Effect of ‘s‘ content on the machining torque.
Free machining steels are generally used after cold processing such as drawing, peeling, grinding etc. The extent of cold work employed in converting black bar of free machining steel into bright bar, decides its surface hardness,which in turn is responsible for its machining performance.
| Condition of Supply | Shapes | Sizes |
1. Black | Hex | 15.5 mm — 38 mm A/F |
| 2. Black | Round | 5.5 mm — 100 mm dia |
| 3. Black | WRD | 5.5 mm — 38 mm dia |
| 4. Drawn | Hex | 14 mm – 36 mm A/F |
| 5. Drawn | Round | 10mm — 50 mm die |
| 6. Peeled & Ground | Round | 10 mm — 90 mm dia |
