ISO 513 Classification of Hard Cutting Materials (P, M, K, N, S, H) Reference Guide
International standard ISO 513 classification of workpiece material groups, cutting force coefficients (kc1.1), and carbide/ceramic/CBN tool grade recommendations.
Standard Scope
Specifies the international standard classification and application guidelines for hard cutting materials (cemented carbides, cermets, ceramics, polycrystalline diamond PCD, and cubic boron nitride CBN) for metal cutting per ISO 513. The standard establishes the primary workpiece material groups (P, M, K, N, S, H) identified by standardized color coding and letter designations.
Typical Applications
- •Machine shop material group classification and cutting tool grade selection with the [Speeds & Feeds PRO Calculator](/calculators/speeds-feeds).
- •CNC cycle time, tool life, and manufacturing economics calculation with the [Machining Cost Estimator](/calculators/machining-cost-estimator).
- •Determination of specific cutting force coefficients ($k_{c1.1}$) and Kienzle chip thickness exponents ($m_c$) for spindle power estimation.
- •Raw engineering stock and alloy selection using our [Engineering Materials Guide](/knowledge/articles/engineering-materials-guide).
Key Engineering Concepts
ISO Material Groups (P, M, K, N, S, H)
Standardized 6-group workpiece classification system:
ISO P (Blue)
Carbon steels, low-alloy steels, tool steels, and long-chipping ferritic/martensitic steels.
ISO M (Yellow)
Austenitic, duplex, and precipitation-hardening stainless steels.
ISO K (Red)
Grey cast iron, nodular ductile iron, and compacted graphite iron (CGI).
ISO N (Green)
Non-ferrous alloys including wrought/cast aluminum, brass, bronze, copper, and engineering polymers.
ISO S (Orange)
Heat-resistant superalloys (HRSA) including Inconel, Waspaloy, Hastelloy, and titanium alloys (Ti-6Al-4V).
ISO H (Grey)
Hardened steels and chilled irons ($45 - 68\text{ HRC}$).
Specific Cutting Force ($k_{c1.1}$)
The baseline cutting resistance (in $\text{N/mm}^2$ or $\text{MPa}$) required to shear a chip cross-section of $1.0\text{ mm}^2$ ($b = 1\text{ mm}, h = 1\text{ mm}$).
Kienzle Chip Thickness Exponent ($m_c$)
Empirical slope exponent modeling chip thickness deformation resistance:
Net Cutting Power ($P_c$)
Theoretical spindle power consumed at the tool shear zone:
Interactive Calculator Call to Action
Shaft Diameter Calculator (Torsion)
Calculate interactively with instant results, step-by-step derivations, and unit conversion. Built on the same engineering standards as this formula reference.
Related Calculators
Engineering Notes & Best Practices
- •Work-Hardening Tendency: ISO M (stainless steels) and ISO S (superalloys) rapidly work-harden if the uncut chip thickness ($h_m$) drops below the hone radius of the cutting edge ($r_\beta \approx 0.015 - 0.03\text{ mm}$); always maintain minimum recommended feed per tooth ($f_z \ge 0.04\text{ mm}$).
- •Flute Evacuation in Non-Ferrous Alloys: ISO N aluminum milling requires generous chip gullets (2-flute or 3-flute end mills with polished or DLC-coated flutes) to prevent aluminum chip packing and spindle stall.
Official Standards Reference
Classification and application of hard cutting materials for metal removal with defined cutting edges
International Organization for Standardization classification standard
Application groups for hard cutting materials
German Institute for Standardization companion code