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APPENDIX A The Technology of Future Manufacturing Although ah the interrelationships and long-term implica- tions of advanced manufacturing technologies are not yet wed un- derstood, the direction of future developments is relatively clear. This appendix describes the technologies that are likely to have a major impact on manufacturing competitiveness, indicates the ways in which those technologies interact, identifies additional re- search needs, and discusses some of the issues that are likely to be encountered in implementation. The technologies have been divided into materials, material handling, material transforma- tion, and data communication and systems integration. These categories are highly interdependent, and divisions are not always distinct, but this categorization provides an effective structure for a broad overview of the major technologies. DEVELOPMENTS IN MANUFACTURING MATERIALS Materials developments have a substantial impact on manu- facturing in both product design and process engineering. New products can require different materials and materials process- ing, and new materials themselves often spur new products and new process development. Many of the materials developments in manufacturing do not involve new materials, but rather substitu- tions, upgradings, and new concepts for conventional materials. Pressure to lower costs and raise product quality has led to some 75
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76 major shifts in materials selection. The consideration of doubly precoated steel for corrosion resistance in automobiles is an ex- ample. Developments in both conventional materials and new materials are equally significant to future manufacturing. This section will focus on materials developments that are ready for manufacturing implementation, with minimal emphasis on research systems that have had little technology transfer effort. Developments in metals, polymers, ceramics, and glasses will be considered, followed by a brief discussion of some emerging issues that should be brought to the attention of policymakers. Metals and Metal-Based Composites Major developments will continue in the processing of con- ventional metallurgical systems. For example, large tonnages of carbon and stainless steed sheet and strip will be continuously cast. Similar developments are certain in nonferrous alloy areas as well. While the continuously cast products will have some mi- nor metallurgical variations to be considered, the major impact will be economic, allowing the basic metals industry to remain competitive in many sheet and strip applications. Increased use of warm- and cold-formed steel parts can be ex- pected, with emphasis on near-net-shape processes to save metal and avoid intermediate processing steps. Similar forces will con- tinue to drive powder metallurgical processing, although it must be emphasized that advances in precision forming and powder metallurgy have been slow over many years rather than a sudden breakthrough. Powder processing will be facilitated as cleaner powders reach the market. Powder metallurgy produced too! steels continue to offer advantages over conventional tooling stock. Superplastic forming will continue to increase in aerospace manufacturing; some initial applications have occurred in the B-1 bomber program. Increased market penetration will entail ma- jor changes in tooling and manufacturing technology. Thermo- mechanically processed 7000 series aluminum alloys are available for such forming, as are aluminum-lithium alloys. However, little of these alloys are available from domestic sources; most of this material is being obtained from the United Kingdom.
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77 Many metal-processing alternatives will be examined to facil- itate in-line processing systems. Improvements can be expected in the control of metal structure, with increasing awareness of the importance of grain orientation (texture), residual stress, and sur- face quality. In steed surface treatment, increased use of induction or laser hardening can be expected as lower cost alternatives to carburizing. I.aser welding is seen as growing in the auto industry, perhaps at the expense of electron beam techniques. Power sys- tems manufacturing may turn to welded rotor fabrication to allow increased use of attractive alloy combinations while sidestepping large forging development problems. Many cases of metals substitution can be expected. The upgrading of alloys in small parts should increase product qual- ity, reliability, and processing response without grossly increasing overall metal procurement cost. Aluminum can be expected to continue to replace copper in many heat exchange applications. Silicon-based switches are expected to replace iron-based mag- netic devices. Also in the electronics industry, changes in plat- ing metals are expected, with gold giving way to palIadium-nicke! and iron. Some observers see increased use of molybdenum-based alloys, particularly as new developments solve some of the tradi- tional corrosion problems. Production of these alloys is energy intensive, however, and the domestic supply is limited. In the new metals area, continued progress is expected in the development of metal matrix composites, particularly using metals such as aluminum and magnesium reinforced with silicon carbide. Three major types of reinforcement are receiving particular at- tention: continuous monofilament, discontinuous, and continuous multifilament yarn. Each reinforcement requires a specific fab- rication process, including diffusion bonding, hot molding, power blending, forging, casting, pultrusion, extrusion, and rolling, often in combination. Many of the material defects and anomalies that have plagued metal matrix development are attributable to the manufacturing process. As experience in these processes builds and the manufacturing technology evolves, application problems caused by material defects should decrease. In aerospace struc- tures, for example, the application of specific metal matrix materi- als varies according to expected environment, design Toads, stress,
