ABSTRACT
Manufacturing is the industrial activity that changes the form of raw materials to create products. The derivation of the word manufacture re ects its original meaning: to make by hand. As the power of the hand tool is limited, manufacturing is done largely by machinery today. Manufacturing technology constitutes all methods used for shaping the raw metal materials into a nal product. As shown in Figure 1.1, manufacturing technology includes plastic forming, casting, welding, and machining technologies. Methods of plastic forming are used extensively to force metal into the required shape. The processes are diverse in scale, varying from forging and rolling of ingots weighing several tons to drawing of wires less than 0.025 mm in diameter. Most large-scale deformation processes are performed at high temperatures so that a minimum of force is needed and the consequent recrystallization re nes the metallic structure. Cold forming is used when smoother surface nish and highdimensional accuracy are required. Metals are produced in the form of bars or plates. On the other hand, casting produces a large variety of components in a single operation by pouring liquid metals into molds and allowing them to solidify. Parts manufactured by plastic forming, casting, sintering, and molding are often nished by subsequent machining operations, as shown in Figure 1.2.
