Grease quantity chart by frame size
These quantities are per bearing (drive end and non-drive end may differ by frame size — DE bearings are typically larger). Quantities are in grams — use a grease gun with a graduated barrel or weigh with a postal scale.
| IEC Frame | NEMA Frame equiv. | Typical power (kW) | DE bearing | Grease (g) DE | NDE bearing | Grease (g) NDE |
|---|---|---|---|---|---|---|
| 63–71 | 42–48 | 0.09–0.25 | 6202 | 1–2 | 6201 | 1 |
| 80 | 56 | 0.37–0.75 | 6204 | 2–4 | 6203 | 2 |
| 90 | 63 | 0.75–1.5 | 6205 | 4–6 | 6204 | 3 |
| 100 | 63–72 | 1.5–3.0 | 6206 | 5–8 | 6205 | 4 |
| 112 | 143–145T | 2.2–5.5 | 6207 | 7–10 | 6206 | 5 |
| 132 | 182–184T | 4.0–11 | 6208 | 9–13 | 6207 | 7 |
| 160 | 213–215T | 7.5–18.5 | 6309 | 13–18 | 6308 | 10 |
| 180 | 254–256T | 11–30 | 6310 | 15–22 | 6309 | 13 |
| 200 | 284–286T | 18.5–37 | 6312 | 18–26 | 6311 | 15 |
| 225 | 324–326T | 30–55 | 6314 | 22–32 | 6312 | 18 |
| 250 | 364–365T | 45–90 | 6316 | 28–40 | 6314 | 22 |
| 280 | 404–405T | 75–132 | 6319 | 35–50 | 6316 | 28 |
| 315 | 444–445T | 110–200 | 6320 | 45–65 | 6319 | 35 |
Note: Always verify bearing designation on the motor nameplate or lubrication plate. Formula: Grease quantity (g) = 0.005 × D × B, where D = bearing bore (mm), B = bearing width (mm). Add in increments of 1/3 of the total quantity.
Relubrication interval table
Intervals assume standard horizontal mounting, ambient temperature ≤25°C, clean environment, and standard loading. Reduce intervals by 50% for: high ambient temperature, vertical mounting, high humidity, dusty/wet environment, or continuous heavy load.
| Motor speed (RPM) | IEC 63–112 (hrs) | IEC 132–200 (hrs) | IEC 225–280 (hrs) | IEC 315+ (hrs) |
|---|---|---|---|---|
| 750 | 10,000 | 8,000 | 6,000 | 4,000 |
| 1,000 | 8,000 | 6,000 | 4,000 | 3,000 |
| 1,500 | 6,000 | 4,000 | 3,000 | 2,000 |
| 3,000 | 3,000 | 2,000 | 1,500 | 1,000 |
| Continuous >3,000 | 2,000 | 1,500 | 1,000 | 750 |
At 24 hrs/day, 365 days/year continuous operation: 1,500 RPM frame 132 motor = 4,000 hrs ÷ 8,760 hrs/year = every ~5.5 months. Always convert to calendar months for your PM schedule.
Grease selection for electric motors
The grease specified in the motor manual must be followed. If the manual is unavailable, the following rules apply for most industrial electric motors:
| Property | Recommendation | Why |
|---|---|---|
| Thickener | Polyurea (preferred) or lithium complex | Polyurea has excellent high-temperature stability, compatibility with motor winding materials, and long service life. SKF LGEM 2, Shell Gadus S5 V142 2, and Mobil Polyrex EM are widely used. |
| NLGI grade | Grade 2 | Correct consistency for most bearing temperatures and speeds |
| Base oil viscosity | 100–130 cSt at 40°C | Appropriate for motor bearing speed range (NDm typically 50,000–300,000 mm·rpm) |
| Temperature rating | -20°C to +130°C minimum | Motor bearing temperatures can reach 90–110°C at rated load |
| Additives | Anti-oxidant, anti-rust, anti-wear | Corrosion resistance is especially important for intermittent-duty motors |
Do not mix greases of different thickener types. Polyurea and lithium greases are generally incompatible — the mixed product can soften significantly, resulting in the grease running out of the bearing. If changing grease type, purge the bearing housing completely of old grease first. See our grease compatibility guide.
Greasing procedure
- Check motor is isolated before removing the grease nipple cover — if greasing with the motor running, ensure hands and grease gun are clear of rotating parts.
- Clean the grease nipple with a clean cloth — never inject grease through a dirty nipple.
- Open the drain/relief plug (if fitted) — this allows old grease to escape as new grease is added. Without a drain plug, grease will pressurise the bearing housing.
- Connect the grease gun to the nipple. Pump slowly — one stroke at a time, waiting a few seconds between strokes.
- Add the correct quantity from the chart above. Count grease gun strokes (calibrate your gun — a standard grease gun typically delivers 1–1.5 g per stroke for NLGI 2).
- If greasing with the motor running: Add grease slowly until old grease is seen at the drain plug, then stop. Let the motor run for 30–60 minutes to allow excess grease to be expelled before replacing the drain plug.
- Replace the drain plug and nipple cap. Record date, motor ID, and grease quantity in CMMS.
Signs of over-greasing
- Bearing temperature rises sharply after greasing — usually peaks within 1–2 hours, then drops as excess grease is expelled
- Grease purging from shaft seals (reddish-brown smear on the shaft)
- Grease contaminating motor windings via the inner seal — visible as brown staining on winding insulation
- Bearing vibration increase after greasing (over-filled housing causes turbulence)
- Repeated premature bearing failures with heat discolouration on bearing rings
If you see temperature rise after greasing, do not add more grease assuming it is insufficient — this is the classic over-greasing mistake. Allow the motor to run and the temperature to normalise before making any decision.
FAQs
Yes — and it is the most common cause of premature electric motor bearing failure in well-maintained plants. Excess grease in the bearing housing cannot escape; the rolling elements churn through it, generating heat. Temperatures can rise 20–40°C above normal within an hour of over-greasing. This degrades the lubricant, softens the grease, and eventually causes bearing failure through lubricant film collapse or heat damage to the cage.
Calibrate your grease gun: pump 10 strokes into a container and weigh. Divide total weight by 10 to get grams per stroke. Standard lever-action grease guns deliver approximately 1.0–1.5 g per stroke. A cartridge gun typically delivers 1.0 g per stroke. A high-pressure pistol grip gun can deliver 2–3 g per stroke. Once calibrated, calculate required strokes = required grams ÷ grams per stroke.
Sealed bearings (2RS or ZZ designation — double lip seal or shield) are pre-packed with grease at the factory and are not designed to be re-greased. They do not have grease nipples. Replace sealed bearings at or before the manufacturer's stated service life. Open bearings in motors equipped with grease nipples can and should be re-greased per the intervals in this guide.