{
  "_comment": "VDI 2230:2003 — Dati filettatura metrica ISO (DIN 13/DIN ISO 262) e proprietà viti",
  "thread_metric_coarse": {
    "_comment": "d=nominale, P=passo, d2=fianco, d3=nocciolo, AS=sez.sforzo, Ad3=sez.nocciolo, AN=sez.nominale — tutti in mm e mm²",
    "M4":  {"d":4,  "P":0.7,  "d2":3.545, "d3":3.242, "AS":8.78,  "Ad3":8.26,  "AN":12.57, "dW_hex":6.9,  "dW_cyl":7.66},
    "M5":  {"d":5,  "P":0.8,  "d2":4.480, "d3":4.134, "AS":14.2,  "Ad3":13.4,  "AN":19.63, "dW_hex":8.9,  "dW_cyl":8.87},
    "M6":  {"d":6,  "P":1.0,  "d2":5.350, "d3":4.917, "AS":20.1,  "Ad3":19.0,  "AN":28.27, "dW_hex":10.9, "dW_cyl":11.3},
    "M7":  {"d":7,  "P":1.0,  "d2":6.350, "d3":5.917, "AS":28.9,  "Ad3":27.5,  "AN":38.48, "dW_hex":12.9, "dW_cyl":13.3},
    "M8":  {"d":8,  "P":1.25, "d2":7.188, "d3":6.647, "AS":36.6,  "Ad3":34.7,  "AN":50.27, "dW_hex":13.9, "dW_cyl":14.2},
    "M10": {"d":10, "P":1.5,  "d2":9.026, "d3":8.376, "AS":58.0,  "Ad3":55.1,  "AN":78.54, "dW_hex":17.0, "dW_cyl":17.6},
    "M12": {"d":12, "P":1.75, "d2":10.863,"d3":10.106,"AS":84.3,  "Ad3":80.1,  "AN":113.1, "dW_hex":19.9, "dW_cyl":20.5},
    "M14": {"d":14, "P":2.0,  "d2":12.701,"d3":11.835,"AS":115.4, "Ad3":110.0, "AN":153.9, "dW_hex":23.8, "dW_cyl":24.9},
    "M16": {"d":16, "P":2.0,  "d2":14.701,"d3":13.835,"AS":156.7, "Ad3":150.3, "AN":201.1, "dW_hex":27.0, "dW_cyl":27.7},
    "M18": {"d":18, "P":2.5,  "d2":16.376,"d3":15.294,"AS":192.5, "Ad3":183.6, "AN":254.5, "dW_hex":30.0, "dW_cyl":31.3},
    "M20": {"d":20, "P":2.5,  "d2":18.376,"d3":17.294,"AS":245.0, "Ad3":234.9, "AN":314.2, "dW_hex":32.9, "dW_cyl":34.6},
    "M22": {"d":22, "P":2.5,  "d2":20.376,"d3":19.294,"AS":303.4, "Ad3":292.4, "AN":380.1, "dW_hex":37.0, "dW_cyl":38.0},
    "M24": {"d":24, "P":3.0,  "d2":22.051,"d3":20.752,"AS":352.5, "Ad3":338.2, "AN":452.4, "dW_hex":40.9, "dW_cyl":41.6},
    "M27": {"d":27, "P":3.0,  "d2":25.051,"d3":23.752,"AS":459.4, "Ad3":443.2, "AN":572.6, "dW_hex":46.0, "dW_cyl":47.3},
    "M30": {"d":30, "P":3.5,  "d2":27.727,"d3":26.211,"AS":560.6, "Ad3":539.2, "AN":706.9, "dW_hex":51.0, "dW_cyl":52.7},
    "M33": {"d":33, "P":3.5,  "d2":30.727,"d3":29.211,"AS":694.0, "Ad3":669.9, "AN":855.3, "dW_hex":57.0, "dW_cyl":58.8},
    "M36": {"d":36, "P":4.0,  "d2":33.402,"d3":31.670,"AS":817.0, "Ad3":787.4, "AN":1017.9,"dW_hex":63.5, "dW_cyl":65.1},
    "M39": {"d":39, "P":4.0,  "d2":36.402,"d3":34.670,"AS":976.0, "Ad3":943.5, "AN":1194.6,"dW_hex":69.5, "dW_cyl":71.3}
  },
  "thread_metric_fine": {
    "M8x1":    {"d":8,  "P":1.0,  "d2":7.350, "d3":6.917, "AS":39.2,  "Ad3":37.6},
    "M10x1":   {"d":10, "P":1.0,  "d2":9.350, "d3":8.917, "AS":64.5,  "Ad3":62.5},
    "M10x1.25":{"d":10, "P":1.25, "d2":9.188, "d3":8.647, "AS":61.2,  "Ad3":58.7},
    "M12x1.25":{"d":12, "P":1.25, "d2":11.188,"d3":10.647,"AS":92.1,  "Ad3":89.0},
    "M12x1.5": {"d":12, "P":1.5,  "d2":11.026,"d3":10.376,"AS":88.1,  "Ad3":84.5},
    "M14x1.5": {"d":14, "P":1.5,  "d2":13.026,"d3":12.376,"AS":125.3, "Ad3":120.2},
    "M16x1.5": {"d":16, "P":1.5,  "d2":15.026,"d3":14.376,"AS":167.3, "Ad3":162.1},
    "M18x1.5": {"d":18, "P":1.5,  "d2":17.026,"d3":16.376,"AS":216.2, "Ad3":210.6},
    "M20x1.5": {"d":20, "P":1.5,  "d2":19.026,"d3":18.376,"AS":272.3, "Ad3":265.1},
    "M24x1.5": {"d":24, "P":1.5,  "d2":23.026,"d3":22.376,"AS":401.3, "Ad3":392.8},
    "M24x2":   {"d":24, "P":2.0,  "d2":22.701,"d3":21.835,"AS":384.4, "Ad3":374.2}
  },
  "strength_classes": {
    "_comment": "Rp0_2min e Rm_min in N/mm², ES in N/mm²",
