Glossary
CNC Machinist Terms & Vocabulary
15 essential CNC machinist terms with plain-English definitions: the vocabulary you’ll hear in training and on day one.
Key CNC machinist vocabulary
These 15 terms come up constantly in CNC machinist training, on the job and in interviews. Knowing them helps you follow instructions, document accurately and sound prepared.
- CAM
- Computer-aided manufacturing software that creates toolpaths.
- Chip load
- The thickness of material removed per cutting edge per revolution.
- CNC
- Computer numerical control: machines driven by programmed instructions.
- Deburring
- Removing sharp edges and burrs after machining.
- End mill
- A rotating cutting tool used on milling machines.
- Feeds and speeds
- Cutting feed rate and spindle speed chosen for the material and tool.
- First-article inspection
- A full inspection of the first part produced in a setup.
- G-code
- Programming language commands that control machine motion.
- GD&T
- Geometric dimensioning and tolerancing: symbols defining form, orientation and location.
- M-code
- Miscellaneous commands such as spindle on/off and coolant.
- Micrometer
- A precision measuring tool, typically accurate to 0.0001 inch.
- SFM
- Surface feet per minute: the cutting speed at the tool’s edge.
- Tolerance
- The allowable variation from a specified dimension.
- Tool length offset
- A stored value compensating for each tool’s length.
- Work offset
- The reference position (such as G54) that defines part zero.
Practice these terms
Test yourself with the free CNC Machinist practice test: it includes vocabulary questions built from this list. For a complete course, see CNC Machinist training.
Browse terms from every career in our career glossary.