CNC Boring Stainless Steel from VT machining delivers precision Stainless Steel parts produced to your exact drawing. Boring enlarges and finishes existing holes to precise diameter, roundness and surface finish, and we tune every parameter to the behaviour of Stainless Steel, which is corrosion resistant, strong, hygienic (304/316 grades).
Starting Parameters for CNC Boring Stainless Steel
| Cutting speed (carbide) | 100-185 m/min |
|---|---|
| Feed | 0.056-0.175 mm/rev |
| Spindle speed, Ø30 mm bore | 1060-1960 rpm |
| Insert / tool class | ISO M — positive-rake PVD/CVD carbide |
| Coolant | Flood emulsion (8-10%) or high-pressure coolant |
Shown for 304 Stainless Steel, the most common Stainless Steel grade we see for CNC Boring. Starting values for 304 Stainless Steel, Annealed; optimised on the first article.
CNC Boring Capability for Stainless Steel
- Bore tolerance to IT6
- Roundness within 0.005 mm
- Fine boring heads
- Large-diameter capability
Stainless Steel material properties, finishing options and grade notes are on our CNC Turning Stainless Steel page.
How CNC Boring Stainless Steel Works
The Stainless Steel bar or billet rotates in the spindle while single-point tools shape outer diameters, bores, faces, grooves and threads. Constant surface speed control keeps cutting conditions stable from large to small diameters.
We start from your supplied geometry and tolerance scheme. The setup is designed to minimise re-clamping, which protects positional accuracy across features. A first article is verified against the drawing before the balance of the batch is released.
Achievable Tolerances for CNC Boring Stainless Steel
| Feature | Standard | Precision |
|---|---|---|
| Outside diameter | ±0.05 mm | ±0.005 mm |
| Bore diameter | H9 | H6 |
| Length / shoulder position | ±0.10 mm | ±0.020 mm |
| Concentricity OD to ID | 0.05 mm TIR | 0.010 mm TIR |
| Roundness | 0.02 mm | 0.005 mm |
| Thread class | 6g / 2A | 4h / 3A |
| Surface finish, as turned | Ra 1.6 µm | Ra 0.4 µm |
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 Boring Stainless Steel
Small design adjustments often cut cost and lead time. Consistent diameters, standard thread forms and avoiding extremely long, slender features help Stainless Steel turned parts stay concentric and economical. If you send your model early, we will return practical DFM feedback before you commit to production.
CNC Boring Tolerances & Surface Finish
Turned Stainless Steel holds diameter tolerances to about ±0.005 mm with concentricity within 0.01 mm and good roundness. Turned finishes of Ra 0.4–0.8 µm are achievable with finishing passes and sharp tooling.
The tightest tolerances are reserved for the features your drawing flags as critical. Share your tolerance scheme and we will confirm what is realistic before quoting.
Applications of CNC Boring Stainless Steel
Stainless Steel parts made this way are found throughout aerospace, medical, automotive, electronics and industrial equipment. Prototype, bridge and production volumes are all welcome.
Typical Stainless Steel Parts for CNC Boring
Illustrative examples of CNC Boring Stainless Steel parts and the callouts that usually drive the process plan. They show the kind of work that fits this process; they are not specific customer orders.
Precision shaft
- Material
- Stainless Steel
- Size
- Ø16 × 240 mm
- Key callouts
- OD h6, concentricity 0.01 mm TIR, keyway 5 H9
- Batch
- 1,000 pcs / year
Turned between centres so both journals share one datum.
Valve seat
- Material
- Stainless Steel
- Size
- Ø28 × 14 mm
- Key callouts
- Seat angle 45° ±0.1°, roundness 0.005 mm, Ra 0.2 µm
- Batch
- 800 pcs
Seat finished with a single-point diamond pass, no interruption.
Connector pin
- Material
- Stainless Steel
- Size
- Ø3.0 × 24 mm
- Key callouts
- OD ±0.005 mm, straightness 0.02 mm over length
- Batch
- 20,000 pcs
Swiss-turned from bar with a guide bushing; nothing else holds Ø3 mm over 24 mm.
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 Boring 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 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.
Other Metals for CNC Boring
Other Processes for Stainless Steel
Send the drawing, the Stainless Steel grade and the quantity. You get pricing, lead time and any DFM notes back — usually within one business day.
Request a QuoteFrequently Asked Questions
What is the typical lead time and minimum order for CNC Boring Stainless Steel?
CNC Boring prototypes for 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 Stainless Steel with CNC Boring?
Surface finish on Stainless Steel is controlled to your specification; we confirm the achievable Ra against your callout.
Can VT machining make custom Stainless Steel parts to my drawing?
Yes. Stainless Steel turning is made to order from your CAD/2D drawing. Share your geometry, material grade, tolerance and quantity and we will confirm feasibility, lead time and pricing.
What is CNC Boring Stainless Steel and how is it done?
CNC Boring Stainless Steel refers to boring enlarges and finishes existing holes to precise diameter, roundness and surface finish. Applied to Stainless Steel — corrosion resistant, strong, hygienic (304/316 grades) — VT machining produces each part to your CAD drawing, selecting parameters from your tolerance, finish and quantity requirements.