ISO material groups: P, M, K, N, S, H
The letter and color stripe on an insert box tell you which material the grade is for, and the number (P10, P25, M30…) whether it leans to finishing or roughing. Explained per ISO 513.
Quick answer
ISO 513 groups and box colors: P blue — steel, M yellow — stainless, K red — cast iron, N green — non-ferrous, S brown — heat-resistant alloys and titanium, H grey — hardened steel. The number after the letter (P10…P40): lower means more wear resistance for finishing, higher means more toughness for roughing.
Steel: all kinds of steel and cast steel except austenitic stainless
For example: 1018, 1045, 4140, 4340, annealed tool steels
P01 · P10 · P20 · P30 · P40 · P50
Stainless steel: austenitic and austenitic/ferritic steel and cast steel
For example: 304, 316, 321, duplex stainless
M01 · M10 · M20 · M30 · M40
Cast iron: grey, spheroidal graphite (ductile), malleable
For example: Class 30 grey iron, 65-45-12 ductile iron, malleable iron
K01 · K10 · K20 · K30 · K40
Non-ferrous: aluminum and other non-ferrous metals, non-metallic materials
For example: 6061, 7075, brass, bronze, copper, nylon, acetal
N01 · N10 · N20 · N30
Heat-resistant alloys based on iron, nickel and cobalt; titanium and titanium alloys
For example: Inconel 718, Waspaloy, Ti-6Al-4V, Hastelloy
S01 · S10 · S20 · S30
Hard materials: hardened steel, hardened cast iron, chilled cast iron
For example: hardened 52100, 4140, D2, typically from ~45 HRC
H01 · H10 · H20 · H30
What the number means: P10, P25, P40
The maker places its grade on this scale itself: "P15–P30" on the box means the grade is meant for steel from semi-finishing to medium roughing. Per the standard a group is not a grade: grades from different makers in the same group can perform differently, so ISO 513 gives no grade cross-reference charts.
Insert material codes: HC — P10
The full ISO 513 designation is the material code, a dash and the group: HW — P10 (uncoated carbide for steel), HC — K20 (coated carbide for cast iron), CA — K10 (oxide ceramic for cast iron).
| HW | uncoated carbide, mainly tungsten carbide (WC), grain ≥ 1 µm |
| HF | the same, fine grain < 1 µm |
| HT | uncoated, mainly TiC/TiN — cermets |
| HC | coated carbides |
| CA | ceramic, mainly aluminum oxide Al₂O₃ |
| CM | mixed ceramic: Al₂O₃ plus non-oxide components |
| CN | silicon nitride ceramic Si₃N₄ |
| CR | reinforced Al₂O₃ ceramic |
| CC | coated ceramics |
| BL | cubic boron nitride (CBN), low content |
| BH | CBN, high content |
| BC | coated CBN |
Groups, colors, materials, application groups and codes follow ISO 513:2004 (official text: IS 2428:2007, identical, open at law.resource.org); the current ISO 513:2012 keeps the same main groups. Example grades and the hardness threshold for group H are typical catalog values. Diamond codes (table 3) are unreadable in the scan and not listed.
Cutting speeds by material are in the RPM calculator, the insert code itself on the ISO 1832 insert designation page.