We machine tin, aluminum and manganese bronze into bushings, bearings, valve bodies and prototype hardware. Tolerances to ±0.005 mm, finishes from Ra 1.6 to Ra 0.2 μm. Upload a STEP file and we return a DFM review with your quote.
Bronze cuts differently from aluminum and steel. These are the failures we see most often on first-article parts.
Bronze is abrasive. Free-machining grades like C36000 cut clean, but hard tin bronzes such as C93200 or C95400 will dull carbide in minutes if the tool is run dry or at steel cutting speeds. A broken tool mid-run means scrapped parts and a re-machined setup.
Bronze has high thermal expansion. If a bushing is bored hot and measured cold, the bore shrinks after the part cools. The fit is lost. We rough, cool, then finish-bore to hold ±0.005 mm on diameters that actually matter.
Phosphor bronze and manganese bronze are gummy. Standard taps grab and peel material instead of shearing it. Rolled threads and spiral-flute taps solve most of this, but the tap selection has to be made before the program is written.
A single prototype machined from bar stock can pass inspection, then fail when the same part is cast and finish-machined. Starting stock condition, grain direction and cooling rate all shift the final dimensions. We plan for that before the first cut.
Bronze is not one material. Tin, aluminum, manganese and silicon bronze each need their own speeds, feeds and tool geometry.
Tin bronze with a high lead content, such as C93200, machines at cutting speeds in the 150 to 250 m/min range with uncoated carbide. Aluminum bronze C95400 is harder and gummier, so we drop to 80 to 120 m/min and take lighter depths of cut. Manganese bronze C86300 work-hardens at the surface if the tool rubs, so feed per tooth stays high enough to cut under the hardened layer.
The tool path matters as much as the numbers. We use climb milling on outer profiles to push the chip out of the cut and reduce built-up edge. Boring bars get positive rake geometry so the tool shears bronze instead of pushing it. On thin-wall bushings, we leave a roughing allowance of 0.5 mm and finish in two passes to control deflection.
Bronze expands about 18 × 10⁻⁶ per °C. On a Ø80 mm bearing bore, a 10 °C temperature swing moves the diameter by roughly 0.014 mm. That is nearly three times our tolerance. We rough with high-pressure coolant, let the part return to room temperature, then take the finish pass and measure on the machine while the part is still clamped.
For deep bores and long bushings, we use through-tool coolant and peck cycles to clear chips. Bronze chips are stringy and abrasive. Recutting them scratches the finished surface and loads the edge. Air blast plus minimal lubrication works for most turning operations. Flood coolant is reserved for deep-hole drilling and tapping.
Match the alloy to the load, the environment and the feature you need to machine.
| Grade | Typical use | Machinability | Watch out for |
|---|---|---|---|
| C93200 tin bronze | Sleeve bearings, bushings | Good | Lead content limits some applications |
| C95400 aluminum bronze | Valve seats, worm gears | Moderate | Work-hardens, gummy chips |
| C86300 manganese bronze | Heavy-load gears, wear plates | Moderate | High tensile, abrasive to tooling |
| C65500 silicon bronze | Corrosion-resistant hardware | Good | Lower strength than aluminum bronze |
| C17200 beryllium copper | Spring contacts, non-sparking tools | Good | Dust control required, higher cost |
Complex bronze housings, impellers and manifolds machined in one setup. 16 simultaneous 5-axis centers handle contoured surfaces and angled ports without re-fixturing.
Bushings, sleeves, valve stems and threaded fittings turned on high-speed lathes. Live tooling adds cross-drilled holes and milled flats in the same cycle.
Plates, brackets and covers with pockets, slots and drilled patterns. 3-axis and 4-axis mills cover flat and prismatic bronze parts.
From one part upward. Bar stock or near-net forgings machined to print, inspected and shipped in 3-5 days for form-fit-function testing.
Bead blasting, tumbling, brushing and polishing. Electroless nickel and silver plating for conductivity or corrosion resistance on bronze contacts.
100% inspection before shipment. Raw material certificates, in-process records and final dimensional reports on request.
