Cutting Tool Coating Guide: TiN, TiAlN, AlTiN, TiCN, DLC

The right coating extends cutting tool life by 5-10×. The wrong one performs worse than no coating. Here are the 5 main coating types and a selection guide.

1. TiN (Titanium Nitride) — Gold

• Hardness: 2300 HV
• Max temp: 600°C
• Best for: General purpose, mild steel, aluminium, plastic
• Classic coating: Low cost, reliable

2. TiAlN (Titanium Aluminium Nitride) — Purple/Black

• Hardness: 3200 HV
• Max temp: 800°C
• Best for: Hardened steel, stainless steel, cast iron
• Dry cutting: Ideal — high heat insulation

3. AlTiN (Aluminium Titanium Nitride) — Dark Grey

• Hardness: 3500 HV
• Max temp: 900°C
• Best for: High-speed dry cutting, hardened steel (>50 HRC)
• HSM: Top choice

4. TiCN (Titanium Carbonitride) — Blue-Grey

• Hardness: 3000 HV
• Max temp: 400°C
• Best for: Low-speed wet cutting, wood, aluminium, cast iron
• Tapping & reaming: Excellent

5. DLC (Diamond-Like Carbon) — Black

• Hardness: 4000+ HV
• Max temp: 350°C
• Best for: Aluminium, copper, plastic, dry cutting
• Anti-stick: Excellent — no aluminium adhesion

Quick Decision Table

Bolelli Metal applies all these coatings in-house. Send a sample for our coating recommendation.