CNC Boring Bronze is a core capability at VT machining. We combine controlled turning with material-aware setup for Bronze — an alloy that is wear resistant with good bearing properties — to produce parts that meet your specification first time.
CNC Boring Capability for Bronze
- Bore tolerance to IT6
- Roundness within 0.005 mm
- Fine boring heads
- Large-diameter capability
Bronze Material Data
| Density | 8.80 g/cm³ |
|---|---|
| Tensile strength | 240 MPa |
| Yield strength (0.2%) | 125 MPa |
| Hardness | 65 HB |
| Melting point | 855–980 °C |
| Thermal conductivity | 59 W/m·K |
| Thermal expansion | 18.0 ×10⁻⁶/K |
| Electrical conductivity | 12% |
| Machinability (C36000 = 100%) | 70% |
| Grades we run | C93200 SAE 660, C54400, C63000 aluminium bronze, C86300 manganese bronze |
Published typical values for C93200 (SAE 660). Other grades in the family differ — the certificate supplied with your order carries the actual heat-lot figures.
Cast bearing bronze has porosity. On sealing faces we specify continuous-cast stock rather than sand-cast, because a pinhole in a bore face is not repairable.
How CNC Boring Bronze Works
The Bronze 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.
Programming is driven directly by your 3D model or print. Work-holding, tool selection and the cutting strategy are planned around the critical features and the material before the first chip is cut. First-off inspection confirms the process is centred before production continues.
Achievable Tolerances for CNC Boring Bronze
| 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.
CNC Boring Tolerances & Surface Finish
Turned Bronze 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.
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.
Working with Bronze
As a material, Bronze is wear resistant with good bearing properties. Our setup reflects the alloy's machinability so the finished part is accurate and free of avoidable defects.
We verify the exact grade and condition before machining, and traceable mill certs are available on request. We can work to your nominated material source or specification when required.
Secondary Operations & Finishing
Finished Bronze 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.
CNC Boring 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 Bronze part to print. Inspection reports, material certificates and first-article documentation can be supplied on request.
Design Tips for CNC Boring Bronze
We are happy to suggest design tweaks that improve manufacturability. Consistent diameters, standard thread forms and avoiding extremely long, slender features help Bronze turned parts stay concentric and economical. If you send your model early, we will return practical DFM feedback before you commit to production.
Applications of CNC Boring Bronze
Customers order CNC Boring Bronze 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 Boring Bronze
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.
Parts We Have Run in Bronze
Three representative CNC Boring Bronze jobs, with the callouts that actually drove the process plan. Yours will differ — these are here so you can judge whether your part is in our range before you spend time on an RFQ.
Precision shaft
- Material
- Bronze
- 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
- Bronze
- 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
- Bronze
- 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.
Finishing Options for Bronze
| Finish | Thickness / effect | Why it gets specified |
|---|---|---|
| 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 Boring Bronze
- 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 Bronze 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 Bronze
Send the drawing, the Bronze 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 surface finish is achievable on Bronze with CNC Boring?
Surface finish on Bronze is controlled to your specification; we confirm the achievable Ra against your callout.
Can VT machining make custom Bronze parts to my drawing?
Yes. Bronze Bronze 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 tolerances can you hold for CNC Boring Bronze?
Achievable tolerances for Bronze turning depend on the alloy, geometry and feature size. Turning holds diameter tolerances to around ±0.005 mm with concentricity within 0.01 mm. Exact figures are confirmed against your drawing callouts.
Which industries use CNC Boring Bronze parts?
CNC Boring Bronze parts are used across aerospace, medical, automotive, electronics, semiconductor and general industrial sectors — anywhere precise Bronze components are required.
What is CNC Boring Bronze and how is it done?
CNC Boring Bronze refers to boring enlarges and finishes existing holes to precise diameter, roundness and surface finish. Applied to Bronze — wear resistant with good bearing properties — VT machining produces each part to your CAD drawing, selecting parameters from your tolerance, finish and quantity requirements.