Handbook of Industrial Automationedited - Chapter 6 doc

Chapter 6.1 The Future of Manufacturing M. Eugene Merchant Institute of Advanced Manufacturing Sciences, Cincinnati, Ohio 1.1 INTRODUCTION Since the past is a springboard to the future, a brief review of major trends in manufacturing over the years, from the Industrial Revolution to the present, provides our springboard. 1.2 THE BEGINNINGS The Industrial Revolution spawned organized manufacturing activity, in the form of small manufacturing companies. In such small, closely knit companies, every member of the organization could, face-to- face, communicate and co-operate quite freely and easily with every other member of that entity in carrying out the various functions involved in its overall operation. This situation was ideal for engendering manufacturing excellence. That is because the basic key to enabling a manufacturing organization to perform its product realization function most effectively is empowerment of every entity (people and equipment) in it to be able and willing to communicate and co-operate fully with every other entity in the organization. However, as factories grew in size, operating a company in such a manner became more and more dif®- cult, leading to the establishment of functional departments within a company. But the unfortunate result of this was that communication and co-operation between personnel in different departments was not only poor but dif®cult. Thus as companies grew in size, personnel in each department gradually became more and more isolated from those in the others. This situation ®nally led to a ``bits-and-pieces'' approach to the creation of products, throughout the manufacturing industry. 1.3 A WATERSHED EVENT Then, in the 1950s, there occurred a technological event having major potential to change that situation, namely, the invention of the digital computer. This was indeed a watershed event for manufacturing, though not recognized as such at the time. However, by the 1960s, as digital computer technology gradually began to be applied to manufacturing in various ways (as, for example, in the form of numerical control of machine tools) the potential of the digital computer for aiding and perhaps revolu- tionizing manufacturing slowly began to be under- stood. It gradually began to be recognized as an extremely powerful toolÐa systems toolÐcapable of integrating manufacturing's former ``bits-and-pieces.'' This recognition spawned a new understanding of the nature of manufacturing, namely that manufacturing is fundamentally a system. Thus, with the aid of the digital computer, it should be possible to operate it as such. Out of this recognition grew a wholly new concept, namely that of the computer integrated manufacturing 451 Copyright © 2000 Marcel Dekker, Inc. (CIM) system, having the capability not only to ¯ex- ibly automate and online optimize manufacturing, but also to integrate it and thus operate it as a system. By the end of the 1960s this concept had led to initial understanding of the basic components of the CIM system and their interrelationship, as illustrated, for example, in Fig. 1. 1.4 NEW INSIGHT EVOLVES Emergence of such understanding as the above of the potential of digital computer technology to signi®- cantly improve manufacturing's productivity and capabilities resulted in generation of major activity aimed at developing and implementing the application of manufacturing-related computer technology and reducing it to practice in industry, thus reaping its inherent potential bene®ts. What followed during the 1970s and early 1980s was a long, frustrating struggle to accomplish just that. It is important to note, however, that the focus and thrust of this struggle was almost totally on the technology of the system (and not on its human-resource factors). As the struggle progressed, and the technology ®nally began to be implemented more and more widely in the manufacturing industry, observation of the most successful cases of its reduction to practice began to make clear and substantiate the very substantial bene®ts which digital computer technology has the potential to bring to manufacturing. The most signi®cant of these were found to be greatly: Increased product quality Decreased lead times Increased worker satisfaction Increased customer satisfaction Decreased costs Increased productivity Increased ¯exibility (agility) Increased product producibility. However, a puzzling and disturbing situation also emerged, namely, these potential bene®ts were able to be realized fully by only a few pioneering companies, worldwide! The reason why this should be so was not immediately evident. But by the late 1980s the answer to this puzzle, found by benchmarking the pioneering companies, had ®nally evolved. It had gradually become clear that while excellent engineering of the technology of a system of manufacturing is a necessary condition for enabling the system to fully realize the potential bene®ts of that technology, it is not a suf®cient condition. The technology will only perform at its full potential if the utilization of the system's human resources also is so engineered as to enable all personnel to communicate and co-operate fully with one another. Further, the engineering of those resources must also be done simultaneously with the engineering of the application of the technology. Failure to meet any of these necessary conditions defeats the technology! 