Below about 50 rpm a rolling bearing is running on boundary lubrication anyway, so a bronze bush with a grease nipple can outlast it for less money. Conveyors & Bulk Handling duty is slow speed, abrasive dust and frame misalignment; the material is what decides whether the bearing survives it.
| Industry duty | slow rotation under steady belt pull, with abrasive dust at the load point |
|---|---|
| Typical media | abrasive dust, fines, washdown water |
| Housing temperature | −20 to +90 °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 |
At 20 rpm and 30 kN, a rolling bearing is not doing what it was designed for: the rollers never build a film, and shock loads brinell the raceway. A bronze bush is happier there, because it works by conforming rather than rolling, and its wear is gradual and visible. It also tolerates the misalignment a welded trough produces.
| Position | Bearing type | Material / finish | Why it works there |
|---|---|---|---|
| Screw conveyor hanger bearing | CuSn6 bush | Bronze bush, graphite plugged | Runs in the material stream; graphite keeps it alive when grease is forgotten. |
| Slow drum shaft | Bronze bush | Bronze bush with a grease groove | Conforms to a worn shaft instead of spalling. |
| Take-up slide | Bronze wear plate | Bronze wear plate | Sliding contact under a steady load. |
| Material | Fit here | Choose it when |
|---|---|---|
| Bronze | Best fit | Below 50 rpm with heavy load, dirt and limited access. |
| 100Cr6 / 52100 | Workable alternative | Above 50 rpm, where the rolling bearing wins on friction and life. |
| POM | Workable alternative | Clean, light duty where no lubrication is possible. |
Because the rolling bearing cannot form a lubricant film at that speed and brinells under shock, while the bush works by conforming and wearing gradually.
It depends on the PV and the dirt, but a hanger bearing in a screw conveyor usually needs it weekly. Graphite-plugged grades extend that considerably.
Yes, and water is a better lubricant for bronze than most people expect, provided the water is clean.
Hardness, temperature, corrosion and equivalents for cast bronze.
Read →Typical duty, recommended types and suffixes for conveyors.
Read →Head & tail pulleys — head and tail pulley bearings and idler positions in bulk handling.
Read →Washdown food conveyors — food-grade conveyors cleaned with water and caustic every shift.
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.