SHEET METAL AND METAL FORMING Copyright Goodheart-Willcox Co., Inc. Chapter 17 Cold Forming Metal Sheet 277 Plasma cutting systems are ideal for most metal- cutting applications. These systems can produce metal parts with precision tolerance, sharp clean corners, and straight edges requiring little or no secondary opera- tions. Plasma cutting systems are computer-controlled. 17.1.4 Waterjet Cutting Systems Waterjet cutting systems use a high-pressure, high- velocity stream of water propelled at extremely high speeds (over 2500 mph) to cut a variety of materials. Pure waterjet systems are typically used to cut softer materials, such as foam, gasket material, or rubber. An abrasive can be added to the waterjet to cut almost any other material, such as ceramics, composites, almost any metal, or nontempered glass, over a large range of thicknesses. When an abrasive is added, the process is referred to as abrasive waterjet cutting.g g Waterjet cutting occurs at room temperature and pro- duces extremely smooth edges. There is no heat-affected zone in waterjet cutting, so the edges of the material being cut are not weakened. Because these systems do not use heat, there is never a problem with hardened edges. Like plasma and laser cutting systems, most waterjet systems have multiaxis capability. SeeFigure 17-4. Waterjet machin- ing is also referred to as hydrodynamic machining (HDM). g ( ( 17.1.5 Blanking, Punching, and Piercing Blanking and punching are shearing operations per- formed on a punch press with a punch and die. The main difference is that the metal removed in punching operations becomes the waste or scrap, while the metal remaining in blanking operations is the waste. Blanking, g g Figure 17-5, involves cutting flat sheet 5 metal to the shape and size of the finished part. The holes and openings of various shapes are cut with punches and dies. While blanking can be done manually on a punch press, it is typically done automatically on a CNC punch press, Figure 17-6. Vereshchagin Dmitry/Shutterstock.com Figure 17-3. A CNC plasma cutting system. OMAX Corporation Figure 17-4. A CNC waterjet cutting system that can use abrasives (in the waterjet) to machine complex, flat parts from materials such as metal, glass, and ceramics. This machine is capable of cutting parts up to 4′ × 4′ (1.2 m × 1.2 m) and achieving cutting tolerances of ±0.003″(±0.08 mm). Goodheart-Willcox Publisher Figure 17-5. The blanking operation. Punch Punch Die Material Material Blank