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. India 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 Indian sourcing.
| Component | Function | % (m/m) | Indian Supplier |
|---|---|---|---|
| PAO 6 cSt synthetic base oil | Primary synthetic base, thermal + oxidation | 60.0% | INEOS Durasyn / SpectraSyn |
| Ester (TMP-trioleate, secondary base) | Additive solvency + boundary lubricity | 14.0% | Croda Priolube |
| Diisocyanate (MDI / TDI) | Polyurea synthesis reactant | 7.0% | Specialty isocyanate suppliers |
| Mixed amine (octylamine + di-aniline) | Polyurea synthesis — forms di / triurea | 7.0% | Specialty amine suppliers |
| MoDTC FM | Friction modifier + AW | 0.5% | Vanderbilt Vanlube 829 |
| Mixed ZDDP AW (low treat) | Anti-wear (low treat for polyurea-compat) | 0.5% | Lubrizol / LC-AW-ZDDP |
| Sulphurised olefin EP (low-active S) | EP (polyurea-safe low-S version) | 1.5% | Lubrizol Anglamol low-S |
| Methylene-bis-DTBP phenolic AO | Low-volatility primary AO | 1.0% | Albemarle Ethanox 4710 |
| Alkylated DPA aminic AO | High-temp secondary AO | 1.0% | LANXESS Naugalube 438L |
| ASA + TTA CI | Ferrous + yellow-metal CI | 0.5% | King K-Corr + Cobratec |
| Calcium nitrite | Vapour-phase rust | 0.5% | Indian inorganic |
| PIB tackifier (Mn 1300) | Adhesion to bearing race | 0.3% | BASF Glissopal |
| Carbon black (conductive variant) OR insulating dye | Current path for VFD bearing protection | 0.3% | Conductive carbon black |
| PAO 4 cSt diluent | Consistency fine-tune | 5.9% | INEOS Durasyn |
| TOTAL | 100.0% | — | |
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.
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 grease in EV motor — wrong soap, wrong noise, wrong current, early bearing failure.
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.
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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