Welding, riveting, and screw fastener links can all be used as a means of assembly in the metal fabrication process. Welding and riveting is a permanent process. After welding is completed, it can only be cut and separated. If not handled properly, the structure of the sheet metal parts will be damaged. It is more suitable for structures that will not easily change the shape. Linked locations can be unlinked and linked again using special tools. Riveted sheet metal parts have excellent shear resistance but weak tensile properties. Threaded fasteners are flexible links with relatively balanced shear and tension forces and are suitable for most environments.