CNC machining processes, and when each one wins
Most parts need more than one operation. Milling cuts the shape, turning makes the round features, EDM reaches the corners a cutter cannot, grinding fixes the flatness, and finishing makes it survive the field. All of it runs under one roof and one inspection plan.
Which process matches your geometry
Same drawing, different route — the choice is set by geometry, tolerance and quantity, not by what happens to be free this week.
| Process | What it does | Best for |
|---|---|---|
| 3-axis milling | Cuts X, Y and Z with the tool approaching from one direction | Plates, housings, heat sinks and brackets with features on one face |
| 4-axis milling | Adds a rotary table so the part indexes to a new face | Multi-sided parts that still need a rigid set-up |
| 5-axis simultaneous | Tool and part move together on five axes | Impellers, gimbal frames, contoured aerospace brackets, deep cavities with undercuts |
| 3+2 indexed 5-axis | Five faces machined from fixed orientations, tighter rigidity than full simultaneous | Complex prismatic parts where position tolerance matters more than contouring |
| CNC turning | Rotates the workpiece against a single-point tool | Shafts, bushings, pins, adapters, connectors — anything round |
| Live-tool turning | Adds driven tools and often a sub-spindle to a lathe | Turned parts with cross-holes, milled flats, slots or axial drilling |
| Turn-mill complex | Turning and milling in one machine, one set-up | Fittings and hydraulic bodies where re-chucking would cost the tolerance |
| Wire EDM | Burns a 2D profile through hardened material | Punches, dies, thin slots, hardened tool steel, sharp internal corners |
| Sinker EDM | Burns a shaped cavity with a formed electrode | Deep ribs, sharp-bottomed pockets, mold inserts |
| Surface grinding | Removes material with an abrasive wheel for flatness and finish | Gauge parts, sealing faces, thin plates that would deflect under milling |
How the route is actually chosen
Four questions settle most of it. Geometry: a part that is mostly round goes on a lathe; one that is mostly prismatic goes on a mill; one with deep sharp-cornered pockets picks up EDM. Tolerance: if two features have to be true to each other within a few microns, they should be cut in the same set-up — which often decides the machine rather than the geometry. Quantity: at one piece the fastest route wins; at ten thousand the cheapest cycle time wins, and that can mean a fixture that looks over-engineered for a prototype. Finish: a Ra 0.4 µm sealing face usually means grinding after milling, not a slower pass on the same cutter.
Because setup count is the biggest single cost driver in a machine shop, we quote the routing as well as the price. If a small design change removes a second operation or a fourth face, the saving is usually far larger than any negotiation on hourly rate — and it is permanent, because it applies to every future order of that part.
Secondary operations we run in-house or control
Tapping, reaming, counterboring, thread milling, deburring, part marking and light assembly are part of the machining plan rather than an afterthought. Heat treatment, anodizing, plating and powder coating go to qualified Shenzhen partners and come back under the same inspection gate — the certificate is checked against the specification before parts are packed, not after a customer asks.
Processes outside this site
This site covers machining. If your program also needs die casting, hot forging, injection molding, 3D printing or full assembly, those run in the same company and are documented on the main site at jshs-cnc.com. Sending one drawing to one team is usually cheaper than coordinating four suppliers, even when only one process is on the critical path.