Chapter 11 Sawing and Cutoff Machines 165 Copyright Goodheart-Willcox Co., Inc. 11.5 Metal-Cutting Circular Saws Metal-cutting circular saws are found in many areas of met- alworking. Primarily production machines, these saws fall into the following three classifications: • Abrasive cutoff saw. • Cold circular saw. • Friction saw. An abrasive cutoff saw, Figure 11-18, cuts material using a rapidly revolving, thin abrasive wheel. Most materi- als—glass, ceramics, and metals—can be cut to close toler- ances. Hardened steel does not require annealing to be cut. Heat-resistant abrasive wheels are available for high-speed cutoff of hot stock. The two general types of abrasive cutting are dry and wet cutting. Wet abrasive cutting, while not quite as rapid as dry cutting in some applications, produces a finer surface finish and permits cutting to close tolerances. The cuts are burn-free and have few or no burrs. Dry abrasive cutting does not use a coolant and is used for rapid, less critical cutting. A cold circular saw, Figure 11-19, has a circular, toothed blade capable of producing very accurate cuts. Large cold cir- cular saws can sever round metal stock up to 27″ (675 mm) in diameter. Correct Incorrect Goodheart-Willcox Publisher Figure 11-17. Recommended ways to hold sharp-cornered work for cutting. A carefully planned setup ensures that at least three teeth will be cutting, greatly extending blade life. Photo courtesy of Weiler Corporation Figure 11-18. An industrial abrasive cutoff saw. W.J. Savage Co. Figure 11-19. Cold circular saw. This machine can be fi tted with carbide-tipped blades or abrasive discs.