452 Merchant Figure 1 Initial concept of the computer-integrated manufacturing system, 1969. Copyright © 2000 Marcel Dekker, Inc. 1.5 A NEW APPROACH TO THE ENGINEERING OF MANUFACTURING EMERGES It is evident that this ®nding requires a new approach to be taken to the overall process of the engineering of modern systems of manufacturing (i.e., manufacturing enterprises). This approach to such engineering requires that proper utilization of the human resources of the system must be engineered, along with the engineering of its technology. Further, the two must be engineered simultaneously. Many of the features of this new approach began to be recognized early on, as made evident in the ``wheel-type'' diagram of the computer integrated manufacturing enterprise developed by the Computer Automated Systems Association of the Society of Manufacturing Engineers in 1993, reproduced as Fig. 2. However, it is only in the years since 1996 that this new approach has emerged in full. This emerging new approach to the engineering of manufacturing has brought with it a signi®cant present and future challenge, namely that of developing methodology for accomplishment of effective engineering of the utilization of human resources in manufacturing enterprises. Efforts to develop such methodology are The Future of Manufacturing 453 Figure 2 CASA/SME manufacturing enterprise wheel. Copyright © 2000 Marcel Dekker, Inc. of course already underway. Some of the more effective methodologies which have already emerged and been put into practice include: Empower individuals with the full authority and knowledge necessary to the carrying out of their responsibilities. Use empowered multidisciplinary teams (both man- agerial and operational) to carry out the functions required to realize products. Empower a company's collective human resources to fully communicate and co-operate with each other. Further, an important principle underlying the joint engineering of the technology and the utilization of it in modern systems of manufacturing has recently become apparent. This can be stated as follows: So develop and apply the technology that it will support the user, rather than, that the user will have to support the technology. However, these methodologies have barely scratched the surface. Continuation and expansion of research on this subject is an ongoing and long-term need. 1.6 WHERE WE ARE TODAY As a result of the evolution over the years of the technology and social structure of manufacturing, as brie¯y described in the foregoing, we are now at a state where: 1. Manufacturing enterprises, both large and small, are rapidly learning how to achieve a high degree of integration of their equipment, people and overall operation, both locally and globally, through utilization of advanced digital computer technology. 2. Such organizations are also beginning to dis- cover how to so engineer both the technology and the utilization of their human resources in such integrated systems that both that technology and the organization's people are able to perform at their full potential. Further, the development of digital computer technology is now advancing very rapidly in at least three main areas of major importance to the operation of future manufacturing enterprises, namely: 1. Holonic systems. These are systems of autonomous entities which, despite the fact that they are autonomous, are enabled to both communicate and co-operate with all the other entities in the system. The application of this technology to manufacturing systems is currently essentially experimental, but shows considerable potential for enhancing the performance of such systems. 2. Virtual reality. This technology is already being applied on a small scale in manufacturing systems, but still in only a rudimentary way. Even so, it shows great promise. 3. Intelligent systems. At this stage, the degree of intelligence which has been developed and demonstrated in manufacturing systems still represents only a very small fraction of its true potential. However, it is important to bear in mind that a large-scale international co-opera- tive program, known as the intelligent manufacturing systems (IMS) program, is currently underway among the major industrialized coun- tries of the world, aimed at signi®cantly advancing that potential. This overall picture of where we are today contains at least tenuous clues as to what manufacturing may be like in the future. Nevertheless, it has led us to the conclusion that future manufacturing enterprises and manufacturing technologies may well have such characteristics as are set forth in what follows below. 1.7 THE FUTURE MANUFACTURING ENTERPRISE The manufacturing enterprise of the future will be a virtual enterprise comprising an integrated global holonic system of autonomous units, both large and small, located in various places throughout the world. The fact that the system is holonic is its key feature. That fact means that every entity of the system (people, machines, software elements, etc., including its external suppliers, customers, and other stakeholders) within or associated with each of its units will be enabled and empowered to both fully communicate and fully co- operate with one another, for the purpose of attaining a common goal (or goals). The autonomous units making up such an enterprise will resemble conventional companies in a general way, but, in addition to a core unit, they will consist mainly of semispecialized units having special skills necessary to the attainment of one (or more) of the enterprise's current goals. Thus they will be the princi- pal