© 2002 by CRC Press LLC used to cut the material. Water speeds of 2600 ft/s (800 m/s) and nozzle diameters on the order of 0.010 in. (0.25 mm) are typical. For most composite applications, abrasive particles are added with the water to increase the cutting speed and to cut thick composite laminates. A schematic diagram of commercially available waterjet cutting equipment is shown in Figure 10.5. As shown, the water nozzle remains stationary and the sample material travels by a hydraulic cylinder. A 30-gpm (113.5 l/min) hydraulic pump delivers hydraulic oil at up to 3000 psi (21 MPa) to an intensifier via a four-way valve. The intensifier is a differential-area, double- acting piston type in which a large piston is shuttled back and forth by the 3000 psi oil. There are two small pistons attached directly to the large piston. The small pistons have an area 1/20th of the large piston; thus it converts the 3000-psi oil to 60,000 psi water. Compressed water then flows out of the high-pressure cylinders to the nozzle through a pair of check valves. During waterjet cutting, the process parameters that affect cutting perfor- mance include: • Waterjet pressure • Cutting speed • Laminate thickness • Nozzle orifice diameter (0.2–8 mm) Hurlburt and Cheung 6 performed waterjet cutting on graphite/epoxy, glass/epoxy, Kevlar/epoxy, boron/epoxy, and hybrids of graphite/epoxy and FIGURE 10.5 Schematic of waterjet cutting equipment. (Adapted from Hurlburt, G.H. and Cheung, J.B., Waterjet Cutting of Advanced Composite Materials, SME Technical Paper No. MR77-225, So- ciety of Manufacturing Engineers, 1997.) Water inWater in 30 GPM pump 4-way valve Large piston Small piston Intensifier Accumulator Nozzle Water jet Movable cutting bed Sample © 2002 by CRC Press LLC used to cut the material. Water speeds of 2600 ft/s (800 m/s) and nozzle diameters on the order of 0.010 in. (0.25 mm) are typical. For most composite applications, abrasive particles are added with the water to increase the cutting speed and to cut thick composite laminates. A schematic diagram of commercially available waterjet cutting equipment is shown in Figure 10.5. As shown, the water nozzle remains stationary and the sample material travels by a hydraulic cylinder. A 30-gpm (113.5 l/min) hydraulic pump delivers hydraulic oil at up to 3000 psi (21 MPa) to an intensifier via a four-way valve. The intensifier is a differential-area, double- acting piston type in which a large piston is shuttled back and forth by the 3000 psi oil. There are two small pistons attached directly to the large piston. The small pistons have an area 1/20th of the large piston; thus it converts the 3000-psi oil to 60,000 psi water. Compressed water then flows out of the high-pressure cylinders to the nozzle through a pair of check valves. During waterjet cutting, the process parameters that affect cutting perfor- mance include: • Waterjet pressure • Cutting speed • Laminate thickness • Nozzle orifice diameter (0.2–8 mm) Hurlburt and Cheung 6 performed waterjet cutting on graphite/epoxy, glass/epoxy, Kevlar/epoxy, boron/epoxy, and hybrids of graphite/epoxy and FIGURE 10.5 Schematic of waterjet cutting equipment. (Adapted from Hurlburt, G.H. and Cheung, J.B., Waterjet Cutting of Advanced Composite Materials, SME Technical Paper No. MR77-225, So- ciety of Manufacturing Engineers, 1997.) Water inWater in 30 GPM pump 4-way valve Large piston Small piston Intensifier Accumulator Nozzle Water jet Movable cutting bed Sample © 2002 by CRC Press LLC 11 Cost Estimation 11.1 Introduction Cost estimating is an essential element in running a successful business. A design that can be manufactured at low cost will have a significant impact on the market. Success in business decisions relies on how well the cost estimating is performed. Many times, design changes are made or new materials are used to lower the cost of a product. Many product development activities focus on how to reduce the cost of manufacturing or the overall cost of a product. In this globally competitive market, management decisions revolve around the cost of the product. Therefore, it is important to have a good understanding of the factors that affect product cost. Cost estimating should not be left to accountants or salespeople. The manufacturing engineer should play a key role in determining the cost of a new product or an existing product. Any design changes should be discussed with the manufacturing engineer as to the feasibility of making it or achiev- ing it at low cost. The cost estimating job becomes vital in the area of composite materials because the composite product must compete with well-developed metal tech- nologies. A careful consideration must be given to investigate all the possible ways to lower cost. Composite products are often not selected for an applica- tion because they are not cost-competitive. In this competitive market, where the entire world represents a single market, product cost has become a crucial factor in deciding the success or failure of a company. In the automotive industry, where the market is very cost-sensitive, product cost plays a vital role in selecting a technology. Typically, structural and nonstructural product costs range from $2 to $20/lb in the automotive field and $100 to $1000/lb in the aerospace market. Newly developing countries such as Taiwan, Korea, India, China, and Mexico, where the labor cost is low, are competing with well-established nations by acquiring technologies. Today, tooling and com- posite products such as golf shafts, fishing rods, tennis rackets, etc. are cost effectively made in these countries and marketed to the United States and . boron/epoxy, and hybrids of graphite/epoxy and FIGURE 10.5 Schematic of waterjet cutting equipment. (Adapted from Hurlburt, G.H. and Cheung, J.B., Waterjet Cutting of Advanced Composite Materials,. Advanced Composite Materials, SME Technical Paper No. MR7 7-2 25, So- ciety of Manufacturing Engineers, 1997.) Water inWater in 30 GPM pump 4-way valve Large piston Small piston Intensifier Accumulator Nozzle Water. boron/epoxy, and hybrids of graphite/epoxy and FIGURE 10.5 Schematic of waterjet cutting equipment. (Adapted from Hurlburt, G.H. and Cheung, J.B., Waterjet Cutting of Advanced Composite Materials,