ABSTRACT

The single most important mechanical property is proof lo.ad which is a load, axially applied through a mating bolt or hardened mandrel, that the nut must support without any evidence of thread stripping or rupturing of the nut wall. Additionally, after the proof load has been applied and the load released, the nut must be freely removable from the test bolt or mandrel. This latter requirement is interesting because it demonstrates that insufficient thread distortion has occurred to freeze the mating threads together. Tests have shown that a distortion of this magnitude happens when the applied load reaches about 95% of the thread strip-out load.