Hex Tap Bolt are fully threaded hex head bolts that do not have an integrated smooth washer face. Tap bolts are popular because of the versatility a fully threaded fastener provides. One length of a fully threaded tap bolt can be used to replace several lengths of a standard (partially threaded) hex cap screw. Being fully threaded, Tap Bolts lack an unthreaded body section and so may sacrifice shear strength when compared to a partially threaded hex cap screw in some applications.
Unlike Hex Head Cap Screws, Tap Bolts do not have an integrated smooth washer face on the underside of the hex head. A washer face ensures a smooth bearing surface perpendicular to the threads and allows the assembly to develop the desired clamp load when bolting into a blind tapped hole without a nut. Since Tap Bolts do not have a washer face they should only be used in through bolting applications where they can be tightened with a hex nut. Tap bolts are available in heat treated Grades 5 and 8 as well as 18-8 and 316 Stainless Steels.