.
|
||||||
|
|
||||||
|
### Simplified flank bearing stress check
|
||||||
|
|
||||||
|
```
|
||||||
|
σ = Mt / (A_flank × d/2)
|
||||||
|
A_flank = (h/2 − r) × L_eff [contact area on one flank]
|
||||||
|
|
||||||
|
where:
|
||||||
|
Mt = torque to transmit [N·mm]
|
||||||
|
h = key height [mm]
|
||||||
|
L_eff = effective key length (total length − 2×head radius) [mm]
|
||||||
|
d = shaft diameter [mm]
|
||||||
|
|
||||||
|
Allowable flank stress:
|
||||||
|
Construction steel: σ_allow = 100 – 150 N/mm²
|
||||||
|
Cast iron: σ_allow = 60 – 80 N/mm²
|
||||||
|
Aluminium: σ_allow = 50 – 70 N/mm²
|
||||||
|
```
|
||||||
|
|
||||||
|
### Quick check rule (construction steel C45/42CrMo4)
|
||||||
|
- Key holds without issues if engagement ratio L/d ≥ 1.2
|
||||||
|
- If L/d < 0.8 or high torque + shock loading → double key at 180° or splined profile
|
||||||
|
|
||||||
|
---
|
||||||
|
|
||||||
|
## Risks and Practical Notes
|
||||||
|
|
||||||
|
- **Stress concentration**: the keyway reduces shaft fatigue strength by 25–40% at the
|
||||||
|
critical section. Do not position keyway at cross-section changes or peak bending locations.
|
||||||
|
- **Angular backlash**: even the Normal fit has clearance that produces a knock at every torque
|
||||||
|
reversal. On machines with frequent reversals (servo drives, presses) consider splined
|
||||||
|
profiles (ISO 4156) or pure interference fits.
|
||||||
|
- **Splined profile vs key**: consider when torque > 500 Nm on shafts Ø < 50 mm or when
|
||||||
|
torque is highly variable. ISO 4156 involute splines distribute load across all teeth,
|
||||||
|
eliminate backlash with preload, and reduce the stress concentration.
|
||||||
|
- **Woodruff key (semicircular)**: for tapered shafts or reduced sections (small motors,
|
||||||
|
small pumps). Tolerates angular misalignment. Do not use for high-torsion shafts.
|
||||||
@@ -0,0 +1,75 @@
|
|||||||
|
# IT Grades — Surface Roughness Ra Correlation
|
||||||
|
|
||||||
|
## IT Grade to Ra Correlation Table
|
||||||
|
|
||||||
|
Surface roughness must be consistent with the dimensional tolerance: a surface that is too
|
||||||
|
rough prevents achieving the specified tolerance, while over-specifying roughness is an
|
||||||
|
unnecessary cost.
|
||||||
|
|
||||||
|
**Practical rule**: Ra ≤ T/4 (where T = tolerance band) for mating surfaces.
|
||||||
|
For non-mating surfaces: Ra ≤ T/2 is sufficient.
|
||||||
|
|
||||||
|
| IT Grade | Max Ra recommended | Indicative Rz | Typical process |
|
||||||
|
|---|---|---|---|
|
||||||
|
| IT4 | Ra 0.1 µm | Rz 0.6 µm | Lapping, superfinishing |
|
||||||
|
| IT5 | Ra 0.2 µm | Rz 1.0 µm | Fine grinding, honing |
|
||||||
|
| IT6 | Ra 0.4 µm | Rz 2.0 µm | Standard grinding |
|
||||||
|
| IT7 | Ra 0.8 µm | Rz 4.0 µm | Grinding / fine turning |
|
||||||
|
| IT8 | Ra 1.6 µm | Rz 8.0 µm | Fine CNC turning |
|
||||||
|
| IT9 | Ra 3.2 µm | Rz 16 µm | Standard turning |
|
||||||
|
| IT10 | Ra 6.3 µm | Rz 25 µm | Milling / rough turning |
|
||||||
|
| IT11 | Ra 12.5 µm | Rz 50 µm | Economic machining |
|
||||||
|
| IT12–14 | Ra 25 µm + | Rz > 100 µm | Raw, unfinished |
|
||||||
|
|
||||||
|
---
|
||||||
|
|
||||||
|
## Special Applications
|
||||||
|
|
||||||
|
### Interference fit surfaces
|
||||||
|
For interference fits (p6, r6, s6, u6) on steels:
|
||||||
|
- Ra **≤ 0.8 µm** required (Ra 0.4 µm preferred)
|
||||||
|
- Roughness reduces effective interference by approx. 0.6 × (Rz shaft + Rz bore)
|
||||||
|
- When calculating interference, subtract the profile flattening allowance
|
||||||
|
|
||||||
|
### Sliding surfaces (bushings, guides)
|
||||||
|
- Ra **0.4 – 0.8 µm** for lubricated sliding
|
||||||
|
- Ra **0.2 – 0.4 µm** for dry sliding or critical conditions
|
||||||
|
- Avoid Ra < 0.1 µm (adhesion risk — stick-slip)
|
||||||
|
|
||||||
|
### Rolling bearing seats
|
||||||
|
- Shaft: Ra **0.4 – 0.8 µm** (per SKF/FAG: Ra ≤ 0.8 for standard classes)
|
||||||
|
- Housing bore: Ra **0.8 – 1.6 µm**
|
||||||
|
- P5/P4 precision classes: Ra ≤ 0.4 µm on shaft
|
||||||
|
|
||||||
|
### Radial lip seals (shaft surface at seal contact)
|
||||||
|
- Ra **0.2 – 0.4 µm**
|
||||||
|
- Texture: preferably circumferential (not helical — a helical pattern pumps fluid outward)
|
||||||
|
- Minimum surface hardness: 55 HRC or surface treatment
|
||||||
|
|
||||||
|
### Contact / reference planes
|
||||||
|
- Ra **0.8 – 1.6 µm** for functional contact
|
||||||
|
- Ra **3.2 µm** for non-critical bearing surfaces
|
||||||
|
|
||||||
|
---
|
||||||
|
|
||||||
|
## Roughness Symbols (EN ISO 1302)
|
||||||
|
|
||||||
|
```
|
||||||
|
Base symbol: √ (machining process not specified)
|
||||||
|
Material removal: ⊻ (material removal by machining required)
|
||||||
|
No material removal: ⊙ (no material removal: honing, lapping, etc.)