Numbers from our equipment list, not marketing estimates.
| Parameter | Capability | Notes |
|---|---|---|
| Maximum part size | 4,000 mm | Larger travels on specific machines |
| Tolerance | ±0.005 mm | ±0.0002 in on critical diameters |
| Surface finish | Ra 0.2-0.8 μm | Fine finish on bearing bores |
| As-machined finish | Ra 1.6-3.2 μm | Standard milled and turned surfaces |
| Minimum order | One part | No minimum order quantity |
| Lead time | 3-5 days | After drawing approval |
Fifteen years cutting copper alloys. We know which grades need roll taps, which need positive rake, and which will move after unclamping.
127 high-precision CNC machines across three plants. No subcontracting the turning operation to a shop that has never cut bronze.
We measure the feature that matters, not just the outside envelope. Bearing bores and seal diameters get individual attention.
Parts that pass first inspection. When a bronze part fails, we tell you why and how the next run will differ.
ISO 9001:2015, IATF 16949:2016, ISO 13485:2016 and ISO 27001:2022 cover quality, automotive, medical and data security.
Send a STEP file and a drawing. You get a quotation and a manufacturability review within 12 hours.
Bronze shielding cans, contact pins and heat-spreader inserts. Requirements: tight flatness, plated surfaces, no burrs on mating faces.
Worm gears, synchronizer rings and bushing prototypes. Requirements: dimensional repeatability across the run and IATF-documented inspection.
Wear plates, valve bodies and pump components. Requirements: abrasion resistance, straight bores and controlled surface finish on sealing faces.
Bridge tooling and pilot runs from one part to 10,000+. Requirements: consistent setup, documented process, no mid-run tool failures.
C93200 tin bronze for bushings and sleeve bearings, C95400 aluminum bronze for valve seats and worm gears, and C86300 manganese bronze for high-load wear parts.
We also run C65500 silicon bronze for corrosion-resistant hardware and C17200 beryllium copper for spring contacts. If your drawing specifies a grade we have not listed, send it and we will confirm before quoting.
Yes, on bores that are not extremely thin-walled. The limiting factor is thermal growth, not the machine. We rough the bore, let the part cool, then finish-bore and measure on the machine before unclamping.
For wall thickness under 2 mm, we discuss the tolerance with you first. It may be more practical to finish-bore after the part is pressed into its housing.
We choose the tap before writing the program. Spiral-flute taps and roll-form taps work for most phosphor and manganese bronzes. Cutting taps with straight flutes are used only on free-machining grades.
Thread milling is another option for large diameters. It produces a cleaner thread and avoids the torque spike that breaks taps in gummy bronze.
It matters for food-contact, potable-water and some medical applications. Lead is added to improve machinability, and it is why C93200 cuts so cleanly.
If lead is restricted, we can machine lead-free alternatives such as C89833 or bismuth-modified bronze. Machinability drops, so expect different feeds and possibly a longer cycle.
Standard as-machined surfaces run Ra 1.6-3.2 μm. Bearing bores and seal faces can be finished to Ra 0.8-1.6 μm. Fine finishing reaches Ra 0.2-0.8 μm on specific features.
Bronze polishes well, but it also scratches easily. If the part will be handled before assembly, we can add a protective wrap or discuss a light tumble finish.
Yes. We can supply mill certificates showing the heat number, chemical composition and mechanical properties of the starting stock.
Inspection reports covering critical dimensions are available on request. Tell us which features matter and we will document those.
Quotation and DFM analysis come back within 12 hours of receiving a complete STEP file and 2D drawing. Production can start within 24 hours after you approve the quote.
Standard parts ship in 3-5 days. A part with complex 5-axis features or a required plating operation may take longer, and we will say so in the quote.
Yes. We machine near-net castings and forgings when the geometry or the production volume makes bar stock uneconomical.
Send the casting drawing and the finish-machined drawing. We will confirm the stock allowance and flag any areas where the as-cast surface may not clean up.
Upload a STEP file and a 2D drawing. You get a quotation and a free DFM analysis within 12 hours, with no minimum order quantity.
12-hour quote100% inspectionNo minimum orderNDA on request
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Upload your 3D model or 2D drawing and get a quotation with a free DFM analysis. Maximum processing size 4,000 mm.
CNC Metals 13 grades
CNC Plastics 10 grades
Machines & processes 12 options
Surface & post-processing 10 options
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