M20 T-Slot Nuts are manufactured to DIN 508. This page lists the controlling dimensions for the M20 size together with the drive and the installation notes for this type.
M20 Dimensional Row (DIN 508)
| Size | T-slot width a (mm) | Nut width b (mm) | Total height h (mm) | Neck height k (mm) | Chamfer f (mm) | Reference standard |
|---|---|---|---|---|---|---|
| M20 | 22 | 35 | 28 | 14 | 2.5 | DIN 508 |
Spanner & Drive for M20 T-Slot Nuts
Drive geometry for M20 T-Slot Nuts is given by the row above; match the tool to the listed values.
Tightening Torque for M20
| Class 8.8 (dry, ~µ 0.125) | ≈ 410 Nm |
|---|---|
| Class 10.9 (dry, ~µ 0.125) | ≈ 580 Nm |
| Class 12.9 (dry, ~µ 0.125) | ≈ 690 Nm |
Indicative dry-joint values. Lubrication can lower the required torque by 15–25%. Always confirm against the joint design, especially when going up a strength class.
Proof Load & Strength for M20
| Tensile stress area As (ISO 898-1) | 245 mm² |
|---|---|
| Proof load, class 8.8 | 147 kN |
| Proof load, class 10.9 | 203 kN |
| Proof load, class 12.9 | 238 kN |
| Min. ultimate tensile, class 8.8 | 196 kN |
Proof load = stress area × proof stress per ISO 898-1. Design joints so the working preload stays below the proof load of the selected class.
Common Applications for M20 T-Slot Nuts
M20 T-Slot Nuts are commonly specified for structural joints, flange connections and heavy equipment foundations.
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.