|
||||||
|
|
||||||
|
Indication: Ra value
|
||||||
|
e.g. Ra 0.8 / Ra 1.6 / Ra 3.2
|
||||||
|
```
|
||||||
|
|
||||||
|
---
|
||||||
|
|
||||||
|
## Practical Notes for the Designer
|
||||||
|
|
||||||
|
1. **Don't over-specify**: each step down in Ra increases cost by ~30–50%
|
||||||
|
2. **IT–Ra coherence**: specifying IT7 and Ra 6.3 is a contradiction
|
||||||
|
3. **State the parameter**: prefer Ra (arithmetic mean) for general use;
|
||||||
|
Rz (mean peak-valley height) is better for sliding and sealing surfaces
|
||||||
|
4. **Where not specified**: apply the general roughness note (e.g. "unless noted: Ra 3.2")
|
||||||
|
5. **Machining direction**: for rotary seals, specify circumferential vs. axial grinding direction
|
||||||
@@ -0,0 +1,275 @@
|
|||||||
|
#!/usr/bin/env python3
|
||||||
|
"""
|
||||||
|
ISO 286-1 Fit Calculator
|
||||||
|
Usage: python calculate_fit.py <diameter> <fit>
|
||||||
|
Examples:
|
||||||
|
python calculate_fit.py 50 H7/k6
|
||||||
|
python calculate_fit.py 30 H8/f7
|
||||||
|
python calculate_fit.py 80 H7/p6
|
||||||
|
"""
|
||||||
|
|
||||||
|
import json
|
||||||
|
import sys
|
||||||
|
import re
|
||||||
|
import os
|
||||||
|
|
||||||
|
SCRIPT_DIR = os.path.dirname(os.path.abspath(__file__))
|
||||||
|
IT_FILE = os.path.join(SCRIPT_DIR, "it_values.json")
|
||||||
|
DEV_FILE = os.path.join(SCRIPT_DIR, "deviations.json")
|
||||||
|
|
||||||
|
RANGES = [
|
||||||
|
(1, 3), (3, 6), (6, 10), (10, 18), (18, 30), (30, 50),
|
||||||
|
(50, 80), (80, 120), (120, 180), (180, 250), (250, 315), (315, 400), (400, 500)
|
||||||
|
]
|
||||||
|
RANGE_KEYS = [
|
||||||
|
"1-3", "3-6", "6-10", "10-18", "18-30", "30-50",
|
||||||
|
"50-80", "80-120", "120-180", "180-250", "250-315", "315-400", "400-500"
|
||||||
|
]
|
||||||
|
|
||||||
|
|
||||||
|
def load_data():
|
||||||
|
with open(IT_FILE) as f:
|
||||||
|
it_data = json.load(f)
|
||||||
|
with open(DEV_FILE) as f:
|
||||||
|
dev_data = json.load(f)
|
||||||
|
return it_data, dev_data
|
||||||
|
|
||||||
|
|
||||||
|
def get_range_index(diameter: float) -> int:
|
||||||
|
for i, (lo, hi) in enumerate(RANGES):
|
||||||
|
if lo < diameter <= hi:
|
||||||
|
return i
|
||||||
|
if diameter == 1:
|
||||||
|
return 0
|
||||||
|
raise ValueError(f"Diameter {diameter} mm out of range (1–500 mm)")
|
||||||
|
|
||||||
|
|
||||||
|
def get_it_value(it_data: dict, grade: str, range_idx: int) -> float:
|
||||||
|
key = f"IT{grade}"
|
||||||
|
if key not in it_data["grades"]:
|
||||||
|
raise ValueError(f"Unknown IT grade: {grade}")
|
||||||
|
return it_data["grades"][key][range_idx]
|
||||||
|
|
||||||
|
|
||||||
|
def get_fundamental_deviation(dev_data: dict, letter: str, range_idx: int) -> float:
|
||||||
|
"""Returns the fundamental deviation: es for shafts, EI for bores."""
|
||||||
|
if letter in dev_data["shafts"]:
|
||||||
|
return dev_data["shafts"][letter][range_idx]
|
||||||
|
elif letter in dev_data["bores"]:
|
||||||
|
return dev_data["bores"][letter][range_idx]
|
||||||
|
else:
|
||||||
|
raise ValueError(f"Unknown deviation letter: '{letter}'")
|
||||||
|
|
||||||
|
|
||||||
|
def parse_fit(fit_str: str):
|
||||||
|
"""
|
||||||
|
Parse a fit string like 'H7/k6' or 'H7/JS6'.
|
||||||
|
Returns (bore_letter, bore_grade, shaft_letter, shaft_grade).
|
||||||
|
"""
|
||||||
|
m = re.fullmatch(r"([A-Za-z]+)(\d+)/([A-Za-z]+)(\d+)", fit_str.strip())
|
||||||
|
if not m:
|
||||||
|
raise ValueError(
|
||||||
|
f"Invalid fit format: '{fit_str}'. Expected e.g. H7/k6 or H8/f7"
|
||||||
|
)
|
||||||
|
bore_letter = m.group(1).upper()
|
||||||
|
bore_grade = m.group(2)
|
||||||
|
shaft_letter = m.group(3).lower()
|
||||||
|
shaft_grade = m.group(4)
|
||||||
|
return bore_letter, bore_grade, shaft_letter, shaft_grade
|
||||||
|
|
||||||
|
|
||||||
|
def classify_fit(c_max: float, c_min: float):
|
||||||
|
"""Classify the fit type."""
