This page covers M3 Hex Nut to GB/T 6170 / ISO 4032: the full dimensional row, hole and tool sizes, proof-load data and typical applications. All values are taken from the governing standards (GB/T 6170 / ISO 4032 together with ISO 273, ISO 724 and ISO 898-1 where applicable).
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 066)
M3 Hex Nut — GB/T 6170 / ISO 4032 (Series 066) 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 066)
M3 Hex Nut — GB/T 6170 / ISO 4032 (Series 066) are commonly specified for paired with the same-size screws on PCB hardware, light enclosures and small-scale assemblies.
Installation Tips for M3 Hex Nut — GB/T 6170 / ISO 4032 (Series 066)
- 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.
- At M3 the joint is sensitive to over-torque — use a torque-limiting driver and check the head doesn't bury into a softer counterpart.
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.