ISO P — Steel · P01
P01 — Low carbon steel
Hardness range: 125–180 HB. Part of the ISO P — Steels group. Steel is the most widely machined material. Carbon and alloy steels are the target material for the majority of turning and milling operations. Hardness ranges from ~125 HB (low-carbon) to 350 HB (high-strength structural). CVD-coated carbide (TiCN/Al₂O₃ multilayer) dominates. Positive geometry for finishing, negative for heavy roughing.
Material profile — P01
- ISO designation
- P01 (ISO P — Steels)
- Material
- Low carbon steel
- Hardness
- 125–180 HB
- ISO group colour
- Steel
Tooling guidance — P-group
- Group summary
- CVD-coated carbide at Vc 200–400 m/min. Positive geometry for finishing, negative for roughing.
Insert selection for low-carbon / mild steel (1018) — starting point
- ISO application class
- P (steel). Low-carbon mild steel (1018, S235) is gummy, so built-up edge and long stringy chips are the main problems, not wear. Match the ISO P class across brands rather than the brand name (Sandvik, Kennametal, Iscar, Walter, Seco and Mitsubishi each publish one), then confirm the exact grade for your condition.
- Grade & coating
- Coated carbide, P10–P25. A sharp positive geometry and a medium chipbreaker fight built-up edge and stringy chips.
- Geometry
- Positive, sharp edge with a chipbreaker sized to break soft, stringy chips.
- Starting parameters
- Vc ≈ 150–300 m/min, fn ≈ 0.10–0.40 mm/rev. Confirm in the advisor or on a sample part.
Selection table: low-carbon steel (1018)
| Operation | Geometry | ISO class | Coating family | Coolant | First check |
|---|---|---|---|---|---|
| Roughing | Positive, sharp edge with a chipbreaker sized for soft, stringy chips | P10–P25 | Coated carbide | Add coolant against built-up edge | Long stringy chips: increase fn or use a roughing breaker |
| Finishing | Positive, sharp edge, medium chipbreaker | P10–P25 | Coated carbide | Add coolant against built-up edge | Built-up edge: raise Vc, sharper edge |
| Interrupted cut | Positive edge with a robust chipbreaker | P10–P25 (tougher end) | Coated carbide | Add coolant as needed | Smearing at low speed: keep speed in band |
| Low rigidity / thin wall | Positive, sharp edge | P10–P25 | Coated carbide | Add coolant as needed | Poor finish from built-up edge |
low-carbon / mild steel (1018): what goes wrong, and what to check first
- Built-up edge
- Mild steel welds to the edge at low speed. Raise Vc, use a sharper positive edge, and add coolant.
- Long stringy chips / bird-nesting
- Feed too low or wrong chipbreaker. Increase fn or pick a roughing breaker.
- Poor finish from BUE
- The same fix: more speed and a sharper edge so material shears cleanly.
- Smearing at low speed
- Keep the speed in band and the edge keen.
Reference data
Frequently asked questions
What insert for mild steel like 1018?
A coated carbide, P10–P25, with a sharp positive geometry and a chipbreaker. Match the ISO P class across brands and confirm in the advisor.
Why do I get long stringy chips on mild steel?
Mild steel is gummy; too low a feed or the wrong chipbreaker lets chips run. Increase feed or use a roughing breaker.
Why is there built-up edge on mild steel?
It welds to the edge at low speed; raise the speed, use a sharper positive edge, and add coolant.
What cutting speed for low-carbon steel?
Roughly Vc 150–300 m/min, fn 0.10–0.40 mm/rev. Confirm on a sample part.
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Grade designations in this group
Each page cross-references the EN, Werkstoffnummer, AISI/UNS and JIS designations for one material, with the ISO machining group it falls in.
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