Bronze (Cu-Sn)
Frequently asked questions
Can Bronze (Cu-Sn) be laser cut?
With some limitations: Bronze (Cu-Sn) can be laser cut. Adequate extraction/ventilation is required.
Can Bronze (Cu-Sn) be CNC machined?
Yes: Bronze (Cu-Sn) can be CNC machined.
Is Bronze (Cu-Sn) food safe?
No, Bronze (Cu-Sn) is not considered food safe.
Physical properties
| Density | 8800.0–8800.0 kg/m³ |
|---|---|
| Brinell hardness | 115.0 HB |
| Tensile strength | 420.0 MPa |
| Melting point | 850.0–1000.0 °C |
| Thermal expansion | 18.0 µm/m·K |
| Moisture absorption | Negligible |
Laser processing
Heating generates copper oxides and tin oxides. Not acutely toxic in marking quantities, but ventilation recommended for prolonged exposure. Phosphor bronze (with P) releases trace amounts of phosphorus oxides during cutting.
CO₂: High reflectivity like all copper alloys. CO2 cutting is impossible at maker level; surface engraving requires chemical marking sprays (Cermark).
Diode: Impossible to cut or mark directly with diode laser.
Fiber: Marking possible with fiber laser. Bronze responds well to marking by surface oxidation: the result is a dark, permanent mark. Cutting requires very high power given the high thermal conductivity.
CNC / milling processing
Good machinability but more demanding than CW614N brass. The higher hardness and wear resistance that make bronze useful as a bearing material also make machining more intense on tooling. Chips are shorter and more fragmented compared to pure copper. Machinable dry or with air blast for roughing; prefer mist cooling for finishing operations.
Post-processing
Sanding: More demanding to sand than brass given the higher hardness. Use wet silicon carbide abrasives. Mirror polishing is achievable but requires more steps than brass.
Primer: Bronze does not require primer for decorative use: the natural patina is aesthetically appreciated. For painting apply etch primer for non-ferrous metals.
Gluing: Bondable with two-component structural epoxy adhesives after sanding and degreasing with acetone.
Over time: Excellent corrosion resistance, superior to brass. In atmospheric environments it develops a noble patina (browning → green) that further protects the underlying metal. Excellent resistance in marine environments. Used for millennia for components in contact with seawater.
Common defects
- Shrinkage cavities in cast parts if the casting process is not controlled (relevant for artistic bronze casting)
- Higher tool wear than free-machining brass in prolonged dry finishing operations
Safety
Recommended PPE: eye_protection, mask_p2
Copper and tin dust and fumes must not be inhaled. Extraction during machining. The green patina is composed of basic copper carbonates: do not ingest. Not toxic on occasional skin contact.
Availability and formats
Commercial formats: round bars for turning, pre-formed bushings and bearings, sheets, brazing rods
Related materials
Sources
- EN 12163 — Copper and copper alloys (CuSn8 rod and bar)
- MatWeb — Copper Alloy UNS C52100 (Phosphor Bronze) Datasheet
Information on compatibility, processing parameters and safety is purely indicative. MakerSpecs accepts no liability for damage to persons or property arising from the use of this data. Always check the safety rules and the manufacturer's official manuals before carrying out any processing.