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Stainless CNC

Stainless Steel CNC Machining for Medical, Food and Marine Parts

Send your drawing. We match it with shops that cut stainless every week, not shops that will learn work hardening on your part. Reply within 24 business hours.

Get matched with a stainless shopSee the grades
MachinabilityPitting resistance783031845304L1936316L245017-4 PH168541613302205 duplex3510050002040303 cuts twice as fast as 316L and pits where 316L holds
Published typical values. Machinability is rated against free-machining carbon steel B1112 at 100. PREN is calculated from nominal composition as Cr plus 3.3 Mo plus 16 N.

We are a matching service, not a machine shop. We do not own machines and we take no commission on your order.

Free for buyersShops pay for matched requests.
Up to 3 shopsNo mass blasting of your drawing.
NDA on requestFiles stay with us until it is signed.
Reply within 24 business hoursWith matched shops or a clear no.

Does your part need a stainless specialist?

Any shop can cut a block of 304. The trouble starts with work hardening, the finish and the paperwork that comes with food and medical work. Tick what applies to your part. Two or more ticks usually means you want a shop that runs stainless every week.

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Typical machined stainless parts

  • Surgical and dental instrument parts
  • Valve bodies, seats and stems
  • Pump and mixer shafts
  • Food and dairy fittings
  • Filter housings and manifolds
  • Lab and analyser components
  • Marine deck and rigging hardware
  • Vacuum and semiconductor fittings

Stainless holds heat in the part instead of letting it leave with the chip, and it hardens where a dull tool rubs. Shops that run it often solve that with feed, rigidity and fresh tooling rather than by slowing the machine down.

That is also why a quote can look high. You are paying for cycle time, for tooling and for the passes it takes to hold size in a material that moves while it is cut.

Free-machining 303 or corrosion resistant 316L?

This is the decision that sets the price of a stainless part, and the one that goes wrong most often. Both look like stainless on the drawing. One of them costs more than twice as much to cut, and the other one fails in service.

303, the free-machining grade

Sulphur added so the chip breaks. A machinability rating near 78 and a PREN near 18.

  • Right for dry indoor parts with threads, cross holes and small features
  • Shorter cycles, cleaner threads and less tool wear than 304
  • The sulphide stringers that make it cut well are where pits start
  • Not welded, and normally kept out of food contact, medical and marine parts

316L, the corrosion resistant grade

Two to three percent molybdenum instead of sulphur. A machinability rating near 36 and a PREN near 24.

  • Specify it when the part meets chloride, cleaning chemicals or body fluid
  • Welds cleanly and passivates to a stable film
  • Expect longer cycles, more tool changes and a higher price per part
  • The low carbon L version avoids carbide precipitation at the weld

303, 304 and 316L compared for machining and corrosion

Stainless grades and what they cost you in machining

Published typical values for each alloy. Machinability is rated against free-machining carbon steel B1112 at 100, and PREN is the pitting resistance equivalent number. Tolerances are what these grades commonly hold, not what any shop promises on your geometry.

GradeMachinabilityPRENWhat it means on the floorTypical tolerance
303 / 1.43057818Sulphur added so the chip breaks. Cuts fast and threads cleanly. The same sulphide stringers start pits, so it stays out of food contact, medical and marine parts.±0.01 mm is routine
304 / 304L / 1.43014519The default austenitic. Welds and forms well. Work hardens fast, so a rubbing tool makes the next pass harder than the last.±0.025 mm typical
316 / 316L / 1.44043624Two to three percent molybdenum buys chloride resistance. The grade food, pharma and medical buyers ask for by name, and the slowest of the common three to cut.±0.025 mm typical
17-4 PH / 1.45425016Machined soft in condition A, then aged to 30 to 44 HRC. H900 is the hardest and the least corrosion resistant, H1150 the other way around.±0.02 mm typical, ageing moves size slightly
416 / 1.40058513Free-machining martensitic. The cheapest of this group to cut and the weakest against corrosion. Shafts and fasteners that stay dry and indoors.±0.01 mm is routine
2205 duplex / 1.44623035Around twice the yield strength of 316L and far better in chloride. Slow, hard on tools and worth it only when the part needs it.±0.05 mm typical

Not sure which one your part needs? Write the environment on the drawing, for example wash down with caustic daily or immersed in sea water, and leave the grade open. A shop can then offer the cheaper alloy that still survives it.

Passivation, electropolishing and the paperwork

On a medical or food part, the finishing route decides as much as the cutting. Machining smears free iron from the tooling across the surface, and that iron rusts even though the alloy underneath is fine. Say in the RFQ which standard you need so the quote includes it instead of a surprise later.

  1. Deburr and clean

    Cutting oil, embedded iron from tooling and burrs all have to come off first. Passivating a dirty part just locks the contamination under the film.

  2. Passivate

    ASTM A967 or AMS 2700, citric or nitric. It dissolves free iron at the surface and lets the chromium oxide layer rebuild. Citric is the usual choice now for medical and food work.

