M4 Serrated Lock Washers (DIN 6798) are specified by thread size, length and head dimensions. The M4 row from the standard is reproduced below, followed by the drill sizes, spanner size and torque values used when installing this size.
M4 Dimensional Row (DIN 6798)
| For size | Inner diameter d1 (mm) | Outer diameter d2 (mm) | Thickness h (mm) | Type | Reference standard |
|---|---|---|---|---|---|
| M4 | 4.3 | 7.6 | 0.5 | Internal-tooth type A | DIN 6798 A/J |
Spanner & Drive for M4 Serrated Lock Washers
Drive geometry for M4 Serrated Lock Washers is given by the row above; match the tool to the listed values.
Common Applications for M4 Serrated Lock Washers
M4 Serrated Lock Washers are commonly specified for small electronics hardware and precision assemblies.
Mating Parts for M4
A M4 flat washer pairs with a M4 bolt/screw and matching M4 nut.
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.

