Introduction to ISO Material Classification and Cutting Parameters
The ISO 513 standard defines six primary workpiece material groups for metal cutting: P (Steel), M (Stainless Steel), K (Cast Iron), N (Non-Ferrous), S (Superalloys and Titanium), and H (Hardened Materials). Each group demands specific tool substrates, coatings, and cutting parameters to optimize tool life, surface finish, and machining efficiency.
This guide provides a comprehensive parameter reference for modern CVD- and PVD-coated carbide inserts across all six ISO groups. Values are presented for both turning and milling operations, with separate columns for roughing, semi-finishing, and finishing cuts. All parameters assume stable workpiece clamping, adequate coolant delivery, and modern CNC machining centers with rigid spindles.
ISO P – Steel (Non-Alloy, Low-Alloy, and High-Alloy Steel)
ISO P covers the largest volume of machining applications, from unalloyed structural steels to high-strength alloy steels. CVD-coated grades (Al2O3 + TiCN) generally outperform PVD grades at higher cutting speeds due to superior heat insulation.
Turning Parameters for ISO P Materials
| Steel Grade | Hardness | Operation | Vc (m/min) | fn (mm/rev) | ap (mm) |
|---|---|---|---|---|---|
| Low-Carbon Steel (C < 0.25%) | < 180 HB | Roughing | 280–350 | 0.25–0.40 | 2.0–6.0 |
| Semi-Finish | 220–280 | 0.15–0.25 | 1.0–2.5 | ||
| Finishing | 180–240 | 0.08–0.15 | 0.2–1.0 | ||
| Medium-Carbon Steel (0.25–0.55% C) | 180–260 HB | Roughing | 220–300 | 0.20–0.35 | 2.0–5.0 |
| Semi-Finish | 180–240 | 0.12–0.20 | 1.0–2.0 | ||
| Finishing | 150–200 | 0.06–0.12 | 0.2–0.8 | ||
| High-Carbon & Alloy Steel (> 0.55% C) | 260–350 HB | Roughing | 150–220 | 0.15–0.28 | 1.5–4.0 |
| Semi-Finish | 120–180 | 0.10–0.18 | 0.8–1.5 | ||
| Finishing | 100–150 | 0.05–0.10 | 0.15–0.6 |
Milling Parameters for ISO P Materials
| Steel Grade | Operation | Vc (m/min) | fz (mm/tooth) | ap (mm) | ae (% Dc) |
|---|---|---|---|---|---|
| Low-Carbon Steel | Roughing | 250–320 | 0.12–0.20 | 2.0–5.0 | 50–75 |
| Semi-Finish | 200–260 | 0.08–0.14 | 1.0–2.5 | 30–50 | |
| Finishing | 160–220 | 0.05–0.10 | 0.3–1.0 | 15–30 | |
| Medium-Carbon Steel | Roughing | 200–280 | 0.10–0.18 | 2.0–4.5 | 50–70 |
| Semi-Finish | 160–220 | 0.07–0.12 | 0.8–2.0 | 30–50 | |
| Finishing | 130–180 | 0.04–0.08 | 0.2–0.8 | 15–25 | |
| High-Carbon & Alloy Steel | Roughing | 140–200 | 0.08–0.15 | 1.5–3.5 | 40–60 |
| Semi-Finish | 110–160 | 0.06–0.10 | 0.6–1.5 | 25–40 | |
| Finishing | 90–130 | 0.03–0.06 | 0.15–0.5 | 10–20 |
ISO M – Stainless Steel (Austenitic, Ferritic, Martensitic, and Duplex)
Stainless steels combine high tensile strength with poor thermal conductivity and a strong tendency to work-harden. Austenitic grades (304, 316) are particularly gummy and require sharp cutting edges. Martensitic grades (410, 420) behave more like medium-carbon steels but generate more heat.
