VT machining provides CNC Polishing 321 Stainless Steel for customers who need accurate, repeatable 321 Stainless Steel components. The machinability of 321 Stainless Steel is moderate; work-hardens, so positive-rake tooling and steady feeds are used to avoid glazing, so we set the operation up specifically for this grade.
CNC Polishing 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 Polishing
321 Stainless Steel behaves predictably under CNC Polishing once parameters are dialled in: machinability is moderate; work-hardens, so positive-rake tooling and steady feeds are used to avoid glazing, and we tune the operation accordingly.
We hold reference parameters for this grade, so repeat orders of 321 Stainless Steel run consistently from one batch to the next.
Achievable Tolerances for CNC Polishing 321 Stainless Steel
| Feature | Standard | Precision |
|---|---|---|
| Surface roughness | Ra 0.8 µm | Ra 0.05 µm |
| Edge break | 0.1–0.3 mm | 0.05 ±0.02 mm |
| Material removed | 0.02 mm | 0.005 mm |
| Bore roundness after honing | 0.005 mm | 0.002 mm |
| Cross-hatch angle | 45° ±10° | 45° ±5° |
| Cosmetic grade | uniform satin | mirror, no visible lines |
| Masking of datum faces | on request | standard |
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.
CNC Polishing Tolerances & Surface Finish
Finishing brings 321 Stainless Steel to a defined roughness target — from a uniform satin to Ra values as low as 0.05 µm — with controlled, repeatable edge breaks.
Final tolerances are governed by the material's behaviour, wall thickness and overall stiffness. We give honest DFM feedback if a callout would be costly or better achieved another way.
Why 321 Stainless Steel?
321 Stainless Steel is chosen when a part needs what this grade offers — it is corrosion resistant, strong and hygienic. We confirm the grade and any temper or heat-treat condition with you before machining.
CNC Polishing Quality & Inspection
We control quality throughout the process, not just at the end. In-process checks plus final inspection — including CMM where specified — keep every 321 Stainless Steel part to print. Inspection reports, material certificates and first-article documentation can be supplied on request.
Secondary Operations & Finishing
Finished 321 Stainless Steel parts can move straight into secondary operations under one roof. Typical add-ons are deburring, passivation, anodising, plating, blasting, polishing and laser marking. We coordinate the whole chain so you receive complete, inspection-ready parts.
Design Tips for CNC Polishing 321 Stainless Steel
We are happy to suggest design tweaks that improve manufacturability. Telling us the target Ra, the cosmetic faces and any masking needs lets us finish 321 Stainless Steel efficiently without over-processing. If you send your model early, we will return practical DFM feedback before you commit to production.
Applications of CNC Polishing 321 Stainless Steel
Customers order CNC Polishing 321 Stainless Steel components for everything from instrumentation to structural and functional assemblies. Whether you need a single prototype or recurring production volume, the same process discipline applies.
How to Order CNC Polishing 321 Stainless Steel
Getting a quote is simple. Share your model, the material grade, your quantity and target tolerances. You receive a clear quotation with lead time and honest manufacturability feedback.
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 Polishing 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
Related
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
Does CNC Polishing 321 Stainless Steel require dedicated tooling?
Most 321 Stainless Steel finishing work uses standard cutting tools and CNC programs; dedicated fixtures are made only when geometry or volume requires them.
What tolerances can you hold for CNC Polishing 321 Stainless Steel?
Achievable tolerances for 321 Stainless Steel finishing depend on the alloy, geometry and feature size. We hold tight, repeatable tolerances appropriate to the feature and material. Exact figures are confirmed against your drawing callouts.
What is CNC Polishing 321 Stainless Steel and how is it done?
CNC Polishing 321 Stainless Steel refers to cNC polishing refines surfaces to a smooth, reflective finish for cosmetic and functional needs. Applied to 321 Stainless Steel — corrosion resistant, strong and hygienic — VT machining produces each part to your CAD drawing, selecting parameters from your tolerance, finish and quantity requirements.
What surface finish is achievable on 321 Stainless Steel with CNC Polishing?
Our finishing processes refine 321 Stainless Steel surfaces to Ra values as low as 0.05 µm for cosmetic or sealing faces.
How clean are the edges produced by CNC Polishing on 321 Stainless Steel?
Our deburring leaves 321 Stainless Steel with a consistent, controlled edge break and burr-free surfaces.