Dimensional and assembly data for M4 Square Channel-Steel Washer to GB/T 852. 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.
M4 Dimensional Row (GB/T 852)
| For bolt size | Inner diameter d1 (mm) | Outer diameter d2 (mm) | Thickness t (mm) | Reference standard |
|---|---|---|---|---|
| M4 | 4.3 | 9.0 | 0.8 | ISO 7089 / GB/T 97.1 |
Spanner & Drive for M4 Square Channel-Steel Washer — GB/T 852 (Series 083)
Drive geometry for M4 Square Channel-Steel Washer — GB/T 852 (Series 083) is given by the row above; match the tool to the listed values.
Common Applications for M4 Square Channel-Steel Washer — GB/T 852 (Series 083)
M4 Square Channel-Steel Washer — GB/T 852 (Series 083) are commonly specified for small electronics hardware and precision assemblies.
Installation Tips for M4 Square Channel-Steel Washer — GB/T 852 (Series 083)
- At M4 the joint is sensitive to over-torque — use a torque-limiting driver and check the head doesn't bury into a softer counterpart.
When to Step Up or Down from M4
When the joint preload approaches the proof load of M4 class 8.8, step up to M5 class 8.8 (or move to M4 class 10.9). When the joint is over-specified, M3 often saves weight and cost without losing the safety margin.