Bronze vs brass bushings – key differences
Almost every load-carrying bushing is bronze – tin bronzes and aluminium bronzes – because they combine strength, wear resistance and the ability to embed grit without scoring the shaft. Ordinary brass (copper-zinc) is cheaper and easier to machine but has no seizure resistance, and makes sense for light guides, water fittings and decorative parts. The exception most articles miss: high-strength manganese brass C86300 is the strongest of all cast copper alloys and is chosen for the heaviest shock-loaded bushes.
Bronze is copper alloyed mainly with tin (or aluminium), brass is copper alloyed mainly with zinc. For a bearing the difference shows as hardness, fatigue strength, seizure resistance and corrosion behaviour: bearing bronzes have been standardised for the purpose (ASTM B505, EN 1982), ordinary brasses have not.
- Bushings: bronze (C93200, CuSn12, C95400) as the rule; brass only for light duty or water fittings
- Machining brass C36000 / CuZn39Pb3: fastest to machine, but a poor bearing – it galls on steel once the film thins
- High-strength brass C86300: 225 HB, 760 MPa – stronger than any bronze, for shock loads with hardened shafts
- Corrosion: tin and aluminium bronzes resist seawater; ordinary brass dezincifies unless inhibited
- Cost: brass bar is cheaper per kilogram than bearing bronze; the finished bush is priced by weight and machining time
Key differences
Typical values for the grades a buyer actually meets in bushings:
| Property | Bearing bronze (C93200 · CuSn12 · C95400) | Ordinary brass (C36000 · CuZn39Pb3 · C38500) | High-strength brass (C86300) |
|---|---|---|---|
| Composition | Cu + 7 – 12 % Sn (+ Pb, Zn) or Cu + 10 – 11 % Al + Fe | Cu + 35 – 40 % Zn + 2.5 – 3.7 % Pb | Cu + 25 % Zn + 6 % Al + 3 % Fe + 3.5 % Mn |
| Hardness | 65 – 170 HB (cast) | 105 – 150 HB (drawn bar) – hard, but no seizure resistance | 225 HB |
| Tensile strength | 240 – 585 MPa | 340 – 470 MPa (drawn bar) | 760 MPa |
| Wear as a bearing | good – standardised bearing alloys, embeds grit | poor under load – smears, wears the shaft | excellent under shock with a hardened shaft |
| Corrosion | resistant; aluminium bronze in seawater | dezincification in water unless DZR grade | moderate; not for seawater |
| Machinability | good (leaded) to fair (aluminium bronze) | best of all copper alloys (100 % rating) | fair; tough |
| Cost of the finished bush | reference | lower for small turned parts | highest per kg, longest life under shock |
| Typical grades for bushes | C93200 / SAE 660, CuSn12, C95400, LG2 | C36000, CuZn39Pb3, C38500 (turned from bar) | C86300 / SAE 430B, CuZn25Al5Mn4 |
Bronze values from ASTM B505 / EN 1982 typical data; brass bar values from ASTM B16 / EN 12164 typical data.
Why bronze is used for bushings
Four properties, all of them missing in ordinary brass:
- Seizure resistance – tin in the copper matrix gives a surface that does not weld to steel when the film thins; lead or free graphite adds emergency lubricity
- Embeddability – hard grit sinks into the bronze instead of scoring the shaft; a bush is cheaper to replace than a pin
- Fatigue and compressive strength – 25 N/mm² dynamic pressure for decades of oscillation; brass yields and hammers out
- The right partner for steel – softer than the shaft, harder than the film, thermally forgiving: the classic bearing pair since the industrial revolution
When brass makes sense
Why use brass instead of bronze? For:
- Low-load, low-speed guides and spacers where the part locates rather than carries – door hardware, instrument pivots, furniture, light linkages
- Drinking-water and sanitary fittings – lead-free DZR brasses are approved and cheap; a bearing bronze is not needed
- Electrical and decorative parts – conductivity, colour, plating
- Cost-driven small turned parts in volume – free-machining brass turns twice as fast as bearing bronze
The exception: high-strength brass C86300
C86300 / SAE 430B (CuZn25Al5Mn4Fe3, EN CC762S) is a brass by composition – 25 % zinc – but nothing like the machining brasses: aluminium, iron and manganese raise it to 760 MPa tensile, 415 MPa yield and 225 HB, the highest of all cast copper alloys. It is the bushing for the heaviest shock loads – excavator boom pins, crusher and press bushes, rolling-mill and crane pivots – on a hardened, ground shaft with EP grease, and we machine it to drawing like the bronzes. Do not confuse it with "brass bushings" turned from C36000 bar.
Disadvantages of bronze
Honest points against bronze bushes:
- They need lubrication – grease or oil, grooves and a relubrication schedule; self-lubricating types are other constructions
- Price follows the copper and tin markets and the part is heavy (8.9 g/cm³) – a large bush is priced by the kilogram
- Speed limit around 0.5 m/s with grease (more with oil) – above that a rolling bearing or metal-polymer bush
- A soft bronze wears instead of the shaft – that is the design intent, but the bush is a wear part and will be replaced
Frequently asked questions
Is bronze or brass better for bushings?
Bronze, for any bushing that carries load: higher strength, seizure resistance, embeddability and standardised bearing grades (C93200, CuSn12, C95400). Ordinary brass only for light guides, water fittings and decoration. High-strength brass C86300 is the exception – the strongest bushing alloy for shock loads.
Can I replace a brass bushing with bronze?
Usually yes, in the same dimensions: C93200 for general duty, LG2 for water. Check the running clearance (bronze expands like brass, no change needed) and the shaft – a soft steel shaft is fine for 660 and LG2, but tin bronze or aluminium bronze want it hardened. The bronze bush will outlast the brass one several times.
Are brass bushings self-lubricating?
No, and neither are cast bronze bushings; both need grease or oil. Self-lubricating bushes are sintered oil-impregnated bronze, graphite-plugged bronze or metal-polymer types.
What is the HS code for bronze bushings?
8483.30 (plain shaft bearings / bearing housings without rolling bearings) for machinery bushings; EU CN 8483 30 80, US HTS 8483.30.80. Some customs offices classify pure turned rings as 7419 copper articles – see the FAQ page.
Replacing a brass bushing with bronze?
Send the three dimensions and the shaft material – we suggest the grade and quote in 12 hours.