Bolt And Nut is a fastening device used in conjunction with the nut to hold the two objects or machine parts together. Hence nut is always used with a bolt. The nut is necessary for the bolt to function, and vice versa. The threads of nuts and bolts allow them to be connected. Failure may begin at the thread profile is weakest shear plane. In other words, the strength of the link is determined by the weakest substance. In mechanical design, nuts, bolts, and screws are crucial machine components. The nut is a particular kind of fastener that features a hole that can be threaded.