CNC Machining Glossary (A–Z Terms)
Meta description: A complete A-Z glossary of CNC machining terms every beginner should know — from chip load to workholding, explained simply.
Category: CNC Basic & Safety
Introduction
CNC machining comes with its own language. This glossary breaks down the most common terms you’ll run into as a beginner, explained in plain English — no prior experience needed. Bookmark this page and refer back whenever you hit an unfamiliar word.
A
Axis — A direction of movement on a CNC machine (X, Y, Z are the three basic linear axes; some machines add rotational axes A, B, C).
B
Backlash — Small mechanical play/looseness in a machine’s mechanical drive that can cause slight inaccuracy.
Boring — Enlarging an existing hole to a precise diameter.
C
CAD (Computer-Aided Design) — Software used to create the digital 3D model of a part.
CAM (Computer-Aided Manufacturing) — Software that converts a CAD model into machine instructions (G-code).
Chip Load — The thickness of material removed by each cutting edge per revolution; affects tool life and surface finish.
Chatter — Unwanted vibration during cutting that leaves a poor surface finish and can damage tools.
CNC (Computer Numerical Control) — Computer-controlled automation of machine tools.
Coolant — Fluid used to cool and lubricate the cutting tool and workpiece during machining.
D
Datum — A reference point, line, or surface used to establish measurements and positions.
E
End Mill — A rotary cutting tool used in milling for cutting slots, contours, and pockets.
F
Feed Rate — The speed at which the cutting tool moves through the material, usually measured in inches or millimeters per minute.
Fixture — A device used to hold and locate a workpiece securely during machining.
G
G-Code — The programming language that tells a CNC machine how to move.
H
HMC (Horizontal Machining Center) — A CNC mill with a horizontally oriented spindle.
M
M-Code — Machine-specific codes that control non-movement functions (like turning coolant on/off).
Machinability — How easily a material can be cut/shaped.
O
Offset — A programmed adjustment accounting for tool size or workpiece position.
P
Pocket — A recessed cavity machined into a part.
S
Spindle — The rotating component that holds and drives the cutting tool (or workpiece, in turning).
Stock — The raw material block before machining begins (also called “workpiece”).
Surface Finish — The texture/smoothness of a machined surface.
T
Tolerance — The allowable amount of variation in a part’s dimensions from the specified design.
Tool Path — The route a cutting tool follows to shape a part.
Turning — A machining process where the workpiece rotates against a stationary cutting tool.
V
VMC (Vertical Machining Center) — A CNC mill with a vertically oriented spindle — the most common type for general milling.
W
Workholding — Any method (vise, clamp, fixture, chuck) used to securely hold a workpiece during machining.
Workpiece — The material being machined into a finished part.
Frequently Asked Questions
Do I need to memorize all these terms before starting CNC machining? No — this glossary is meant as a reference. Come back to it whenever you hit an unfamiliar word in another article or a machine manual.
What’s the difference between CAD and CAM? CAD is for designing the part. CAM is for programming how the machine will cut it. They’re two separate steps in the workflow.
What to Read Next
- What Is CNC Machining? A Complete Beginner’s Guide
- G-Code Cheat Sheet: Most Common Codes Explained
- How to Calculate Feeds and Speeds