ISO N — Non-Ferrous · N20
N20 — Copper / Brass
Hardness range: 80–160 HB. Part of the ISO N — Non-Ferrous group. Non-ferrous metals (aluminium, copper, brass, magnesium) are soft and thermally conductive. Uncoated or DLC-coated fine-grain carbide with high positive rake, sharp edges, and polished flutes prevents built-up-edge. PCD inserts excel in high-volume aluminium production. No TiN/TiAlN coatings — aluminium welds to them.
Material profile — N20
- ISO designation
- N20 (ISO N — Non-Ferrous)
- Material
- Copper / Brass
- Hardness
- 80–160 HB
- ISO group colour
- Non-Ferrous
Tooling guidance — N-group
- Group summary
- Uncoated or DLC carbide for aluminium. Sharp edges, high positive rake, polished flutes prevent BUE.
Insert selection for copper / brass — starting point
- ISO application class
- N (non-ferrous). Free-machining brass cuts easily; copper is gummy and prone to built-up edge, so the two want different rake. Match the ISO N 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
- Uncoated polished carbide; PCD for high-volume work. Sharp edges throughout.
- Geometry
- For copper, sharp high positive rake plus coolant to avoid smearing. For free-machining brass, a near-neutral or slightly negative rake stops the tool grabbing and self-feeding.
- Starting parameters
- Brass Vc ≈ 200–500 m/min; copper Vc ≈ 150–400 m/min; fn ≈ 0.05–0.30 mm/rev. Confirm in the advisor or on a sample part.
Selection table: copper / brass
| Operation | Geometry | ISO class | Coating family | Coolant | First check |
|---|---|---|---|---|---|
| Roughing | Copper: sharp high positive rake. Brass: near-neutral or slightly negative rake | N (N-class grade) | Uncoated polished carbide; PCD for high-volume work | Coolant for copper to avoid smearing | Rake matched to the alloy: brass grabs, copper builds up |
| Finishing | Sharp edges throughout | N (N-class grade) | Uncoated polished carbide | Coolant for copper | Smearing: a dull or rubbing edge smears soft metal |
| Interrupted cut | Sharp edge, rake per alloy | N (N-class grade) | Uncoated polished carbide | Coolant for copper | Grabbing or self-feeding on free-machining brass |
| Low rigidity / thin wall | Near-neutral rake on brass to stop self-feeding | N (N-class grade) | Uncoated polished carbide | Coolant for copper | Long stringy chips on copper: chipbreaker geometry |
copper / brass: what goes wrong, and what to check first
- Built-up edge on copper
- Copper is gummy and welds to the edge. Use a sharp positive polished edge and coolant; raise the speed.
- Grabbing / self-feeding on brass
- Too positive a rake lets free-machining brass pull the tool in. Use a near-neutral or slightly negative rake.
- Long stringy chips on copper
- Copper does not chip-break easily; use a sharp edge, coolant, and a chipbreaker geometry.
- Smearing / poor finish
- A dull or rubbing edge smears soft non-ferrous metal; keep the edge keen.
Reference data
Frequently asked questions
What insert for brass versus copper?
Both use sharp uncoated polished carbide, but brass wants a near-neutral or slightly negative rake to stop grabbing, while copper wants a sharp positive rake plus coolant. Match the ISO N class and confirm in the advisor.
Why does copper build up on the edge?
Copper is gummy and welds to the edge, especially at low speed. Use a sharp positive polished edge with coolant and raise the speed.
Why does brass grab the tool?
Free-machining brass with too positive a rake pulls the insert in and self-feeds; use a near-neutral or slightly negative rake.
What cutting speed for brass and copper?
Brass roughly Vc 200–500 m/min, copper Vc 150–400 m/min, fn 0.05–0.30 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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