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78 and temperature variations. Designers of flaw-critical parts select materials for their strength and ductility as well as their resistance to crack growth. Unfortunately, research on fracture mechanics in the area of metal matrix composites is much less developed than for polymer matrixes and has not been widely disseminated for use by designers.) Progress in reducing material defects and continued applica- tion experience will result in broader applications for metal ma- trix composites. For example, automobile manufacturers are gain- ing experience with aluminum-silicon carbide in piston ring and crankshaft applications. Power systems applications are seen for nickel superalloy and stainless steel matrix composites strength- ened with silicon carbide. Such systems allow increases in elastic modulus and desirable decreases in the coefficient of thermal ex panslon. Much research has focused on rapidly solidified metals and amorphous metals. Introduction of such materials into the manu- facturing sector is expected to be slow, with the major exception of the iron-boron-silicon-carbon system being broadly used for dis- tribution transformers. Slow emergence is also predicted for nickel and titanium aluminides despite extensive research. Recent alu- minide development has greatly increased its durability, and some jet engine applications can be expected. Polymers and Polymer-Based Composites Polymers and polymer-based composites will probably con- tinue to displace carbon steel and aluminum in a significant seg- ment of structural and paneling applications. This trend may be most prominent in the automobile industry, but it is also likely in electronic hardware, appliance chassis applications, and home building components. Current automobiles contain about 157 pounds of plastics and polymer-based composites. By 1995, this should grow to 213 pounds as polymer materials are used increas- ingly in body panels. The increased use of plastic is expected to save motorists about $200 per year through fuel economy, corro- sion resistance, cheaper repairs, and lower insurance rates.2
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79 The applications seen in models such as the Pontiac Fiero will spread for reasons of economy and safety. In the Fiero, the hori- zontal body panels are made of flexible glass fiber-fi~led polyester (a sheet molding compound) and the vertical panels are made of relatively stiffer glass-reinforced polyurethane (a reaction injec- tion molded product). Beyond the body pane} substitutions, fur- ther use of polymers can be expected in the automobile structure. For example, polymeric leaf springs have been used in some auto- mobiles since 1981. While glass-polyester and glass-polyurethane materials will see major tonnage applications, future use of poly- mers in automobiles con be expected to rely on reaction injection molded thermoplastics as well. Beyond these applications, the ex- panded use of coatings (including paint) on steel can be regarded as an area where polymers will intrude further into the sheet metal markets. The growth of polymer panels and structural shapes has ne- cessitated the development of adhesives as a joining medium. In addition to the increased use of conventional adhesive materi- als, advanced work is under way on adhesive systems for higher- temperature applications (epoxies, polyimides), adhesives with greater strength and elastic range than epoxies, primerIess adhe- sives (silicones perhaps), and faster-curing adhesives (cyanoacry- lates, urethanes, etch. In some instances, adhesive development overlaps sealant systems (silicones). Beyond the relatively sim- ple polymer applications, adhesives are increasingly required for bonding dissimilar materials, particularly when differential ther- mal expansion must be accommodated. For example, rivets can- not be used to join plastic liners to metal trailer bodies because of differential thermal expansion. In some metal joining develop- ments, adhesives are being used in conjunction with spot welding to replace riveting. However, it must be emphasized that the use of adhesives for nonpolymeric joining has been slowed consider- ably by concerns about reliability, contamination, degradation, and consumer acceptance. Another major shift in polymer materials use can be fore- seen where flame retardation is a dominant consideration. Under- writers Laboratory interpretations of smoke, flame, and toxicity
