Selecting Fender Washers, M20, in DIN 9021: the dimensional row from the standard plus the tools and hole sizes follow. Use them with the technical drawing below — the drawing redraws to the exact size you pick.
M20 Dimensional Row (DIN 9021)
| For bolt size | Inner diameter d1 min (mm) | Outer diameter d2 max (mm) | Thickness h (mm) | Reference standard | Notes |
|---|---|---|---|---|---|
| M20 | 21.0 | 60.0 | 4.0 | DIN 9021 / ISO 7093 | Oversized OD for bearing on soft materials |
Spanner & Drive for M20 Fender Washers
Drive geometry for M20 Fender Washers is given by the row above; match the tool to the listed values.
Common Applications for M20 Fender Washers
M20 Fender Washers are commonly specified for high-load load-spreading on structural joints.
Installation Tips for M20 Fender 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.