Turning Parameters for ISO M Materials
| Stainless Grade | Hardness | Operation | Vc (m/min) | fn (mm/rev) | ap (mm) |
|---|---|---|---|---|---|
| Austenitic (304, 316) | 150–220 HB | Roughing | 160–220 | 0.20–0.35 | 2.0–5.0 |
| Semi-Finish | 130–180 | 0.12–0.22 | 1.0–2.0 | ||
| Finishing | 110–150 | 0.07–0.14 | 0.2–0.8 | ||
| Martensitic (410, 420) | 200–320 HB | Roughing | 140–200 | 0.18–0.30 | 1.5–4.0 |
| Semi-Finish | 110–160 | 0.10–0.18 | 0.8–1.8 | ||
| Finishing | 90–130 | 0.06–0.12 | 0.15–0.6 | ||
| Duplex (2205, 2507) | 260–320 HB | Roughing | 100–150 | 0.15–0.25 | 1.5–3.5 |
| Semi-Finish | 80–120 | 0.10–0.16 | 0.6–1.5 | ||
| Finishing | 70–100 | 0.05–0.10 | 0.15–0.5 |
Milling Parameters for ISO M Materials
| Stainless Grade | Operation | Vc (m/min) | fz (mm/tooth) | ap (mm) | ae (% Dc) |
|---|---|---|---|---|---|
| Austenitic (304, 316) | Roughing | 140–200 | 0.10–0.18 | 2.0–4.5 | 50–70 |
| Semi-Finish | 120–160 | 0.07–0.14 | 0.8–2.0 | 30–50 | |
| Finishing | 100–140 | 0.04–0.08 | 0.2–0.8 | 15–25 | |
| Martensitic (410, 420) | Roughing | 120–180 | 0.09–0.16 | 1.5–4.0 | 45–65 |
| Semi-Finish | 100–140 | 0.06–0.12 | 0.6–1.8 | 25–45 | |
| Finishing | 80–120 | 0.04–0.07 | 0.15–0.6 | 10–20 | |
| Duplex (2205, 2507) | Roughing | 90–130 | 0.08–0.14 | 1.5–3.5 | 40–60 |
| Semi-Finish | 70–110 | 0.06–0.10 | 0.5–1.5 | 25–40 | |
| Finishing | 60–90 | 0.03–0.06 | 0.15–0.5 | 10–18 |
ISO K – Cast Iron (Gray, Nodular, and Malleable Cast Iron)
Cast iron machining is characterized by abrasive particles, intermittent cuts, and relatively low cutting forces. Gray cast iron (GJL) is highly abrasive but machines easily. Nodular (ductile) iron (GJS) is tougher and generates higher cutting forces. Both require strong insert geometries and abrasion-resistant coatings.
Turning Parameters for ISO K Materials
| Cast Iron Grade | Hardness | Operation | Vc (m/min) | fn (mm/rev) | ap (mm) |
|---|---|---|---|---|---|
| Gray Cast Iron (GJL-200 to GJL-300) | 180–260 HB | Roughing | 180–250 | 0.25–0.45 | 2.0–6.0 |
| Semi-Finish | 150–200 | 0.15–0.28 | 1.0–2.5 | ||
| Finishing | 120–170 | 0.08–0.15 | 0.2–1.0 | ||
| Nodular Cast Iron (GJS-500 to GJS-700) | 200–300 HB | Roughing | 120–180 | 0.20–0.35 | 1.5–5.0 |
| Semi-Finish | 100–140 | 0.12–0.22 | 0.8–2.0 | ||
| Finishing | 80–120 | 0.06–0.12 | 0.15–0.6 |
Milling Parameters for ISO K Materials
| Cast Iron Grade | Operation | Vc (m/min) | fz (mm/tooth) | ap (mm) | ae (% Dc) |
|---|---|---|---|---|---|
| Gray Cast Iron | Roughing | 160–220 | 0.15–0.28 | 2.5–6.0 | 60–80 |
| Semi-Finish | 130–180 | 0.10–0.18 | 1.0–2.5 | 35–55 | |
| Finishing | 110–150 | 0.06–0.10 | 0.3–1.0 | 15–25 | |
| Nodular Cast Iron | Roughing | 110–160 | 0.12–0.22 | 2.0–5.0 | 50–70 |
| Semi-Finish | 90–130 | 0.08–0.15 | 0.8–2.0 | 30–50 | |
| Finishing | 70–110 | 0.05–0.09 | 0.2–0.8 | 12–20 |
ISO N – Non-Ferrous Metals (Aluminum, Copper, Magnesium, and Their Alloys)
Non-ferrous metals are soft, ductile, and have high thermal conductivity. Built-up edge (BUE) is the primary challenge. Uncoated polished carbide or PCD inserts are preferred. High cutting speeds and sharp positive rake angles are essential.
