M12 is one of the standard coarse-thread sizes for thin hex nut, fine pitch under GB/T 6173 / ISO 8675. The sections below reproduce the dimensional row, list the matching tools and hole sizes, and summarize where this size is normally specified.
M12 Dimensional Row (GB/T 6173 / ISO 8675)
| Size | Pitch (mm) | Width across flats s (mm) | Width across corners e (mm) | Nut height m (mm) | Reference standard |
|---|---|---|---|---|---|
| M12 | 1.75 | 18.0 | 20.03 | 6.0 | ISO 4035 / GB/T 6172 |
Spanner & Drive for M12 Thin Hex Nut, Fine Pitch — GB/T 6173 / ISO 8675 (Series 056)
M12 Thin Hex Nut, Fine Pitch — GB/T 6173 / ISO 8675 (Series 056) have a width across flats of 18.0 mm — fit a 18.0 mm open-ended spanner or socket. Use a 6-point socket for tight clearances and to reduce rounding; for repeated assembly choose a torque wrench so the joint preload is repeatable.
Common Applications for M12 Thin Hex Nut, Fine Pitch — GB/T 6173 / ISO 8675 (Series 056)
M12 Thin Hex Nut, Fine Pitch — GB/T 6173 / ISO 8675 (Series 056) are commonly specified for medium-duty structural joints and motor / chassis mounting.
Installation Tips for M12 Thin Hex Nut, Fine Pitch — GB/T 6173 / ISO 8675 (Series 056)
- Use a 6-point socket where access allows — 12-point sockets are more prone to rounding the corners on smaller sizes.
- On flanged or serrated variants, do NOT add a separate flat washer — the flange already spreads the load and the washer can defeat the locking serrations.
Mating Parts for M12
Pair M12 with the matching M12 bolt or screw, plus a M12 flat washer where required to distribute load on softer materials.