The ISO 513 standard classifies workpiece materials into six primary groups—P, M, K, N, S, and H—based on their machinability characteristics and metallurgical composition. Selecting the correct carbide insert grade, geometry, and cutting parameters for each group is fundamental to achieving optimal tool life, surface finish, and metal removal rates in both turning and milling operations. This guide provides a comprehensive technical reference of recommended cutting speeds (Vc), feed rates (fz), and depth of cut (ap) values for each ISO material group, drawing on industry benchmarks from leading manufacturers including Sandvik Coromant, Iscar, and Kyocera.
Understanding the ISO 513 Material Classification System
Before selecting cutting parameters, machinists must correctly identify the material group. The ISO 513 system is not a simple hardness scale; it accounts for work-hardening tendency, thermal conductivity, chip formation behavior, and chemical reactivity at elevated cutting temperatures.
- ISO P – Steel and Cast Steel: Includes unalloyed steels, low-alloy steels, and high-alloy steels up to approximately 45 HRC. This is the largest machining volume segment.
- ISO M – Stainless Steel and Ferritic/Martensitic Steels: Austenitic and duplex stainless steels, plus manganese steels and ferritic heat-resistant alloys. Characterized by high work-hardening rates and poor thermal conductivity.
- ISO K – Cast Iron: Gray cast iron (GJL), nodular (ductile) cast iron (GJS), malleable cast iron, and chilled cast iron. Abrasive graphite structures dominate wear mechanisms.
- ISO N – Non-Ferrous Metals: Aluminum and aluminum alloys, copper, brass, bronze, magnesium, and zinc-based alloys. Soft, gummy, and high thermal conductivity.
- ISO S – Superalloys and Titanium: Heat-resistant superalloys (HRSAs) based on nickel, cobalt, and iron-nickel, plus titanium alloys. Extremely high strength at temperature and low thermal conductivity.
- ISO H – Hardened Steel: Tool steels, hardened steels, and chilled cast irons above 45–68 HRC. Demands extreme substrate hardness and heat resistance from the cutting tool.
ISO P: Steel Turning and Milling Parameters
Steel machining represents the backbone of most production environments. The ISO P group demands a balance between abrasion resistance and toughness in the insert substrate, with PVD-coated fine-grained carbides (e.g., Sandvik GC4325, Iscar IC9150, Kyocera CA525) being the most common choices for general turning.
Turning Parameters for ISO P Steels
| Material Sub-Group | Hardness (HB) | Cutting Speed Vc (m/min) | Feed f (mm/rev) | Depth of Cut ap (mm) |
|---|---|---|---|---|
| Unalloyed steel (C < 0.25%) | 90–200 | 220–350 | 0.15–0.40 | 1.0–5.0 |
| Low-alloy steel (C 0.25–0.55%) | 125–325 | 150–280 | 0.12–0.35 | 1.0–4.0 |
| High-alloy steel / Tool steel (annealed) | 180–350 | 100–200 | 0.10–0.30 | 0.5–3.0 |
| Steel castings | 150–300 | 120–240 | 0.12–0.35 | 1.0–5.0 |
Milling Parameters for ISO P Steels
| Operation Type | Cutting Speed Vc (m/min) | Feed per Tooth fz (mm) | Axial Depth ap (mm) | Radial Engagement ae (%) |
|---|---|---|---|---|
| Face milling (roughing) | 180–300 | 0.12–0.25 | 2.0–5.0 | 50–75 |
| Face milling (finishing) | 250–400 | 0.08–0.15 | 0.5–2.0 | 20–40 |
| Shoulder milling | 150–280 | 0.10–0.20 | 1.0–4.0 | 30–60 |
| Slot milling | 120–220 | 0.08–0.18 | 1.0–3.0 | 100 |
ISO M: Stainless Steel Turning and Milling Parameters
Stainless steels, particularly austenitic grades such as 304 and 316, present significant challenges due to rapid work hardening, built-up edge (BUE) formation, and elevated cutting zone temperatures. Positive-rake geometries with sharp cutting edges and PVD-coated grades optimized for edge security (e.g., Sandvik GC2025, Iscar IC907, Kyocera PR1535) are essential.
