EV Motor Bearing Grease —
Polyurea NLGI 2 BOM & Recipe
EV traction motor + reduction gearbox bearings need polyurea grease for: sealed-for-life service (no maintenance access), 10,000-20,000 RPM operation, electric current management (VFD bearing arcing prevention), wide temperature window. Serving EV programmes worldwide — across India, the Middle East, Africa, Asia, Europe and beyond — with India's own EV market growing 25-40%/year (Tata Nexon EV / Mahindra / MG / Hyundai factory-fill). This guide gives the polyurea NLGI 2 BOM, conductive vs insulating decision, and global and Indian sourcing.
Working EV Motor Grease
Polyurea NLGI 2 BOM & %
| Component group | Typical role | Typical share |
|---|---|---|
| Base oil(s) | Carrier fluid (mineral / synthetic / bio) | ~75–90% |
| Thickener / soap system | Builds structure & consistency (NLGI grade) | ~8–15% |
| EP / anti-wear additive package | Load-carrying & wear protection | ~2–6% |
| Antioxidant, corrosion inhibitor, tackifier | Service life, rust protection, adhesion | balance |
Indicative high-level composition only. The exact components, treat rates, performance additives and approved suppliers are shared under NDA as part of a Lubechem formulation engagement.
Process: in-situ polyurea synthesis — charge PAO base + ester at 80 °C; add diisocyanate (MDI / TDI) and mixed amine slowly with high agitation; exothermic reaction at 150-180 °C forms diurea / triurea thickener in-situ; cool to 90 °C and add polyurea-compatible EP (low-active-S only) + AW + AO + CI + tackifier + conductive carbon black; mill to NLGI 2. QC: drop >260 °C, penetration 270-285, 4-ball weld 315 kgf, D942 oxidation <5 kPa @ 100 hr, 15,000 RPM bearing life >10,000 hr (R0F / FE9 test). Ex-works cost ₹340-480 / kg at 5 MT batch. CRITICAL: polyurea is amine-sensitive — ZDDP and EP must be polyurea-compatible grades. The AW / EP / AO chemistry here is supplied as a ready grease additive package, and every batch is released against the full ASTM lubricant and grease testing panel listed above.
Frequently Asked About
EV Motor Bearing Grease
EV traction motor and reduction gearbox bearings face unique demands: (1) Very high RPM — modern EV motor runs 10,000-20,000 RPM. (2) Sealed-for-life requirement. (3) Electric current passage — VFD-driven AC motor creates bearing current that can cause electric arc damage (EDM pitting). (4) Wide temperature window.
Polyurea NLGI 2 grease meets all four — drop >260 °C, sealed-for-life capability, exceptional oxidation life (10+ years), and conductive (or insulating) variants for current management. Tata, Mahindra, MG, Hyundai EV factory-fill polyurea.
EV polyurea NLGI 2 BOM (%): PAO 6 cSt 60%, ester (TMP-trioleate) 14%, diisocyanate (MDI / TDI) 7%, mixed amine (octylamine + di-aniline) 7%, MoDTC 0.5%, mixed ZDDP low treat 0.5%, sulphurised olefin EP low-S 1.5%, methylene-bis-DTBP phenolic AO 1%, alkylated DPA aminic AO 1%, ASA + TTA CI 0.5%, Ca nitrite 0.5%, PIB tackifier 0.3%, carbon black (conductive) 0.3%, balance PAO diluent.
Process: in-situ polyurea synthesis at 150-180 °C; cool to 90 °C and add additives; mill to NLGI 2. Drop >260 °C, 4-ball weld 315 kgf, 15,000 RPM life >10,000 hr.
Two strategies for VFD bearing current: (1) CONDUCTIVE grease — carbon black or specialty conductive additive at 0.5-2% gives grease low resistivity. Current flows through grease without arcing. (2) INSULATING grease — standard polyurea, NO conductive additive. Combined with insulated (ceramic-coated) bearings on one motor end to break the current path.
OEM design dictates which grease. India EV: Tata Nexon / Punch EV use insulating + ceramic-coated bearing; Mahindra XUV400 uses conductive throughout. Aftermarket must match OEM-specified type.
Different. ICE wheel bearing grease (lithium complex NLGI 2 GC-LB) lubricates hub bearing at 1,000-2,000 RPM, 80-150 °C. EV motor bearing grease (polyurea NLGI 2) lubricates traction motor bearing at 10,000-20,000 RPM, 80-130 °C, with sealed-for-life and current management.
Same NLGI 2 consistency but different chemistry. EV reduction gearbox uses similar polyurea for planetary gear bearings. DON'T substitute ICE wheel bearing grease in EV motor — wrong soap, wrong noise, wrong current, early bearing failure. The same high-speed sealed-bearing logic also drives our wind turbine bearing grease design.
India EV ~3-5% of new vehicle sales 2024. Volume: Tata Nexon EV / Punch EV / Tiago EV, Mahindra XUV400 / BE 6e / XEV 9e, MG ZS EV / Comet, Hyundai Kona EV / Ioniq 5, Maruti upcoming EVs. Plus 3W (Mahindra Treo, Bajaj RE Etec) and 2W (Ola, Ather, TVS iQube).
EV motor grease ~80-200 g per vehicle factory-fill; aftermarket replacement minimal (sealed-for-life). India EV grease ~100-300 MT/year, growing 25-40%/year. OEM-licensed Klueber Asonic, Mobil SHC Polyrex, Castrol Polyurea EV, Shell Gadus PU. Lubechem custom (LC-EV-PU-NLGI2) ex-works ₹340-480 / kg. Producers entering this segment should review the grease plant setup cost for an in-situ polyurea line.
VFD electrical inverters in EV motors generate high-frequency voltage spikes that pass through bearing oil film as electric current. When current density exceeds ~1 A/mm², a micro-arc discharge occurs at rolling-element / race contact — like EDM spark. Micro-arc removes microscopic material from bearing race, leaving 'frosting' or 'fluting' (washboard waves). Bearing fails in 5,000-10,000 hr.
Two prevention strategies: insulated bearing on one end (ceramic-coated balls / polymer cage) breaks current path; OR conductive grease provides low-resistance path avoiding arcing. EV OEM design uses one or both; grease must support the chosen strategy.
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