Clinching is a combination of drawing and forming that locks together layers of sheet metal without using any fasteners. In clinching a punch drives the layers of metal into a die that produces an impression; additional force spreads the upper layer of the material into the lower layer so it cannot be pulled out. The clinching method is primarily used for metals with less ductility such as stainless steel or where there is considerable thickness or ductility difference between the sheets being joined.