Use of Anaerobic Adhesive for Prevailing Torque Locking Feature in Threaded Fasteners
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This paper presents results from tests to assess the use of anaerobic adhesive for providing a prevailing torque locking feature in threaded fasteners. Test procedures are developed and tests are performed on three fastener materials, four anaerobic adhesives, and both seated and unseated assembly conditions. Five to ten samples are tested for each combination. Tests for initial use, reuse without additional adhesive, and reuse with additional adhesive are performed for all samples. A 48 h cure time was used for all initial use and reuse tests. Test data are presented as removal torque versus removal angle with the specification required prevailing torque range added for performance assessment. Percent specification pass rates for all combinations of fastener material, adhesive, and assembly condition are tabulated and reveal use of anaerobic adhesive as a prevailing torque locking feature is viable. Although not every possible fastener material and anaerobic adhesive combination provides prevailing torque values within specification, any combination can be assessed using the test procedures presented. Reuse without additional anaerobic adhesive generally provides some prevailing torque, and in some cases within specification. Reuse with additional adhesive often provides comparable removal torque data as in initial use.
KeywordsFastener Anaerobic adhesive Prevailing torque Locking Aerospace Aviation
The authors gratefully acknowledge the funding and support of the NASA Engineering and Safety Center (NESC) and Dr. Michael Dube for this work.
- 1.NASM25027, Nut, self-locking, 250°F, 450°F and 800°F, National Aerospace Standard (1999)Google Scholar
- 2.NASM8846, Inserts, screw-thread, helical coil, National Aerospace Standard (1998)Google Scholar
- 3.MIL-I-45914A, Insert, screw thread – locked in, key locked, Department of Defense Military Specification (1991)Google Scholar
- 4.MIL-I-45932/1C, Insert, screw thread – thin wall, locked in, Department of Defense Military Specification (1994)Google Scholar
- 5.NAS3350, Nuts, self-locking, 450°F and 800°F, high quality, National Aerospace Standard (2006)Google Scholar
- 6.MIL-DTL-18240F, Fastener element, self-locking, threaded fastener - 250°F maximum, Department of Defense Detail Specification (1997)Google Scholar
- 8.J. McManamen, Orbiter Window Fastener Issue Summary, NASA SSP presentation (2008)Google Scholar
- 9.T. Roberts, Orbiter Window Installation Fasteners, United Space Alliance presentation (2008)Google Scholar
- 11.A. Hernandez, Use of Anaerobic Adhesive for Prevailing Torque Locking Feature on Threaded Product, University of South Florida MS Thesis (2015)Google Scholar