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80 requirements are leading to shifts away from polyvinyl chioride- based systems to fluorocarbons. High-Technology Ceramics Advanced high-technology ceramics3 are nonmetallic materi- als having combinations of fine-scale microstructures, purity, com- plex crystal structures, and precisely controlled additives. In con- trast to traditional ceramics, which are made from natural raw materials such as silica and clay, advanced ceramics are made from artificial raw materials, such as aluminum oxide, zirconia, yttria, silicon nitride, and silicon carbide, which are formed, sintered, and treated under precisely controlled conditions. The advantage of such fine ceramics is their ability to play both functional and structural roles. Functional uses include optical devices, motors, transducers, sensors, and semiconductors; structural uses include those that require high specific strength, high wear resistance, and high corrosion resistance. Both roles will be increasingly impor- tant in manufacturing applications. Currently, high-technology ceramics are used most often in electronics, including optical fibers, multilayer ceram~c-to-metal interconnecting and mounting packages for integrated circuits, ce- ramic multilayer chip capacitors, piezoelectric ceramic transduc- ers, and chemical, mechanical, and thermal sensors. Processing for these applications is generally an extension of standard ceramic technology, in which powders are pressed or formed with binders and sintered to density the ceramics. Incremental progress has im- proved results, but major improvements cannot be expected until semiconductor processing techniques are applied to ceramic com- ponents. Techniques such as selective-area ion implantation and laser-induced recrystallization will greatly improve many of the properties of electronics ceramics. High-technology structural ceramics are used as coatings and for monolithic and composite components. Major applications in- clude tooling for metal working, wear components in a variety of abrasive environments, bioceram~cs for bone replacement, and military ceramics for radomes and armor. Major efforts are un- der way in both the United States and Japan to use structural
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81 ceramics in a variety of automotive applications, including engine wear components, turbochargers, bearings, and a variety of diesel engine components. Significant strides have been made in the mechanical prop- erties and reliability of monolithic structural ceramics. Under- standing of strength-limiting flaws and temperature-brittle frac- ture behavior has improved greatly, but further work is needed to improve reliability. Improvements are needed in powder synthe- sis, powder properties, near-net-shape fabrication methods, mi- crostructure control, mechanical properties, and nondestructive testing methods. Important research also is needed to identify new, more complex ceramics. Significant advances also are being made in thermal barrier coatings and ceramic matrix composites. Ceramic matrices com- bined with particulates, whiskers, or fibers of a different ceramic compound or metal have yielded composites with five times the resistance to fracture of the monolithic ceramics. Recent success has been reported in the use of metal ion implantation to reduce the relative friction resistance of ceramic diesel engine parts.4 New research is needed to quantify the improved mechanical properties of composites, particularly fracture resistance. In addition to the research required on the composition and properties of ceramic materials, much work is needed on the pro- cessing and product design requirements of ceramics. Promising directions in ceramic processing include the use of ultrafine pow- ders and the use of chemical routes to supplement or bypass some of the powder-processing stages. Other requirements include the processing of fine-scale layered structures, processing of ceramic composites, joining of ceramic parts, and near-net-shape process- ing of complex parts to minimize machining requirements. The rate of technical progress in ceramic materials and pro- cessing will determine the pace of commercial application. Major market penetration for structural ceramics depends largely on the progress made in automobile applications. Several Japanese firms have already introduced ceramic turbocharger rotors, piston rings, swirl chambers, and camshafts.5 An almost totally ceramic engine is a major research objective of virtually every automobile manu- facturer and should be extant by the early 1990s. As these auto
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82 motive applications increase and the price falls, high-technology ceramics can be expected to see rapid growth in product and pro- cess (cutting tools) applications.6 General Issues Related to Materials It is important to recognize the critical lack of data on and basic understanding of the physical properties of many materials. This lack is a severe handicap in manufacturing process develop- ment. Most materials handbook data have been generated for use in product design and service performance analysis rather than for process analysis. The lack of knowledge has become acute as software systems have emerged with powerful process control and process design capabilities. The requisite data inputs often involve combinations of stress, strain, strain rate, temperature, heat transfer, friction, and so on, which have not been studied even for classic engineering materials. This lack of data on manufacturing materials grossly compro- mises the effectiveness of computer-based process models, and it tends to foster