With the steady demand for electrified equipment and EV (Electric Vehicle) platforms, engineers are being forced to rethink their bearing designs. More specifically, traditional metal bearings involve serious challenges in high-voltage environments, including vulnerability to electrical erosion, heavy weight, and the need for constant lubrication. However, engineered-grade polymer bearings have emerged as a viable replacement, offering unique physical and chemical properties that address challenges posed by battery-powered mobility and high-voltage architectures.
Solutions Addressed by Polymer Bearings in Electrified Equipment
There are four challenges posed by electrified systems that polymer bearings can solve. The first is electrical insulation. Metal bearings carry electricity, while unfilled polymers are non-conductive. This eliminates issues with electrical pitting, fluting, and spark erosion. This eliminates the most common types of damage caused by electrical flow.
Another obvious benefit of polymer bearings is the weight savings. Polymers can be up to 80% lighter than traditional steel and bronze bearings. And in applications such as EV, every bit of weight savings adds up to benefits like improved overall efficiency and extended battery range.
Polymer bearings are going to run more quietly as they absorb shock and dampen vibrations. For EV, this means an NVH (Noise, Vibration, and Harshness) reduction that leads to a quieter, more pleasant ride.
In addition, there are types of polymers that are self-lubricating and allow for dry running. This not only reduces maintenance requirements but also eliminates parasitic drag from lubricant shear and the need for greases that can attract contamination. but enhances bearing reliability.
Polymer bearings are not going to rust, which means they are extremely reliable for situations like exterior chassis components exposed to weather. They also work well for thermal management systems that involve glycol-based coolants and water.
Types of Polymers, Features, and Applications
High-Performance Polymers
There are several top-tier plastics that are used inside or adjacent to electrical drive units. These include PI, PEEK, PPS, and PAI.
Polyimide (PI / Vespel) provides excellent dielectric strength and can withstand massive bearing loads even at extreme temperatures without experiencing creep. PI works best in high-voltage applications that demand maximum insulation. PI bearings work very well for insulating bearing sleeves inside EV traction motors.
PEEK (Polyetheretherketone) is known for its outstanding chemical resistance and high-temperature performance (up to 480°F continuous). PEEK bearings work very well in systems that are continuously exposed to aggressive coolants, fuels, and synthetic fluids, such as thermal management coolant pumps, high-speed actuators, and components submerged in e-axle or automatic transmission fluids.
PPS (Polyphenylene Sulfide) stands out because of its excellent chemical compatibility, low rigidity, low moisture absorption, and excellent thermal stability up to 400°F, as well as being a more cost-effective alternative to PEEK. The best areas for PPS bearings are applications requiring table electrical and mechanical performance under heat and chemical exposure. PPS bearings are often found with under-hood actuators, valves, and plastic over-moldings for deep groove ball bearings in eAxles.
PAI (Polyamide-Imide) is the highest-strength thermoplastic available for bearings. PAI bearings exhibit exceptional thermal resistance (up to 500°F) and extreme compressive strength (up to 1,000 psi). These bearings do their best work in extreme load-bearing environments where mechanical strength cannot be compromised. They are often found in high-temperature turbine environments, compressors, and heavy-duty robotic joints.
Engineering Polyamides
Engineers in search of a balance of cost-effectiveness, toughness, and reduced weight, an engineering Polyamide might be the best option.
PA46 and PA66 (Nylon) are able to resist deformation even at extreme speeds and are usually able to reduce the rotating mass of bearing assemblies. In addition, PA46 and PA66 are ideal for high-speed internal moving parts. In fact, an excellent example of usage would be bearing cages that hold steel or ceramic ball bearings inside EV traction motors spinning up to 30,000 RPM.
Fiber-Reinforced Nylon is another option when it comes to engineering polyamides. Filled solutions involve reinforcement with glass or carbon fibers in order to significantly increase mechanical and structural strength. Fiber-reinforced bearings are excellent for applications that require heavy-duty, load-bearing structural joints. Examples include replacements for the heavier metal bearings found in EV chassis, steering columns, and suspension components.