Turning Parameters for ISO N Materials
| Material | Hardness | Operation | Vc (m/min) | fn (mm/rev) | ap (mm) |
|---|---|---|---|---|---|
| Wrought Aluminum (1xxx–7xxx) | 30–150 HB | Roughing | 400–800 | 0.20–0.40 | 2.0–8.0 |
| Semi-Finish | 350–600 | 0.12–0.25 | 1.0–3.0 | ||
| Finishing | 300–500 | 0.06–0.15 | 0.2–1.0 | ||
| Cast Aluminum (Al-Si < 12%) | 40–120 HB | Roughing | 350–600 | 0.20–0.40 | 2.0–8.0 |
| Semi-Finish | 300–500 | 0.12–0.25 | 1.0–3.0 | ||
| Finishing | 250–400 | 0.06–0.15 | 0.2–1.0 | ||
| Copper and Brass | 40–200 HB | Roughing | 250–450 | 0.20–0.35 | 2.0–6.0 |
| Semi-Finish | 200–350 | 0.12–0.22 | 1.0–2.5 | ||
| Finishing | 180–300 | 0.06–0.14 | 0.2–1.0 |
Milling Parameters for ISO N Materials
| Material | Operation | Vc (m/min) | fz (mm/tooth) | ap (mm) | ae (% Dc) |
|---|---|---|---|---|---|
| Wrought Aluminum | Roughing | 400–700 | 0.10–0.20 | 3.0–8.0 | 60–80 |
| Semi-Finish | 350–550 | 0.08–0.14 | 1.0–3.0 | 35–55 | |
| Finishing | 300–450 | 0.05–0.10 | 0.3–1.0 | 15–25 | |
| Copper and Brass | Roughing | 250–400 | 0.10–0.18 | 2.0–6.0 | 55–75 |
| Semi-Finish | 200–320 | 0.07–0.12 | 0.8–2.5 | 30–50 | |
| Finishing | 180–280 | 0.04–0.08 | 0.2–0.8 | 12–20 |
ISO S – Superalloys and Titanium Alloys
ISO S materials retain strength at elevated temperatures, work-harden rapidly, and generate high heat in the cutting zone. Ti-6Al-4V and Inconel 718 represent the most challenging workpieces in modern aerospace and energy sectors. Low cutting speeds, positive rake geometries, and robust coolant strategies are mandatory.