elements of the supply chain required for the attainment of those goals. However, the composition 454 Merchant Copyright © 2000 Marcel Dekker, Inc. of the overall enterprise will be dynamic, changing as new goals are chosen. Furthermore, to be accepted as a ``member'' of a given enterprise, a unit will have to negotiate ``employment'' in it, based not only on its special skills but also on the entire spectrum of its capabilities. ``Employment'' will terminate if it fails to perform as required, or as new goals are chosen for the attainment of which it has failed to prepare itself. The operation of the product realization process in such global manufacturing enterprises will be based on concurrently engineering both the technology required to carry out that product realization process and the utilization of the human resources required to carry out that same process, to enable both the technology and the human resources to perform at their full joint (synergistic) potential. 1.8 FUTURE MANUFACTURING TECHNOLOGIES It is obvious from the foregoing that a wealth of new or improved technologies will be needed to accomplish full realization of the future manufacturing enterprise as described above. In particular, two main types of technology will need considerable development. These are: 1. Technologies to enable the enterprise to be holonic. 2. Technologies to enable the enterprise to be effectively managed. Concerning the ®rst, these are technologies needed to enable and empower every entity (persons, machines, software systems, etc.) to both fully communicate and fully co-operate online and in real time, with every other entity of the enterprise (including its external suppliers, customers and other stakeholders) and to do so wherever they are, worldwide. The ultimate need is to enable such communication and co-operation to be of a character that is equal to that possible if they are in the same room and face-to-face with each other. First of all, this will require that the technology have the capability to ¯awlessly transfer and share between persons not only information, but also knowledge, understanding and intent. Here (taking a ``blue- sky'' type of approach for a moment), development of technology that can provide capability for mind-to- mind communication would be the ultimate goal. Secondly, to fully enable such communication and co-operation between all entities (persons, machines, software, etc.) will require capability to fully replicate the environment of a distant site at the site which must join in the physical action required for co-operation. Here, development of the emerging technologies associated with virtual reality is a must. Concerning the second of the two types of needed technology, referred to above, the major problems to be dealt with in enabling the future enterprise to be effectively managed arise from two sources. The ®rst of these is the uncertainty engendered by the sheer complexity of the system. The second is the fact that (like all sizable systems of manufacturing) the future enterprise is, inherently, a nondeterministic system. This comes about because systems of manufacturing have to interface with the world's economic, political, and social systems (as well as with individual human beings), all of which are nondeterministic. This results in a high degree of uncertainty in the performance of such systems, which, when no other measures prove able to handle it, is dealt with by exercise of human intuition and inference. The technology which shows greatest promise for dealing with this inherent uncertainty is that of arti®cial-intelligence-type technology. This will, in particular, need to be developed to provide capability for performance of powerful intuition and inference which far exceeds that of humans. 1.9 CONCLUSION It seems evident from a review of the evolution of manufacturing from its beginnings to the present, that, under the impact of today's rapidly advancing computer technology, major changes for the better still lie ahead for manufacturing. It can be expected that the global manufacturing enterprises which are evolving today will unfold into holonic systems in which all entities (people, machines, software elements, etc.) will be enabled to communicate and co-operate with each other globally as fully as though they were in the same room together. Further, the composition of the enterprises themselves will consist of semispecialized units which compete and negotiate for ``member- ship'' in a given enterprise. The operation of the product realization process in such global manufacturing enterprises will be based on integration of the engineering of the technology required to carry out that process with the engineering of the utilization of the human resources required to carry out that same process, to enable both the technology and the human resources to perform at their full joint (synergized) potential. The Future of Manufacturing 455 Copyright © 2000 Marcel Dekker, Inc. Chapter 6.2 Manufacturing Systems Jon Marvel Grand Valley State University, Grand Rapids, Michigan Ken Bloemer Ethicon Endo-Surgery Inc., Cincinnati, Ohio 2.1 INTRODUCTION This chapter provides an overview of manufacturing systems. This material is particularly relevant to organizations considering automation because it is always advisable to ®rst streamline and optimize operations prior to automation. Many automation attempts have had less than transformational results because they focused on automating existing processes without re-engineering