Meldin® 7000 Flies High and Hot!
Meldin® 7000 Series is a high performance polyimide material now recognized by the aircraft and aerospace industry as an outstanding performer. Several grades of Meldin® 7000 are available for applications as diverse as electrical or thermal insulators, bearings, bushings, and wear pads.
A major aircraft valve supplier to Airbus Industries has recently approved the new Meldin® 7000 Series of polyimides for piston rings and bearings. The application is employed in an engine hot air bleed valve that demands superior performance in a difficult temperature environment. The customer required 50,000 hours of service life with normal temperature cycles running between 400 – 600° F. The application also required minimal air leakage across the piston seals at all temperatures, low friction, thermal stability and compatibility with the aluminum bore.
The solution to this requirement was Meldin® 7022, a graphite reinforced polyimide, which offers the end user a single material to meet all of the demands of this application. Since the installation of the seals is in a closed groove, the piston sealing ring is split with a special modified z-cut. This allows for easy installation and removal without damaging the seal. A wear ring made of Meldin® 7022 is also used to help support the reciprocating pistons.
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