Below is a list of Open Die Forging manufacturers from Diamond Bar, California. Also known as smith forging, open die forging uses simply-shaped, non-encompassing dies to hammer or press a metal workpiece into a certain shape. It is distinct from closed-die forging, in which the dies fully enclose the workpiece when they are brought together. The open die forging process allows for larger products to be forged than other types of forging - up to 150 tons and 80 feet long or more.