over the six year period 1992–1997.
▪Consumers realized an actual decline of just over $100 billion in the cost of durable goods from 1996 to 1999.
▪Consumers also saved billions from product quality improvements such as cars with higher fuel efficiency ($50 billion in 1999), reduced maintenance needs ($21 billion in 1998), and savings from lower electricity bills for energy efficient refrigerators and air conditioners ($19.6 billion in 1997).
MANUFACTURING TECHNOLOGY ADVANCES
America is back as a manufacturing powerhouse.
Manufacturing today is complex, competitive, and quality conscious. Consumer demand for mass customization has replaced the earlier “one size fits all” notion of mass production. Manufacturers are now driven by a “faster, better, cheaper” mantra.
To deliver what customers want, manufacturers have reinvented themselves, finding new ways of doing things and reevaluating every aspect of production to improve productivity. To respond to this demand, machine tool makers have instituted changes to enhance productivity and competitiveness in a variety of industries including automobiles, refrigeration, heating and air conditioning, aerospace, construction and mining equipment, and farm and garden machinery (See Table 2.1).
Machine tools have also become increasingly tied to information technologies to form a combined system of manufacturing that produces goods more quickly and with greater accuracy than before. Among the most important advances has been the change from manual control of the machine tool’s movements to numeric control and computer numerical control. This has fostered new uses for machine tools. Five axis machine tools are now widely used, not only in the defense industry but also in civilian applications. The ability to produce complex geometric patterns more quickly and accurately, without using templates, has increased the number of items for which the use of machine tools is practical.
During the last two decades, a revolution in manufacturing technology generally and advances in machine tools specifically enabled manufacturers to reinvent themselves and to restore the competitive power of the United States as a world class producer of durable goods.
There has also been a marked increase in the use of computing power and automation in machine tools, such as the ability to read computer aided design math models into the machine to determine its movements. The aircraft industry provides a good example of how advances in machine tool technology have improved the manufacturing process. In one dramatic example, an aerospace company [McDonnell Douglas] changed the manufacturing process for landing gear bulk heads of the C 17 aircraft to take advantage of high speed machining. Under the new process, bulkheads are made with two parts, rather than 72, and require only 35 fasteners to hold them together, rather than 1,720 under the previous method. Furthermore, machining was completed 15 times faster.
BENEFITS OF QUALITY IMPROVEMENTS TO CONSUMERS
Advances in machine tool technologies have made it possible to improve quality dramatically and build better, longer lasting products at lower prices. The Consumer Price Index (CPI) documents these improvements. Between 1982 and 1999, the overall CPI increased by 73 percent, or at an annual average rate of 3.3 percent. Over the same period, the price index for durable goods increased by only 35 percent, or an annual average of only 1.8 percent. More striking still, the price of durable goods actually declined between 1996 and 1999, saving consumers approximately $101.3 billion.
Table 2.1: Improvements in Machine Tool Technology Since the 1970s
Increased accuracy due to
▪Thermal effect compensation
▪Geometric compensation through CNC
▪Real-time compensation for tool wear
▪Dynamic compensation for die-height (for effects of thermal and speed vaiations)
Improved operations due to more capable CNC:
▪Download of instructions rather than tape
▪Remote diagnostics
▪Visual representation of cycle progress at the machine
▪More accurate contouring
▪Programming at CNC machine
▪Automatic die changes
Improvements in components of machines
▪Switch from hydraulic drives to electric drives
▪Linear Drives
▪Higher spindle speeds
▪Variable spindle speed used in conjunction with electric drives
▪Faster die changes and automatice bolster/die changers
Improved tool materials provide longer tool life and allow more demanding machining:
▪Coated carbides
▪Cubic Boron Nitride (CBN) Grinding wheels
▪Ceramic tools
Increased capabilities of machining centers:
▪Greater tool storage
▪Ability to handle more pallets
▪Live tool stations on turning centers
Multiple operations performed with a single machine set-up
Combining processes in one machine: mill, turn, grind
High-speed presses
Wire electro-discharge machining
Waterjet machining
Laser machining
Flexible manufacturing systems (an arrangement of machines interconnected with a transport system and both being controlled by a computer system)
Programmable logic controllers
Stereolithography ( a rapid prototyping process whereby a 3-D object is created using cross-sectional data from a computer-aided design file and “printing” it with a solid-object printer)
Improving handling of parts:
▪Robotics and handling of parts of rotation
▪Automatic loading and unloading of parts from presses
Automobiles illustrate this trend. Consumers spend more on cars and light trucks than any other durable good. According to the Bureau of Labor Statistics, vehicle quality between 1967 and 1998 increased at an annual average rate of 2.2 percent. This means that a car built in 1998 has twice the quality as one built in 1967 in terms of per formance, reliability, durability, and warranty. Today, owners of new cars produced by U.S. companies experience fewer than 30 problems per 100 cars during the first year of ownership, compared with 104 per 100 cars in 1980.
