M8 Thin Hex Nut are manufactured to GB/T 901 / DIN 939. This page lists the controlling dimensions for the M8 size together with the drive and the installation notes for this type.
M8 Dimensional Row (GB/T 901 / DIN 939)
| Size | Pitch (mm) | Width across flats s (mm) | Width across corners e (mm) | Nut height m (mm) | Reference standard |
|---|---|---|---|---|---|
| M8 | 1.25 | 13.0 | 14.38 | 4.0 | ISO 4035 / GB/T 6172 |
Spanner & Drive for M8 Thin Hex Nut — GB/T 901 / DIN 939 (Series 094)
M8 Thin Hex Nut — GB/T 901 / DIN 939 (Series 094) have a width across flats of 13.0 mm — fit a 13.0 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.
Tightening Torque for M8
| Class 8.8 (dry, ~µ 0.125) | ≈ 25 Nm |
|---|---|
| Class 10.9 (dry, ~µ 0.125) | ≈ 35 Nm |
| Class 12.9 (dry, ~µ 0.125) | ≈ 41 Nm |
Indicative dry-joint values. Lubrication can lower the required torque by 15–25%. Always confirm against the joint design, especially when going up a strength class.
Proof Load & Strength for M8
| Tensile stress area As (ISO 898-1) | 36.6 mm² |
|---|---|
| Proof load, class 8.8 | 21 kN |
| Proof load, class 10.9 | 30 kN |
| Proof load, class 12.9 | 36 kN |
| Min. ultimate tensile, class 8.8 | 29 kN |
Proof load = stress area × proof stress per ISO 898-1. Design joints so the working preload stays below the proof load of the selected class.
Common Applications for M8 Thin Hex Nut — GB/T 901 / DIN 939 (Series 094)
M8 Thin Hex Nut — GB/T 901 / DIN 939 (Series 094) are commonly specified for general-purpose joints in machinery, fixturing and equipment frames.
Mating Parts for M8
Pair M8 with the matching M8 bolt or screw, plus a M8 flat washer where required to distribute load on softer materials.
When to Step Up or Down from M8
When the joint preload approaches the proof load of M8 class 8.8, step up to M10 class 8.8 (or move to M8 class 10.9). When the joint is over-specified, M6 often saves weight and cost without losing the safety margin.