|
||||||
|
if c_min >= 0:
|
||||||
|
return "GUARANTEED CLEARANCE", "clearance"
|
||||||
|
elif c_max <= 0:
|
||||||
|
return "GUARANTEED INTERFERENCE", "interference"
|
||||||
|
else:
|
||||||
|
return "TRANSITION (clearance or interference)", "transition"
|
||||||
|
|
||||||
|
|
||||||
|
def fit_description(shaft_letter: str, shaft_grade: str) -> str:
|
||||||
|
"""Functional hint for common shaft deviation letters."""
|
||||||
|
descriptions = {
|
||||||
|
"a": "Very loose clearance (articulated linkages)",
|
||||||
|
"b": "Loose clearance",
|
||||||
|
"c": "Generous clearance (cranks, connecting rods)",
|
||||||
|
"d": "Wide functional clearance (long shafts, flanges)",
|
||||||
|
"e": "Generous clearance (misaligned joints)",
|
||||||
|
"f": "Standard functional clearance (guides, lubricated bushings)",
|
||||||
|
"g": "Precision clearance (precision guides, rotating pins)",
|
||||||
|
"h": "Nominal zero clearance (positioning, removable centering)",
|
||||||
|
"js": "Light transition (removable pins, loose keys)",
|
||||||
|
"k": "Transition — slight interference (bushings, keys)",
|
||||||
|
"m": "Transition — medium interference (sleeves, fixed bushings)",
|
||||||
|
"n": "Light interference (fixed bushings, rings)",
|
||||||
|
"p": "Interference (gears, fixed pulleys)",
|
||||||
|
"r": "Strong interference (high-torque hubs)",
|
||||||
|
"s": "Very strong interference (thermal assembly mandatory)",
|
||||||
|
"t": "High interference",
|
||||||
|
"u": "Maximum interference (bronze/cast-iron bushings)",
|
||||||
|
}
|
||||||
|
return descriptions.get(shaft_letter, "—")
|
||||||
|
|
||||||
|
|
||||||
|
def assembly_and_roughness(fit_class: str, bore_grade: str) -> str:
|
||||||
|
lines = []
|
||||||
|
is_interference = fit_class == "interference"
|
||||||
|
is_transition = fit_class == "transition"
|
||||||
|
|
||||||
|
if is_interference:
|
||||||
|
lines.append("ASSEMBLY METHOD:")
|
||||||
|
lines.append(" Thermal (heat hub to 80–300°C depending on interference level)")
|
||||||
|
lines.append(" or press fit if interference is small (< 0.020 mm)")
|
||||||
|
lines.append("")
|
||||||
|
lines.append("RECOMMENDED ROUGHNESS:")
|
||||||
|
lines.append(" Shaft: Ra ≤ 0.8 µm (Ra 0.4 preferred) — cylindrical grinding")
|
||||||
|
lines.append(" Bore: Ra ≤ 0.8 µm — fine boring or internal grinding")
|
||||||
|
lines.append(" Note: roughness reduces effective interference by ~0.6×(Rz_shaft + Rz_bore)")
|
||||||
|
|
||||||
|
elif is_transition:
|
||||||
|
lines.append("ASSEMBLY METHOD:")
|
||||||
|
lines.append(" Light press fit — requires press or mallet")
|
||||||
|
lines.append(" Removable with puller — not by hand")
|
||||||
|
lines.append("")
|
||||||
|
lines.append("RECOMMENDED ROUGHNESS:")
|
||||||
|
lines.append(" Shaft: Ra ≤ 1.6 µm — fine CNC turning")
|
||||||
|
lines.append(" Bore: Ra ≤ 1.6 µm — CNC boring")
|
||||||
|
|
||||||
|
else:
|
||||||
|
lines.append("ASSEMBLY METHOD:")
|
||||||
|
lines.append(" Hand-removable or with light tooling")
|
||||||
|
lines.append("")
|
||||||
|
g = int(bore_grade)
|
||||||
|
if g <= 6:
|
||||||
|
ra, proc_shaft, proc_bore = "0.8 µm", "fine turning / grinding", "CNC boring"
|
||||||
|
elif g <= 8:
|
||||||
|
ra, proc_shaft, proc_bore = "1.6 µm", "standard CNC turning", "standard boring"
|
||||||
|
else:
|
||||||
|
ra, proc_shaft, proc_bore = "3.2 µm", "standard turning", "drilling / reaming"
|
||||||
|
lines.append("RECOMMENDED ROUGHNESS:")
|
||||||
|
lines.append(f" Shaft: Ra ≤ {ra} — {proc_shaft}")
|
||||||
|
lines.append(f" Bore: Ra ≤ {ra} — {proc_bore}")
|
||||||
|
|
||||||
|