them ®rst. This was particularly evident with the massive introduction of robots in the auto- mobile industry in the 1970s and early 1980s. Automation, in the form of robots, was introduced into existing production lines, essentially replacing labor with mechanization. This resulted in only mar- ginal returns on a massive capital investment. Therefore, the authors present manufacturing techniques and philosophies intended to encourage organizations to ®rst simplify and eliminate non-value- added elements prior to considering automation. This chapter begins with a categorization of the various types of manufacturing strategies from make- to-stock through engineer-to-order. This is followed by a discussion covering the spectrum of manufacturing systems including job shops, project shops, cellular manufacturing systems, and ¯ow lines. The primary content of this chapter deals with current manufacturing techniques. Here readers are introduced to the con- cepts of push versus pull systems and contemporary manufacturing philosophies including just in time, theory of constraints, and synchronous and ¯ow manufacturing. Lastly, the authors present several world-class manufacturing metrics which may be use- ful for benchmarking purposes. It is important to note that the term manufacturing system, although sometimes used interchangeably with production system, consists of three interdependent systems.AsseeninFig.1,themanufacturingsystem incorporates enterprise support, production, and production support. Production has the prime responsibility to satisfy customer demand in the form of high- quality low-cost products provided in timely manner. The enterprise and production support system provides the organization with the infrastructure to enable production to attain this goal. Many of the manufacturing strategies addressed in this chapter include all three interdependent systems. 2.1.1 Product Positioning Strategies The manufacturing organization, operating within its manufacturing system, must determine which product positioning strategy is most appropriate to satisfy the market. The product positioning strategy is associated 457 Copyright © 2000 Marcel Dekker, Inc. with the levels and types of inventories that the organization holds. Manufacturing lead time, level of product customization, delivery policy, and market demand are the typical factors which in¯uence the choice of strategies. Organizations will usually follow one or any combination of the following strategies: 1. Make-to-stock: a manufacturing system where products are completed and placed into ®nished goods inventory or placed in a distribution cen- ter prior to receiving a customer order. This strategy highlights the immediate availability of standard items. The organization must maintain an adequate stock of ®nished goods in order to prevent stockouts, since the customers will not accept delays in product availability. 2. Assemble-to-order: a manufacturing system where products undergo ®nal assembly after receiving a customer order. Components or subassemblies used for ®nal assembly are pur- chased, stocked, or planned for production prior to receiving the customer order. This system is able to produce a large variety of ®nal products from standard components and subassemblies with short lead times. This type of system is also known as ®nished-to-order or packaged-to-order. 3. Make-to-order: a manufacturing system where the product is manufactured after a customer has placed an order. In this environment, production must be able to satisfy the demands of individual customers. Longer lead times are usually tolerated, since the product is customized to the customer's speci®c needs. 4. Engineer-to-order: a manufacturing system where the customer order requires engineering design or other degrees of product specializa- tion. A signi®cant amount of the manufacturing lead time is spent in the planning or design stages. The organization receives customer orders based on technical ability to design and produce highly customized products. This type of system is also known as design-to-order. 2.1.2 Product Processing Strategies 2.1.2.1 Job Shop Jobshops(Table1)areoneofthemostcommontypes of product processing systems used in the United States today. Machines, typically general purpose, with similar functional or processing capabilities are grouped together as a department. Parts are routed through the different departments via a process plan. This environment satis®es a market for nonstandard or unique products. Products are manufactured in small volumes with high product variety. These types of functional layouts are also referred to as process layouts. Products manufactured in a job shop could include space vehicles, reactor vessels, turbines, or aircraft. An example of a job shop layout, also known as aprocesslayout,isshowninFig.2. As product volumes increase, job shops are trans- formed into production job shops. these types of environments typically require machines with higher production rates in order to regulate medium-size production runs. Machine shops and plastic molding plants are typically classi®ed as production job shops. 