Figure 1: (left) An automotive seat frame showing (in red) the location of NORGLIDE® bearings that provide superior comfort due to consistent torque and reduced noise and vibration, (middle and right) magnification of the pivot points on the seat height adjuster and cross-tube where NORGLIDE® bearings can make a big difference to the overall driving experience.
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NORGLIDE® bearings comprise a unique composite (seen in Figure 2) that offers superior vibration damping properties, as can be seen in Figure 3, reducing the level of vibration induced discomfort. With up to 11 pivot points loacated in each seat, manufacturers need to ensure they do all they can to damp vibration and reduce noise indside the cabin at high speeds or on bumpy roads.
Figure 2: Cross-section through the unique NORGLIDE® materials (left - SMTL-type, right - T-type) that will perform consistently throughout the lifetime of the part due to the thick PTFE layer.
With car sharing becoming increasingly popular, seat frames are going to be adjusted more and more to the needs of the driver, sometimes on a daily basis. This creates potential for additional wear on the parts in the seating system and Saint-Gobain engineers place great importance on the parts providing great performance, drive after drive. Figure 4 shows that due to our unique NORGLIDE® materials we are able to maintain the low friction performance for much longer than competing PTFE-based bearings.
There can be a trade-off between having a low-effort seat height adjustment mechanism that rattles due to free play and a quiet mechanism that requires high forces to adjust due to interference. However, the thick PTFE layer exhibited by the unique NORGLIDE® bearings allows for a level of tolerance compensation through-out which our bearings perform consistently when compared to competing solutions. This can be seen in Figure 5 where the torque required to turn a shaft within different bearings was examined for several different shaft diameters.
Saint-Gobain engineers use the power of finite element analysis (FEA) to understand system level problems by fully understanding component level performance and its impact on the complete seat structure. Figure 6shows a pressure analysis performed on both a NORGLIDE® bearing and a competing solution, which in this case is a plastic part. Seat linkages are often made using stamping techniques which often mean a breakout region in the bearing housing cross section that causes line contact on the bearing. So as a person sits on the seat, a force is exerted through the seat height adjuster pivot points which could cause permanent deformation on the bearing through high loads, leading to a possible failure mode. However, with our unique NORGLIDE® bearings, comprising a strong metal backing layer and a thick PTFE layer, the external forces are spread out, reducing the pressure exerted onto the sliding surface of the bearing.