Turning Parameters for ISO S Materials
| Material | Hardness | Operation | Vc (m/min) | fn (mm/rev) | ap (mm) |
|---|---|---|---|---|---|
| Ti-6Al-4V (Annealed) | 280–340 HB | Roughing | 40–70 | 0.15–0.28 | 1.5–4.0 |
| Semi-Finish | 30–55 | 0.10–0.18 | 0.6–1.5 | ||
| Finishing | 25–45 | 0.05–0.10 | 0.15–0.5 | ||
| Inconel 718 (Solution Treated) | 350–450 HB | Roughing | 25–45 | 0.12–0.22 | 1.0–3.0 |
| Semi-Finish | 20–35 | 0.08–0.15 | 0.5–1.2 | ||
| Finishing | 15–30 | 0.04–0.08 | 0.1–0.4 |
Milling Parameters for ISO S Materials
| Material | Operation | Vc (m/min) | fz (mm/tooth) | ap (mm) | ae (% Dc) |
|---|---|---|---|---|---|
| Ti-6Al-4V | Roughing | 40–65 | 0.08–0.15 | 1.5–3.5 | 40–60 |
| Semi-Finish | 30–50 | 0.06–0.12 | 0.5–1.5 | 25–40 | |
| Finishing | 25–40 | 0.03–0.07 | 0.15–0.5 | 10–20 | |
| Inconel 718 | Roughing | 25–40 | 0.07–0.14 | 1.0–3.0 | 35–55 |
| Semi-Finish | 18–32 | 0.05–0.10 | 0.4–1.2 | 20–35 | |
| Finishing | 15–28 | 0.03–0.06 | 0.1–0.4 | 8–15 |
ISO H – Hardened Materials (Hardened Steel, Chilled Cast Iron, and Hardened Stainless Steel)
Hardened materials in the 45–70 HRC range require specialized substrates (micro-grain carbide, ceramics, or CBN) and geometrically stable inserts. Hard turning and hard milling are increasingly replacing grinding operations for improved flexibility and reduced setup times.
Turning Parameters for ISO H Materials
| Material / Hardness | Insert Type | Operation | Vc (m/min) | fn (mm/rev) | ap (mm) |
|---|---|---|---|---|---|
| Hardened Steel (45–55 HRC) | CBN or Ceramic | Roughing | 120–180 | 0.10–0.20 | 0.3–1.0 |
| Semi-Finish | 150–220 | 0.06–0.12 | 0.1–0.4 | ||
| Finishing | 180–280 | 0.03–0.08 | 0.05–0.2 | ||
| Hardened Steel (55–65 HRC) | CBN | Roughing | 80–130 | 0.08–0.15 | 0.2–0.6 |
| Semi-Finish | 100–160 | 0.05–0.10 | 0.08–0.25 | ||
| Finishing | 120–200 | 0.02–0.06 | 0.03–0.12 | ||
| Chilled Cast Iron (> 400 HB) | Ceramic or CBN | Roughing | 80–130 | 0.12–0.25 | 0.5–1.5 |
| Semi-Finish | 100–150 | 0.08–0.15 | 0.2–0.6 | ||
| Finishing | 120–180 | 0.04–0.10 | 0.08–0.25 |
Milling Parameters for ISO H Materials
| Material / Hardness | Operation | Vc (m/min) | fz (mm/tooth) | ap (mm) | ae (% Dc) |
|---|---|---|---|---|---|
| Hardened Steel (45–55 HRC) | Roughing | 100–160 | 0.08–0.15 | 0.5–1.5 | 30–50 |
| Semi-Finish | 130–200 | 0.05–0.10 | 0.2–0.6 | 20–35 | |
| Finishing | 160–250 | 0.02–0.06 | 0.05–0.2 | 8–15 | |
| Hardened Steel (55–65 HRC) | Roughing | 60–100 | 0.06–0.12 | 0.3–1.0 | 25–45 |
| Semi-Finish | 80–130 | 0.04–0.08 | 0.15–0.4 | 15–30 | |
| Finishing | 100–160 | 0.02–0.05 | 0.03–0.12 | 6–12 |
Major Insert Grade Cross-Reference by ISO Application Area
The following table maps commercially available insert grades from leading manufacturers to the ISO material groups discussed above. Grades are grouped by substrate/coating technology.
