Carbide Inserts by Material: The Complete Selection

ISO Material Classification —The Universal Color Code

Every carbide grade on the market is engineered for a specific ISO material class. The color-coded label on the insert box tells you what to use it on. Match the workpiece to the grade —not the other way around.

Steel (ISO P-class) —The Workhorse Material

Steel accounts for 70% of CNC turning work. P-class inserts dominate this segment, typically with CVD coatings featuring thick Al2O3 + TiCN layers that resist crater wear at high cutting temperatures.

Recommended Steel Grades (continuous ↔interrupted cuts)

Steel Turning Speeds & Feeds

Browse our Mitsubishi positive turning inserts (366 SKUs) or ZCC·CT negative turning inserts for steel to see the full grade range.

Stainless Steel (ISO M-class) —Work-Hardening Risk

Stainless steel is the most demanding common material. It work-hardens under heat, conducts heat poorly (heat stays at the cutting edge), and chips weld to the tool. The solution is sharp PVD edges with positive rake and high-pressure coolant.

Recommended Stainless Grades

For stainless turning, see our TaeguTec positive turning (200 SKUs) and the Mitsubishi Grade Cross-Reference Tool to map your current grade to a PVD equivalent.

Cast Iron (ISO K-class) —Abrasive Wear Dominates

Cast iron contains abrasive carbide particles and free graphite. The abrasive wear mode is different from steel —not heat, but mechanical abrasion. CVD-coated K-grade carbides handle this with thick, hard coatings on tough substrates.

Recommended Cast Iron Grades

Aluminum (ISO N-class) —Sharp Edge is King

Aluminum is gummy. Chips weld to the cutting edge (built-up edge, BUE) at high temperatures. The solution is a polished uncoated edge with sharp geometry and high cutting speed (300-600 m/min) that evacuates heat through the chip.

Recommended Aluminum Grades

Hardened Steel (ISO H-class, >48 HRC)

Above 48 HRC, conventional carbide wears too fast. The standard solution is CBN (cubic boron nitride) inserts. For lower-hardness H-class (48-55 HRC), coated carbide with reduced cutting speed still works.

HRSA Superalloys (ISO S-class) —Inconel, Hastelloy, Titanium

Heat-Resistant Superalloys (HRSA) including Inconel 718, Waspaloy, and titanium alloys retain strength at high temperatures. They are abrasive, work-harden rapidly, and generate extreme cutting heat. Use tough PVD grades with low cutting speeds and high-pressure coolant.

Recommended HRSA Grades

Cross-Material Quick Reference: Best Grade by Material × Brand

Need a cross-reference between brands? Use our Insert Grade Cross-Reference Tool or the deeper Mitsubishi Grade Finder covering 20 grades across 12 brands.

Decision Tree: How to Choose the Right Insert

1. Identify your workpiece material ↔ISO class (P/M/K/N/S/H)
   ↔2. Identify the operation type ↔finishing / medium / roughing
   ↔3. Match grade family ↔CVD for steel/cast iron, PVD for stainless/HRSA, uncoated for aluminum
   ↔4. Pick chipbreaker geometry
   —Finishing ↔-FF / -FV / -SF (sharp positive)
   —Medium ↔-PM / -MM / -GM (balanced)
   —Roughing ↔-PR / -MR / -GR (strong negative)
   ↔5. Verify with our Speeds & Feeds Calculator ↔start at low end of range, listen to chip color
   ↔6. Cross-check with grade cross-ref tool if switching brands

Frequently Asked Questions

Talk to a Tooling Engineer

Not sure which grade fits your material and operation? Send us your workpiece alloy, hardness, operation type (roughing/medium/finishing), and machine specs. Our engineering team responds within one business day with a tailored recommendation and quote.