return "\n".join(lines)
|
||||||
|
|
||||||
|
|
||||||
|
def compute_js_deviation(it_value: float) -> float:
|
||||||
|
return it_value / 2.0
|
||||||
|
|
||||||
|
|
||||||
|
def calculate(diameter: float, fit_str: str, it_data: dict, dev_data: dict) -> str:
|
||||||
|
bore_l, bore_g, shaft_l, shaft_g = parse_fit(fit_str)
|
||||||
|
ri = get_range_index(diameter)
|
||||||
|
range_key = RANGE_KEYS[ri]
|
||||||
|
|
||||||
|
it_bore = get_it_value(it_data, bore_g, ri)
|
||||||
|
it_shaft = get_it_value(it_data, shaft_g, ri)
|
||||||
|
|
||||||
|
# Bore deviations
|
||||||
|
if bore_l == "H":
|
||||||
|
EI, ES = 0.0, it_bore
|
||||||
|
elif bore_l == "JS":
|
||||||
|
half = compute_js_deviation(it_bore)
|
||||||
|
EI, ES = -half, +half
|
||||||
|
else:
|
||||||
|
EI = get_fundamental_deviation(dev_data, bore_l, ri)
|
||||||
|
ES = EI + it_bore
|
||||||
|
|
||||||
|
# Shaft deviations
|
||||||
|
if shaft_l == "h":
|
||||||
|
es, ei = 0.0, -it_shaft
|
||||||
|
elif shaft_l == "js":
|
||||||
|
half = compute_js_deviation(it_shaft)
|
||||||
|
es, ei = +half, -half
|
||||||
|
else:
|
||||||
|
es = get_fundamental_deviation(dev_data, shaft_l, ri)
|
||||||
|
ei = es - it_shaft
|
||||||
|
|
||||||
|
c_max = ES - ei # positive = clearance
|
||||||
|
c_min = EI - es # negative = interference
|
||||||
|
|
||||||
|
fit_label, fit_class = classify_fit(c_max, c_min)
|
||||||
|
|
||||||
|
sep = "═" * 62
|
||||||
|
thin = "─" * 62
|
||||||
|
|
||||||
|
lines = [
|
||||||
|
"",
|
||||||
|
sep,
|
||||||
|
" FIT DATA SHEET — ISO 286-1",
|
||||||
|
sep,
|
||||||
|
f" Nominal diameter : Ø{diameter} mm",
|
||||||
|
f" Diameter range : {range_key} mm",
|
||||||
|
f" Fit : {bore_l}{bore_g}/{shaft_l}{shaft_g}",
|
||||||
|
f" Type : {fit_label}",
|
||||||
|
thin,
|
||||||
|
" BORE DEVIATIONS",
|
||||||
|
f" Letter/grade : {bore_l}{bore_g} (IT{bore_g} = {it_bore:.1f} µm)",
|
||||||
|
f" EI (lower) : {EI:+.1f} µm",
|
||||||
|
f" ES (upper) : {ES:+.1f} µm",
|
||||||
|
f" Drawing dim. : Ø{diameter} {EI/1000:+.4f}/{ES/1000:+.4f} mm",
|
||||||
|
thin,
|
||||||
|
" SHAFT DEVIATIONS",
|
||||||
|
f" Letter/grade : {shaft_l}{shaft_g} (IT{shaft_g} = {it_shaft:.1f} µm)",
|
||||||
|
f" es (upper) : {es:+.1f} µm",
|
||||||
|
f" ei (lower) : {ei:+.1f} µm",
|
||||||
|
f" Drawing dim. : Ø{diameter} {es/1000:+.4f}/{ei/1000:+.4f} mm",
|
||||||
|
thin,
|
||||||
|
]
|
||||||
|
|
||||||
|
if fit_class == "clearance":
|
||||||
|
lines += [
|
||||||
|
" RESULTING CLEARANCE",
|
||||||
|
f" Max clearance : {c_max:+.1f} µm ({c_max/1000:+.4f} mm)",
|
||||||
|
f" Min clearance : {c_min:+.1f} µm ({c_min/1000:+.4f} mm)",
|
||||||
|
]
|
||||||
|
elif fit_class == "interference":
|
||||||
|
i_max, i_min = abs(c_min), abs(c_max) if c_max < 0 else 0
|
||||||
|
lines += [
|
||||||
|
" RESULTING INTERFERENCE",
|
||||||
|
f" Max interference: {i_max:+.1f} µm ({i_max/1000:+.4f} mm)",
|
||||||
|
f" Min interference: {i_min:+.1f} µm ({i_min/1000:+.4f} mm)",
|
||||||
|
]
|
||||||
|
else:
|
||||||
|
lines += [
|
||||||
|
" CLEARANCE / INTERFERENCE (transition fit)",
|
||||||
|
f" Max value : {c_max:+.1f} µm ({c_max/1000:+.4f} mm) {'→ clearance' if c_max > 0 else '→ interference'}",
|
||||||
|
f" Min value : {c_min:+.1f} µm ({c_min/1000:+.4f} mm) {'→ clearance' if c_min > 0 else '→ interference'}",
|
||||||
|
]
|
||||||
|
|
||||||
|
lines += [
|
||||||
|
thin,
|
||||||
|
" TYPICAL FUNCTION",
|
||||||
|
f" {fit_description(shaft_l, shaft_g)}",
|
||||||
|
thin,
|
||||||
|
assembly_and_roughness(fit_class, bore_g),
|
||||||
|
sep,
|
||||||
|
"",
|
||||||
|
]
|
||||||
|
|
||||||
|
return "\n".join(lines)
|
||||||
|
