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Minnesota Rubber and Plastics
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One Piece V-Cup Seal Replaces Two-Part Assembly

MINNEAPOLIS, Minn--A new piston V-cup seal used in fuel assembly applications was recently redesigned by Minnesota Rubber and Plastics to combine two components into a single part while maintaining part function and life. According to the company, a Minneapolis-based manufacturer offering six decades of experience with fluid sealing applications in harsh operating environments, the redesigned seal provides improved seal life and reduced manufacturing and assembly costs.

In the original two-part design, which the manufacturer described as "functionally satisfactory but overly complicated by today's standards," the two components acted as a horizontal, dynamic piston seal. The sealing function occurred for pressure traveling in either direction--in and out; two parts were stacked back-to-back to accomplish this bi-direction sealing process. The seal reportedly worked well enough without trapping pressure between the seal surfaces, but the assembly process to achieve the seal consistency was labor-intensive, requiring skillful part handling and placement, as well as special testing.

In a joint customer/supplier program, Minnesota Rubber and Plastics developed a new, single V-cup seal design that simplified and sped up the assembly process, resulting in improved efficiencies, reduced labor content, and lower costs. The company's selection of material for the seal was critical to the success of the single-part design: A special fuel-resistant, fluoro-elastomer material was formulated so that the part would withstand the harshness of extended fuels. Besides providing the needed fuel resistance, the fluoro-elastomer provided excellent flex fatigue resistance, excellent compression set, and--most important--lower cost, the company reported.

Minnesota Rubber and Plastics (www.mnrubber.com) produced the seal in automated presses, meeting just-in-time volume requirements while reducing part cost by 23 percent versus the previous two-part assembly. Delivery time was shortened, and part quality and repeatability were enhanced because of the one-piece design, the company said.