Case History: Serrated Austenitic Screws
Customer problem: Austenitic screws were losing preload and loosening during low temperature environmental testing.
What NHML did to solve problem: Testing at NHML indicated that the serrated design on the underside of the screw heads resulted in far less axial preload than predicated by common mechanical equations based on tightening torque and torque tables. Recommended that customer perform testing to determine the tightening torque versus axial preload relationship for his specific screw design.
Benefit to customer: Determination of the correct tightening torque to sufficiently preload the bolts so they stay tight during operation.
June 25, 2009 by Tony Tipton, Chief Metallurgist
Published July 1, 2009, in our http://archive.constantcontact.com/fs049/1102403349589/archive/1102609302907.html newsletter.
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