When the world’s leading automotive manufacturers unveiled their latest models this year, it was clear that the look of luxury was changing. Post-recession era consumers are demanding smaller and less luxurious vehicles while prioritizing quality features and comfort.
Read: What’s Driving the Future of the Automotive Industry?
This trend seems in keeping with findings from the 2012 Car-Brand Perception Survey conducted by the Consumer Reports National Research Centre. According to the report, when consumers were asked what factor topped their considerations in car selection, they ranked quality second only to safety. Amid this trend, more mass-market brands are offering high-end features that deliver value and performance by incorporating high-quality materials.
So, what constitutes quality? A vehicle’s quality is equal to the sum of its parts. In some cases, those parts are small and often go unnoticed by consumers. Such is the case with bearings. Bearings are necessary components in automotive design and are used in a range of applications throughout a vehicle, from the powertrain to the car interior.
But regardless of where they’re used, the right component can make a big difference to performance while ensuring a smooth, comfortable ride – the trademark of any high-quality vehicle. To achieve this, suppliers and automotive manufacturers must select the correct bearing solution for their application and technology.
Following is a breakdown of factors that system suppliers and automotive manufacturers should consider when determining the ideal bearings for their needs.
Seat Mechanisms
Bearings are used in seat mechanisms, enabling them to be adjusted by the driver or passenger for comfort. When selecting bearings for these applications, it is important to consider the friction control offered by the bearing for high-quality performance, as well as its robustness and weight.
With a self-lubricating polytetrafluoroethylene (PTFE) liner, composite bearings offer consistent friction control for the mechanism’s long life with no need to replenish oil or grease. Composite bearings can be fitted with different lightweight and/or high-strength materials that result in a slimmer, lighter component that contributes to overall weight reduction efforts and the smart design of the vehicle. Manufacturers can also install them quickly thanks to the split-ring design as they can be compressed into place with no adhesives or extra tools required.
Composite bearings can be adapted when customisation is needed. Composite bearings designed with a PTFE liner absorb excess vibration in the mechanism to eliminate rattling for a noise-free driving experience at higher speeds and when encountering adverse road conditions.
The PTFE liner also compensates for the manufacturing tolerances of the mating components, ensuring quality mechanism performance.
Other types of bearings for this application include plastic bushings. While they are also designed to facilitate movement between the shaft and housing of the seat mechanism, they have a stiff inner surface which cannot absorb excess vibration as the PTFE liner of composite bearings does.
This can lead to rattling, vibration and harshness as the car travels over rough terrain, impacting the end user’s perception of car quality. Plastic bushings are also more sensitive to fluctuations in ambient temperature, which can result in more noise and vibration over time if the material expands. They are not as robust as metal-backed composite bearings, limiting their use to seat mechanisms designed to support lighter loads.
Belt Tensioner
The belt tensioner, featuring a bearing in the pivot point, maintains tension in the timing or accessory belt by allowing small, high-frequency oscillating movement that ensures each component driven by the belt operates in synchronicity for optimum engine performance. The mechanism must be able to react quickly when needed to prevent any loosening of the belt, which can damage the engine.
Bearings used in belt tensioners must carry high loads and tolerate high temperatures. They must also maintain the right level of friction for dampening and be wear- and corrosion-resistant to ensure the mechanism’s durability.
A composite bearing will add value in this application. Composite bearings’ high-strength, robust laminated metal backing as well as their unique wear-resistant filler compounds within the PTFE liners allow them to withstand the high temperatures and stresses in the belt tensioner application.
In addition, composite bearings’ ability to provide consistent, controlled friction enables it to maintain a certain dampening in the tensioner for optimum performance. The unique PTFE liner acts as a cushion that absorbs vibrations from moving parts and facilitating the mechanism’s long life.
Steering Yoke
At the interface between the steering rack and the steering column sits the steering yoke. This component requires a bearing to ensure smooth movement of the steering rack for quick, responsive handling of the car.
Used in the steering yoke, composite bearings offer consistent low friction, enhancing steering response and feel for the motorist. The PTFE liner, in combination with the yoke contact pattern, enables the rack shaft load to be spread over the widest possible area, allowing for consistent steering feel over the system’s long life.
Plastic bushings can also be found in steering yokes. However, higher friction values compared to the PTFE composite bearings can result in early wear and tear and, ultimately, poorer steering response over time.
Door Hinge
In doors, bearings sit between the hinge pin and housing to ensure smooth movement when the door is opened and closed. Bearings also play an important role in the assembly process, when the hinge must hold the door open while the car body is painted. Automotive manufacturers have specific torque requirements on the production line to ensure that doors do not close while the car is painted.
The PTFE composite bearings are sizable to ensure sufficient torque level to hold the door ajar. In addition, the conductive properties of composite bearings enable the use of an electrostatic painting process on the automotive manufacturer’s line. In this instance, the composite bearing allows the transfer of electricity through the hinge during the painting process so the door is properly painted.
As opposed to the plain bearing, composite bearings’ PTFE liner also compensates for any misalignment of the door and frame during assembly, providing a consistent gap between the door and car body for ensuring smooth movement.
When the vehicle is in use, the PTFE liner within the composite bearing compensates for tolerance variations, such as thermal expansion, ensuring the perfect fit between the hinge pin and the housing. This minimises the risk of the door squeaking when opened or closed throughout the car’s life cycle.
In this application, PTFE composite bearings also improve corrosion resistance, boosting brand loyalty. With their self-lubricating properties, composite bearings do not require grease to ensure smooth hinge movement when the door is opened, thus further enhancing the quality perception of the vehicle.
Small Parts, Big Difference
Bearings are a vital component in automobiles that can boost comfort and consumer perception of quality. Though a small component, the bearing must be capable of withstanding projected stresses, interact well with other materials in the application and be able to tolerate exposure to external conditions. They must undergo rigorous testing to ensure that they enhance performance of the mechanism and of the vehicle as a whole.
The right bearing supplier will provide robust testing as well as the customisation necessary to ensure the component meets the automobile manufacturer’s needs. Extensive testing coupled with the right materials and design will enhance the consumer experience with the car and help strengthen brand loyalty.
Contributing authors include Mirko Hundertmark, Global Market Manager, Automotive Interior, Hans-Jürgen Jäger, Global Market Manager, Automotive Exterior & Chris Needes, Global Market Manager, Automotive Chassis and Powertrain, NORGLIDE Bearings and RENCOL Tolerance Rings, Saint-Gobain.
