For Square Nuts, the M20 thread sits in the heavy-duty range of the catalog and is one of the most-asked square nuts in this family. The dimensional and assembly data follow.
M20 Dimensional Row (DIN 557)
| Size | Pitch (mm) | Width across flats s (mm) | Width across corners e min (mm) | Nut height m (mm) | Reference standard | Notes |
|---|---|---|---|---|---|---|
| M20 | 2.5 | 30.0 | 42.0 | 16.0 | DIN 557 / DIN 562 | Square nut, general / channel use |
Spanner & Drive for M20 Square Nuts
Drive geometry for M20 Square Nuts is given by the row above; match the tool to the listed values.
Common Applications for M20 Square Nuts
M20 Square Nuts are commonly specified for structural joints, flange connections and heavy equipment foundations.
Installation Tips for M20 Square Nuts
- 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
Pair M20 with the matching M20 bolt or screw, plus a M20 flat washer where required to distribute load on softer materials.
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.