Start with the shape of the part

CNC turning is typically the natural starting point for rotational parts: shafts, sleeves, rings, threaded bodies and other components built around a central axis. A workpiece rotates while cutting tools create outside diameters, bores, faces, grooves and threads.

CNC milling is typically the better fit for prismatic or freeform geometry: plates, housings, brackets, pockets, slots, contours and multi-face features. The cutting tool rotates while the workpiece is held in a fixture.

When a combined process makes sense

Many production parts include both rotational and non-rotational features. A turned body may need milled flats, cross holes, keyways or mounting patterns. In those cases, the quote should identify every feature on the drawing or model so the manufacturing route can be planned as one workflow rather than two disconnected jobs.

What to include in your RFQ

• A 2D drawing for dimensions, threads, tolerances and finish callouts.
• A 3D model when available to clarify geometry.
• Material grade, quantity and any approved substitution rules.
• Critical features and inspection expectations.
• Required anodizing, heat treatment or other post-machining steps.

Material and finish affect the route

Aluminum alloys such as 6061 and 7075, stainless steel and titanium respond differently to cutting, workholding and finishing. Surface requirements can also determine when features are machined, masked or checked. Defining the final use of the part helps ensure that the selected process supports both geometry and appearance.

A simple decision framework

Choose turning first when

The main dimensions are diameters along a central axis, and the part is primarily round or tubular.

Choose milling first when

The main features are pockets, planes, patterns, complex profiles or multiple machined faces.

Ask for a combined route when

The part has a rotational base plus milled features, or when your drawing includes both diameter-driven and prismatic geometry.