CNC milling removes material from a solid block with rotating cutters controlled by a computer program. It produces precise parts in metal and engineering plastics without tooling.
When to choose milling
- Prototypes and low-to-medium volumes.
- Parts with flat faces, pockets, slots and holes.
- Tight tolerances, typically ±0.01–0.05 mm.
What drives cost
- Machine time — complex shapes and deep pockets take longer.
- Number of setups — every flip of the part adds cost; 5-axis machines reduce setups.
- Material — aluminum is fast to cut; stainless and titanium are slower.
- Tolerances and finish — tighter than needed costs more.
How to specify
Send a STEP file plus a 2D drawing marking critical dimensions and tolerances. Apply tight tolerances only where they matter and state the surface finish and any coating.
3-axis vs. 5-axis milling
3-axis machines move the cutter along X, Y and Z; parts with features on several sides need several setups. 5-axis machines also tilt and rotate, reaching most faces in one setup — better accuracy between features and less handling, at a higher hourly rate. Complex aerospace-style parts, impellers and organic shapes need 5-axis; most brackets, housings and plates do not.
Typical cost drivers in China
- Machine hour rates of roughly US$10–30 for 3-axis and US$25–60 for 5-axis, depending on region and machine.
- Setup and programming, spread over the quantity — the main reason prototypes cost more per piece.
- Material price and machinability.
- Finishing, inspection reports and packaging.
Quality documents to request
- First article inspection (FAI) report with measured values.
- Material certificate for the bar or plate stock.
- CMM report for complex or tight-tolerance parts.
- Finish and coating thickness records where relevant.
Browse CNC machining in China for tolerances, MOQs and the regions where it is strongest.
