Milling or turning – which process suits your part?
Milling and turning are the two most common machining methods. Both remove material to create a finished part, but they do it in different ways and suit different shapes. Here we go through the differences and what to consider when developing a new part.
What is the difference between milling and turning?
In turning, the workpiece rotates while a stationary cutting tool removes material. This produces round, rotationally symmetrical shapes such as shafts, bushings, flanges and threaded parts.
In milling, the workpiece is stationary and the tool rotates and moves along several axes. This produces flat surfaces, pockets, slots, holes and more complex geometries.
Typical turned parts
- Shafts, pins and bolts
- Bushings, sleeves and spacers
- Flanges and covers with a round basic shape
- Parts with internal and external threads
Typical milled parts
- Brackets, mounts and plates
- Housings and covers with pockets and slots
- Machined castings, for example in zinc and aluminium
- Parts with holes and surfaces in several directions
When does a part need both milling and turning?
Many parts are not simply round or square. A shaft may need a milled keyway, and a milled part may have a round section that needs turning. In the past, this meant two machines and two set-ups. Today there are machines that can handle both operations.
Lathe with Y-axis and sub-spindle
A CNC lathe with driven tools and a Y-axis can mill flat surfaces, slots and off-centre holes while the part stays clamped. With a sub-spindle, the back side can also be machined, so the part comes out finished. Our Mori-Seiki NL2500 is built for exactly that.
5-axis mill with turning capability
Conversely, a 5-axis machining centre with a rotary table can also turn. Our Brother Speedio M300 can mill from five sides and turn in the same set-up.
Why fewer set-ups give better parts
Every time a part is re-clamped, there is a risk that it ends up a few hundredths of a millimetre out. The more operations that can be done in the same set-up, the better the dimensions between different surfaces relate to each other. Set-up time is also shortened, which lowers the price per part.
Tips when sending an enquiry
- Attach both a drawing (PDF) and a 3D model (STEP) if you have them.
- State the material and whether it is bar stock or a casting.
- Give the approximate annual volume and batch size, as this determines which machine and set-up are most cost-effective.
- Mark which dimensions and tolerances are critical for the part.
Do you have a part you want machined? Send us the drawing and we will come back with suggestions and a quote.
