The M4 size of Flat Plain Washer is dimensioned by GB/T 95 / ISO 7091. The tables below give the dimensional row from the standard, the drill and spanner sizes that go with it, and the assembly torque per property class. The technical drawing on this page redraws to the exact values selected.
M4 Dimensional Row (GB/T 95 / ISO 7091)
| 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 Flat Plain Washer — GB/T 95 / ISO 7091 (Series 079)
Drive geometry for M4 Flat Plain Washer — GB/T 95 / ISO 7091 (Series 079) is given by the row above; match the tool to the listed values.
Common Applications for M4 Flat Plain Washer — GB/T 95 / ISO 7091 (Series 079)
M4 Flat Plain Washer — GB/T 95 / ISO 7091 (Series 079) are commonly specified for small electronics hardware and precision assemblies.
Installation Tips for M4 Flat Plain Washer — GB/T 95 / ISO 7091 (Series 079)
- 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.