|
||||||
|
|
||||||
|
def main():
|
||||||
|
if len(sys.argv) < 3:
|
||||||
|
print(__doc__)
|
||||||
|
print("Examples:")
|
||||||
|
print(" python calculate_fit.py 50 H7/k6")
|
||||||
|
print(" python calculate_fit.py 30 H8/f7")
|
||||||
|
print(" python calculate_fit.py 80 H7/p6")
|
||||||
|
sys.exit(1)
|
||||||
|
|
||||||
|
try:
|
||||||
|
diameter = float(sys.argv[1])
|
||||||
|
fit_str = sys.argv[2]
|
||||||
|
it_data, dev_data = load_data()
|
||||||
|
result = calculate(diameter, fit_str, it_data, dev_data)
|
||||||
|
print(result)
|
||||||
|
except (ValueError, KeyError) as e:
|
||||||
|
print(f"Error: {e}", file=sys.stderr)
|
||||||
|
sys.exit(1)
|
||||||
|
|
||||||
|
|
||||||
|
if __name__ == "__main__":
|
||||||
|
main()
|
||||||
@@ -0,0 +1,744 @@
|
|||||||
|
{
|
||||||
|
"_note": "Fundamental deviations ISO 286-1 in micrometres (\u00b5m). Shafts = upper deviation es. Bores = lower deviation EI. JS/js = \u00b1IT/2 (not tabulated, calculated at runtime).",
|
||||||
|
"ranges": [
|
||||||
|
"1-3",
|
||||||
|
"3-6",
|
||||||
|
"6-10",
|
||||||
|
"10-18",
|
||||||
|
"18-30",
|
||||||
|
"30-50",
|
||||||
|
"50-80",
|
||||||
|
"80-120",
|
||||||
|
"120-180",
|
||||||
|
"180-250",
|
||||||
|
"250-315",
|
||||||
|
"315-400",
|
||||||
|
"400-500"
|
||||||
|
],
|
||||||
|
"_shafts_note": "es = upper deviation in \u00b5m (negative = below zero). ei = es - IT",
|
||||||
|
"shafts": {
|
||||||
|
"a": [
|
||||||
|
-270,
|
||||||
|
-270,
|
||||||
|
-280,
|
||||||
|
-290,
|
||||||
|
-300,
|
||||||
|
-310,
|
||||||
|
-320,
|
||||||
|
-340,
|
||||||
|
-360,
|
||||||
|
-380,
|
||||||
|
-410,
|
||||||
|
-440,
|
||||||
|
-480
|
||||||
|
],
|
||||||
|
"b": [
|
||||||
|
-140,
|
||||||
|
-140,
|
||||||
|
-150,
|
||||||
|
-150,
|
||||||
|
-160,
|
||||||
|
-170,
|
||||||
|
-180,
|
||||||
|
-200,
|
||||||
|
-210,
|
||||||
|
-230,
|
||||||
|
-240,
|
||||||
|
-260,
|
||||||
|
-280
|
||||||
|
],
|
||||||
|
"c": [
|
||||||
|
-60,
|
||||||
|
-70,
|
||||||
|
-80,
|
||||||
|
-95,
|
||||||
|
-110,
|
||||||
|
-120,
|
||||||
|
-130,
|
||||||
|
-145,
|
||||||
|
-160,
|
||||||
|
-170,
|
||||||
|
-180,
|
||||||
|
-190,
|
||||||
|
-200
|
||||||
|
],
|
||||||
|
"cd": [
|
||||||
|
-34,
|
||||||
|
-46,
|
||||||
|
-56,
|
||||||
|
0,
|
||||||
|
0,
|
||||||
|
0,
|
||||||
|
0,
|
||||||
|
0,
|
||||||
|
0,
|
||||||
|
0,
|
||||||
|
0,
|
||||||
|
0,
|
||||||
|
0
|
||||||
|
],
|
||||||
|
"d": [
|
||||||
|
-20,
|
||||||
|
-30,
|
||||||
|
-40,
|
||||||
|
-50,
|
||||||
|
-65,
|
||||||
|
-80,
|
||||||
|
-100,
|
||||||
|
-120,
|
||||||
|
-145,
|
||||||
|
-170,
|
||||||
|
-190,
|
||||||
|
-210,
|
||||||
|
-230
|
||||||
|
],
|
||||||
|
"e": [
|
||||||
|
-14,
|
||||||
|
-20,
|
||||||
|
-25,
|
||||||
|
-32,
|
||||||
|
-40,
|
||||||
|
-50,
|
||||||
|
-60,
|
||||||
|
-72,
|
||||||
|
-85,
|
||||||
|
-100,
|
||||||
|
-110,
|
||||||
|
-125,
|
||||||
|
-135
|
||||||
|
],
|
||||||
|
"ef": [
|
||||||
|
-10,
|
||||||
|
-14,
|
||||||
|
-18,
|
||||||
|
0,
|
||||||
|
0,
|
||||||
|
0,
|
||||||
|
0,
|
||||||
|
0,
|
||||||
|
0,
|
||||||
|
0,
|
||||||
|
0,
|
||||||
|
0,
|
||||||
|
0
|
||||||
|
],
|
||||||
|
"f": [
|
||||||
|
-6,
|
||||||
|
-10,
|
||||||
|
-13,
|
||||||
|
-16,
|
||||||
|
-20,
|
||||||
|
-25,
|
||||||
|
-30,
|
||||||
|
-36,
|
||||||
|
-43,
|
||||||
|
-50,
|
||||||
|
-56,
|
||||||
|
-62,
|
||||||
|
-68
|
||||||
|
],
|
||||||
|
"fg": [
|
||||||
|
-4,
|
||||||
|
-6,
|
||||||
|
-8,
|
||||||
|
0,
|
||||||
|
0,
|
||||||
|
0,
|
||||||
|
0,
|
||||||
|
0,
|
||||||
|
0,
|
||||||
|
0,
|
||||||
|
0,
|
||||||
|
0,
|
||||||
|
0
|
||||||
|
],
|
||||||
|
"g": [
|
||||||
|
-2,
|
||||||
|
-4,
|
||||||
