CNC Machined Parts
Stainless Steel CNC Turned & Milled Parts
Stainless steel 303, 304 and 316 parts turned, milled and mill-turned in-house — shafts, fittings, housings and manifolds held to ±0.025 mm where marked, with passivation, polishing and electroless nickel available. Free DFM and quote within 24 hours; CMM and material reports on request.
Stainless steel parts usually fail in one of two ways: the grade is wrong for the environment, or the threads and sealing faces that looked fine on the drawing come back out of tolerance. Both problems are cheaper to catch on paper than on your assembly line. HAFO Mould turns and mills stainless parts in its own Dongguan factory — machining, inspection and finishing under one roof since 2007. Send your drawing; an engineer reviews it free and we quote within 24 hours.
Upload Your Drawing — Free DFM + Quote Within 24 Hours. STEP, STP, IGES, STL, X_T and 2D PDF accepted. Files are confidential; NDAs welcome.
Since 2007 · 80 staff, 35 engineers · turning + milling + mill-turn in-house · 3 fully automatic CMMs · ISO 9001:2015 certified — scope: Manufacturing of Hardware Molds and Parts · Regular shipments to the US, Germany, France, Portugal, Sweden and Spain.
What We Machine in Stainless Steel
- Turned parts — shafts, bushings, spindles, threaded fittings, connectors and valve components
- Milled parts — housings, manifolds, plates, brackets and pump bodies
- Mill-turn parts — components needing a turned profile plus milled flats, cross-holes or keyways in one setup
- Threaded components — metric and imperial threads, internal and external, machined or tapped
- Marine and washdown hardware — 316 parts for corrosive or frequently cleaned environments
Turning and Milling Under One Roof
A stainless part that needs both turning and milling suffers every time it changes machines or suppliers: tolerance stack-up grows, lead time doubles, and responsibility blurs. We run the complete part in-house — bar work on lathes, prismatic features on our 3, 4 and 5-axis machining centers, and combined mill-turn operations where the geometry calls for them. Maximum CNC travel is 800 mm (31.5 in). Wire EDM and EDM in the same factory handle slots, keyways and internal features that rotating tools cannot reach.
Our free DFM review checks the things that quietly drive stainless cost: deep small-diameter holes, thin walls that will chatter, thread specs that could be simplified, and surface finishes specified tighter than the application needs. You get the feedback with your quote, within 24 hours.
Stainless Grades We Machine
- 303 — the free-machining grade. Sulphur added for machinability makes it the economical choice for high-volume turned parts, shafts and fittings that do not need welding or severe corrosion resistance.
- 304 — the general-purpose grade: good corrosion resistance for food-adjacent, architectural and general industrial parts.
- 316 — molybdenum-bearing grade for marine, chemical and washdown environments, and any part that sees chlorides.
Also machining carbon steel 1018/1045, alloy steel 4140, brass, copper, titanium, magnesium and the full aluminum range Precision Aluminum CNC Machined Parts in the same shop. A mixed-material assembly can be quoted as one order.
Tolerances
Default standard: ISO 2768-mK. Quoted levels for stainless steel:
Level | Tolerance | In inches |
|---|---|---|
Standard | ±0.13 mm | ±0.005 in |
Precision | ±0.025 mm | ±0.001 in |
Precision tolerances hold where your assembly needs them — bearing seats, sealing faces, thread gauges, mating bores. Our DFM review marks which dimensions we propose to hold at precision level and which stay standard, so you see the cost logic before ordering. More detail in CNC Machining Tolerances Explained: Standard vs. Precision.
Finishes for Stainless Steel
- As-machined — standard for internal and functional parts
- Passivation — restores and strengthens the corrosion-resistant chromium oxide layer after machining; recommended for most stainless parts
- Polishing — smooth, bright finishes for visible or hygienic surfaces
- Brushing — directional satin finish for panels and visible hardware
- Bead blasting — uniform matte finish
- Electroless nickel plating — even, hard coating for wear and added corrosion protection on complex shapes
- Black oxide — dark, low-build finish where specified
Finishes that build thickness are quoted with the machining allowance considered, so your dimensions arrive as drawn.
Specifications
Item | Value |
|---|---|
Processes | CNC turning, 3/4/5-axis milling, mill-turn, wire EDM, EDM, drilling & tapping |
Materials | Stainless 303 / 304 / 316 (also 1018, 1045, 4140, brass, copper, titanium, magnesium, aluminum) |
Standard tolerance | ±0.13 mm (±0.005 in), ISO 2768-mK |
Precision tolerance | ±0.025 mm (±0.001 in) on marked dimensions |
Max part size | Up to 800 mm (31.5 in) CNC travel |
MOQ | 1 piece |
Inspection | CMM, dimensional, material certificates; FAI on request |
Lead time | Depends on part size, quantity and finish — confirmed in your quote; expedite available on request |
Shipping terms | DDP, EXW or FOB; payment by T/T |
Quality and Inspection
HAFO Mould is ISO 9001:2015 certified (scope: Manufacturing of Hardware Molds and Parts). Stainless parts are verified on 3 fully automatic CMMs and standard metrology. On request we supply: CMM reports, dimensional reports, material certificates supplied with your order, finish certificates, FAI reports, and pre-shipment photos or video. Material certificates matter in stainless — they are how you know the 316 you specified is the 316 you received.
How Ordering Works
- Send your files — 3D file or 2D drawing, with grade, quantity and finish specified. NDAs welcome.