undue reliance on the few materials for which an adequate data base seems to exist. Power systems in particular are plagued by a lack of materials innovation due to the awesome data base requirements for service performance analysis, manu- facturing modeling, and code adherence. With the current low return on investment in much of the primary materials industry, little supplier information is being generated. While some man- ufacturers develop their own data bases, others find that largely empirical trials are the least expensive approach (from a local point of view). The scientific community has been reluctant to get involved in data-generating efforts that involve "no new science." Federal funding agencies, reinforced by peer review systems, also have shunned this area. Progress in generating this data could have a significant impact on a variety of industries and process applica- tions. Another recurring concern is the frequent lack of domestic suppliers for new materials, such as some ceramics. Manufacturers are reluctant to begin using new materials systems when only one
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83 or perhaps no domestic supplier exists. Many new materials are initially imported in quantity from Japan or Europe. A related problem is the growing tendency for manufacturers and wholesalers to limit inventory. Indeed, limiting inventories has emerged as a smart manufacturing practice, especially with high interest rates. However, this practice grossly limits the availability of new and many old materials for manufacturing trials. In fact, most of the materials in reference handbooks are not available in tryout quantities. Lastly, there is an important interaction between the use of new materials and recycling and scrap practices. This is particu- larly the case in the automobile industry, in which a by-product of primarily steel construction has been the relative purity of car bodies as a source of steed scrap. The ease of recycling car bodies is being compromised by the materials substitutions now occur- ring, which could significantly increase material costs in a number of industries. Although these problems slow progress, none is sufficient to prevent increased use of new materials in manufacturing if those materials are cost effective in production, performance, and main- tenance. Limited availability is probably the greatest handicap, because the machining, tooling, and processing required for many new materials can be vastly different from those for traditional metal cutting; significant research in a production environment is a prerequisite for increased use. Fortunately, enough produc- tion experience is being accumulated with many new materials, particularly polymers, to demonstrate their advantages and to encourage efforts in other areas of materials research. Despite the handicaps, significant breakthroughs can be expected so that changes in manufacturing materials will keep pace with the many other developments on the factory floor. MATERIAL HANDLING TECHNOLOGY TRENDS This section will assess the major trends in material handling technology. Material handling systems are used to enhance hu- man capabilities in terms of speed of movement, weight lifted, reach distance, speed of though", sensory abilities of touch, sight,
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84 smell, and hearing, and the ability to deal with harsh environ- ments. In this area, it is important to distinguish between equip- ment technology and design technology. Equipment technology is categorized by its primary functions: transporting, storing, and controlling materials. Transporting The material handling function of transporting material has been affected significantly by two trends toward smaller loads and toward asynchronous movement. The former is the result of the drive to lower inventory levels through just-in-time pro- duction. It has been manifested in the development of numerous equipment alternatives that have been downsized for transporting tote boxes and individual items rather than the traditional pallet Toads. The inverted power-and-free conveyor, powered by linear induction motors for precise positioning and automatic loading and unloading, is one example of the trend to develop transport equipment for small loads. Automatic guided vehicles (AGVs) for transporting individual tote boxes are also being developed, as are specially designed conveyors and monorails for tote box movement. The use of asynchronous movement in support of assembly has existed for many years. For example, asynchronous material handling systems were prevalent in automotive assembly before the paced assembly line was adopted at Ford in the early l900s, and the concept has been applied recently in some European au- tomotive assembly operations. In the early 1970s, Volvo began using AGVs to achieve asynchronous handling in support of job enlargement. Asynchronous material handling equipment is often used to allow a worker to control the pace of the process. The trend toward asynchronous movement appears to be par- tially motivated by the apparent success of Japanese electronics firms in using specially designed chain conveyors that place the control of the assembly process in the hands of the assembly op- erators. A workpiece is mounted on a platform or small pallet which is powered by two constantly moving chains. The platform is freed from the power chain when it reaches an operator's station.