Turning Parameters for ISO M Stainless Steels
| Material Sub-Group | Hardness (HB) | Cutting Speed Vc (m/min) | Feed f (mm/rev) | Depth of Cut ap (mm) |
|---|---|---|---|---|
| Ferritic stainless steel (430, 446) | 150–250 | 150–250 | 0.12–0.30 | 1.0–4.0 |
| Austenitic stainless steel (304, 316) | 130–220 | 120–220 | 0.12–0.28 | 1.0–4.0 |
| Duplex stainless steel (2205, 2507) | 200–320 | 80–160 | 0.10–0.25 | 1.0–3.0 |
| Martensitic stainless steel (410, 420) | 180–350 | 100–180 | 0.10–0.25 | 0.8–3.0 |
| Precipitation-hardening (17-4PH, 15-5PH) | 300–450 | 60–120 | 0.08–0.20 | 0.5–2.5 |
Milling Parameters for ISO M Stainless Steels
| Operation Type | Cutting Speed Vc (m/min) | Feed per Tooth fz (mm) | Axial Depth ap (mm) | Radial Engagement ae (%) |
|---|---|---|---|---|
| Face milling (roughing) | 100–200 | 0.10–0.20 | 1.5–4.0 | 50–75 |
| Face milling (finishing) | 150–280 | 0.08–0.15 | 0.5–2.0 | 20–40 |
| Shoulder milling | 90–180 | 0.10–0.18 | 1.0–3.5 | 30–60 |
| High-feed milling | 80–150 | 0.30–1.00 | 0.5–2.0 | 5–15 |
ISO K: Cast Iron Turning and Milling Parameters
Cast iron machining is characterized by abrasive graphite inclusions and intermittent cutting forces, especially with nodular cast iron. Al₂O₃-coated CVD grades with thick coatings and strong substrates (e.g., Sandvik GC3215, Iscar IC830, Kyocera CA310) provide the abrasion resistance required. Gray cast iron permits the highest cutting speeds of all ISO groups.
Turning Parameters for ISO K Cast Irons
| Material Sub-Group | Hardness (HB) | Cutting Speed Vc (m/min) | Feed f (mm/rev) | Depth of Cut ap (mm) |
|---|---|---|---|---|
| Gray cast iron (GJL 150–250) | 150–250 | 200–400 | 0.15–0.50 | 1.0–6.0 |
| Gray cast iron (GJL 300–350) | 250–350 | 150–300 | 0.12–0.40 | 1.0–5.0 |
| Nodular cast iron (GJS 400–700) | 180–320 | 120–250 | 0.12–0.40 | 1.0–5.0 |
| Vermicular (CGI) cast iron | 180–280 | 100–200 | 0.10–0.30 | 1.0–4.0 |
| Chilled / White cast iron | 350–550 | 40–100 | 0.08–0.20 | 0.5–2.0 |
Milling Parameters for ISO K Cast Irons
| Operation Type | Cutting Speed Vc (m/min) | Feed per Tooth fz (mm) | Axial Depth ap (mm) | Radial Engagement ae (%) |
|---|---|---|---|---|
| Face milling (roughing) | 180–350 | 0.15–0.35 | 2.0–6.0 | 50–80 |
| Face milling (finishing) | 250–450 | 0.10–0.20 | 0.5–2.0 | 20–40 |
| Shoulder milling | 150–300 | 0.12–0.25 | 1.0–4.0 | 30–60 |
ISO N: Non-Ferrous Metal Turning and Milling Parameters
Aluminum, copper, and magnesium alloys require uncoated or DLC-coated polished inserts with highly positive rake angles and large clearance angles to prevent built-up edge and ensure excellent surface finish. Chip evacuation and coolant delivery are critical.
