We machine 303, 304, 316L and 17-4PH stainless on 127 CNC machines, 16 of them simultaneous 5-axis. Tight tolerances, documented inspection, and no minimum order quantity.
Most of these are visible at first article, not at final assembly. That is the expensive part.
Stainless work-hardens fast when the tool rubs instead of cuts. Feed too light, coolant aimed at the wrong spot, and the next pass tears the surface. A thread that looked fine in the machine gauges loose on the mating part.
316 and 17-4PH hold heat. A bore that measures on size at the spindle can close 0.01 mm once the part reaches room temperature. If the shop inspects hot, the parts ship out of tolerance and nobody finds out until assembly.
Cold-drawn stainless varies in straightness and diameter from lot to lot. Skip the incoming material check and a turned shaft comes out with wall thickness variation you cannot see until it is ground or assembled into a housing.
Bead blasting and electropolishing hide tool marks. They also hide a crack at a corner radius. When the finish is applied before final inspection, a rejected part can look like a good one until it sees load or pressure.
Cutting data, workholding and inspection are set per alloy, not per drawing.
303 machines cleanly. 304 and 316 do not, and the difference shows up in surface finish. We set feed per tooth high enough to cut under the hardened layer instead of rubbing across it, and we keep the tool engaged so the edge never dwells.
For deep pockets and thin walls we rough with a larger tool and leave enough stock that the finishing pass removes the hardened skin in one clean cut. Coolant goes through the tool, not around it.
Stainless is stiff, so chatter usually comes from the setup rather than the tool. On our simultaneous 5-axis centers we can reach five faces in one setup, which removes the re-clamping error that shows up on thin flanges and long brackets.
The largest 5-axis travel is 4,000 × 400 × 150 mm, and we hold a Ø400 mm rotary table for round and offset work. Mill-turn centers cut turned and milled features on the same part without a second fixture.
Pick the grade before the process, not after.
| Grade | Typical parts | Machine it when |
|---|---|---|
| 303 | Fittings, bushings, spacers | You need volume and free-machining behavior |
| 304 / 304L | Brackets, panels, housings | General corrosion resistance is enough |
| 316 / 316L | Marine, medical, food contact | Chlorides or washdown are in the environment |
| 17-4PH | Shafts, valves, aerospace fittings | You need high strength after heat treat |
| 420 / 440C | Wear plates, knife edges | Hardness matters more than corrosion |
| 430 | Decorative and magnetic parts | Cost control with mild corrosion exposure |
One shop for the machining, the finish and the inspection report.
Simultaneous 5-axis for contoured stainless parts, impellers, housings and angled features that would need three fixtures on a 3-axis machine.
3-axis, 4-axis and mill-turn centers. Turned shafts, threaded fittings and milled pockets on the same part, one program.
Functional stainless prototypes in 3–5 days so you can test fit and function before committing to a production run.
Bead blasting, tumbling, brushing, polishing, passivation and electroless nickel. Laser marking down to 1.5 mm character height.
No minimum order quantity. One prototype or a 10,000+ part run, same process control and same inspection routine.
Raw material check, in-process monitoring and 100% final inspection. Dimensional reports and material certs on request.
Numbers we hold on stainless, not best-case claims.
| Item | Range | Notes |
|---|---|---|
| Tolerance | ±0.005 mm (±0.0002 in) | Held on critical features, verified at final inspection |
| Surface finish | Ra 0.2–0.8 μm fine | Ra 1.6–3.2 μm as-machined where finish is not critical |
| Maximum part size | 4,000 mm | 4,000 × 400 × 150 mm 5-axis travel |
| Volume | 1 to 10,000+ parts | No minimum order quantity |
| Lead time | Parts ship in 3–5 days | Production can start within 24 hours |
| Quote turnaround | 12 hours | Includes free DFM analysis |
Equipment counts. Setup discipline and inspection count more.
Fifteen years on austenitic and precipitation-hardening grades. We know which alloys fight back and plan the setup for it.
Complex geometry cut in fewer setups. Fewer datum shifts means tighter position between features.
±0.005 mm on critical features, checked with calibrated instruments and reported if you ask.
Parts that pass final inspection on the first submission. The number comes from our own records, not a sales sheet.
Drawings reviewed within 12 hours. If a wall is too thin to hold, we say so before the tool hits metal.
Start with one functional prototype and scale to a 10,000+ run without changing shops or processes.
316L and 17-4PH components need clean surfaces and traceable material. We machine, passivate and document the lot.
Stainless brackets and fittings must hold position across a production run, not just on the first part.
Long stainless shafts and rails are machined in one program on 4,000 mm travel machines.
Thin-wall stainless housings chatter if the fixture is wrong. We plan workholding before the first cut.
Start with the environment. If chlorides, salt spray or repeated washdown are present, go to 316 or 316L. If the part only sees indoor air and mild moisture, 304 is cheaper and machines about the same.
Use 303 when the part is simple and you want volume. It machines faster and gives better surface finish, but it is not the right choice for welded assemblies and it corrodes sooner than 304.
On short and medium features, yes. Length-to-diameter ratio drives the answer. A 300 mm shaft at Ø20 mm is a different problem from a 60 mm bore.
Send the drawing. We check the ratio, the wall thickness and the datum scheme, then tell you which tolerance we can hold and where we need a change.
Yes. Passivation removes free iron left by cutting tools and improves corrosion resistance. It is standard on 304, 316 and 17-4PH parts that see moisture or washdown.
We usually passivate after bead blasting or tumbling, not before, because the mechanical finish needs to come off first.
Quotation and DFM feedback come back within 12 hours. Production can start within 24 hours of approval, and parts ship in 3–5 days.
For one-off prototypes the machine time is small compared to setup and inspection, so the schedule depends more on fixture planning than on cut time.
We check incoming stainless bar and plate against the mill certificate before it goes to a machine. Diameter, straightness and grade are verified at that point.
Copies of the material cert and the dimensional report go out with the shipment if you ask for them on the purchase order.
We machine 17-4PH in the condition you specify, from solution-treated to H900 and H1150. Hardened material cuts slower and tool life drops, so expect a different cycle time than 304.
If the drawing calls for tight bores after heat treat, tell us early. It is usually cheaper to leave grinding stock and finish after hardening than to fight the hardness in the machine.
No. One functional prototype and a 10,000+ part run go through the same process control.
Unit cost drops with volume because setup is spread across more parts, but nothing stops a single-part order.
Uploads are treated as confidential and we do not share files outside the project team. A non-disclosure agreement is available on request before you send anything.
If your program requires document control, say so in the first message and we will follow your numbering and revision scheme.
Upload your STEP file and 2D drawing. An engineer reviews it for manufacturability and comes back with a price, a lead time and any changes we would make.
12-hour quoteFree DFM analysis100% inspectionNo minimum order quantityNDA on request
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CNC Metals 13 grades
CNC Plastics 10 grades
Machines & processes 12 options
Surface & post-processing 10 options
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