|
-5,
|
||||||
|
-6,
|
||||||
|
-7,
|
||||||
|
-9,
|
||||||
|
-10,
|
||||||
|
-12,
|
||||||
|
-14,
|
||||||
|
-15,
|
||||||
|
-17,
|
||||||
|
-18,
|
||||||
|
-20
|
||||||
|
],
|
||||||
|
"h": [
|
||||||
|
0,
|
||||||
|
0,
|
||||||
|
0,
|
||||||
|
0,
|
||||||
|
0,
|
||||||
|
0,
|
||||||
|
0,
|
||||||
|
0,
|
||||||
|
0,
|
||||||
|
0,
|
||||||
|
0,
|
||||||
|
0,
|
||||||
|
0
|
||||||
|
],
|
||||||
|
"k": [
|
||||||
|
0,
|
||||||
|
1,
|
||||||
|
1,
|
||||||
|
1,
|
||||||
|
2,
|
||||||
|
2,
|
||||||
|
2,
|
||||||
|
3,
|
||||||
|
3,
|
||||||
|
4,
|
||||||
|
4,
|
||||||
|
4,
|
||||||
|
5
|
||||||
|
],
|
||||||
|
"m": [
|
||||||
|
2,
|
||||||
|
4,
|
||||||
|
6,
|
||||||
|
7,
|
||||||
|
8,
|
||||||
|
9,
|
||||||
|
11,
|
||||||
|
13,
|
||||||
|
15,
|
||||||
|
17,
|
||||||
|
20,
|
||||||
|
21,
|
||||||
|
23
|
||||||
|
],
|
||||||
|
"n": [
|
||||||
|
4,
|
||||||
|
8,
|
||||||
|
10,
|
||||||
|
12,
|
||||||
|
15,
|
||||||
|
17,
|
||||||
|
20,
|
||||||
|
23,
|
||||||
|
27,
|
||||||
|
31,
|
||||||
|
34,
|
||||||
|
37,
|
||||||
|
40
|
||||||
|
],
|
||||||
|
"p": [
|
||||||
|
6,
|
||||||
|
12,
|
||||||
|
15,
|
||||||
|
18,
|
||||||
|
22,
|
||||||
|
26,
|
||||||
|
32,
|
||||||
|
37,
|
||||||
|
43,
|
||||||
|
50,
|
||||||
|
56,
|
||||||
|
62,
|
||||||
|
68
|
||||||
|
],
|
||||||
|
"r": [
|
||||||
|
10,
|
||||||
|
15,
|
||||||
|
19,
|
||||||
|
23,
|
||||||
|
28,
|
||||||
|
34,
|
||||||
|
41,
|
||||||
|
51,
|
||||||
|
63,
|
||||||
|
77,
|
||||||
|
98,
|
||||||
|
98,
|
||||||
|
108
|
||||||
|
],
|
||||||
|
"s": [
|
||||||
|
14,
|
||||||
|
19,
|
||||||
|
23,
|
||||||
|
28,
|
||||||
|
35,
|
||||||
|
43,
|
||||||
|
53,
|
||||||
|
71,
|
||||||
|
92,
|
||||||
|
100,
|
||||||
|
108,
|
||||||
|
114,
|
||||||
|
126
|
||||||
|
],
|
||||||
|
"t": [
|
||||||
|
0,
|
||||||
|
0,
|
||||||
|
23,
|
||||||
|
28,
|
||||||
|
35,
|
||||||
|
43,
|
||||||
|
53,
|
||||||
|
71,
|
||||||
|
92,
|
||||||
|
100,
|
||||||
|
108,
|
||||||
|
114,
|
||||||
|
126
|
||||||
|
],
|
||||||
|
"u": [
|
||||||
|
18,
|
||||||
|
23,
|
||||||
|
28,
|
||||||
|
33,
|
||||||
|
41,
|
||||||
|
53,
|
||||||
|
66,
|
||||||
|
90,
|
||||||
|
109,
|
||||||
|
130,
|
||||||
|
150,
|
||||||
|
171,
|
||||||
|
190
|
||||||
|
],
|
||||||
|
"v": [
|
||||||
|
0,
|
||||||
|
0,
|
||||||
|
0,
|
||||||
|
0,
|
||||||
|
47,
|
||||||
|
59,
|
||||||
|
75,
|
||||||
|
102,
|
||||||
|
122,
|
||||||
|
150,
|
||||||
|
172,
|
||||||
|
202,
|
||||||
|
228
|
||||||
|
],
|
||||||
|
"x": [
|
||||||
|
20,
|
||||||
|
28,
|
||||||
|
34,
|
||||||
|
40,
|
||||||
|
50,
|
||||||
|
64,
|
||||||
|
80,
|
||||||
|
108,
|
||||||
|
146,
|
||||||
|
172,
|
||||||
|
210,
|
||||||
|
248,
|
||||||
|
280
|
||||||
|
],
|
||||||
|
"y": [
|
||||||
|
0,
|
||||||
|
0,
|
||||||
|
0,
|
||||||
|
50,
|
||||||
|
63,
|
||||||
|
80,
|
||||||
|
100,
|
||||||
|
134,
|
||||||
|
180,
|
||||||
|
214,
|
||||||
|
258,
|
||||||
|
310,
|
||||||
|
355
|
||||||
|
],
|
||||||
|
"z": [
|
||||||
|
26,
|
||||||
|
35,
|
||||||
|
42,
|
||||||
|
50,
|
||||||
|
63,
|
||||||
|
80,
|
||||||
|
100,
|
||||||
|
134,
|
||||||
|
180,
|
||||||
|
214,
|
||||||
|
258,
|
||||||
|
310,
|
||||||
|
355
|
||||||
|
],
|
||||||
|
"za": [
|
||||||
|
32,
|
||||||
|
42,
|
||||||
|
52,
|
||||||
|
64,
|
||||||
|
77,
|
||||||
|
98,
|
||||||
|
120,
|
||||||
|
160,
|
||||||
|
210,
|
||||||
|
258,
|
||||||
|
310,
|
||||||
|
365,
|
||||||
|
415
|
||||||
|
],
|
||||||
|
"zb": [
|
||||||
|
40,
|
||||||
|
50,
|
||||||
|
67,
|
||||||
|
90,
|
||||||
|
108,
|
||||||
|
136,
|
||||||
|
168,
|
||||||
|
218,
|
||||||
|
284,
|
||||||
|
340,
|
||||||
|
415,
|
||||||
|
490,
|
||||||
|
560
|
||||||
|
],
|
||||||
|
"zc": [