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85 After work is completed on the workpiece, the operator connects the pallet to the chain, and it moves to the next station; if the next station has not completed its work on the previous piece, the pallets accumulate on the chain. Asynchronous alternatives include using AGVs as assembly platforms and for general transport functions; "smart" monorails for transporting parts between work stations; transporter con- veyors to control and dispatch work to individual work stations; robots to perform machine loading, case packing, palletizing, as- sembly, and other material handling tasks; microload automated storage and retrieval machines for material transport, storage, and control functions; cart-on-track equipment to transport material between work stations; and manual carts for low-volume material handling activities. Storing The major trends in material storage technology are strongly influenced by the reduction in the amount of material to be stored and the use of distributed storage. Rather than installing eight to ten aisles of automated storage and retrieval equipment, firms are now considering one- and two-aisTe systems. Rather than being designed to store pallet loads of material, systems are designed to store tote boxes and individual parts. Also, rather than a centralized storage system, a decentralized approach is used to store materials at the point of use. Among the storage technology alternatives that have emerged are storage carouse! conveyors; both horizontal and vertical rota- tion designs are available. Furthermore, one particular carouse! allows each individual storage level to rotate independently, clock- wise or counterclockwise. A further enhancement of the carousel conveyor is automatic loading and unloading through the use of robots and special fixtures. A number of microload automated storage and retrieval sys- tems have been introduced in recent years. The equipment is used to store, move, and control individual tote boxes of material. Rather than performing pick-up and deposit operations at the end of the aisle, the microload machine typically performs such oper
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115 of adaptive feedback is the key to improving product quality, with zero defects a realistic goal (see Figure A-1. Adaptive feedback is also one key to better management, since only in this way can a manager know exactly the state of production, including exact costs. Systems of manufacturing have a feedforward property that will allow management to control the factory floor with an effectiveness and immediacy never before pos- sible. (A more global discussion of hierarchical control is found in the subsection Computer-Integrated Manufacturing Systems.) Feedback and feedforward properties can also provide ma- chines and systems with sel£diagnosis features. Thus, a manu- facturing system can tell if something is wrong with it and what is wrong and can suggest the remedy to a higher entity. For ex- ample, researchers at the AMRF have already demonstrated the ability to sense when a too] is about to break so that automated equipment can change the too! without the disruption caused by untimely failure. Next will be limited self-maintenance and repair capabilities. When a data-intensive system breaks down, the in- tegrity of that data is threatened. Self-diagnosis will inform the data base system of the integrity of the data and, if it is threat- ened, the system will take either conservative or remedial action. Factory Management and Control The factory of the future will be managed and controlled through automated process planning, scheduling, modeling, and optimization systems. The successful implementation of large- scale factory-level systems depends upon structured analysis and design systems that depend heavily on GT. Limited structured analysis systems, such as the Air Force-sponsored Integrated Com- puter-Aided Manufacturing Definition, have been in use for years in the analysis and design of large projects. Only through such sys- tems can a manager know the exact state of his factory, and only through such exact knowledge of the present can a manager intel- ligently implement systems of manufacturing for the future. New systems development methodology packages, such as STRADIS, promise help in this area, but much work remains to be done be- fore such systems are easily used by the actual decision makers.
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116 Similar work must be done on process planning and scheduling systems before they can use the feedback and feedforward prop- erties of the hierarchical and adaptive closed-Ioop control systems to be found in future manufacturing systems. Management functions will be hierarchically distributed so that "go" an;d "halt" decisions may be made effectively from many levels and by human or machine. Through the use of terminals on the factory floor and throughout the decision-making structure, the system can respond instantaneously to human command. At first, most of the decision making will rest in the hands of humans. Low-leve} manufacturing systems now work in this way. As the systems become integrated at higher and higher levels, decision rules and methods will be built into them; systems wiD develop plans to carry out human-specified activities. On the authorized human's approval, the system will carry out the task, making low- leve] decisions on its own. If a low-level decision-making entity does not have a certain level of confidence in its decision, it may pass the decision up to the next-higher entity, be it human or computer. This new kind of man-machine interaction will allow humans to do what they do best: create, define, and communicate. The machine will do what it does best: work hard, steadily, and accurately. Modeling and Optimization Systems One tried and true method of representing an activity to a computer is through mathematical modeling. Computerized mod- eling tools, such as SLAM, have been used by simulation experts for years, but simulation is still more an art than a science. With experience and feedback, our ability to represent complex activ- ities mathematically will be refined. A modeling and simulation package will be a necessary part of an intelligent structured anal- ysis and design system. It is hard to overstate the importance of structured analysis and design systems; they will operate at high levels, with much built-in decision making. System modeling will become a commonplace and necessary prerequisite to the successful design and implementation of large- scale manufacturing systems. This is because large projects con
