For Spring Lock Washers, the M20 thread sits in the heavy-duty range of the catalog and is one of the most-asked spring lock washers in this family. The dimensional and assembly data follow.
M20 Dimensional Row (ISO 7980 / DIN 127)
| For bolt size | Inner diameter d1 min (mm) | Outer diameter d2 max (mm) | Width b (mm) | Thickness s (mm) | Reference standard |
|---|---|---|---|---|---|
| M20 | 20.2 | 33.6 | 10.0 | 4.0 | ISO 7980 / DIN 127 |
Spanner & Drive for M20 Spring Lock Washers
Drive geometry for M20 Spring Lock Washers is given by the row above; match the tool to the listed values.
Common Applications for M20 Spring Lock Washers
M20 Spring Lock Washers are commonly specified for high-load load-spreading on structural joints.
Installation Tips for M20 Spring Lock Washers
- At M20 the stretch in the bolt becomes the controlling factor — for critical joints, use angle-controlled or stretch-controlled tightening instead of pure torque.
Mating Parts for M20
A M20 flat washer pairs with a M20 bolt/screw and matching M20 nut.
When to Step Up or Down from M20
When the joint preload approaches the proof load of M20 class 8.8, step up to M24 class 8.8 (or move to M20 class 10.9). When the joint is over-specified, M16 often saves weight and cost without losing the safety margin.