| ISO Group | Sandvik Coromant | Iscar | Kyocera | Korloy | TaeguTec | Walter | Mitsubishi |
|---|---|---|---|---|---|---|---|
| P – Steel | GC4215, GC4325, GC4415 | IC8150, IC8250, IC8350 | CA515, CA525, CA530 | NC3120, NC3220, NC3320 | TT8125, TT8225, TT9080 | WKP25S, WKP35S, WPP20S | UE6110, UE6020, VP15TF |
| M – Stainless | GC2015, GC2025, GC2030 | IC907, IC908, IC910 | CA5535, CA6515, PR1535 | NC3030, NC3120, PC8110 | TT9030, TT9080, TT9100 | WMP20S, WMP45S, WSM35S | VP20RT, VP30RT, MC7015 |
| K – Cast Iron | GC3210, GC3225, GC3330 | IC830, IC8350, IC840 | CA310, CA510, CA511 | NK3030, NK3120, NK350 | TT8020, TT9030, TT9080 | WKK25S, WSP45, WKK20S | UE6110, HTi10, UC5115 |
| N – Non-Ferrous | H13A, N331.1, CD1810 | IC20, IC28, IC30N | DLC-coated KPD001, PR1005 | NC6110, H01, NK4 | TT010, TT050, TT8020 | WNN15, WSM01, WSM20 | NX2525, HTi10, TF15 |
| S – Superalloys | S30T, S40T, GC1105 | IC500A, IC530N, IC907 | CA6535, PR1725, CA310 | NC9110, PC5300, NC3120 | TT9030, TT9080, TT9100 | WKP10S, WSM01, WSM20 | VP15TF, MP9015, MC6015 |
| H – Hardened | CB7015, CB7025, CC670 | IC1008, IC5008, IC5010 | CA310, KPD001, PR1725 | NC9110, CBN, PCBN | CBN grade, TT8020 | CBN WBK20, WBK30, WKK20S | BC8110, CBN, UC5115 |
Key Factors That Modify Recommended Parameters
The tabulated values represent starting points for stable machining conditions. Several variables require upward or downward adjustment:
- Machine Rigidity: Older machines with backlash or spindle runout greater than 5 µm require 15–30% reduction in Vc and fz.
- Workpiece Overhang: Long slender parts reduce effective rigidity. Reduce ap by 30–50% and use lower fn to minimize deflection.
- Coolant Type and Pressure: High-pressure coolant (70–150 bar) allows 10–20% higher Vc in stainless steel and superalloy machining. For cast iron, dry machining is often preferred to avoid thermal shock.
- Insert Nose Radius: Larger nose radii (1.2 mm vs. 0.4 mm) permit higher fn but increase radial cutting force. For finishing, 0.4–0.8 mm is standard; for roughing, 0.8–1.6 mm.
- Entry Angle: A 45° or 75° entry angle distributes cutting force more favorably than 90°, enabling higher ap in interrupted cuts.
- Coated vs. Uncoated: CVD-coated inserts typically sustain 20–40% higher Vc than uncoated equivalents in steel and cast iron. PVD coatings excel in stainless steel and superalloys due to smoother surfaces and better edge sharpness.
Practical Recommendations for Parameter Selection
When translating these tables to a live production environment, follow this decision sequence:
- Identify the ISO group of your workpiece material and confirm hardness.
- Select the operation type (roughing, semi-finishing, or finishing) based on stock allowance and tolerance requirements.
- Choose an insert grade from the cross-reference table that matches your machine’s coolant capability and your tool supplier’s availability.
- Start at the lower third of the recommended Vc range for the first component, monitoring insert wear, chip form, and surface finish.
- Increase Vc in 10% increments until tool life falls below the economic threshold (typically 15 minutes per edge for roughing, 30–45 minutes for finishing).
- Optimize fn last, as feed rate has the strongest influence on surface roughness (Ra ≈ fn² / 8rε for turning).
Conclusion
This parameter reference covers the full spectrum of ISO 513 workpiece groups from soft aluminum to hardened steel beyond 65 HRC. While modern CAM software and tool manufacturer catalogs provide increasingly sophisticated starting values, understanding the underlying relationships between cutting speed (Vc), feed (fn / fz), and depth of cut (ap) remains essential for troubleshooting chatter, premature wear, and dimensional instability.
Use the values in this guide as robust starting points, then refine based on your specific machine capability, part geometry, and batch size. For applications at the extreme ends of each range — such as Inconel 718 turbine blades or 62 HRC mold cavities — consult your insert supplier’s application engineers for grade-specific optimization beyond these general recommendations.
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