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117 tain too many facets to be managed effectively with only hu- man memory and computation capability. Artificial intelligence techniques will be needed to reduce the tremendous amounts of data generated by such systems to humanly understandable terms. This intelligence must be of a higher order than the Al expert sys- tems in existence today. With the addition of Al, a modeling system can become an optimization system, guiding its human managers to the most productive, most cost-effective, or highest-quality utilization of re- sources. With such optimization capability, managers will be able to sit at their work stations and, in real time, analyze the vari- ous possibilities to determine optimal solutions and mixes. The availability of accurate information on cost, time, and quality will eliminate much of the guesswork in manufacturing decision mak- ing. Flexible Manufacturing Systems Flexible manufacturing systems are expected to dominate the factory automation movement within 10 years. These FMSs will be tied into larger-scale manufacturing systems, but it is valuable to consider the FMS as a critical unit or building block in total factory integration. An FMS may be described as an integrated system of machines, equipment, and work and too} transport ap- paratus, using adaptive closed-Ioop control and a common com- puter architecture to manufacture parts randomly from a select family. The hardware components of an FMS may include an NC tool, a robot, or an inspection station. The part family processed by the FMS is defined by GT classification. For greatest produc- tivity, the FMS is optimized to produce only one family of parts, and conversely, the parts produced by the FMS are designed to facilitate processing by the FMS. The concept of flexibility as used in an FMS includes parts; · use of GT to achieve a part mix of related but different batching, adding, and deleting of parts during operation; dynamic routing of parts to machines;
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118 and rapid response to design changes; making production volume sensitive to immediate demand; dynamic reallocation of production resources In case of breakdown or bottleneck. Flexible manufacturing has been a reality in U.S. industry since its introduction in 1972, and the number of new FMS instal- lations is doubling every two years. The number and flexibility of FMSs is expected to increase, and the cost of FMS installations is expected to drop. Although the United States was largely re- sponsible for the technological development of the FMS, Western Europe and Japan both have more FMS installations than this country. In fact, one of the most frequently cited FMS instal- lations is located in the Messerschmidt-Boelkow-Blohm (MBB) plant in Augsburg, West Germany. The basic elements of this FMS are 25 NC machining centers and multispindIe gantry and traveling-column machines; automated too! transport and tool- changing systems; an AGV workplace transfer system; and hier- archical computer control of all these elements. The FMS is used to build wing-carrythrough boxes for Tornado fighter-bombers. Comparisons by MBB of the performance of this FMS versus the projected performance of stand-alone NC machine tools doing the same work clearly show the advantages of the FMS approach: number of machine tools decreased 52.6 percent; workforce reduced 52.6 percent; · tooling costs reduced 30 percent; · throughput increased 25 percent; · capital investment 10 percent less than for stand-alone equipment; and · annual costs decreased 24 percent.~4 U.S. statistics for FMS installations are no less startling. An FMS at General Electric (GE) improves motor frame productivity 240 percent; an AVCO FMS enables 15 machines to do the work of 65; and at Mack Trucks, an FMS parrots 5 people to do what 20 did before. In addition to productivity enhancements, the FMS offers increased floor space capacity. GE, for example, reported
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119 that floor space capacity was increased 50 percent, with a net floor space reduction of 30 percent. An FMS can make a factory more responsive to its market GE reported a shortening of its manufacturing cycle from 16 days to 16 hours. Computer-Integrated Manufacturing Systems The technologies discussed above will be integrated to create CIM systems whose synergy will make the whole greater than the sum of its separate technologies. CIM systems promise dramatic improvements in productivity, cost, quality, and cycle time. How- ever, since full CIM has not yet been accomplished and depends on continued technological progress, the benefits are difficult to quantify accurately. Incremental gains from the implementation of individual technologies and subsystems will be substantial. These benefits are illustrated by the following data from five companies that have implemented advanced manufacturing technologies over the past 1~20 years:~5 Reduction in engineering design cost Reduction in overall lead-time Increase in product quality Increase in capability of engineers Increase in productivity of production operations Increase in productivity of capital equipment Reduction in work-in-process Reduction in personnel costs 15-30 percent 30-60 percent 2-5 times 3-35 times 40-70 percent 2-3 times 30-60 percent 5-20 percent The cumulative gains of total system integration can be expected to build on these results exponentially. The long-range goal of CIM is the complete integration of all the elements of the manufacturing subsystems, starting with the conception and modeling of products and ending with ship- ment and servicing. It includes the tie-in with activities such as optimization, mathematical modeling, and scheduling. A CIM system is created by the interconnection or integra- tion of the processes of manufacturing with other processes or
