M3 Hex Nut are manufactured to GB/T 6170 / ISO 4032 with a coarse thread pitch of 0.5 mm. This page lists the controlling dimensions for the M3 size — head geometry, width across flats, matching spanner size — together with the clearance hole, tapping drill and tightening torque used at assembly.
M3 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 |
|---|---|---|---|---|---|
| M3 | 0.5 | 5.5 | 6.01 | 2.4 | ISO 4032 / GB/T 6170 |
Spanner & Drive for M3 Hex Nut — GB/T 6170 / ISO 4032 (Series 059)
M3 Hex Nut — GB/T 6170 / ISO 4032 (Series 059) have a width across flats of 5.5 mm — fit a 5.5 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 M3 Hex Nut — GB/T 6170 / ISO 4032 (Series 059)
M3 Hex Nut — GB/T 6170 / ISO 4032 (Series 059) are commonly specified for paired with the same-size screws on PCB hardware, light enclosures and small-scale assemblies.
Mating Parts for M3
Pair M3 with the matching M3 bolt or screw, plus a M3 flat washer where required to distribute load on softer materials.
When to Step Up or Down from M3
When the joint preload approaches the proof load of M3 class 8.8, step up to M4 class 8.8 (or move to M3 class 10.9). When the joint is over-specified, M2 often saves weight and cost without losing the safety margin.