ISO M — Stainless Steel · M01
M01 — Austenitic (304, 316L)
Hardness range: 150–220 HB. Part of the ISO M — Stainless Steel group. Stainless steel presents work-hardening as the main challenge. Austenitic grades (304, 316L) built-up-edge and notch-wear rapidly. Positive, sharp geometry with high-pressure coolant at 15–20 bar is standard. Consistent depth of cut prevents re-cutting the hardened chip ramp.
Material profile — M01
- ISO designation
- M01 (ISO M — Stainless Steel)
- Material
- Austenitic (304, 316L)
- Hardness
- 150–220 HB
- ISO group colour
- Stainless Steel
Tooling guidance — M-group
- Group summary
- Work hardening is the main challenge. Sharp positive geometry, high-pressure coolant 15–20 bar, consistent DOC.
Insert selection for 304 / 316L — starting point
- ISO application class
- M (stainless). Match the insert's ISO class, not the brand name: an M15–M25 grade is the brand-independent common denominator. Sandvik, Kennametal, Iscar, Walter, Seco and Mitsubishi each publish an M-class grade for 304/316L — pick by ISO class, then confirm the exact grade for your condition.
- Grade & coating
- Tough PVD-coated carbide. Roughing ≈ M25–M30 for heat and edge security; finishing ≈ M10–M20 for a sharper edge and better surface.
- Geometry
- Positive rake, sharp or lightly honed edge, open polished chipbreaker. Avoid a heavy negative land or chamfer — it pushes the material and accelerates work-hardening.
- Starting parameters (carbide)
- Vc ≈ 120–200 m/min, fn ≈ 0.10–0.35 mm/rev, high-pressure coolant 15–20 bar aimed at the edge. Typical starting band — confirm in the advisor or on a sample part before production.
Selection table: austenitic stainless (304 / 316L)
| Operation | Geometry | ISO class | Coating family | Coolant | First check |
|---|---|---|---|---|---|
| Roughing | Positive rake, lightly honed edge, open polished chipbreaker; avoid a heavy negative land | M25–M30 | Tough PVD-coated carbide | High-pressure coolant 15–20 bar aimed at the edge | Consistent depth of cut: stay above the work-hardened layer |
| Finishing | Positive rake, sharp edge, polished chipbreaker | M10–M20 | PVD-coated carbide, sharper edge | High-pressure coolant 15–20 bar | Built-up edge: Vc too low or tool dwelling |
| Interrupted cut | Positive but robust honed edge | M25–M30 | Tougher PVD-coated carbide | High-pressure coolant 15–20 bar | Notch wear at the depth-of-cut line: vary DOC between passes |
| Low rigidity / thin wall | Positive rake, sharp edge to avoid pushing the material | M10–M20 | PVD-coated carbide | High-pressure coolant 15–20 bar | Feed high enough for the chipbreaker to engage |
304 / 316L: what goes wrong, and what to check first
- Built-up edge
- Smeared finish and sudden chipping usually mean cutting speed too low, or the edge dwelling in the cut. Raise Vc into the working band, switch to a sharper positive polished edge, and get coolant to the edge. See the tool-wear guide.
- Work-hardened skin
- Rapid flank wear and re-cutting come from an inconsistent depth of cut, or the tool stopping in cut and leaving a hardened ramp the next pass re-cuts. Keep DOC above the previously hardened layer and never let the tool dwell.
- Notch wear at the DOC line
- Oxidation and abrasion concentrate at the depth-of-cut line on austenitics. Vary DOC slightly between passes, ease Vc back, and use a tougher edge grade.
- Long gummy chips
- Feed too low for the chipbreaker to engage. Increase fn into the band above — controlled chips, not lower speed, is usually the fix.
Reference data
Frequently asked questions
What insert grade should I use for 304 / 316L?
Use a tough PVD-coated carbide in the ISO M class. Match the insert's ISO application class rather than the brand: an M15–M25 grade is the brand-independent common denominator, with roughing around M25–M30 and finishing around M10–M20. Confirm the exact grade for your condition in the advisor.
Why does 316L work-harden, and how do I avoid it?
Austenitic stainless has low thermal conductivity and hardens under deformation, so an inconsistent depth of cut or a tool dwelling in the cut leaves a hardened ramp the next pass re-cuts. Keep the depth of cut above the previously hardened layer, never let the tool stop in cut, and use a sharp positive edge.
What causes built-up edge on 304 / 316L?
Built-up edge on austenitic stainless usually means the cutting speed is too low or the edge is dwelling. Raise the cutting speed into the working band, use a sharper positive polished geometry, and aim high-pressure coolant at 15–20 bar at the edge.
What is a typical starting cutting speed for 316L with carbide?
A typical carbide starting band for turning 304/316L is roughly Vc 120–200 m/min and fn 0.10–0.35 mm/rev with high-pressure coolant. Treat this as a starting point and confirm for your setup in the advisor or 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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