Low-Friction & Solid Lubricant Polymers
There are a couple of engineering polymers that provide exceptionally low friction and are self-lubricating.
PTFE (Polytetrafluoroethylene / Teflon): PTFE is the lowest-friction engineering material available with near-universal chemical resistance and electrical isolation properties. Because it has poor mechanical strength on its own, PTFE is often compounded with glass, carbon, or bronze fillers to handle loads. PTFE bearings are an excellent choice for low-load, low-to-moderate-speed applications or other operating environments requiring entirely dry operation. This includes Planetary gearsets, cooling pumps, and robotic automation gearboxes.
POM (Polyacetal / Acetal): POM is a valid option for cabins and interior systems where NVH control (eliminating squeaks/rattles) and avoiding messy liquid greases is paramount. It offers high rigidity and very low moisture absorption, and when combined with PTFE, it provides an ultra-smooth, silent glide. POM bearings can be found in EV pedal boxes, seat tracks, hinges, and steering columns.
UHMW-PE (Ultra-High Molecular Weight Polyethylene) offers extreme abrasion resistance and excellent durability, which is ideal for sliding applications that involve high wear. UHMW-PE bearings are commonly used in automated robotic manufacturing equipment for assembling EV battery packs.
| Material | Electrical insulation | Temp. resistance | Load capacity | Chemical resistance | Self-lubricating | Weight savings |
|---|---|---|---|---|---|---|
| High-performance polymers | ||||||
| PI (Vespel) | ★★★★★ | ★★★★☆ | ★★★★☆ | ★★★★☆ | ★☆☆☆☆ | ★★★☆☆ |
| PEEK | ★★★★★ | ★★★★☆ | ★★★☆☆ | ★★★★★ | ★☆☆☆☆ | ★★★☆☆ |
| PPS | ★★★★☆ | ★★★★☆ | ★★★☆☆ | ★★★★☆ | ★☆☆☆☆ | ★★★☆☆ |
| PAI | ★★★★☆ | ★★★★★ | ★★★★★ | ★★★★☆ | ★☆☆☆☆ | ★★★☆☆ |
| Engineering polyamides | ||||||
| PA46/PA66 (Nylon) | ★★★☆☆ | ★★★☆☆ | ★★★☆☆ | ★★☆☆☆ | ★★☆☆☆ | ★★★★☆ |
| Fiber-reinforced nylon | ★★★☆☆ | ★★★☆☆ | ★★★★☆ | ★★☆☆☆ | ★★☆☆☆ | ★★★☆☆ |
| Low-friction & self-lubricating | ||||||
| PTFE (Teflon) | ★★★★★ | ★★★☆☆ | ★★☆☆☆ | ★★★★★ | ★★★★★ | ★★★☆☆ |
| POM (Acetal) | ★★★☆☆ | ★★☆☆☆ | ★★★☆☆ | ★★★☆☆ | ★★★☆☆ | ★★★☆☆ |
| UHMW-PE | ★★☆☆☆ | ★★☆☆☆ | ★★☆☆☆ | ★★★☆☆ | ★★★☆☆ | ★★★★☆ |
Conclusion
Polymer bearings have been proven to be much more than just a lightweight substitute for metal. Polymer bearings in electrified equipment and EV platforms are an active efficiency enabler. And by minimizing friction, managing heat, preventing parasitic electrical erosion, and eliminating liquid lubrication, polymer bearings can significantly extend the lifespan and reliability of electric drivetrains.
As the EV industry rapidly transitions from 400V to 800V architectures, the challenges of electrical discharge and thermal management will double. Highly engineered polymer bearings, especially insulating composites and over-molded solutions, will be critical in maintaining the efficiency, safety, and operational longevity of the next generation of electrified equipment.
If you are looking for a polymer bearing solution for electricfied equipment, the experts at Advanced EMC are waiting to assist in every step from material selection to the final design and after. Contact us today!