  3. Electropolish if asked

    ASTM B912. It takes off a thin layer, rounds the peaks and lowers Ra. Specify it when the part has to be cleanable or it goes into a pharma or vacuum process.

  4. Test and document

    Copper sulphate, high humidity or salt spray per ASTM A967, plus the certificate. Say in the RFQ which test and which paperwork you need back.

Passivation against electropolishing, and when you need both

Where machined stainless parts go

Each of these brings its own paperwork. Mention material certificates, surface finish reports, cleanliness or first article inspection in your RFQ so we match shops that already work that way.

Medical and dental

Instrument components, handles and lab fixtures in 316L and 17-4 PH, usually passivated and documented.

Food and beverage

Fittings, nozzles and machine parts where the finish spec and the cleaning regime matter more than the tolerance.

Pharma and biotech

Manifolds, housings and vessel parts in 316L, often electropolished with a surface finish report.

Marine and offshore

Deck hardware, shafts and fasteners where chloride decides the grade and 303 is off the table.

Chemical and process

Valve bodies, pump parts and heat exchanger components in 316L and duplex.

Vacuum and semiconductor

Flanges, feedthroughs and chamber fittings in 316L with cleanliness and outgassing requirements.

How it works

One RFQ from you. A short list of shops that fit. No bidding platform and no middleman on the order.

  1. Send your RFQ

    Upload a STEP file or PDF drawing and tell us the grade, quantity, tolerance and finish. Takes about three minutes.

  2. We match up to 3 shops

    We read the drawing and pick shops whose machines, stainless experience and part size fit. You hear from us within 24 business hours.

  3. Shops quote you directly

    Each shop contacts you with a quote. You compare, ask questions and place the order with the one you choose.

What drives the price of a machined stainless part

Six things decide most stainless quotes. If a price looks high, one of these is usually the reason, and two of them you can change on the drawing.

What drives the cost of a stainless part

  • GradeThe same shape in 303 and in 316L are two different prices. 303 cuts more than twice as fast, and it is the wrong alloy the moment the part gets wet with chloride.
  • Work hardeningStainless hardens under a rubbing tool, so light finishing passes cost more than heavy ones. Cycle time, tool wear and scrap all sit on this one point.
  • Tolerance and heatThe part grows while it is cut and moves again when it is aged or welded. Tight tolerances mean extra passes, a settling step and more inspection.
  • Passivation and finishBead blast, Ra 0.8 micrometre or better, passivation to ASTM A967 and electropolishing each add cost and a few days, often at a second supplier.
  • Certificates and traceabilityMill certs, heat numbers, first article reports and lot control are real hours in a real office, not a checkbox.
  • Quantity and setupStainless setups take longer to prove out. That time spreads over the batch, so the price per part drops quickly with quantity.

Have a stainless drawing ready?

Send the short version now. We will ask for anything missing. To give full details up front, including tolerance, passivation and the certificates you need, use the full RFQ form.

Your files go only to the shops we match. Ask for an NDA and nothing is shared until it is signed.

STEP, IGES, PDF, DWG or DXF. Cannot upload from your phone? Email the files to after you send this form.
Reply within 24 business hours.

Cut stainless every week? Get RFQs that suit it.

Shops see a preview of each request before paying for it and talk to the buyer directly. We take no commission on the order. Questions first? Email .

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Questions buyers ask

Something else? Email .

Do you machine the parts yourselves?

No. We are a matching service, not a machine shop. We read your RFQ and pass it to shops that cut stainless every week. They quote you, and you place the order with the one you pick.

Is this free for buyers?

Yes. Sending an RFQ and receiving quotes costs you nothing. Shops pay us for matched requests. Price, terms and delivery are agreed between you and the shop.

Which stainless grade should I put on the drawing?

If the part touches food, body fluid, salt water or bleach, ask for 316L and keep 303 off the print. If it stays dry and indoors, 304 is usually enough. If you need hardness above 30 HRC with some corrosion resistance, that is 17-4 PH. Write the environment next to the grade so a shop can suggest a cheaper alloy that still meets it.

Why is 303 cheaper to machine but wrong for my part?

Sulphur is added to 303 so the chip breaks, which is why it cuts more than twice as fast as 316L. Those same manganese sulphide stringers are where pitting starts, so 303 is normally kept out of food contact, medical and marine parts even though its chromium content looks close to 304.

Can the shops passivate and electropolish?

Some do it in house and most send it out. Name the standard in your RFQ, usually ASTM A967 citric or nitric for passivation and ASTM B912 for electropolishing, so we only match shops that already work to it and can return the certificate you need.

Who sees my drawing?

Shops first see a short preview: part type, grade, size, quantity, tolerance and finish. It does not carry your name, your company or your files. Your contact details and files go only to the shops we match, up to 3. If you ask for an NDA we hold the files until it is signed.

Which file formats can I send?

STEP or IGES for the model plus a PDF drawing with tolerances, surface finish and the passivation or electropolish callout. DWG and DXF work for flat parts. A STEP file together with a PDF drawing gets the most accurate quotes.

Guides for stainless buyers

Twenty of them, covering grades, finishing, cost and how to brief a shop. See them all.

All guides