Manufacturing services · Chapter C · Method 14

CNC turning

The workpiece rotates while a fixed tool cuts it, producing round parts such as shafts, pins and bushes quickly and accurately.

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Finishing a bore on a CNC lathe. Representative process photo · Leedonaldson911 · CC BY-SA 4.0 · Wikimedia Commons

How it works

CNC turning, step by step.

A labelled schematic of the process (not to scale), and the four steps every job goes through.

Labelled diagram showing how cnc turning works — Schematic · not to scale. Drawn by TCI Group.

STEP 01

Load bar

Load bar or billet into the chuck or collet.

STEP 02

Face & turn

Face the end; turn outside diameters.

STEP 03

Bore & thread

Drill, bore, groove and thread.

STEP 04

Part off

Cut the part from the bar and deburr.

Reference figures

What to expect.

Typical industry values to help you plan. We agree the figures for your part on the drawing.

Tolerance±0.13 mm metalsTighter on request

FinishRa 3.2 µmAs turned

ConcentricityExcellentOne set-up

Volume1 – 10,000sBar-fed

Materials	Free-machining steel, stainless, brass, aluminium, titanium; POM, nylon, PEEK and PTFE.
Finishes	As turned, polished, knurled, anodised or plated.
Design guidance	Keep length-to-diameter ratio sensible to avoid chatter. Use standard thread and groove sizes. Add undercuts at shoulder threads.
Best suited to	Shafts, spacers, mandrels, bushes and fittings.
Watch-outs	Non-round features need live tooling or a second operation.

Other methods in CNC machining

Previous: CNC milling Next: 3, 4 & 5-axis machining

Next step

Not sure this is the right route?

Send a sketch, photo, sample or CAD file with your quantity and target date. We will recommend the most sensible route and explain the trade-offs before quoting.

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Reference figures are typical published industry values for planning, not a guarantee; final tolerances, materials and finishes are agreed in writing for each project.