CNC Turning

CNC turning shapes round parts by rotating the workpiece against a computer-controlled cutting tool. It is the most efficient way to make shafts, bushes, pins, spacers, fittings and other rotationally symmetric components with consistent accuracy from one piece to thousands.

What it is

Bar stock or a blank is held in the lathe chuck and spun while the CNC program moves turning, boring, grooving, threading and parting tools along the part. Diameters, faces, tapers, radii, threads and internal bores are produced in one setup.

Turning centres with live tooling can also drill cross holes, mill flats and cut keyways without moving the part to another machine, which reduces handling and improves concentricity.

Points to consider

• Call out only the tolerances that matter; very tight tolerances on every diameter increase cost without adding function.
• Standard bar sizes reduce material waste; a finished diameter just below a standard bar size is most economical.
• Internal sharp corners cannot be turned; allow a small radius or undercut, especially at thread runouts.
• Long, slender parts (length over about 4–5 times diameter) may need tailstock support or grinding for straightness.

Frequently asked questions