DIN 912 (ISO 4762) screw: socket head, dimensions and property classes
DIN 912 is the cylindrical head screw with an internal hexagon, the one everybody calls Allen. Its current equivalent is ISO 4762. Compared with the DIN 933 hex bolt, the head and the tightening tool change; the thread and the property classes are the same.
It is chosen when the head has to sit in a recess or there is no room to turn a spanner: tooling, moulds, machine bases and machined assemblies. Outdoors and in steel structures the hex head bolt still rules, because the internal hexagon fills with dirt or rounds off.
We supply it in property classes 8.8 and 10.9; 12.9 exists mainly in smaller diameters, so in large metric sizes availability and lead time must be confirmed before the project is closed.
| Standard | Equivalent | Head |
|---|---|---|
| DIN 912 | ISO 4762 | Cylindrical with internal hexagon (Allen) |
Allen key size and thread pitch
| Thread size | Allen key size | Pitch |
|---|---|---|
| M16 | 14 mm | 2 |
| M20 | 17 mm | 2.5 |
| M24 | 19 mm | 3 |
| M30 | 22 mm | 3.5 |
| M36 | 27 mm | 4 |
| M42 | 32 mm | 4.5 |
| M48 | 36 mm | 5 |
Coarse metric thread pitch, in millimetres. Before buying the Allen key or socket, confirm the key size on the data sheet of the batch manufacturer.