Catalogue data and standard-part designations in this guide follow the cBallast C-Parts range, supplied through Bufab (Värnamo, Sweden). Values are nominal reference data; confirm against the controlling standard revision before procurement.The DIN fastener standards most plants still quote have been withdrawn in favour of ISO equivalents, and a handful of dimensions changed on the way: hexagon across-flats on M10, M12, M14 and M22 bolts and nuts, nut heights, some thread lengths. This guide lists the DIN → ISO pairs for bolts, socket screws, nuts, washers, set screws, tapping screws, pins and rivets, flags the standards that have no ISO equivalent and stay DIN (DIN 127, DIN 471/472, DIN 580, DIN 975/976, DIN 6798, DIN 2093), and gives the across-flats and nut-height tables so mixed inventories can be assessed for interchangeability.
Catalogue data and standard-part designations in this guide follow the cBallast C-Parts range, supplied through Bufab (Värnamo, Sweden). Values are nominal reference data; confirm against the controlling standard revision before procurement.
Most DIN fastener standards were withdrawn between the 1990s and 2010s once the corresponding ISO standard existed, and the ISO documents were adopted in Germany as DIN EN ISO. For the majority of parts the ISO version is dimensionally identical and the two designations can be treated as interchangeable. The exceptions are well known but still cause spanner and socket mismatches on site: ISO reduced the hexagon across-flats of M10, M12 and M14 by 1 mm and increased M22 by 2 mm, made hexagon nuts slightly taller, and revised some thread lengths. Where no ISO equivalent exists, the DIN standard remains current and continues to be used worldwide.
| DIN | ISO | Part | Dimensional change |
|---|---|---|---|
| DIN 931 | ISO 4014 | Hexagon bolt, partially threaded | Across-flats M10 17→16, M12 19→18, M14 22→21, M22 32→34; thread length b unchanged |
| DIN 933 | ISO 4017 | Hexagon screw, fully threaded | Same across-flats changes as DIN 931/ISO 4014 |
| DIN 960 / 961 | ISO 8765 / 8676 | Hexagon bolt/screw, fine pitch | Same across-flats changes |
| DIN 6921 | ISO 4162 (small series) / EN 1665 | Hexagon flange bolt | Across-flats M10 15→ (ISO 4162 uses 15 on M10, 18 on M12); check per size |
| DIN 912 | ISO 4762 | Socket head cap screw | Head and key sizes unchanged; thread length b and some transitional radii differ slightly |
| DIN 7984 | — (stays DIN) | Low-head socket cap screw | No ISO equivalent |
| DIN 6912 | — (stays DIN) | Low-head socket cap screw with pilot recess | No ISO equivalent |
| DIN 7991 | ISO 10642 | Countersunk socket screw | Head diameter and key unchanged; M12 key 8 in both |
| DIN 7380 | ISO 7380-1 / -2 | Button head socket screw (plain / flanged) | Identical |
| DIN 913 / 914 / 915 / 916 | ISO 4026 / 4027 / 4028 / 4029 | Set screws: flat / cone / dog / cup point | Identical dimensions; class 45H retained |
| DIN 934 | ISO 4032 (style 1) | Hexagon nut | Across-flats M10 17→16, M12 19→18, M14 22→21, M22 32→34; nut height increased (see table below) |
| DIN 439 | ISO 4035 | Thin hexagon nut | Same across-flats changes; class 04/05 |
| DIN 985 | ISO 10511 (thin) / ISO 7040 (normal height) | Prevailing-torque nut, nylon insert | DIN 985 height lies between the two ISO types; across-flats changes apply |
| DIN 982 | ISO 7040 | Prevailing-torque nut, nylon insert, full height | Across-flats changes apply |
| DIN 980 | ISO 7042 / ISO 10513 | All-metal prevailing-torque nut | Across-flats changes apply |
| DIN 6923 | ISO 4161 / EN 1661 | Hexagon flange nut | Flange diameter and height differ slightly by size |
| DIN 1587 | — (stays DIN) | Domed cap nut | No ISO equivalent |
| DIN 315 | — (stays DIN) | Wing nut | No ISO equivalent |
| DIN 125 | ISO 7089 (200 HV) / ISO 7090 (chamfered) | Plain washer, normal series | Dimensions identical for M3–M36; hardness now 200 HV or 300 HV classes |
| DIN 126 | ISO 7091 (100 HV) | Plain washer, product grade C | Identical |
| DIN 433 | ISO 7092 | Plain washer, small series | Identical |
