Upsetting

Upsetting is the process of thickening the metal by reducing one dimension and increasing the other two. It can be described as pushing the metal back into itself to thicken it. For example in preparation for making a bolt head, a smith will hammer the end of a rod, thickening the end of the rod and shortening its overall length. The heated end of the rod is placed pointing down on an anvil. The cool end is then struck repeatedly, which produces a bulge at the hot end of the metal.