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One Piece TPE Valve From Minnesota Rubber and Plastics Replaces Two Piece Metal Automotive Assembly - Part Cost Reduced 80 Percent

Minneapolis, Minnesota: For a Tier 1 customer, Minnesota Rubber and Plastics injection molds a thermoplastic elastomer (TPE) butterfly valve that regulates heated radiator coolant flow from the engine to the passenger compartment heater core. These butterfly valves replace a previous design which consisted of two stamped steel components welded together and over-molded with a rubber elastomer.

The original design was functionally satisfactory but overly complicated by today’s standards. Component production and assembly was slow, costly and quality was not always consistent. Responding to the requirements of the automotive industry for improved component performance while lowering cost, Minnesota Rubber and Plastics brought to bear its five decades of experience with fluid sealing applications in harsh operating environments.

The challenge was to design a one-piece butterfly valve with the correct sealing and strength features that would function trouble-free for hundreds of thousands of cycles. The goal was to develop a single step process using one material and eliminate assembly and welding operations. The material used had to withstand radiator coolant temperature extremes of 190° F over extended periods. Tight part tolerances also were required so valve sealing was assured with each open and close cycle.

Minnesota Rubber and Plastics one-piece butterfly valve design eliminated metallic parts with secondary over-molding operations. Injection molded of a specialized TPE, prototypes proved the soundness of both design configuration and material selection. Choosing the right material was crucial because it provided both high and low temperature resistance, excellent flex fatigue resistance, excellent compression set and most important, low cost.

The successful new butterfly valve design not only replaced the metal assembly with the over-molded elastomer sealing flange, the part design became a standard used in a line of cars sold world-wide. By producing in high speed, automated, injection molding presses, just-in-time volume requirements were met while part cost was reduced by nearly 80 percent. Delivery time was shortened while part quality and repeatability was enhanced because of the one-piece design.