AIA: Clip Nuts Reduce Corrosion on Aircraft
It's just a small part, but a clip nut made from Torlon polyamide-imide (PAI) can make a really big difference when used on commercial aircraft to secure flooring, fairings, interior trim and bulkheads.
"Whether it's on a wide body jetliner built by Boeing or Airbus, or on the smallest Cessna that rolls off the assembly line, corrosion is a major concern in the aircraft industry," says Jacques P. Gauron, vice president of product development at Marketing Masters Inc. (Issaquah, WA), a manufacturer of composite fasteners.
Manufacturers spend a tremendous amount of money priming and plating aircraft parts to reduce the potential effects of corrosion. Yet, the metal clip nuts that the industry has used for the past 40 years can gouge the surface of metal structures when they are installed, making the structures susceptible to attack from both galvanic and environmental corrosion.
When Marketing Masters was looking for a resin to mold clip nuts, it chose Solvay Advanced Polymers' (Alpharetta, GA) Torlon PAI.
Marketing Masters' clip nuts made of this resin won't scratch through the protective covering to bare metal during installation or corrode during use. This can significantly reduce the hours of labor and costly procedures associated with replacing corroded metal parts. They can withstand torque loads in excess of 100 in.-lbs, yet have enough elongation to clip easily into place.
Clip nuts made from Torlon resin are noncorrosive and weigh a fraction of their metal counterparts. However, they match the strength of metal clip nuts. "A typical DC-10 may have 15,000 clip nuts on the floor structure. Using a lighter weight clip nut can reduce the weight of the plane by 20 pounds," says Gauron. "That may not seem like much, but even a modest drop in weight can significantly reduce cost by burning less fuel."
The strength of Torlon resin is competitive with metal across a wide temperature range, and the plastic maintains its high mechanical properties in temperatures up to 260 C. It passes Federal Aviation Authority flammability tests and is unaffected by aggressive aviation fluids, such as MEK, Tric 1,1,1 and Skydrol hydraulic fluid.
The resin is an ultra high-performance thermoplastic that can be processed by such standard methods as injection molding, extrusion and compression molding. It is also available in special wear-resistant grades that offer less friction and longer life than metals and other polymers even when lubrication is marginal or nonexistent.
For more information on plastic fasteners, call 425-454-5610 or visit www.marketingmasters.us.
For more information on Torlon resin, call 770-772-8200 or visit www.solvayadvancedpolymers.com.