Bottom projection-weld threaded studs install in an existing hole, eliminating the need for additional drilling or setup. They are typically stronger than top projection welds but require access to both sides of the mounting surface. The studs are secured to the workpiece by welding the projections on the underside of the flange.Projection-weld threaded studs are fasteners that are welded to or through a metal surface to create a permanent male thread. They have raised weld points (projections) to better control placement of the fastener than by welding the entire head. Projection weld studs are ideal for use in heavy duty applications, such as those in the construction and automotive industries. They are also used in hard-to-reach places, such as narrow channels and other confined spaces.