Core Diameter — Definition in CNC Machining
September 25, 2026 · Exactalloy Technical Team
Glossary entry for core diameter, one of the terms that most often decide whether a tooling process runs at the expected cost.
Quick answer: core diameter: Central material of a fluted tool; larger cores resist bending.
What it means
Central material of a fluted tool; larger cores resist bending.
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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