Optimizing Stick Slip Performance in Automotive Interiors by Material Selection, Additives and Design Strategies

The automotive industry is highly competitive, especially in terms of design and perceived quality. The use of hard plastics with a high gloss finish is driven by styling trends and the push towards zero gaps, making interfaces critical. In-cabin mood lighting is another feature being offered as a theme for interiors. Dashboard or cockpit designs often incorporate a significant amount of polycarbonate-acrylonitrile butadiene styrene (PC-ABS) and polycarbonate (PC). These materials provide strength and design flexibility but have the disadvantage of material incompatibility when used together, leading to stick-slip phenomena. Traditionally, felt tapes were used as interface isolation to solve this problem, but this increased manufacturing costs and assembly complications. The study focuses on the stick-slip phenomenon and material interface modifications. Specifically, it examines selecting the right surface finish on one side of the PC & PC-ABS interface to change adhesion and friction characteristics. Stick-slip results of different surface finishes under various thermal conditions were studied using the SSP04 stick-slip testing apparatus. Various surface finishes, such as material additives, coatings, and grains, were explored to improve stick-slip phenomena. Test results showed a significant breakthrough in reducing stick-slip phenomena by lowering friction between interfaces at ambient conditions. However, only a few surface finishes were effective in all thermal conditions according to VDA standards. Implementing this surface finish offers the advantage of no additional manufacturing costs, depending on the product development stage, and minimizes or eliminates the use of felt in the interface. The major advantage is the design freedom it offers without impacting aesthetics or restricting material usage.