Tribological Performance Comparison of Lubricating Greases for Electric Vehicle Bearings
EV motors and machine elements operate at higher speeds, generate significant heat and noise (vibration), and subject lubricants (bearings) to multiple degrading factors, requiring thermal stability, wear protection, mitigating wear mechanisms like pitting and scuffing, and low electrical conductivi...
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| Language: | English |
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MDPI AG
2025-03-01
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| Series: | Lubricants |
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| Online Access: | https://www.mdpi.com/2075-4442/13/3/108 |
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| author | Deepika Shekhawat Ayush Jain Nitesh Vashishtha Arendra Pal Singh Rahul Kumar |
| author_facet | Deepika Shekhawat Ayush Jain Nitesh Vashishtha Arendra Pal Singh Rahul Kumar |
| author_sort | Deepika Shekhawat |
| collection | DOAJ |
| description | EV motors and machine elements operate at higher speeds, generate significant heat and noise (vibration), and subject lubricants (bearings) to multiple degrading factors, requiring thermal stability, wear protection, mitigating wear mechanisms like pitting and scuffing, and low electrical conductivity to prevent arcing damage to bearings. This study evaluates the tribological performance of four types of greases—PUEs, PUPao, PUEth (polyurea-based), and LiPAO (lithium–calcium complex-based)—to determine their suitability for electric motor bearings. Key performance metrics include tribological properties, electrical resistivity, leakage, bearing noise, and wear behavior. A four-ball wear test ranks the greases by scar diameter as PUPao < PUEs < PUEth < LiPAO, while the coefficient of friction is observed in the range of 0.15–0.18, with LiPAO exhibiting the lowest friction. Electrical resistivity tests reveal that PUEs grease has the lowest resistivity. Electrical leakage tests, conducted with a voltage differential across bearings, assess pitting damage, with PUEth and LiPAO showing evidence of surface pitting. Optical microscopy and scanning electron microscopy analysis is carried out to examine the pitting. In bearing noise tests, PUEs demonstrates the lowest noise levels, whereas LiPAO produces the highest. Visual and microscopic examination of the greases further characterizes their lubricating properties. Based on overall performance, the greases are ranked in suitability for electric motor applications as PUEs > PUPao > PUEth > LiPAO. The findings highlight the critical need for selecting appropriate grease formulations to ensure optimal bearing performance under varying operational conditions. |
| format | Article |
| id | doaj-art-b1fe6b097a2d49b3b9147f407901aff4 |
| institution | OA Journals |
| issn | 2075-4442 |
| language | English |
| publishDate | 2025-03-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Lubricants |
| spelling | doaj-art-b1fe6b097a2d49b3b9147f407901aff42025-08-20T02:11:26ZengMDPI AGLubricants2075-44422025-03-0113310810.3390/lubricants13030108Tribological Performance Comparison of Lubricating Greases for Electric Vehicle BearingsDeepika Shekhawat0Ayush Jain1Nitesh Vashishtha2Arendra Pal Singh3Rahul Kumar4Tribology Laboratory, Research and Development, National Engineering Industries Ltd., Jaipur 302006, Rajasthan, IndiaTribology Laboratory, Research and Development, National Engineering Industries Ltd., Jaipur 302006, Rajasthan, IndiaTribology Laboratory, Research and Development, National Engineering Industries Ltd., Jaipur 302006, Rajasthan, IndiaTribology Laboratory, Research and Development, National Engineering Industries Ltd., Jaipur 302006, Rajasthan, IndiaLaboratory for Tribology and Interface Nanotechnology, University of Ljubljana, Askerceva 6, SI-1000 Ljubljana, SloveniaEV motors and machine elements operate at higher speeds, generate significant heat and noise (vibration), and subject lubricants (bearings) to multiple degrading factors, requiring thermal stability, wear protection, mitigating wear mechanisms like pitting and scuffing, and low electrical conductivity to prevent arcing damage to bearings. This study evaluates the tribological performance of four types of greases—PUEs, PUPao, PUEth (polyurea-based), and LiPAO (lithium–calcium complex-based)—to determine their suitability for electric motor bearings. Key performance metrics include tribological properties, electrical resistivity, leakage, bearing noise, and wear behavior. A four-ball wear test ranks the greases by scar diameter as PUPao < PUEs < PUEth < LiPAO, while the coefficient of friction is observed in the range of 0.15–0.18, with LiPAO exhibiting the lowest friction. Electrical resistivity tests reveal that PUEs grease has the lowest resistivity. Electrical leakage tests, conducted with a voltage differential across bearings, assess pitting damage, with PUEth and LiPAO showing evidence of surface pitting. Optical microscopy and scanning electron microscopy analysis is carried out to examine the pitting. In bearing noise tests, PUEs demonstrates the lowest noise levels, whereas LiPAO produces the highest. Visual and microscopic examination of the greases further characterizes their lubricating properties. Based on overall performance, the greases are ranked in suitability for electric motor applications as PUEs > PUPao > PUEth > LiPAO. The findings highlight the critical need for selecting appropriate grease formulations to ensure optimal bearing performance under varying operational conditions.https://www.mdpi.com/2075-4442/13/3/108EV tribologylubricantfrictionresistivityelectrical leakagebearing noise |
| spellingShingle | Deepika Shekhawat Ayush Jain Nitesh Vashishtha Arendra Pal Singh Rahul Kumar Tribological Performance Comparison of Lubricating Greases for Electric Vehicle Bearings Lubricants EV tribology lubricant friction resistivity electrical leakage bearing noise |
| title | Tribological Performance Comparison of Lubricating Greases for Electric Vehicle Bearings |
| title_full | Tribological Performance Comparison of Lubricating Greases for Electric Vehicle Bearings |
| title_fullStr | Tribological Performance Comparison of Lubricating Greases for Electric Vehicle Bearings |
| title_full_unstemmed | Tribological Performance Comparison of Lubricating Greases for Electric Vehicle Bearings |
| title_short | Tribological Performance Comparison of Lubricating Greases for Electric Vehicle Bearings |
| title_sort | tribological performance comparison of lubricating greases for electric vehicle bearings |
| topic | EV tribology lubricant friction resistivity electrical leakage bearing noise |
| url | https://www.mdpi.com/2075-4442/13/3/108 |
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