ISO Material Classification
ISO 513 is the shared vocabulary of tooling. It sorts workpiece materials by how they behave in the cut, which is why a tool catalogue can recommend anything at all without knowing your alloy.
General engineering reference Standard, publicly established machining knowledge — formulas, ISO classifications and industry practice. This is not EUROCUTPRECISION-specific cutting data and no value here is a test result obtained with a EUROCUTPRECISION tool.
What the standard does
ISO 513 classifies hard cutting materials and the workpiece materials they are applied to. For a machinist, the useful half is the workpiece side: six groups, each with a letter, a colour used consistently across tooling catalogues worldwide, and a numeric subdivision that runs from the toughest application to the most wear-resistant.
The classification is behavioural, not metallurgical. It is not a materials standard and it does not tell you a composition; it tells you which family of cutting problems you are about to have.
The six groups
| Group | Colour | Covers | Characteristic machining behaviour |
|---|---|---|---|
| P | Blue | Unalloyed, low-alloy and high-alloy steel; cast steel; ferritic and martensitic stainless | Long continuous chips; crater wear driven by temperature |
| M | Yellow | Austenitic and duplex stainless; austenitic cast steel | Work hardening; poor heat conduction; notching |
| K | Red | Grey cast iron, nodular (ductile) iron, malleable and compacted graphite iron | Short breaking chips; abrasive flank wear |
| N | Green | Aluminium and other non-ferrous metals, copper, brass, non-metallics | High permissible speed; adhesion and evacuation dominate |
| S | Orange | Heat-resistant nickel and cobalt superalloys, titanium alloys | Heat concentrated at the edge; notch wear; reactivity |
| H | Grey | Hardened steel, hardened and chilled cast iron | Very high hardness; edge integrity and rigidity govern |
The colours are worth learning. A catalogue that marks a tool "P25" in blue and "M30" in yellow is telling you at a glance both the intended material family and where in that family's toughness-to-wear-resistance spectrum the grade sits.
Reading the subgroup number
Each letter is followed by a number, conventionally from about 01 to 50. The number is a position on a single axis:
- Low numbers (01–10) — maximum wear resistance, minimum toughness. Finishing operations, light cuts, stable conditions, high speeds.
- Middle numbers (15–30) — general-purpose balance. The majority of production work sits here.
- High numbers (35–50) — maximum toughness, reduced wear resistance. Interrupted cuts, unstable setups, heavy roughing, cast skin.
So P10 and P40 are both for steel, and choosing between them is a question about the cut, not the material: a stable finishing pass wants P10, a shock-loaded roughing cut through cast skin wants P40. Running P10 in an interrupted cut chips it; running P40 in a stable finishing cut wears it out early.
Using the classification in practice
- Identify the group from the workpiece material — the drawing or material certificate gives the alloy; the group follows from the table above.
- Read across the tooling catalogue for the group's colour and letter. This eliminates most of the range immediately.
- Choose the subgroup number from the stability of the cut, not from the material — interrupted, unstable or heavy cuts push the number up.
- Take the starting parameters from the tool manufacturer's data for that specific tool and group, then verify on a test cut.
A caution worth stating plainly: an ISO group is not a guarantee of interchangeability. Two alloys in the same group can differ substantially in hardness and hot strength, and the group tells you nothing about the condition the material is in — annealed, normalised, quenched and tempered, or work-hardened from a previous operation.
The Z5 series is tabulated by its manufacturer for ISO P, M, K and S, with a named workpiece material and a hardness band for each. The range, and the parameters that go with it, are published on every Z5 product page. N and H carry no row — that is an absence of manufacturer guidance, not a statement that the tool is unsuitable for them, and it is not published as one.
What determines the final material group selection
Every figure on this page is a starting point for a calculation, not a setting to type into a control. The value that is correct for your job depends on:
- workpiece material
- workpiece hardness
- tool diameter
- radial engagement (ae)
- axial depth of cut (ap)
- holder and tool-assembly rigidity
- machine rigidity and spindle power
- coolant strategy
- spindle capability (speed, torque, runout)
- the actual machining conditions on the job
The manufacturer’s own starting parameters for the Z5 series are published, per workpiece material and per operation, on each variant’s product page. Start from those rather than from anything you derive here: this page explains a calculation, it does not describe a EUROCUTPRECISION tool. Either way, verify on a test cut and adjust from the behaviour of the chip, the sound of the cut and the finished surface.