The steels for high-speed machining, commonly called free-cutting steels, have been specially designed to be machined by chip removal with high productivity. Free-cutting steels – which are commonly used in many mass production fields such as the automobile industry and household appliances – contain sulfur and some other elements, including tellurium, bismuth and lead, which promote machinability. In particular, the sulfur ensures the fragmentation of the chip, lead reduces the friction between the tool and piece, extending the life of the tools, and the tellurium and bismuth further accentuate these characteristics. Free-cutting steels are usually supplied in bars or rolls without heat treatment; some of these can however be tempered, normalized or annealed before finishing.
| Form | Execution | Section | Dia. | Finish | Tolerances |
|---|---|---|---|---|---|
| Bar | Hot-Rolled | Round | 20-105 mm | Raw, peeled iron product | - |
| Bar | Cold-Drawn |
Round
Hexagonal Square / Special |
2-80 mm
4-80 mm 4-70 mm |
Polished | EN 10278 h9 h10 h11 |
| Bar | Peeled - Rolled | Round | 20-100 mm | Polished | EN 10278 h9 h10 h11 |
| Bar | Ground | Round | 3-100 mm | Polished | EN 10278 h7 h8 h9 h10 h11 |
| Wire | Cold-Drawn |
Round
Hexagonal Square / Special |
2-22 mm
3-12 mm 4-12 mm |
Polished, phosphated | EN 10278 h9 h10 h11 |
