The turning vs milling decision starts with the shape of the part. In CNC turning, the workpiece spins and a stationary tool cuts it, which makes round features such as diameters, bores, grooves and threads efficient and accurate. In CNC milling, the tool spins and moves around a fixed workpiece, which suits flat faces, pockets, slots and hole patterns. Many parts need both, and modern lathes with live tooling and Y-axis can often finish them in one setup.
Turning vs Milling: Comparison Table
Figures are typical. Cost is a relative per-part index for a part suited to each process, where a milled part at quantity 1 equals 100.
| Factor | CNC turning | CNC milling |
|---|---|---|
| Relative cost, qty 1 | 70 to 90 | 100 |
| Relative cost, qty 10 | 25 to 35 | 40 |
| Relative cost, qty 100 | 10 to 15 | 18 |
| Relative cost, qty 1,000 | 5 to 8 | 10 |
| Typical tolerance | ±0.0005 to ±0.002 in on diameters | ±0.001 to ±0.005 in on features and positions |
| Surface finish | Ra 16 to 63 µin on turned diameters | Ra 32 to 125 µin |
| Materials | Round, hex or square bar; tube; forgings | Plate, block, bar, castings, forgings |
| Lead time | Days to a few weeks | Days to a few weeks |
| Geometry | Axisymmetric: shafts, pins, bushings, fittings | Prismatic: housings, plates, brackets, manifolds |
| Typical use case | Shafts, spacers, nozzles, threaded fittings, rollers | Blocks, housings, fixtures, valve bodies |
When Turning Wins
- Round parts. If most features are concentric diameters, turning is faster and holds roundness and concentricity better.
- Tight diameters and concentricity. Bearing journals and seal diameters held to tenths are routine on a lathe.
- Threads. External and internal threads, including large diameters, are single-point turned accurately.
- Bar-fed volume. Bar feeders let lathes run many parts with minimal handling.
When Milling Wins
- Prismatic parts. Blocks, plates and housings with features on several faces are milling work.
- Pockets, slots and contours. Anything not symmetric about an axis requires a milling cutter.
- Multi-face hole patterns. A 4-axis horizontal machining center can reach four sides of a part in one setup.
Mill-Turn: When a Part Needs Both
A shaft with a keyway, cross holes or wrench flats used to go from the lathe to a mill. Lathes with live tooling can drill, tap and mill while the part is still chucked, and a Y-axis allows off-center features. This removes a setup, improves feature-to-diameter relationships, and shortens lead time. Parts that are mostly prismatic with one bored diameter are usually better on a machining center, where the bore can be interpolated or bored in the same setup as the other features.
Common Mistakes
- Designing a round part with square internal corners or features that force it off the lathe.
- Specifying concentricity where runout or position would be easier to measure and equally functional.
- Assuming milled round features hold the same roundness as turned ones. Interpolated bores are good but turning is usually tighter.
- Using a large round bar for a part that is mostly flat, which wastes material. Plate stock is usually better for prismatic parts.
How This Applies at Wexmar
Wexmar runs both processes on one floor. Our 10 CNC lathes, including Mazak Nexus and Multiplex machines and Doosan Lynx lathes, have live tooling and Y-axis for mill-turn work. Our six Mazak horizontal machining centers with pallet changers handle 3- and 4-axis prismatic parts. Small, long turned parts to 32 mm diameter run on four Maier Swiss-type machines. See CNC turning, CNC milling, and the guide on Swiss vs CNC lathe.
Getting a Quote
We will route your part to the right machine as part of the quote. You can upload a drawing for an instant estimate, with every quote confirmed by a human estimator, or call (315) 400-2654.