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120 systems. The resultant aggregate system provides one or more of the following functions or characteristics: · An information communication utility that accesses data from the constituent parts of the system and serves as an infor- mation communication and retrieval system. · An information-sharing utility that integrates data across system elements into a unified data base. · An analysis utility that provides a mathematical mode! of a real or hypothetical manufacturing system. Employing sim- ulation and, when possible, optimization, this utility is used to characterize the behavior of the modeled system in various con- figurations. A resource-sharing utility that employs mathematical or heuristic algorithms to plan and control the allocation of a set of resources to meet a demand profile. A higher-order entity that integrates information and pro- cessing functions into a more capable, effective processing system. These functions and characteristics are not mutually exclusive in actual manufacturing systems; rather, they overlap significantly with all of the elements interconnected and integrated continually to form a single aggregated CIM. Perhaps the most important and least understood step in this process is the creation of an integrated system that is a higher-order entity; this is the true system-building goal. Both horizontal and vertical growth of CIM systems can be expected as the year 2000 approaches. State-of-the art technol- ogy now includes small aggregates of computer-integrated tasks, often called islands of automation. Such islands of automation are found in design, where CAD work stations from different vendors share their data through a common data base and data conver- sion interfaces; in planning, with manufacturing resource planning (MRP) systems; and in production, where a work cell composed of a robot, machine tool, and inspection station may be coordinated by a cell controller. In leading-edge plants, several of these islands of automa- tion have been aggregated into larger manufacturing subsystems, termed continents of automation. At this level of integration, links
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121 exist between the design and engineering departments, with CAD terminals and data bases sharing data with CAE work stations and data bases. In planning, MRP can be linked to traditional data bases containing ordering and shipping information. On the factory floor, several work cells may be integrated with a material handling system to create an FMS. In the factory of the future, these continents of automation will be integrated into worlds of automation that wfl] eventually encompass not only entire factories, but also entire corporations. Because of the volume of data and complexity of decisions needed for full integration, a hierarchical structure is the only feasible way to achieve it. A hierarchical structure has certain implications for the ar- chitecture of CIM systems. Data use and decision making must occur at the lowest levels possible. Only certain summary data will be passed upward in the hierarchy to be used in reporting the factory's state and in statistical trend analysis. Thus, an in- formation and decision hierarchy is needed that practices man- agement by exception. If additional information is required at upper levels, it will be requested. If local decision making can- not resolve a conflict, a decision wiB be requested from above. Conversely, management decisions may be communicated almost instantly throughout the system for rapid compliance. The hierarchical structure further implies the use of district uted data bases and distributed processing. A mainframe com- puter may be the host computer to the factory of the future. Connected to it will be an array of minicomputers, one level down in the hierarchy, each acting as host controller to an intermediate- level manufacturing system. A mix of local and centralized data storage will be appropriate for each computer. Below the m~ni- computers will be microcomputers acting as cell controllers, graph- ics work stations, or executive work stations. The elements of this hierarchical structure can be thought of as subsystems, categorized by the role they play, although it must be remembered that categories may overlap considerably. Most subsystems of manufacturing fall into one of the following broad categories: (1) information and communication, (2) inte- gration of processes, or (3) resource allocation. Note that each
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122 category cuts across traditional manufacturing boundaries. An information-communication subsystem, for example, could include a network that permits the geometric part data stored in the CAD data base to be transformed through GT techniques into an actual process plan and then into robot and NC programs communicated to the factory floor. The data would then be transformed and com- municated for process scheduling and material handling, right up to the delivery of the finished product. Information-oriented subsystems include traditional manage- ment information system and data processing roles. These sub- systems will be able to expand to include geometrical data from CAD systems, material and process data from GT coding, parts- in-process data, and order and inventory data. Information sum systems will have analytic capabilities by which the data can be massaged for quality control and trend analysis. Data retrieval will be easier for operators and decision makers through the use of new query languages or programs that wiD allow nonexperts access to complex data. Most, if not all, manufacturing subsys- tems have strong information and communication