Cubic Boron Nitride — Definition in CNC Machining
September 27, 2026 · Exactalloy Technical Team
Glossary entry for cubic boron nitride, one of the terms that most often decide whether a tooling process runs at the expected cost.
Quick answer: cubic boron nitride: Superhard material used for machining hardened steel above HRC45.
What it means
Superhard material used for machining hardened steel above HRC45.
Why it matters in practice
Getting this right typically changes tool life and surface finish more than any single parameter tweak.
How to apply it
Record the value for every job, and compare against the recommended band for the material group you are cutting.
Frequently asked questions
Where is this used most?
In production CNC milling, turning and drilling, and in any tool-selection decision.
Can I ignore it?
You can, but the cost usually appears as unpredictable tool life.
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