CNC Machining
CNC machining makes precise parts by removing material from a solid workpiece with computer-controlled cutting tools.
Definition
CNC means computer numerical control. CNC mills and lathes follow programmed toolpaths to remove material from a metal or plastic workpiece in a controlled way. The result combines dimensional accuracy, repeatability, and production in real engineering materials.
Related Terms
- STEP: a CAD exchange format that carries solid geometry and accurate surfaces into CNC preparation.
- Tolerance: the acceptable lower and upper limit for each critical dimension.
- DFM: analysis of tool access, internal corner radii, workholding, and operation count.
- Aluminum: a metal family widely used in CNC because it machines efficiently.
Common Uses
CNC is used for functional prototypes, fixtures, precise housings, shafts, brackets, and low-to-medium-volume end-use parts. Milling suits prismatic and freeform surfaces, while turning suits rotationally symmetric geometry.
Watchouts
Sharp internal corners that a cutting tool cannot reach cannot be machined directly; use a suitable radius. Deep pockets, thin walls, unnecessarily tight general tolerances, and geometry requiring several setups increase cost. Apply drawing tolerances only where they affect function.