Product/Service

Coated Fasteners

Source: Aerospace Rivet Manufacturers Corp.

Coated Fasteners
Aerospace Rivet applies an organic coating to the aluminum-alloy rivet during the manufacturing process and prior to the final age
In early 1995 Aerospace Rivet Manufacturers Corporation in concert with Boeing-MTA (McDonnell-Douglas C-17) program and the hi-shear Corporation developed and is using a method to protect aluminum-alloy fasteners from corrosion. Since aluminum fasteners must be heat treated at a much lower temperature than fasteners made of other materials, it has not been practical to coat aluminum-alloy fasteners to prevent corrosion. Instead a costly wet-sealant application to the fasteners has been the standard for many military aircraft programs. This program was initiated to evaluate and develop an alternative corrosion prevention method to the above standard. Aerospace Rivet applies an organic coating to the aluminum-alloy rivet during the manufacturing process and prior to the final age, depending on the alloy, cures the coating without any detrimental effect to the metallurgical or mechanical properties.

Benefits

The main and foremost benefits are the elimination of wet-sealant installation with equivalent or better corrosion protection along with improved fatigue strength clean installation, and the large levels of cost savings primarily in reduced labor-hours. These labor-hours are associated with the practice of applying the wet-sealant to the rivet installations and the resulting clean-up required for the excess sealant, additional cost savings accompanying the elimination of solvents and hazardous waste used and produced during this procedure may also be realized.

Testing

Comparison tests run on both methods showed in all cases the coated rivet met, or exceeded existing requirements for wet sealant installation. Test methods used include Salt fog per ASTM B 117 for 2000 hours; Beach exposure for 6 months and 2 years, corrosion fatigue, thermal cycle/flexure, as well as coating adhesion and resiliency. An increase of 25%-60% in joint fatigue life was obtained due to improved preload, hole fill, and decreased levels of fretting during installation.

Potential Applications

Coated aluminum-alloy fasteners can save steps and reduce cost anywhere wet or dry aluminum fasteners are installed.

Aerospace Rivet Manufacturers Corp., 17425 Railroad St, City of Industry, CA 91748. Tel: 626-646-2150; Fax: 626-646-2160.