|
||||||
|
60,
|
||||||
|
80,
|
||||||
|
97,
|
||||||
|
130,
|
||||||
|
150,
|
||||||
|
188,
|
||||||
|
236,
|
||||||
|
308,
|
||||||
|
390,
|
||||||
|
470,
|
||||||
|
575,
|
||||||
|
660,
|
||||||
|
740
|
||||||
|
]
|
||||||
|
},
|
||||||
|
"_bores_note": "EI = lower deviation in \u00b5m. ES = EI + IT. For H: EI=0 always.",
|
||||||
|
"bores": {
|
||||||
|
"A": [
|
||||||
|
270,
|
||||||
|
270,
|
||||||
|
280,
|
||||||
|
290,
|
||||||
|
300,
|
||||||
|
310,
|
||||||
|
320,
|
||||||
|
340,
|
||||||
|
360,
|
||||||
|
380,
|
||||||
|
410,
|
||||||
|
440,
|
||||||
|
480
|
||||||
|
],
|
||||||
|
"B": [
|
||||||
|
140,
|
||||||
|
140,
|
||||||
|
150,
|
||||||
|
150,
|
||||||
|
160,
|
||||||
|
170,
|
||||||
|
180,
|
||||||
|
200,
|
||||||
|
210,
|
||||||
|
230,
|
||||||
|
240,
|
||||||
|
260,
|
||||||
|
280
|
||||||
|
],
|
||||||
|
"C": [
|
||||||
|
60,
|
||||||
|
70,
|
||||||
|
80,
|
||||||
|
95,
|
||||||
|
110,
|
||||||
|
120,
|
||||||
|
130,
|
||||||
|
145,
|
||||||
|
160,
|
||||||
|
170,
|
||||||
|
180,
|
||||||
|
190,
|
||||||
|
200
|
||||||
|
],
|
||||||
|
"D": [
|
||||||
|
20,
|
||||||
|
30,
|
||||||
|
40,
|
||||||
|
50,
|
||||||
|
65,
|
||||||
|
80,
|
||||||
|
100,
|
||||||
|
120,
|
||||||
|
145,
|
||||||
|
170,
|
||||||
|
190,
|
||||||
|
210,
|
||||||
|
230
|
||||||
|
],
|
||||||
|
"E": [
|
||||||
|
14,
|
||||||
|
20,
|
||||||
|
25,
|
||||||
|
32,
|
||||||
|
40,
|
||||||
|
50,
|
||||||
|
60,
|
||||||
|
72,
|
||||||
|
85,
|
||||||
|
100,
|
||||||
|
110,
|
||||||
|
125,
|
||||||
|
135
|
||||||
|
],
|
||||||
|
"F": [
|
||||||
|
6,
|
||||||
|
10,
|
||||||
|
13,
|
||||||
|
16,
|
||||||
|
20,
|
||||||
|
25,
|
||||||
|
30,
|
||||||
|
36,
|
||||||
|
43,
|
||||||
|
50,
|
||||||
|
56,
|
||||||
|
62,
|
||||||
|
68
|
||||||
|
],
|
||||||
|
"G": [
|
||||||
|
2,
|
||||||
|
4,
|
||||||
|
5,
|
||||||
|
6,
|
||||||
|
7,
|
||||||
|
9,
|
||||||
|
10,
|
||||||
|
12,
|
||||||
|
14,
|
||||||
|
15,
|
||||||
|
17,
|
||||||
|
18,
|
||||||
|
20
|
||||||
|
],
|
||||||
|
"H": [
|
||||||
|
0,
|
||||||
|
0,
|
||||||
|
0,
|
||||||
|
0,
|
||||||
|
0,
|
||||||
|
0,
|
||||||
|
0,
|
||||||
|
0,
|
||||||
|
0,
|
||||||
|
0,
|
||||||
|
0,
|
||||||
|
0,
|
||||||
|
0
|
||||||
|
],
|
||||||
|
"K": [
|
||||||
|
0,
|
||||||
|
2,
|
||||||
|
2,
|
||||||
|
2,
|
||||||
|
2,
|
||||||
|
3,
|
||||||
|
4,
|
||||||
|
4,
|
||||||
|
4,
|
||||||
|
5,
|
||||||
|
5,
|
||||||
|
5,
|
||||||
|
6
|
||||||
|
],
|
||||||
|
"M": [
|
||||||
|
-2,
|
||||||
|
-4,
|
||||||
|
-6,
|
||||||
|
-7,
|
||||||
|
-8,
|
||||||
|
-9,
|
||||||
|
-11,
|
||||||
|
-13,
|
||||||
|
-15,
|
||||||
|
-17,
|
||||||
|
-20,
|
||||||
|
-21,
|
||||||
|
-23
|
||||||
|
],
|
||||||
|
"N": [
|
||||||
|
-4,
|
||||||
|
-8,
|
||||||
|
-10,
|
||||||
|
-12,
|
||||||
|
-15,
|
||||||
|
-17,
|
||||||
|
-20,
|
||||||
|
-23,
|
||||||
|
-27,
|
||||||
|
-31,
|
||||||
|
-34,
|
||||||
|
-37,
|
||||||
|
-40
|
||||||
|
],
|
||||||
|
"P": [
|
||||||
|
-6,
|
||||||
|
-12,
|
||||||
|
-15,
|
||||||
|
-18,
|
||||||
|
-22,
|
||||||
|
-26,
|
||||||
|
-32,
|
||||||
|
-37,
|
||||||
|
-43,
|
||||||
|
-50,
|
||||||
|
-56,
|
||||||
|
-62,
|
||||||
|
-68
|
||||||
|
],
|
||||||
|
"R": [
|
||||||
|
-10,
|
||||||
|
-15,
|
||||||
|
-19,
|
||||||
|
-23,
|
||||||
|
-28,
|
||||||
|
-34,
|
||||||
|
-41,
|
||||||
|
-51,
|
||||||
|
-63,
|
||||||
|
-77,
|
||||||
|
-98,
|
||||||
|
-98,
|
||||||
|
-108
|
||||||
|
],
|
||||||
|
"S": [
|
||||||
|
-14,
|
||||||
|
-19,
|
||||||
|
-23,
|
||||||
|
-28,
|
||||||
|
-35,
|
||||||
|
-43,
|
||||||
|
-53,
|
||||||
|
-71,
|
||||||
|
-92,
|
||||||
|
-100,
|
||||||
|
-108,
|
||||||
|
-114,
|
||||||
|
-126
|
||||||
|
],
|
||||||
