What Is Piercing?
Piercing is a sheet metal working process in which a tool is used to pierce a round or other shaped holes in sheet metal with no or tiny scrap, in order to obtain the perforated sheet.
What Is Punching?
Compared to piercing, the purpose of punching is also to obtain a perforated sheet, except that, in most cases, the punching operation produces a round hole and more scrap.
What Is Blanking
Blanking is easily confused with piercing and punching. Blanking is also punching holes in the sheet metal. Still, they are distinctly different: piercing and punching are intended to obtain sheet metal with holes, while the purpose of the blanking process is to retain and use small pieces of metal that have fallen from the metal sheet.