Thread Failure, Why Always the 1st Thread
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Threaded fasteners are used to hold parts, components, and assemblies together. In a static environment application in which no external loads are applied, the threaded joint may last forever. However, most joints rarely exist in this type of stationary environment. In fact, most joints are subjected to some sort of external loading, which in some cases, actually fails the joint. When the screw/bolt fails, it can be a result of the threads stripping, cracking under the head, or cracking at the 1st thread. A vast majority of failures occur at the 1st thread and this article discusses the reasons why.