|
"T": [
|
||||||
|
0,
|
||||||
|
0,
|
||||||
|
-23,
|
||||||
|
-28,
|
||||||
|
-35,
|
||||||
|
-43,
|
||||||
|
-53,
|
||||||
|
-71,
|
||||||
|
-92,
|
||||||
|
-100,
|
||||||
|
-108,
|
||||||
|
-114,
|
||||||
|
-126
|
||||||
|
],
|
||||||
|
"U": [
|
||||||
|
-18,
|
||||||
|
-23,
|
||||||
|
-28,
|
||||||
|
-33,
|
||||||
|
-41,
|
||||||
|
-53,
|
||||||
|
-66,
|
||||||
|
-90,
|
||||||
|
-109,
|
||||||
|
-130,
|
||||||
|
-150,
|
||||||
|
-171,
|
||||||
|
-190
|
||||||
|
],
|
||||||
|
"V": [
|
||||||
|
0,
|
||||||
|
0,
|
||||||
|
0,
|
||||||
|
0,
|
||||||
|
-47,
|
||||||
|
-59,
|
||||||
|
-75,
|
||||||
|
-102,
|
||||||
|
-122,
|
||||||
|
-150,
|
||||||
|
-172,
|
||||||
|
-202,
|
||||||
|
-228
|
||||||
|
],
|
||||||
|
"X": [
|
||||||
|
-20,
|
||||||
|
-28,
|
||||||
|
-34,
|
||||||
|
-40,
|
||||||
|
-50,
|
||||||
|
-64,
|
||||||
|
-80,
|
||||||
|
-108,
|
||||||
|
-146,
|
||||||
|
-172,
|
||||||
|
-210,
|
||||||
|
-248,
|
||||||
|
-280
|
||||||
|
],
|
||||||
|
"Z": [
|
||||||
|
-26,
|
||||||
|
-35,
|
||||||
|
-42,
|
||||||
|
-50,
|
||||||
|
-63,
|
||||||
|
-80,
|
||||||
|
-100,
|
||||||
|
-134,
|
||||||
|
-180,
|
||||||
|
-214,
|
||||||
|
-258,
|
||||||
|
-310,
|
||||||
|
-355
|
||||||
|
],
|
||||||
|
"ZA": [
|
||||||
|
-32,
|
||||||
|
-42,
|
||||||
|
-52,
|
||||||
|
-64,
|
||||||
|
-77,
|
||||||
|
-98,
|
||||||
|
-120,
|
||||||
|
-160,
|
||||||
|
-210,
|
||||||
|
-258,
|
||||||
|
-310,
|
||||||
|
-365,
|
||||||
|
-415
|
||||||
|
],
|
||||||
|
"ZB": [
|
||||||
|
-40,
|
||||||
|
-50,
|
||||||
|
-67,
|
||||||
|
-90,
|
||||||
|
-108,
|
||||||
|
-136,
|
||||||
|
-168,
|
||||||
|
-218,
|
||||||
|
-284,
|
||||||
|
-340,
|
||||||
|
-415,
|
||||||
|
-490,
|
||||||
|
-560
|
||||||
|
],
|
||||||
|
"ZC": [
|
||||||
|
-60,
|
||||||
|
-80,
|
||||||
|
-97,
|
||||||
|
-130,
|
||||||
|
-150,
|
||||||
|
-188,
|
||||||
|
-236,
|
||||||
|
-308,
|
||||||
|
-390,
|
||||||
|
-470,
|
||||||
|
-575,
|
||||||
|
-660,
|
||||||
|
-740
|
||||||
|
]
|
||||||
|
}
|
||||||
|
}
|
||||||
@@ -0,0 +1,22 @@
|
|||||||
|
{
|
||||||
|
"_note": "Valori tolleranza IT in micrometri (µm) per campo di diametro — ISO 286-1 Tabella 1",
|
||||||
|
"ranges": ["1-3", "3-6", "6-10", "10-18", "18-30", "30-50", "50-80", "80-120", "120-180", "180-250", "250-315", "315-400", "400-500"],
|
||||||
|
"grades": {
|
||||||
|
"IT1": [0.8, 1, 1, 1.2, 1.5, 1.5, 2, 2.5, 3.5, 4.5, 6, 7, 8 ],
|
||||||
|
"IT2": [1.2, 1.5, 1.5, 2, 2.5, 2.5, 3, 4, 5, 7, 8, 9, 10 ],
|
||||||
|
"IT3": [2, 2.5, 2.5, 3, 4, 4, 5, 6, 8, 10, 12, 13, 15 ],
|
||||||
|
"IT4": [3, 4, 4, 5, 6, 7, 8, 10, 12, 14, 16, 18, 20 ],
|
||||||
|
"IT5": [4, 5, 6, 8, 9, 11, 13, 15, 18, 20, 23, 25, 27 ],
|
||||||
|
"IT6": [6, 8, 9, 11, 13, 16, 19, 22, 25, 29, 32, 36, 40 ],
|
||||||
|
"IT7": [10, 12, 15, 18, 21, 25, 30, 35, 40, 46, 52, 57, 63 ],
|
||||||
|
"IT8": [14, 18, 22, 27, 33, 39, 46, 54, 63, 72, 81, 89, 97 ],
|
||||||
|
"IT9": [25, 30, 36, 43, 52, 62, 74, 87, 100, 115, 130, 140, 155],
|
||||||
|
"IT10": [40, 48, 58, 70, 84, 100, 120, 140, 160, 185, 210, 230, 250],
|
||||||
|
"IT11": [60, 75, 90, 110, 130, 160, 190, 220, 250, 290, 320, 360, 400],
|
||||||
|
"IT12": [100, 120, 150, 180, 210, 250, 300, 350, 400, 460, 520, 570, 630],
|
||||||
|
"IT13": [140, 180, 220, 270, 330, 390, 460, 540, 630, 720, 810, 890, 970],
|
||||||
|
"IT14": [250, 300, 360, 430, 520, 620, 740, 870, 1000,1150,1300,1400,1550],
|
||||||
|
"IT15": [400, 480, 580, 700, 840, 1000,1200,1400,1600,1850,2100,2300,2500],
|
||||||
|
"IT16": [600, 750, 900, 1100,1300,1600,1900,2200,2500,2900,3200,3600,4000]
|
||||||
|
}
|
||||||
|
}
|
||||||
Reference in New Issue
Block a user