- Free DFM + quote within 24 hours — engineering review covers machinability, grade selection and tolerance cost drivers; quote confirms lead time in writing.
- Production — turning and milling in our own factory, with photo/video updates available.
- Inspection and documentation — parts checked against your drawing; certificates and reports supplied as requested.
- Delivery — DDP, EXW or FOB shipping; we regularly deliver across the US and Europe. Payment by T/T.
Why HAFO for Stainless Parts
- Both processes, one factory. Turned, milled and mill-turn features completed without hand-offs.
- Grade honesty. Material certificates back the grade on your drawing.
- Engineers, not order-takers. Every RFQ gets a DFM review by the team that will machine the part.
- Prototype to production in one place — and if the part later becomes a molded product, our toolroom sits in the same building Custom Plastic Injection Molds.
Applications
Fluid handling and valve components, food and beverage equipment parts, marine hardware, medical-adjacent equipment housings (non-implant), automation shafts and couplings, instrumentation fittings. See also Industrial Equipment & Robotics.
Choosing the Grade — a Practical Summary
- Choose 303 when the part is turned in quantity, will not be welded, and works in a mild environment. It is the fastest-machining stainless and usually the lowest-cost route to a stainless part.
- Choose 304 when you need a dependable all-rounder: better corrosion resistance than 303, suitable for most industrial, architectural and food-adjacent applications.
- Choose 316 when chlorides are present — marine air, coastal installations, chemical splash, frequent washdown with chlorinated cleaners — or when the part must keep its appearance and integrity for years outdoors.
Material cost differences between grades are usually smaller than the machining and failure costs of choosing wrong. If a 303 part corrodes in service, the replacement costs more than the 316 upgrade ever would have. Describe the working environment in your RFQ and the DFM review will confirm the grade — that conversation is free.
Design Tips for Stainless Parts
Stainless work-hardens and conducts heat poorly compared with aluminum, so design choices show up in the quote more strongly:
- Avoid very long, thin turned sections without support in the design. Slender shafts are machinable, but tolerances and finish on them take extra operations — expect the DFM review to discuss diameter-to-length ratio.
- Standardize threads. One thread size across an assembly reduces tool changes and gauging; mixing near-identical thread standards invites errors.
- Specify surface finish by function. A polished finish on every face costs polishing time on every face. Reserve cosmetic finishes for visible surfaces and Ra callouts for sealing faces.
- Passivate by default. Unless there is a reason not to, plan passivation after machining — it restores the corrosion protection that machining disturbs, and it is inexpensive insurance for a stainless part.
- Mark the critical dimensions. Precision tolerances on stainless cost more than on aluminum because the material machines slower; spend them only where the assembly needs them, and let ISO 2768-mK carry the rest.
A Note on Surface Finish Callouts
Buyers often copy a finish requirement from an old drawing without knowing what it commits them to. On stainless, very smooth finishes on large faces mean polishing time on every part; conversely, a sealing face genuinely needs its finish controlled or the gasket will not seat. In the DFM review we check finish callouts against function — faces that seal, slide or show get the finish they need; faces that do none of these stay as-machined, and the saving lands in your unit price. If your drawing uses Ra values, we machine and inspect to them as specified; if it does not, tell us which surfaces are functional and we will propose sensible callouts before quoting.
FAQ
Which stainless grade should I choose — 303, 304 or 316?
303 machines fastest and suits high-volume turned parts without welding or harsh corrosion exposure. 304 is the safe general-purpose grade. 316 is the one to specify for marine, chemical or chloride exposure. If you are unsure, describe the environment in your RFQ — the DFM review includes a grade recommendation.
Can you hold ±0.025 mm on stainless parts?
Yes, on the dimensions you mark as precision. Standard dimensions run at ±0.13 mm under ISO 2768-mK. Stainless work-hardens, so precision features are planned carefully — that planning is part of the DFM review, and it costs nothing.
Do you provide material certificates?
Yes. Material certificates are supplied with your order, and CMM reports, dimensional reports and FAI reports are available on request.
Can a part be both turned and milled without splitting the order?
Yes. Mill-turn capability in-house means turned diameters, milled flats, cross holes and keyways are completed by one supplier in coordinated setups — better feature-to-feature accuracy and one accountable delivery date.
What finishes suit stainless steel?
Passivation (recommended after machining), polishing, brushing, bead blasting, electroless nickel and black oxide. Tell us the service environment and we will advise if a finish is unnecessary cost.
What is your minimum order?
1 piece. Prototype shafts and one-off fittings are routine work for us.
What is the largest stainless part you can make?
Within our 800 mm (31.5 in) maximum CNC travel. Long slender shafts depend on diameter-to-length ratio as much as travel — send the drawing and the DFM review will confirm.
How quickly will I receive my quote?
Within 24 hours, after a free engineering review — not an automated estimate. Tolerances, finish and lead time are confirmed in the quote itself.
Can you sign an NDA before I send drawings?
Yes. NDAs are welcome and all files are handled as confidential by default.
Do you machine imperial threads?
Yes, metric and imperial threads, internal and external. Specify the thread standard on your drawing and we machine and gauge to it.
What payment and delivery terms do you offer?
Payment by T/T; delivery on DDP, EXW or FOB terms, with regular shipments to the US, Germany, France, Portugal, Sweden and Spain.
Related guides: CNC Machining Tolerances Explained: Standard vs. Precision · How to Get an Accurate CNC Machining Quote · Materials hub: Stainless Steel
