In a washdown plant the motor bearing is usually replaced because it rusted, not because it wore out — which makes 440C a maintenance decision rather than a metallurgical one. Electric Motors & Drives duty is continuous speed, long grease life and shaft voltages from PWM drives; the material is what decides whether the bearing survives it.
| Industry duty | 1,500–6,000 rpm continuous, up to 20,000 rpm on servo drives |
|---|---|
| Typical media | cooling air, dust, occasional washdown |
| Housing temperature | −20 to +120 °C |
| Material and grade | 440C martensitic stainless steel |
| Hardness | 58–60 HRC |
| Temperature ceiling | 250 °C |
| Corrosion / chemical | fresh water, food and mild chemicals; pits in chlorides |
| Relative cost | ≈3× of a standard 52100 bearing |
A food plant washes with 60–80 °C water and caustic, sometimes with a chlorine sanitiser, and the motor sits in the splash zone. 52100 forms a rust film on the raceway overnight, and that film is abrasive: the bearing then fails by wear rather than fatigue, usually within a quarter. 440C is martensitic, so it can still be hardened to 58–60 HRC and ground to a motor-grade finish — it buys corrosion resistance without giving up the load rating the way 316 does.
| Position | Bearing type | Material / finish | Why it works there |
|---|---|---|---|
| Drive end, washdown motor | Deep groove ball | 440C, C3, 2RS with NSF H1 grease | The seal keeps the wash out; 440C survives the film that gets past the lip. |
| Non-drive end | Deep groove ball | 440C, C3, 2RS | Floating position; the same material avoids the rust ring that would seize the outer ring in the housing. |
| Gear reducer input | Tapered roller | 440C on request, or 52100 with zinc-nickel | Where load is high and the wash is intermittent, coated 52100 is the cheaper compromise. |
| Material | Fit here | Choose it when |
|---|---|---|
| 440C | Best fit | Fresh-water and caustic wash with a food-grade grease. The standard upgrade. |
| 316 | Workable alternative | Hypochlorite or brine wash: 440C pits, 316 does not, at roughly half the load rating. |
| 100Cr6 / 52100 | Workable alternative | Wipe-down cleaning only — a zinc-nickel coated ring survives splashes at a third of the price. |
It is rust-resistant, not rust-proof. Fresh water and caustic are fine; chlorine sanitiser and brine pit it. The distinction matters because a pitted raceway fails suddenly, while a rusted one usually gives warning.
No. The grease does not protect the raceway once water passes the seal. Coating the outer ring helps with the housing seat but leaves the races exposed.
About three times the bearing price. On a motor that takes two hours of production downtime to change, that is usually the cheaper option by a wide margin.
Hardness, temperature, corrosion and equivalents for 440C stainless.
Read →Typical duty, recommended types and suffixes for electric motors.
Read →Standard duty — shaft ends and bearing housings in induction motors from 0.75 to 200 kW.
Read →VFD & high speed — VFD-driven motors and high-speed servo spindles where shaft voltage erodes the raceway.
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.