| DIN 9021 | ISO 7093-1 | Plain washer, large series | Identical |
| DIN 127 / DIN 128 / DIN 7980 | — (stay DIN) | Spring lock washers | No ISO equivalent (spring lock washers are not recognised by ISO as locking elements) |
| DIN 6798 / 6797 | — (stay DIN) | Serrated / tooth lock washers | No ISO equivalent |
| DIN 6796 | — (stays DIN) | Conical spring washer | No ISO equivalent |
| DIN 2093 | — (stays DIN) | Disc spring | No ISO equivalent |
| DIN 471 / 472 | — (stay DIN) | Retaining rings for shafts / bores | No ISO equivalent in general use |
| DIN 6799 | — (stays DIN) | E-clip retaining washer | No ISO equivalent |
| DIN 7 | ISO 2338 | Parallel pin (dowel), m6 / h8 | Identical |
| DIN 6325 | ISO 8734 | Hardened dowel pin | Identical |
| DIN 1481 | ISO 8752 | Slotted spring pin, heavy duty | Identical |
| DIN 7346 | ISO 13337 | Slotted spring pin, light duty | Identical |
| DIN 7343 / 7344 | ISO 8750 / 8748 | Spiral pin, standard / heavy | Identical |
| DIN 94 | ISO 1234 | Split pin (cotter pin) | Identical |
| DIN 1 / DIN 258 | ISO 2339 / ISO 8737 | Taper pin, plain / threaded | Identical |
| DIN 603 | ISO 8677 | Carriage bolt (mushroom head, square neck) | Identical |
| DIN 580 / 582 | — (stay DIN) | Lifting eye bolt / eye nut | No ISO equivalent; DIN 580 remains the reference (CE-marked variants to the Machinery Directive) |
| DIN 975 / 976 | — (stay DIN) | Threaded rod 1 m / 2 m, stud | No ISO equivalent |
| DIN 84 | ISO 1207 | Slotted cheese head screw | Identical |
| DIN 85 | ISO 1580 | Slotted pan head screw | Identical |
| DIN 963 / 964 | ISO 2009 / ISO 2010 | Slotted countersunk / raised countersunk | Identical |
| DIN 7985 | ISO 7045 | Pan head screw, cross recess (H/Z) | Identical |
| DIN 965 / 966 | ISO 7046 / ISO 7047 | Countersunk / raised countersunk, cross recess | Identical |
| DIN 7981 / 7982 / 7983 | ISO 7049 / ISO 7050 / ISO 7051 | Tapping screws: pan / countersunk / raised countersunk, cross recess | Identical (ST thread ISO 1478) |
| DIN 7971 / 7972 / 7973 | ISO 1481 / ISO 1482 / ISO 1483 | Tapping screws, slotted | Identical |
| DIN 7976 | ISO 1479 | Hexagon head tapping screw | Identical |
| DIN 7504 | ISO 15480 / 15481 / 15482 | Self-drilling screws (hex flange / pan / countersunk) | Identical |
| DIN 660 / 661 | ISO 1051 | Solid rivets, round / countersunk head | Identical |
| DIN 7337 | ISO 15977–15984 | Blind rivets | ISO series split by head form and material |
| DIN 908 / 910 / 906 | — (stay DIN) | Screw plugs (socket / hexagon head / conical) | No ISO equivalent |
| DIN 988 | — (stays DIN) | Shim ring / supporting ring | No ISO equivalent |
M5: 8 / 8. M6: 10 / 10. M8: 13 / 13. M10: 17 / 16. M12: 19 / 18. M14: 22 / 21. M16: 24 / 24. M18: 27 / 27. M20: 30 / 30. M22: 32 / 34. M24: 36 / 36. M27: 41 / 41. M30: 46 / 46. M36: 55 / 55. (DIN 931/933/934 vs ISO 4014/4017/4032.) Consequence: a 17 mm socket does not fit an ISO M10 bolt, and a 16 mm wrench slips on a DIN M10 nut. Mixed sets on one machine are common; specify ISO for new drawings and keep both socket sizes in the kit.
M5: 4.0 / 4.7. M6: 5.0 / 5.2. M8: 6.5 / 6.8. M10: 8.0 / 8.4. M12: 10.0 / 10.8. M16: 13.0 / 14.8. M20: 16.0 / 18.0. M24: 19.0 / 21.5. M30: 24.0 / 25.6. M36: 29.0 / 31.0. ISO nuts are taller (m ≈ 0.9 d) to meet the ISO 898-2 proof-load requirement; where stack height or thread protrusion was designed around DIN 934, check that the ISO nut still fully engages and clears.
Quote the ISO number on new drawings and orders, with the DIN number in brackets during transition ("ISO 4017 (DIN 933)"). Add the property class, finish and, for nuts, the ISO 4032 style. Where a legacy drawing calls DIN 931 M12 and the spare is supplied as ISO 4014, the only visible difference is the 18 mm hexagon; the mechanical properties, thread and length are the same. Treat DIN and ISO part numbers as one stock item only after the across-flats difference has been accepted by the maintenance team that carries the tools.
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