Cutting Tool Material Classification | P M K N S H Guide
The tool material series (P, M, K, N, S, H) is the most important CNC tool-selection logic, matching workpiece materials such as steel, stainless steel, cast iron, non-ferrous metals and heat-resistant alloys. Classifying by carbide, coated carbide, cermet and CBN lets you quickly match the best grade. This guide covers the full series and tool-grade reference. For workpiece grouping itself, see ISO Workpiece Material Classification.
Tool Material Series (ISO Classification)
Tool materials split into six series by workpiece; materials, traits and example grades below.
| Series | Material | Trait | Example grades |
|---|---|---|---|
| P (Steel) | Carbon / alloy steel | Stable cutting, broad use | UTi20T, NX2525, NX3035, NX4545 |
| M (Stainless) | Austenitic stainless steel | Gummy, work-hardening | MC7015, MP7035, NX2525, NX4545 |
| K (Cast Iron) | Grey / ductile iron | Brittle, wear-resistant | HTi05T, MC5005, UC5105, NX2525 |
| N (Non-Ferrous) | Aluminum, copper | Low hardness, ductile | HTi10, MD220 (PCD) |
| S (Heat Resistant) | Titanium, nickel-based alloys | High-temp strength | RT9005, MP9015, VP10RT, MP9030 |
| H (Hardened Steel) | Hardened steel | High-hardness machining | MBC010, BC8020 (CBN) |
Tool Material Structure
By substrate and process, tool materials further divide as follows.
| Class | Representative / grade | Use |
|---|---|---|
| Carbide series | General UTi, HTi; wear GTi05–GTi40; corrosion GC15–GC30 | General cutting, wear/corrosion duty |
| Coated carbide | PVD: VP series, MP series | High wear resistance, long life |
| Cermet | — | High precision, good surface finish |
| Ultra-high-pressure sintered | CBN (hardened steel), diamond (non-ferrous) | Super-hard and non-ferrous use |
| Ultra-fine grain carbide | — | High toughness, precision machining |
Wear-Resistant Tool Classes & Use Advice
| Use | Grade / series |
|---|---|
| General wear resistance | GTi05–GTi40 |
| Corrosion resistance | GC15, GC20, GC30 |
| Special wear | TF15, MF10, GM30 |
| General machining | MG10–MG60 series |
| High wear machining | GTi series |
| High-precision machining | Cermet |
| High-hardness machining | CBN tools |
CNC Tool-Selection Logic (3 Steps)
Identify the workpiece’s ISO group first, then set the tool material for roughing (lean to toughness) or finishing (lean to wear resistance), and choose the coating last; for how each step maps and what each of the six groups calls for, see Choosing Tool Material and Coating by Workpiece: The P-M-K-N-S-H Guide.
For per-brand coating (CVD/PVD) grades, see Carbide Insert Coating Chart; for hardness and trait comparison of tool materials, see Cutting Tool Materials Guide. For cutting parameters, see End Mill Cutting Conditions Guide.
※ Grades are examples (mostly a single brand's series) for classification and selection reference only; verify exact grades and applicability against each brand's catalog.
FAQ
What do P/M/K/N/S/H mean for tools?
They match the workpiece — P steel, M stainless, K cast iron, N non-ferrous (Al/Cu), S heat-resistant (Ti/Ni-based), H high-hardness (hardened steel). Identify the group first, then pick the matching tool series.
What is the basic selection flow?
Three steps — Step 1 identify material (steel P, stainless M, cast iron K); Step 2 assess conditions (roughing→high toughness, finishing→high wear); Step 3 choose material (general→carbide, high-speed→coated, super-hard→CBN/diamond).
Which tool for hardened steel?
It is the H series; use CBN tools (e.g. example grades MBC010, BC8020) for hard turning/milling. Diamond suits non-ferrous, not steel.
What are GTi and GC in the carbide series?
They are example carbide grades — GTi05–GTi40 for general wear resistance, GC15–GC30 for corrosion resistance; verify actual grades against the maker's catalog.
This article is part of Tool Materials and Coatings: The Complete Guide - Separate Substrate From Coating, Then Work Back From the Workpiece; that guide shows how the whole topic fits together.
Published: 2026-03-25 | Last updated: 2026-10-25