Turning Parameters for ISO N Materials
| Material Sub-Group | Hardness (HB) | Cutting Speed Vc (m/min) | Feed f (mm/rev) | Depth of Cut ap (mm) |
|---|---|---|---|---|
| Aluminum wrought alloys (1xxx–7xxx) | 30–150 | 300–1000 | 0.10–0.50 | 0.5–6.0 |
| Aluminum cast alloys (silicon < 12%) | 40–120 | 250–800 | 0.12–0.45 | 1.0–5.0 |
| Aluminum cast alloys (silicon > 12%) | 50–140 | 200–600 | 0.10–0.40 | 1.0–4.0 |
| Copper and copper alloys | 60–200 | 150–400 | 0.12–0.40 | 1.0–5.0 |
| Magnesium alloys | 40–90 | 400–1200 | 0.15–0.60 | 1.0–6.0 |
Milling Parameters for ISO N Materials
| Operation Type | Cutting Speed Vc (m/min) | Feed per Tooth fz (mm) | Axial Depth ap (mm) | Radial Engagement ae (%) |
|---|---|---|---|---|
| Face milling (roughing) | 500–2000 | 0.10–0.30 | 2.0–8.0 | 50–80 |
| Face milling (finishing) | 800–3000 | 0.08–0.20 | 0.3–2.0 | 15–35 |
| High-speed shoulder milling | 600–2500 | 0.08–0.25 | 0.5–4.0 | 25–50 |
| Slot milling | 400–1500 | 0.08–0.20 | 1.0–4.0 | 100 |
ISO S: Superalloy and Titanium Turning and Milling Parameters
Nickel-based superalloys (Inconel 718, Waspaloy, Hastelloy) and titanium alloys (Ti-6Al-4V, Ti-5Al-5V-5Mo-3Cr) demand specialized insert geometries with positive rake, narrow land widths, and optimized edge preparation. PVD-coated fine-grained substrates with high hot hardness (e.g., Sandvik GC1105, Iscar IC800, Kyocera PR1725) are standard.
Turning Parameters for ISO S Materials
| Material Sub-Group | Hardness (HB) | Cutting Speed Vc (m/min) | Feed f (mm/rev) | Depth of Cut ap (mm) |
|---|---|---|---|---|
| Titanium alloys (annealed) | 250–370 | 40–90 | 0.10–0.25 | 1.0–3.0 |
| Titanium alloys (aged / high strength) | 320–420 | 25–60 | 0.08–0.20 | 0.5–2.5 |
| Nickel-based superalloys (Inconel 718) | 300–450 | 25–60 | 0.10–0.22 | 0.5–2.5 |
| Cobalt-based superalloys (Haynes, Stellite) | 250–450 | 15–45 | 0.08–0.18 | 0.5–2.0 |
| Iron-nickel superalloys (A-286, Incoloy) | 200–350 | 30–70 | 0.10–0.22 | 0.8–2.5 |
Milling Parameters for ISO S Materials
| Operation Type | Cutting Speed Vc (m/min) | Feed per Tooth fz (mm) | Axial Depth ap (mm) | Radial Engagement ae (%) |
|---|---|---|---|---|
| Face milling (roughing) | 30–80 | 0.08–0.18 | 1.0–3.0 | 40–70 |
| Face milling (finishing) | 50–120 | 0.06–0.12 | 0.3–1.5 | 15–30 |
| High-feed milling | 25–60 | 0.20–0.60 | 0.5–1.5 | 5–12 |
| Trochoidal slot milling | 30–70 | 0.06–0.14 | 0.8–2.0 | 8–18 |
ISO H: Hardened Steel Turning and Milling Parameters
Hardened steels above 45 HRC require cubic boron nitride (CBN) or extremely hard ceramic and carbide grades. In the 45–55 HRC range, advanced PVD-coated fine-grained carbides (e.g., Sandvik GC1030, Iscar IC902, Kyocera TN610) can be used for light finishing and semi-finishing operations. Above 55 HRC, CBN or whisker-reinforced ceramics become necessary.
Turning Parameters for ISO H Materials
| Material Sub-Group | Hardness (HRC) | Cutting Speed Vc (m/min) | Feed f (mm/rev) | Depth of Cut ap (mm) |
|---|---|---|---|---|
| Hardened steel (45–55 HRC) | 45–55 | 60–150 | 0.05–0.15 | 0.1–0.5 |
| Hardened steel (55–62 HRC) | 55–62 | 30–80 | 0.04–0.12 | 0.05–0.3 |
| Hardened steel (62–68 HRC) | 62–68 | 20–50 | 0.03–0.10 | 0.03–0.2 |
| Chilled cast iron | 350–600 HB | 30–80 | 0.05–0.15 | 0.1–0.5 |
Milling Parameters for ISO H Materials
| Operation Type | Cutting Speed Vc (m/min) | Feed per Tooth fz (mm) | Axial Depth ap (mm) | Radial Engagement ae (%) |
|---|---|---|---|---|
| Ball-nose finishing (45–55 HRC) | 80–200 | 0.05–0.12 | 0.05–0.30 | 1–5 |
| Ball-nose finishing (55–62 HRC) | 40–120 | 0.04–0.10 | 0.03–0.20 | 1–4 |
| Flat-end semi-finishing | 60–150 | 0.06–0.14 | 0.10–0.50 | 10–30 |
| High-feed hard milling | 50–120 | 0.15–0.40 | 0.10–0.40 | 3–10 |
Recommended Insert Grade Selection Matrix
The following matrix summarizes leading carbide insert grades from Sandvik Coromant, Iscar, and Kyocera mapped against ISO application groups. These grades represent current-generation technologies with optimized substrate-coating combinations.
