A significant advantage of a bolted joint over other joint types, such as welded and riveted joints, is that they are capable of being dismantled. This feature however, can cause problems if it unintentionally occurs as a result of operational conditions. Such unintentional loosening, frequently called vibration loosening in much of the published literature. It is widely believed that vibration causes bolt loosening. By far the most frequent cause of loosening is side sliding of the nut or bolt head relative to the joint, resulting in relative motion occurring in the threads. If this does not occur, then the bolts will not loosen, even if the joint is subjected to severe vibration. By a detailed analysis of the joint it is possible to determine the clamp force required to be provided by the bolts to prevent joint slip. Junker's vibration test rig is the most popular method to measure the vibration loosening of bolts or commonly referred to as bolt decay phenomenon. The Junkers vibration test rig uses a special form spring to connect the eccentric arrangement for providing vibration to the test specimen .Commonly used material for the material of this form spring steel in the tempered form.