Ultra Hard Special CBN Inserts Ideal for Hardened Steel Cast Iron Machining

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What are CBN Inserts?

CBN (Cubic Boron Nitride) inserts are ultra-hard cutting tools used for precision machining of hardened steels, cast irons, and superalloys. As the second-hardest material after diamond, CBN provides exceptional heat resistance and wear durability, making it ideal for high-speed, high-precision turning, milling, and boring operations where traditional carbide tools fail.

Materials of CBN Inserts

1. CBN Particles – Synthetic cubic boron nitride crystals (40%–90% concentration).

2. Ceramic Binder (TiN, Al₂O₃, TiC) – Enhances thermal stability and toughness.

3. Carbide Substrate – Tungsten carbide base for structural support (e.g., WC-Co).

Surface Treatments

• TiN/TiAlN Coating – Reduces friction and extends tool life.

• Mirror Polishing – Improves surface finish on machined parts.

• Micro-Grain CBN – Refines edge sharpness for finishing cuts.

Specifications

• Shape: Round (R), square (S), triangular (T), diamond (D).

• Grain Size: Fine (0.5–2µm) for finishing / Coarse (5–10µm) for roughing.

• CBN Content:

  • Low (40–50%) – For interrupted cuts (e.g., hardened steel milling).

  • High (80–90%) – For continuous turning (e.g., cast iron).

• Nose Radius: 0.2mm–1.2mm (affects surface finish and tool strength).

Applications of CBN Inserts

1. Automotive – Machining hardened crankshafts, brake discs.

2. Aerospace – Turbine blades, landing gear components.

3. Oil & Gas – Drilling tool inserts for hard alloys.

4. Die/Mold Making – Precision finishing of tool steels (HRC 45+).

5. Medical Implants – Machining cobalt-chromium alloys.

Excellent Case: High-Speed Machining of Jet Engine Turbine Shafts

Scenario: A jet engine manufacturer needs to machine Inconel 718 turbine shafts (HRC 45) with tight tolerances (±0.01mm) and mirror finishes (Ra < 0.4µm). Traditional carbide tools wear out after 10 minutes.

Solution:

• High-CBN (80%) inserts with TiAlN coating:

  • Shape: Round (R) with 0.4mm nose radius for fine finishing.

  • Cutting Parameters:

    • Speed: 250 m/min (vs. 80 m/min for carbide).

    • Feed: 0.05mm/rev.

  • Coolant: High-pressure through-tool cooling.

Results:

• Tool Life: 120+ minutes (12× longer than carbide).

• Surface Finish: Ra 0.3µm, eliminating manual polishing.

• Cost Savings: $18,000/year per machine in reduced tool changes.