| ISO Group | Sandvik Coromant | Iscar | Kyocera | Primary Wear Mechanism |
|---|---|---|---|---|
| ISO P (Steel) | GC4325, GC4415, GC2025 | IC9150, IC928, IC830 | CA525, CA310, PR1725 | Flank wear, crater wear |
| ISO M (Stainless) | GC2025, GC1115, GC1125 | IC907, IC908, IC806 | PR1535, PR1725, CA310 | Notch wear, built-up edge |
| ISO K (Cast Iron) | GC3215, GC3225, GC3325 | IC830, IC8350, IC5008 | CA310, CA320, CA4515 | Abrasion, edge chipping |
| ISO N (Non-Ferrous) | GC1005, H10, CD1810 | IC20, IC328, IC08 | KW10, TN60, PR1005 | Built-up edge, adhesion |
| ISO S (Superalloys) | GC1105, GC1115, S05F | IC800, IC5500, IC54 | PR1725, PR1535, CA310 | Depth-of-cut notch, diffusion |
| ISO H (Hardened Steel) | GC1030, CB7015, CB7025 | IC902, IC903, IC30N | TN610, TN620, TB010 | Abrasion, plastic deformation |
Practical Machining Guidelines
While the parameter tables above provide a robust starting point, successful machining depends on additional factors beyond Vc, fz, and ap.
Coolant Strategy
- ISO P and K: Flood coolant at 6–10% emulsion concentration is standard. High-pressure coolant (70–150 bar) through tool channels significantly improves chip breaking in ISO P steels.
- ISO M and S: Consistent coolant delivery is critical to prevent thermal cracking. For some titanium alloys, minimum quantity lubrication (MQL) or high-pressure coolant shows superior tool life compared to conventional flood coolant.
- ISO N: Polished uncoated aluminum grades often run best with air blast or MQL to avoid thermal shock. Flood coolant can be used but must be kept clean to prevent staining.
- ISO H: Hard turning with CBN or ceramic inserts is typically performed dry or with compressed air to avoid thermal cracking from coolant quenching.
Machine Tool Requirements
- Rigidity: ISO S and M materials demand maximum machine rigidity. Deflections above 0.01 mm can cause chatter and accelerated notch wear in superalloys.
- Spindle Power: High-speed aluminum machining (ISO N) may require spindle speeds exceeding 20,000 rpm for small-diameter end mills, demanding adequate spindle power and dynamic balancing (G2.5 or better).
- Feed Drive Resolution: Hard milling (ISO H) and superalloy finishing require precise feed control. Servo systems should achieve positioning accuracy within ±0.005 mm.
Chip Control and Evacuation
- ISO M and S materials produce long, springy chips. Chip breakers with tight groove geometries (e.g., Sandvik Coromant -PF, -PM profiles) are essential at low feeds.
- ISO N aluminum produces fine, powdery chips that pack into flutes. Through-spindle air blast or internal coolant end mills with large chip flutes are recommended.
- ISO K cast iron generates abrasive dust. Effective enclosure sealing and dust extraction protect machine slideways and ball screws.
Conclusion
This ISO P/M/K/N/S/H cutting parameter reference provides machinists and manufacturing engineers with a comprehensive technical foundation for selecting carbide insert grades and establishing initial cutting data across the full spectrum of engineering materials. The parameter ranges presented are derived from manufacturer data sheets, tooling catalogs, and field application experience from Sandvik Coromant, Iscar, and Kyocera product lines. Always perform test cuts and adjust parameters based on specific machine tool capability, workpiece geometry, surface finish requirements, and tool life targets. Documenting parameter iterations and their outcomes builds a proprietary knowledge base that delivers compounding productivity gains over time.
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