Allegheny Performance Plastics recently teamed up with GETEC Getriebe Technik GmbH, and Solvay, to explore the possibility of replacing a traditionally metal helical pump gear in a transmission with a Torlon PAI gear. The gear powers an oil pump that is used to circulate oil, to lubricate and cool the transmission. When the car is idling and during low engine speed, with rpms from 800-2000, this gear is the single largest contributor to system noise. 

The use of high temperature, high performance thermoplastic injection-molded parts in automotive applications is growing. The benefits of Torlon PAI include the economies of injection-molding and lower noise, vibration and harshness (NVH) will continue to drive the replacement of many traditional metal parts with thermoplastic components. Traditionally, thermoplastic parts have been considered for metal replacement on non-critical components. However, during the last decade components manufactured from high performance thermoplastics have replaced bearings and other components in demanding automotive transmission applications. The Torlon PAI oil pump gear represents a thermoplastic replacement of yet another crucial component and places thermoplastic parts within the critical function of the transmission. 

At this early stage, the Torlon PAI gear was designed to be a drop-in replacement. In other words, the plastic part has the exact same dimensions as the metal gear that it is replacing. GETEC completed a full NVH test at their testing facility, and the plastic part performed 3 decibels lower than the metal gear at the critical idling and low engine rpms. This represents a significant reduction in noise.

Sven Steinwascher, GETEC managing director and CTO said, “The metal gear that we replaced with this first prototype had undergone six years of refinement to reach the level of NVH performance it has today. It’s encouraging that we surpassed that on our very first attempt with this thermoplastic part.”

Solvay’s Head of Marketing-Automotive Brian Baleno said, “Reducing NVH and identifying components to save space are two significant challenges for electrified vehicle powertrains. Torlon PAI has a long history of replacing metal in thrust washers and bearings so we see metal replacement in oil pump gears as the next evolution and are excited to be partnered with Allegheny Performance Plastics and GETEC to help to refine the part and perhaps even decrease the NVH further.”

Greg Shoup, president of Allegheny Performance Plastics, stated, “We are thrilled to be working with Solvay and their engineering and material expertise, as well as GETEC, with their testing facilities and willingness to explore innovative transmission solutions with us.” He continued, “We know Torlon and we are well equipped to develop machining and injection molding processes that take our customers from application development and prototyping to high rate production volumes. As we develop this application in conjunction with Solvay and GETEC, we’ll be focused on creating a part with a consistent process that can be injection-molded to within very tight tolerances.”

Steinwascher added, “The implications of this gear replacement are enormous, nearly every automobile with a DCT or AT that is manufactured has one of these gears, and HEVs often have two. E-vehicles also run much quieter at higher rpms, which means that lowering the NVH of this particular gear would affect the overall NVH of the vehicle for a wider range of rpms, not just in idling speeds.”

As this process of part development unfolds, the next step for the team is to perform durability testing on the part, as well as refine the part design to further enhance the gear’s performance.