3.1 Introduction

Products made of sheetmetals are all around us. They include a very wide range of consumer andindustrial products, such as beverage cans, cookware, file cabinets, metaldesks, appliances, car bodies, and aircraft fuselages（Fig.3-1. Sheet forming dates backto about 5000 B.C., when household utensils and jewelry were made by hammingand stamping gold, silver, and copper. Compared to those made by casting and byforging, sheet-metal parts offer the advantages of light weight and versatileshape.

FIGURE 3-1  Examples of stamped sheet-metalparts and products.

The term pressworking or pressforming is used commonly in industry todescribe general sheet-forming operations, because they typically are performedon presses using a set of dies (Fig.3-2). A sheet-metal part produced in presses is called a stamping. Stampingis carried out by dies and press, and has a high productivity. Mechanizationand automatization for stamping can be realized conveniently owing to its easyoperation. Because the stamping part is produced by dies, it can be used toproduce the complex part that may be manufactured with difficulty by otherprocesses. The stamping part can be used generally without further machining.Usually, stamping process can be done without heating. Therefore, not only doesit save material but also energy. Moreover, the stamping part has thecharacteristics of light weight and high rigidity.