PROCESS SELECTION · SYD PRECISION
The right machining route depends on the features that must be produced and inspected. Start with the geometry, then review how the part will be held and how its critical surfaces relate to each other.
Milling uses a rotating cutting tool to create features such as pockets, slots and flat faces. Turning rotates the workpiece to produce features around its axis, such as diameters, shoulders and bores. A part with both types of features may need both processes.
Choose the starting process from the main features
| Part feature | Likely starting point | What to review |
|---|---|---|
| Housing with pockets and mounting holes | CNC milling | Tool access, internal corners and mating faces |
| Bracket or fixture plate | CNC milling | Hole locations, flatness and clamping surfaces |
| Stepped shaft or cylindrical sleeve | CNC turning | Diameters, shoulders, bores and reference axis |
| Shaft with flats or cross holes | Turning plus milling or drilling | Angular position and relationships between features |
These are starting points for a review, not a final production plan. Share the complete drawing so the supplier can assess the actual geometry and requirements rather than selecting a machine from the product name alone.
Can a part require milling and turning?
Yes. Consider a cylindrical shaft with a milled flat and a cross hole. The outside diameters may be turned, while the flat and hole require additional operations. Some equipment can combine operations; other routes use separate setups. The quotation should reflect the proposed route and its ability to meet the drawing.
Ask which features are completed together and how the remaining features will be located. This is particularly useful when a hole, flat or shoulder must have a controlled relationship to a turned diameter. The number of visible features alone does not tell you the setup effort.
Three questions to resolve before quoting
1. Which surfaces locate the part in the assembly?
Mark the functional references on the drawing. A finished component must fit the intended assembly, so the relationship between mating features may matter more than an isolated size.
2. Which tolerances are functionally necessary?
Separate critical dimensions from general requirements. A blanket request for the tightest possible tolerances makes the scope harder to interpret. State your fits and geometric requirements explicitly, and request review of features that may need special measurement.
3. What happens after machining?
Include heat treatment, coating, masking and surface requirements. Tell us whether important dimensions apply before or after those steps. A completed machining operation is only one part of the route to an acceptable finished component.
What SYD needs to review your process
- A 3D model and a current dimensioned drawing, with matching revision identifiers.
- Material grade and condition, quantity and required delivery date.
- Critical diameters, hole positions, threads and surface finish requirements.
- Inspection documentation and any packaging needs.
Explore our CNC milling service, CNC turning service and quality inspection approach. If you are unsure which process applies, send the drawing and identify the features that matter most. We can review the machining scope before preparing the quotation.
Have a part with mixed features?
Send the model and drawing so we can review the required operations.
Request a Machining Review →Process reference: Protolabs: CNC machining overview. Examples in this guide explain typical geometry; they do not represent a promised machine configuration or a completed customer order.