High Strength HNBR - The New Benchmark Elastomer for Automotive Synchronous and Serpentine Belts

Global competition in the automotive industry, specifically new trends in engine design, involve the replacement of traditional engines with high performance overhead cam engines and multi valve designs. This has created a unique challenge to the engineering of timing belts with increasing underhood temperatures due to hotter running engines and compact engine compartments. These factors along with increased load bearing requirements has pushed traditional synchronous belt materials beyond their limits. Materials suppliers and belt manufacturers have combined efforts to develop new designs and materials which address these performance needs.

This paper evaluates the performance of past, present and future belt compounds including polychloroprene (CR), alkylated chlorosulfonated polyethylene (ACSM), hydrogenated nitrile butadiene rubber (HNBR), and high strength HNBR utilizing static and dynamic testing equipment. These findings illustrate that high strength HNBR will provide improved heat and ozone resistance, higher abrasion resistance and improved dynamic performance. Its higher load bearing capabilities will help establish this material as the new benchmark for extended warranties and dynamic performance in synchronous and serpentine belts.