458 Marvel and Bloemer Figure 1 Manufacturing system components. Copyright © 2000 Marcel Dekker, Inc. Manufacturing Systems 459 Table 1 Job Shop Characteristics People Personnel require higher skill levels in order to operate a variety of equipment Personnel are responsible for a diversity of tasks Specialized supervision may be necessary Machinery Production and material-handling equipment are multipurpose Machine utilizations are maximized General-purpose equipment requires lower equipment investment Increased ¯exibility of machinery allows uncomplicated routing manipulation to facilitate even machine loading and accommodate breakdowns Methods Product diversity creates jumbled and spaghetti-like ¯ow Lack of coordination between jobs prevents balanced product ¯ow Low demand per product Detailed planning and production control is required to handle variety of products and volumes Materials Parts spending a long time in the process creating with high work-in-process inventory Low throughput rates Products run in batches Increased material-handling requirements Figure 2 Job shop. Copyright © 2000 Marcel Dekker, Inc. 2.1.2.2 Project Shop In a project shop (Table 2), the products position remains stationary during the manufacturing process due to the size, weight, and/or location of the product. Materials, people, and machinery are brought to the product or product site. This type of environment is also called a ®xed-position or ®xed-site layout. Products manufactured in a project shop could include aircraft, ships, locomotives, or bridge and building construction projects. An example of a project shop layout is shown in Fig. 3. 2.1.2.3 Cellular Manufacturing System Acellularmanufacturingsystem(Table3)formspro- duction cells by grouping together equipment that can process a complete family of parts. The production 460 Marvel and Bloemer Table 2 Project Shop Characteristics People Personnel are highly trained and skilled Opportunities for job enrichment are available General supervision is required Pride and quality in job are heightened due to workers' ability to complete entire job Machinery Resources are required to be available at proper time in order to maintain production capacity Equipment duplication exists Methods General instructions provide work plans rather than detailed process plans Continuity of operations and responsibility exist Production process is ¯exible to accommodate changes in product design Tight control and coordination in work task scheduling is required Materials Material movement is reduced Number of end items is small but lot sizes of components or subassemblies ranges from small to large Increased space and work-in-process requirements exist Figure 3 Project shop. Copyright © 2000 Marcel Dekker, Inc. environment contains one or more cells which are scheduled independently. The ¯ow among the equipment in the cells can vary depending on the composition of parts within the part family. The family parts are typically identi®ed using group technology techniques. An example of a project shop layout is showninFig.4. 2.1.2.4 Flow Line The last major style of con®guring a manufacturing systemisa¯owline(Table4).Ina¯owline,machines and other types of equipment are organized according to the process sequence and the production is rate based. These types of layout are also known as product or repetitive manufacturing layouts. Dedicated repetitive and mixed-model repetitive are the most common types of ¯ow lines for discrete products. Dedicated repetitive ¯ow lines produce only one product on the line or variations if no delay is incurred for changeover time. Mixed model repetitive refers to manufacturing two or more products on the same line. Changeover between products is minimized and mixed model heuristics determine the sequence of product variation that ¯ow through the line. When the ¯ow line produces liquids, gases, or powders, such as an oil re®nery, the manufacturing process is referred to as a continuous system rather than a ¯ow line. An exampleofa¯owlinelayoutisshowninFig.5. A special type of ¯ow line is the transfer line. Transfer lines utilize a sequence of machines dedicated to one particular part or small variations of that part. Usually the workstations are connected by a conveyor, setups take hours if not days, and the capacity is fully utilized. Examples of transfer lines include automotive assembly, beverage bottling or canning, and heat treat- ing facilities. Automated transfer line which include NC or CNC machines, and a material handling system that enables parts to follow multiple routings, are generally referred to as ¯exible machining systems (FMS). 2.2 PUSH VERSUS PULL TECHNIQUES A basic functional requirement in a production system is the ability to provide a constant supply of materials to the manufacturing process. The production system must not only ensure that there is a constant supply of materials but that these materials must be the correct materials supplied at the appropriate time in the correct quantity for the lowest overall cost. Generally, material release systems can be categorized as either ``push'' or ``pull'' systems. Push systems will normally schedule material release based on predetermined sche- dules, while pull systems utilize downstream demand to authorize the release of materials. Traditional manufacturing environments, which normally utilize material requirements planning Manufacturing Systems 461 Table 3 Cellular Manufacturing Characteristics People Job enlargement and cross-training opportunities exist Labor skills must extend to all operations in cell Provides team atmosphere General supervision is required Personnel are better utilized Provides better communication between design and manufacturing engineering Machinery Increased machine utilization results from product groupings Standardization based on part families helps decrease machine setup