Bronze is the material you choose when the shaft is already worn and the fluid has grit in it: it conforms, embeds the grit and wears instead of spalling. Pumps & Compressors duty is continuous running, thrust reversal and process fluid along the shaft; the material is what decides whether the bearing survives it.
| Industry duty | continuous radial load plus axial thrust that reverses on start-up |
|---|---|
| Typical media | water, process fluid, washdown, solvent |
| Housing temperature | −20 to +150 °C |
| Material and grade | cast bronze (CuSn6 / C93200) |
| Hardness | 60–80 HB |
| Temperature ceiling | 250 °C |
| Corrosion / chemical | water and seawater; needs grease or graphite plugs |
| Relative cost | ≈1.5× of a standard 52100 bearing |
Rolling bearings need clean lubricant and a stiff housing. A sump pump has neither: the shaft is long, the fluid carries grit and the maintenance interval is set by the process, not the bearing. Bronze works because it is soft enough to embed a particle instead of spalling on it, and because a worn shaft can be re-used with the next bush — the bush is the wear part by design.
| Position | Bearing type | Material / finish | Why it works there |
|---|---|---|---|
| Sump pump lower bearing | CuSn6 bush | Bronze bush, grease or graphite plugged | Runs submerged with grit; bronze embeds particles instead of spalling. |
| Slurry pump shaft sleeve | C93200 bush | Leaded bronze bush | Conforms under misalignment from a worn shaft. |
| Line shaft bearing | Bronze bush | Bronze bush, water lubricated | Water-lubricated at low PV; no grease to wash away. |
| Vertical pump thrust collar | Thrust | Bronze washer or plate | Carries rotor weight on a flat face at low speed. |
| Material | Fit here | Choose it when |
|---|---|---|
| Bronze | Best fit | Dirty fluid, low speed, worn or misaligned shafts. |
| 316 | Workable alternative | Clean fluid and higher speed — a rolling bearing with stainless rings. |
| POM | Workable alternative | Non-metallic option at low load and chemical duty, but it creeps under a steady shaft load. |
Because the lubricant cannot stay clean. Grit in a raceway spalls it in weeks, while the same grit in a bronze bush is embedded and the bush keeps running.
Only with graphite plugs, and only at low PV. Plain bronze without a film will pick up on the shaft.
Yes, but aluminium bronze or a nickel-aluminium-bronze is better than tin bronze for continuous seawater service.
Hardness, temperature, corrosion and equivalents for cast bronze.
Read →Typical duty, recommended types and suffixes for pumps.
Read →Standard process pumps — impeller and seal-side positions in ISO and ANSI process pumps.
Read →Washdown & food pumps — food, beverage and CIP-washdown pumps where water reaches the bearing housing.
Read →Send the position, bore size, quantity and the medium it sees. We reply with the material certificate, clearance class, lubricant and price within 30 minutes on working days.