Dimensional and assembly data for M12 Hex Nut to GB/T 6170 / ISO 4032. Includes head size and width across flats, clearance-hole and tapping-drill diameters, tightening torque per property class, and the sizes to step up or down to when the joint requires it.
M12 Dimensional Row (GB/T 6170 / ISO 4032)
| 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 | 10.8 | ISO 4032 / GB/T 6170 |
Spanner & Drive for M12 Hex Nut — GB/T 6170 / ISO 4032 (Series 061)
M12 Hex Nut — GB/T 6170 / ISO 4032 (Series 061) 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 Hex Nut — GB/T 6170 / ISO 4032 (Series 061)
M12 Hex Nut — GB/T 6170 / ISO 4032 (Series 061) are commonly specified for medium-duty structural joints and motor / chassis mounting.
Installation Tips for M12 Hex Nut — GB/T 6170 / ISO 4032 (Series 061)
- 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.
When to Step Up or Down from M12
When the joint preload approaches the proof load of M12 class 8.8, step up to M16 class 8.8 (or move to M12 class 10.9). When the joint is over-specified, M10 often saves weight and cost without losing the safety margin.