times by 65±80% Required ¯oor space is reduced 20±45% to produce same number of products as a job shop General-purpose rather than dedicated equipment is common Methods Smoother ¯ow, reduced transportation time, less expediting, decreased paperwork, and simpler shop ¯oor controls result Families of parts, determined through group technology, have same set or sequence of manufacturing operations Production control has responsibility to balance ¯ow Cells are less ¯exible than job shop layouts Materials Material buffers and work-in-process are required if the ¯ow is not balanced Reduction of 70±90% in production lead times and WIP inventories compared to job shops Parts move through fewer material-handling operations, 75±90% reduction compared to job shops Quality-related problems decrease 50±80% Copyright © 2000 Marcel Dekker, Inc. [...]... centers or other subsets of the manufacturing enterprise, organi- 4 76 Marvel and Bloemer zations are more likely to achieve the global goal of making money The second element of synchronous manufacturing is to develop straightforward cause-and-effect relationships between individual actions and the global goal and its associated metrics Here we can see the relationship of the theory of constraints to synchronous... just-in-time (JIT) manufacturing system developed by Taiichi Ohno of Toyota Copyright © 2000 Marcel Dekker, Inc Current cycle time Value-added time The average ratio among manufacturers in the United States is 120:1 This ratio implies that there are 120 hr of non-value-added time for every hour of value-added time! The manufacturer who achieves a ratio of 10:1 has a signi®cant competitive advantage for numerous... days based on an annual purchasing agreement or blanket purchase order The average on-hand inventory in this scenario is 60 00 screws (including a 2-day safety stock of 1000 screws) as depicted in Fig 10 Copyright © 2000 Marcel Dekker, Inc 467 Figure 9 Two-bin kanban system There are numerous advantages of this two-bin kanban material replenishment strategy, including: Raw materials are ordered based... is enhanced through use of these TQC sheets and the ability to detect defects or rejects at early points in the process Additionally, the sequence of events sheets are able to identify non-value-added steps which increase manufacturing costs and are not dictated by product speci®cations or customer demand The identi®cation of non-value-added steps allows for the calculation of the process design ef®ciency,... nonvalue-added activities, acquiring additional resources to increase the capacity at the bottleneck stations, or creating WIP inventory by running bottleneck stations more hours than the rest of the line One of the more common techniques is the use of in-process kanbans In-process kanbans are placed on the downstream side of two imbalanced operations to balance the line The calculation for the number of. .. Speed to Market Denver, CO: JIT Institute of Technology, 1994 BIBLIOGRAPHY Adair-Heeley C The Human Side of Just-in-Time: How to Make the Techniques Really Work New York: American Management Association, 1991 Black JT The Design of the Factory with a Future New York: McGraw-Hill, 1991 Chryssolouris G Manufacturing Systems: Theory and Practice New York: Springer-Verlag, 1992 Cox III JF, Blackstone Jr... designed to organize a sequence of abstract actions or rules from a set of primitives stored in a long-term memory regardless of the present world model In other words, it serves as the generator of the rules of an inference engine by processing (intelligently) a high level of information, for reasoning, planning, and decision making This can be accomplished by a two-level neural net, analytically... machine by Saridis and Moed [5] The co-ordination level is an intermediate structure serving as an interface between the organization and execution levels It deals with real-time information of the world by generating a proper sequence of subtasks pertinent to the execution of the original command It involves co-ordination of decision making and learning on a short-term memory, e.g., a buer Originally,... minimum amount of material required to meet immediate customer demand is received nearest its point of use, ``just in time'' for production Processing waste There are numerous categories of processing wastes ranging from removal of excess materials from components (e.g., removal of gates from a casting) and materials consumed in the manufacturing process (e.g., cutting ¯uids) to non-value-added machine... (DFM), design for assembly (DFA), single minute exchange of dies (SMED) and line balancing are examples of methods aimed at the elimination of processing wastes Inventory waste As mentioned above, many Western interpretations of JIT focused almost solely on reduction of inventory In numerous cases this has had the net effect of merely pushing the burden of inventory carrying costs further upstream to the . non-value- added elements prior to considering automation. This chapter begins with a categorization of the various types of manufacturing strategies from make- to-stock through engineer-to-order large variety of ®nal products from standard components and subassemblies with short lead times. This type of system is also known as ®nished-to-order or packaged-to-order. 3. Make-to-order: a manufacturing. constant). Guarantees ®rst-in ®rst-out inventory rotation. A west-coast manufacturer of medical devices replaced their cumbersome MRP system with a two- Manufacturing Systems 467 Figure 9 Two-bin