Motor Bearing Grease Quantity Calculator

G = 0.005 × D × B grams. The defaults model a 6309 motor bearing (OD 100 mm, width 25 mm → 12.5 g) — measure or look up your bearing's OD and width and the tool recomputes instantly. This is the replenishment charge, not the initial fill (which is 30–50% of the free space for most speeds).

Follow the construction: motors up to ~15 kW usually carry sealed-for-life bearings — never grease, replace at end of life. Larger motors with grease fittings and relief plugs are designed for scheduled regreasing per this rule. The damage happens at the boundary: pumping grease at a sealed bearing's housing (some frames have a fitting anyway) packs the cavity until it breaches the bearing shields or the windings. Check the motor manual once and label the machine accordingly.

The rolling elements churn through excess grease, temperature climbs sharply (often 10–30 °C), the thickener shears down and bleeds oil, and pressure can lip the seals open — after which contaminants walk in. Electric motors suffer the extra failure mode of grease forced into the windings. If you see grease purging from seals and a temperature spike after lubing, you found the cause.

Interval depends on speed factor (n·dm), temperature, load and orientation — use the OEM's table or SKF's relubrication chart as your starting point, then halve it for every 15 °C the bearing runs above 70 °C, for vertical shafts, or for wet/dusty service. Enter that interval here and pair this tool with a bearing-temperature trend to validate it.