    "8.8":  {"Rp0_2min": 640,  "Rm_min": 800,  "ES": 206000},
    "10.9": {"Rp0_2min": 940,  "Rm_min": 1040, "ES": 206000},
    "12.9": {"Rp0_2min": 1100, "Rm_min": 1220, "ES": 206000}
  },
  "materials_clamped": {
    "_comment": "EP in N/mm², alpha in 1/K, pG in N/mm²",
    "steel_S235":     {"EP": 210000, "alpha": 11.5e-6, "pG_min": 800,  "pG_max": 900,  "shear_ratio": 0.60},
    "steel_S355":     {"EP": 210000, "alpha": 11.5e-6, "pG_min": 900,  "pG_max": 1000, "shear_ratio": 0.60},
    "steel_hardened": {"EP": 206000, "alpha": 11.5e-6, "pG_min": 1100, "pG_max": 1250, "shear_ratio": 0.62},
    "cast_iron_GJL":  {"EP": 120000, "alpha": 10.5e-6, "pG_min": 400,  "pG_max": 600,  "shear_ratio": 0.64},
    "cast_iron_GJS":  {"EP": 170000, "alpha": 11.0e-6, "pG_min": 700,  "pG_max": 900,  "shear_ratio": 0.64},
    "aluminum_6082":  {"EP": 70000,  "alpha": 23.0e-6, "pG_min": 300,  "pG_max": 450,  "shear_ratio": 0.60},
    "aluminum_cast":  {"EP": 70000,  "alpha": 21.0e-6, "pG_min": 150,  "pG_max": 250,  "shear_ratio": 0.58}
  },
  "friction_classes": {
    "_comment": "µ_min e µ_max per filettatura (µG) e appoggio (µK)",
    "A": {"mu_min": 0.04, "mu_max": 0.10, "description": "MoS2/PTFE/grafite in vernice o pasta; cera fusa"},
    "B": {"mu_min": 0.08, "mu_max": 0.16, "description": "Stato di consegna (legg. oliato); grassi; Zn galv."},
    "C": {"mu_min": 0.14, "mu_max": 0.24, "description": "Senza lubrificante; fosfatato; Zn-Fe secco"},
    "D": {"mu_min": 0.20, "mu_max": 0.35, "description": "Zincato a caldo senza lubrificante"},
    "E": {"mu_min": 0.30, "mu_max": 0.50, "description": "Austenitici / Al-Mg senza lubrificante"}
  },
  "friction_interface_muT": {
    "steel_steel_dry":     {"mu_min": 0.10, "mu_max": 0.23},
    "steel_steel_oiled":   {"mu_min": 0.07, "mu_max": 0.12},
    "steel_castiron_dry":  {"mu_min": 0.12, "mu_max": 0.24},
    "steel_castiron_oiled":{"mu_min": 0.06, "mu_max": 0.10},
    "steel_aluminum_dry":  {"mu_min": 0.10, "mu_max": 0.28},
    "steel_aluminum_oiled":{"mu_min": 0.05, "mu_max": 0.18}
  },
  "tightening_factors_alphaA": {
    "torque_manual_classC":     {"alphaA_min": 2.5, "alphaA_max": 4.0, "note": "Chiave a forchetta/stella manuale"},
    "torque_wrench_classB":     {"alphaA_min": 1.6, "alphaA_max": 2.0, "note": "Chiave dinamometrica manuale, classe B"},
    "torque_wrench_classA":     {"alphaA_min": 1.2, "alphaA_max": 1.6, "note": "Chiave dinamometrica calibrata, classe A"},
    "power_tool_controlled":    {"alphaA_min": 1.4, "alphaA_max": 1.6, "note": "Avvitatore controllato in coppia"},
    "yield_or_angle_controlled":{"alphaA_min": 1.0, "alphaA_max": 1.0, "note": "Serraggio angolare o al limite di snervamento"}
  },
  "embedding_fZ_micron": {
    "_comment": "fZ in µm per interfaccia — funzione della rugosità Rz",
    "head_bearing_Rz_le10":  {"fZ_min": 2.0, "fZ_max": 4.0},
    "head_bearing_Rz_gt10":  {"fZ_min": 4.0, "fZ_max": 7.0},
    "flat_joint_Rz_le10":    {"fZ_min": 1.5, "fZ_max": 2.5},
    "flat_joint_Rz_gt10":    {"fZ_min": 2.5, "fZ_max": 6.5},
    "thread_engagement":     {"fZ_min": 1.0, "fZ_max": 2.0}
  },
  "min_engagement_length_ratio": {
    "_comment": "meff_min / d — rapporto lunghezza avvitamento / diametro nominale",
    "steel_8.8":       0.85,
    "steel_10.9":      0.90,
    "steel_12.9":      0.95,
    "cast_iron_8.8":   1.30,
    "cast_iron_10.9":  1.50,
    "cast_iron_12.9":  1.70,
    "aluminum_8.8":    2.00,
    "aluminum_10.9":   2.50,
    "aluminum_12.9":   3.00
  }
}