VT machining specialises in CNC Centerless Grinding 321 Stainless Steel. Because 321 Stainless Steel is corrosion resistant, strong and hygienic, and its machinability is moderate; work-hardens, so positive-rake tooling and steady feeds are used to avoid glazing, we plan each job around the grade to protect accuracy and surface quality.
CNC Centerless Grinding Capability for 321 Stainless Steel
- Austenitic/martensitic grades
- Corrosion resistant
- Tolerance to ±0.01 mm
- Typical hardness 70–200 HB (annealed)
321 Stainless Steel Material Data
| Density | 8.00 g/cm³ |
|---|---|
| Tensile strength | 515 MPa |
| Yield strength (0.2%) | 205 MPa |
| Hardness | 170 HB |
| Melting point | 1400–1450 °C |
| Thermal conductivity | 16.2 W/m·K |
| Thermal expansion | 17.3 ×10⁻⁶/K |
| Electrical conductivity | 2.4% |
| Machinability (C36000 = 100%) | 45% |
| Grades we run | 303, 304/304L, 316/316L, 321, 410, 416, 420, 17-4PH, 2205 duplex |
Published typical values for 304. Other grades in the family differ — the certificate supplied with your order carries the actual heat-lot figures.
It work-hardens the moment a tool dwells. Constant feed and positive-rake tooling; a rubbing pass leaves a glazed skin the next tool cannot get through.
Machining 321 Stainless Steel with CNC Centerless Grinding
When grinding 321 Stainless Steel, machinability is moderate; work-hardens, so positive-rake tooling and steady feeds are used to avoid glazing. Our process plan reflects this so the finished part holds its tolerances without distortion or poor finish.
Documented parameters for 321 Stainless Steel mean predictable cycle times and stable, repeatable results.
Achievable Tolerances for CNC Centerless Grinding 321 Stainless Steel
| Feature | Standard | Precision |
|---|---|---|
| Size (OD, ID, thickness) | ±0.005 mm | ±0.002 mm |
| Flatness over 100 mm | 0.010 mm | 0.003 mm |
| Parallelism | 0.010 mm | 0.003 mm |
| Roundness | 0.005 mm | 0.002 mm |
| Squareness | 0.010 mm | 0.005 mm |
| Surface finish | Ra 0.4 µm | Ra 0.1 µm |
| Workpiece hardness | up to 62 HRC | up to 65 HRC |
Standard is what a normal quotation assumes. Precision is available on nominated features and is priced separately, because it needs extra setups, in-process gauging and CMM verification. Call out only the features that need it — blanket-tightening a drawing is the single most common reason a quote comes back expensive.
Design Tips for CNC Centerless Grinding 321 Stainless Steel
Small design adjustments often cut cost and lead time. Allowing adequate grind stock, specifying realistic flatness over the true datum, and relieving corners help us hit tight tolerances on 321 Stainless Steel efficiently. If you send your model early, we will return practical DFM feedback before you commit to production.
CNC Centerless Grinding Tolerances & Surface Finish
Ground 321 Stainless Steel reaches single-micron tolerances on size, flatness and parallelism, with surface finishes down to Ra 0.1–0.4 µm — and a near-mirror finish on suitable alloys.
Exact achievable figures depend on the alloy, the feature size and the part geometry. Tell us which dimensions are critical and we will advise feasibility up front.
Secondary Operations & Finishing
Most 321 Stainless Steel parts need some finishing, which we manage in-house or through vetted partners. Options include deburring and edge-breaking, heat treatment, surface grinding, polishing, and plating or anodising for corrosion resistance and appearance. Give us the finished-part requirement and we will sequence every operation correctly.
CNC Centerless Grinding Quality & Inspection
Quality is built in, not inspected on. We monitor key features during the run and confirm them at final inspection, with CMM verification available for tight tolerances. We provide the inspection and traceability records your quality system requires.
Why 321 Stainless Steel?
Customers select 321 Stainless Steel for CNC Centerless Grinding because it is corrosion resistant, strong and hygienic. We handle grade verification and any required heat treatment or finishing.
Applications of CNC Centerless Grinding 321 Stainless Steel
321 Stainless Steel parts made this way are found throughout aerospace, medical, automotive, electronics and industrial equipment. Prototype, bridge and production volumes are all welcome.
How to Order CNC Centerless Grinding 321 Stainless Steel
Starting your project takes one email. Send your CAD or 2D drawing, the 321 Stainless Steel grade and condition, the quantity and any finish or inspection requirements. We respond quickly with price, lead time and any DFM notes, in clear English.
Finishing Options for 321 Stainless Steel
| Finish | Thickness / effect | Why it gets specified |
|---|---|---|
| Citric passivation | — | ASTM A967 / AMS 2700, removes free iron |
| Electropolish | 5–25 µm removed | Ra improves by roughly half, hygienic surface |
| Brushed / grained | Ra 0.4–1.6 µm | No. 4 finish, directional |
| PVD coating | 2–5 µm | TiN, TiCN for wear surfaces |
| Deburr / edge break | 0.05–0.3 mm | All parts unless the drawing says otherwise |
| Bead blast | Ra 1.6–3.2 µm | Uniform matt finish, hides tool marks |
| Laser marking | — | Part number, lot code, data matrix |
No drawing yet? Build one in the browser.
Set the metal, dimensions and features, watch the 3D model update as you type, then switch to the 2D sheet to add dimensions and tolerances. Download it or send it straight to us with your RFQ.
What We Need to Quote CNC Centerless Grinding 321 Stainless Steel
- GeometrySTEP or IGES for the 3D model, plus a PDF drawing if you have tolerance callouts. A dimensioned sketch is enough to start.
- MaterialThe exact 321 Stainless Steel grade and condition — temper, heat-treat state or hardness. If you are not sure, tell us the function and we will suggest one.
- QuantityPrototype count and the expected annual volume. Both change how the part is made and therefore what it costs.
- TolerancesWhich features are critical. Everything else runs to our standard tolerance, which is what keeps the price sensible.
- FinishSurface treatment, cosmetic requirements, and any faces that must be masked.
- DocumentsWhether you need a material certificate, dimensional report, FAIR or PPAP with the shipment.
Missing something from the list is not a problem — send what you have. We will come back with the specific questions rather than a generic form.
321 Stainless Steel in Other Processes
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Send the drawing, the 321 Stainless Steel condition and the quantity — pricing and lead time come back the same or next business day.
Request a QuoteFrequently Asked Questions
What material thickness or size range suits CNC Centerless Grinding 321 Stainless Steel?
We machine 321 Stainless Steel across a broad size range; share your part envelope for confirmation.
What is the typical lead time and minimum order for CNC Centerless Grinding 321 Stainless Steel?
CNC Centerless Grinding prototypes for 321 Stainless Steel can be produced quickly and scaled to series production. Send your drawing and quantity and we will advise lead time and any minimum order.
What surface finish is achievable on 321 Stainless Steel with CNC Centerless Grinding?
Grinding can take 321 Stainless Steel to a fine finish — typically Ra 0.1–0.4 µm, and to a mirror grade on suitable alloys.
Why is 321 Stainless Steel a good choice for CNC Centerless Grinding?
321 Stainless Steel is corrosion resistant, strong and hygienic, which makes it well suited to CNC Centerless Grinding. We tune the process to the alloy so the finished 321 Stainless Steel grinding part meets your dimensional and functional requirements.