functions, even if they are primarily process or resource oriented. Manufacturing subsystems on the factory floor will integrate traditional manufacturing processes by coupling and controlling previously separated processes and by carrying out computer- generated process plans. At the lowest level, this will involve data communication from sensors to a computer-controlled machine or robot. This provides the real-time adaptive control necessary to improve the work quality and throughput of individual stations. At the next level, factory floor manufacturing subsystems can in- tegrate several processes, such as an NC machining station, an automated inspection station, and the robot which services them. In this example, the coordination is supplied by a computer which controls the work cell. The process plan is downloaded from a computer, which may be in the CAE area, to the work cell con- troller, which coordinates the processing by the machines in its cell. With automated inspection and data collection, the process plan may be modified to eliminate defects by responding in real time to tolerance changes. At yet a higher level, work cells are integrated into an EMS so that an automated scheduling system
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123 can assign a part in process to the next available work cell that can perform the necessary operation. This allows a system with fewer parts in process, shorter queues, fewer holding areas, and much more efficient use of floor space. Resource aBocation subsystems span a broad scope from small-scale material handling systems serving individual work cells to broadly implemented systems that monitor and control inven- tory, schedule work, and allocate materials to the factory floor on tight schedules. Automated material handling systems can be integrated into work cells and families of work cells to produce a powerful FMS. In turn, the FMS can be linked to production plan- ning and capacity planning systems to form the fully computer- integrated manufacturing systems illustrated in Figure A-1. One of the most important reasons for implementing smaB- scale subsystems of manufacturing now is that they can be suc- cessively integrated into these higher order entities, CIM sys- tems, that benefit from the synergy between operational pro- grams, product data, and process data. CONCLUSION All of these advanced manufacturing technologies, from ma- terials and machine tools to the subsystems and CIM systems, provide the ability to perform traditional manufacturing tasks in a highly advantageous but nontraditional manner. Many of the individual technologies and subsystems of manufacturing can be implemented today and, in fact, must be implemented soon for a manufacturer to remain competitive. Real progress toward the factory of the future will take place through the higher-level in- tegration of these technologies. Although a handful of domestic manufacturers continue to make progress in implementing and in- tegrating many of the technologies described in this appendix, real barriers to full integration remain. Specifically, standards are critically needed for the definition and communication of part data. At higher levels, the need is for proven systems of hierarchical control and feedback and usable methods of automated classification of parts and processes (GT). Required at the highest level are the evolution of structured anal
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124 ysis and design systems that include modeling and optimization packages, as well as intelligent user interfaces that can be used interactively by managers in read time. The technology Is here now or just around the corner. U.S. manufacturing needs far- sighted management and trained manufacturing engineers to put the pieces together. NOTES iMore detailed and comprehensive information on current de- velopments in metal matrix composites can be obtained from the National Research Council's National Materials Advisory Board. 2 The New York Times. November 17, 1985. Goodbye to Heavy Metal, p. F-1. 3 this section is based on Research Briefing Pane! on Ceramics and Ceramic Composites. 1985. Research Briefings 1985, pp. 60 71. Washington, D.C.: National Academy Press. 4Advanced Ceramics Technology. Pp. 23-24 in Technology Today, March 1986. Committee on the Status of High-Technology Ceramics in Japan. 1984. High-Technology Ceramics in Japan, p. 30. Wash- ington, D.C.: National Academy Press. 6 Ibid, pp. 24-25 and 33-34. Gives market growth projections in Japan, as well as different applications given several price sce- nar~os. 7Interestingly, the initial patents for AGVs were held by a U.S. firm, the Barrett Corporation. However, consistent with the European dominance in material handling equipment technology that has existed for many years, the Barrett Corporation was ac- quired by a European firm, the Mannesmann Demag Corporation. This section is based on Thompson, Brian, 1985, Fixtur- ing: The Next Frontier in the Evolution of Flexible Manufacturing Cells, CIM (March/April):1~13. 9A good description of current developments in micromechan- ics can be found in Brandt, Richard, 1986, Micromechanics: The Eyes and Ears of Tomorrow's Computers, Business Week (March 17):88-89.
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125 '°Smith, Donald N., and Peter Heyler, Jr. 1985. U.S. Indus- trial Robot Forecast and Trends: A Second Edition Delphi Study. Dearborn, Mich.: Society of Manufacturing Engineers. iiCommittee on Army Robotics and Artificial Intelligence. 1983. Applications of Robotics and Artificial Intelligence to Re- duce Risk and Improve Effectiveness, p. 58. Washington, D.C.: National Academy Press. i2 Committee on the CAD/CAM Interface. 1984. Computer Integration of Engineering Design and Production: A National Opportunity, p. 11. Washington, D.C.: National Academy Press. i3Shunk, Dan. Integrated Cellular Manufacturing. Paper pre- sented at the WESTEC conference, Los Angeles, March 1983. id Computer Integration of Engineering Design and Produc- tion, p. 50. i5Ibid., p. 17.
Representative terms from entire chapter: