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Electronically networked assembly systems for global manufacturing
Journal of Materials Processing Technology 107 (2000) 319±329
Electronically networked assembly systems for global manufacturing K. Feldmann*, H. Rottbauer Institute for Manufacturing Automation and Production Systems, University of Erlangen±Nuremberg, 91058 Erlangen, Germany
Abstract In industrial production engineering a radical structural change is taking place. The developments in microelectronics, the data and communication technology as well as the fast evolving markets result in changing requirements for the productivity, ¯exibility and availability of assembly systems. The ¯exibility of future assembly systems is not only a question of technology but is determined by a holistic view of the value adding chain. The application of electronics is a key factor for achieving and maintaining competitiveness in the major economic ®elds. The impact of electronics on different steps in the value adding chain will be discussed exemplarily in the ®eld of electronic assembly. # 2000 Elsevier Science B.V. All rights reserved. Keywords: Assembly; Globalization; Flexible manufacturing
1. Introduction Today's competitive environment is characterized by an intensive competition resulting from market saturation and increasing demands for a customer-orientated production. Additionally, technological innovations have in¯uence on the competitive environment. These facts have dramatically altered the character of manufacturing. Meeting the customer's demands requires a high degree of ¯exibility, lowcost/low-volume manufacturing skills and short delivery times [1]. So, production and thereby manufacturing performance have gained signi®cant increase and are conceived as a strategic weapon for both achieving and maintaining competitiveness [2]. Especially in high-tech markets, where product technology is rapidly evolving, manufacturing process innovation is becoming an increasingly critical capability for product innovation [3]. To meet the requirements of today's markets, new paths must be trodden both in organizational methods and in manufacturing and automation technology. 2. Challenges to assembly in global manufacturing Rationalization of assembly is still technologically impeded by high product variety and the various in¯uences resulting from the manufacturing tolerances of the parts to * Corresponding author. Tel.: 49-9131-85-27569; fax: 49-9131-3025-28. E-mail addresses: [email protected] (K. Feldmann), [email protected] (H. Rottbauer).
be joined [4]. As a result considerable disturbance rates are leading to a reduced availability of the assembly systems and a delay of the assembly operations [5]. This complicates an ef®cient automation and consolidates considerations for a displacement of assembly plants into lower cost regions. Additionally, assembly is in¯uenced by innovative developments in the manufacturing of parts like surface technology or connecting technology, which can have essential in¯uence on the assembly structures. This effect is also reinforced by the in¯uence of microelectronics on the product design and the manufacturing structure as well as by the global communication possibilities. Within the framework of assembly rationalization electronics almost has a double effect (Fig. 1, [6]). In the ®rst step, ef®cient assembly solutions can be built up by electronically controlled systems with programmable controllers and sensors. In a second step, the assembly task can be completely substituted with an electronically provided function. Examples are the substitution of electromechanical ¯uorescent lamp starters with an electronic solution or on a long-term basis, the substitution of the technically complex letter-sorting installations with purely electronic communication via global computer networks. The substitution of electromechanical solutions with electronic functional carriers does not only reduce assembly expenditure. Additionally, electronics production can be automated more ef®ciently. In many cases the functionality and thus the customer bene®t can be expanded by the transition to entirely electronic solutions. The high signi®cance of assembly to a company's success is given by its function and quality determining in¯uence on
0924-0136/00/$ ± see front matter # 2000 Elsevier Science B.V. All rights reserved. PII: S 0 9 2 4 - 0 1 3 6 ( 0 0 ) 0 0 6 7 4 - 9
320
K. Feldmann, H. Rottbauer / Journal of Materials Processing Technology 107 (2000) 319±329
Fig. 1. The impact of electronics on rationalization and substitution of assembly.
the product at the end of the direct production chain (Fig. 2). Due to the fast changing market and production conditions the role and the design of the individual functions within the entire value adding chain are also changing. Facing the
customer's demands, the after sales or service function, for example, is becoming increasingly important for a company's success. More and more customers wish to make the availability of the product a part of the purchasing contract.
Fig. 2. Changing role and signi®cance of assembly in the value adding chain.
K. Feldmann, H. Rottbauer / Journal of Materials Processing Technology 107 (2000) 319±329
Due to the fact that assembly is the last step in the value adding chain towards customers, the set-up of local assembly plants is one of the ®rst steps of globalization. Two generic global manufacturing strategies have evolved and have been widely implemented in recent years [7]: the factor-input strategy has a primary objective, the enhancement of a ®rm's competitive position through the acquisition and use of the best low-cost or high-quality mix of factor inputs available. In contrast, the market-access strategy focuses on increasing the ®rm's access to foreign markets by the local set-up of manufacturing and assembly plants. With regard to site selection for assembly plants two major strategies can be identi®ed [6]: assembly follows the markets, and/or assembly is being transferred to national economies in pursuit of lower production costs (Fig. 3). In the triad US, Japan and Europe there are grave differences of labor costs compared to those of the respective neighboring states. These cost differences lead partly to the relocation of prefabrication, so that the function determining assembly further remains in the country of origin with more favorable costs. Another strategy is the arrangement of assembly plants in the new target markets. There is a whole range of considerations favoring in-market assembly. In addition to a quicker market-speci®c access to customers and suppliers these include local content requirements of the target countries, currency ¯uctuations and the opportunity to develop new operating methods on the basis of local technical and organizational developments [8].
321
3. Change of assembly technology The manufacturing process in industry is characterized by growing complexity, which has its origin in the globalization of the markets, the customer demands for systems instead of single products and the introduction of new materials and technologies. Designing a product for the ease of assembly using the design for manufacture and assembly (DFMA) methodology leads to a reduced number of variants and parts, higher quality, shorter time-to-market, lower inventory and few suppliers and makes a signi®cant contribution to the reduction of complexity in assembly [9]. The in¯uence of the different branches and product structures is more evident in the range of assembly technology than in prefabrication. In general, for all industries four fundamental solutions in assembly design can be distinguished (Fig. 4): manual assembly at small batch sizes is opposed by automated serial assembly. Thus the introduction of ¯exible assembly systems is reinforced. Again, these ¯exible automated assembly systems offer two alternatives. The integration of NC-axes increases the ¯exibility of conventional automats, whereas the introduction of robot solutions is aimed at opening up further assembly tasks for an ef®cient automation. There have been many technological responses to the global demand for a large product variety coupled with short delivery times. In this context the concept of human integrated production systems is gaining ground. The intention here is to allow the human
Fig. 3. Decentralization of assembly plants following the markets and labor costs.
322
K. Feldmann, H. Rottbauer / Journal of Materials Processing Technology 107 (2000) 319±329
Fig. 4. The basic technological alternatives in assembly.
operator to be vital participant in the future computer integrated manufacturing systems. This has also an impact on the design of assembly systems. Prevalent drivers for assembly rationalization are changes in the product structure and the in¯uence of electronics. A common approach from car assembly up to the assembly in the electronics industry is the stronger concentration on higher functional density in subsystems (Fig. 5). In car assembly this means preassembling of complex units like doors or cockpits, in electronics this means circuit design with few, but highly integrated circuits. In the following, new potentials for the automation of assembly are shown exemplarily in the case of the assembly of large lightweight components. At the Institute for Manufacturing Automation and Production Systems, University of Erlangen±Nuremberg, failure-tolerant assembly systems are developed to detect deviations of the process in¯uencing parameters and to deduce extended strategies for compensation of ¯uctuations [10]. Preliminary analysis showed that close part tolerances are often caused by the insuf®cient error tolerances of automated assembly systems and not necessarily by high qualitative demands on the ®nal products. Fig. 6 shows the approach of hierarchical internal system control loops in combination with assembly spanned coordination of assembly, manufacturing and design. The major goal to achieve with this approach is to create robust, shortened process sequences in order to increase assembly quality and to reduce costs of production.
4. Rationalization and substitution of assembly by electronics As mentioned before the use of electronics in the broad range of assembly tasks leads in different ways to ef®cient assembly solutions. In the following the rationalization effect of electronics will be shown in the ®eld of electrical engineering in the whole range from coil winding technology up to the assembly of electronic devices. An example of the rationalization in assembly by electronics is the realization of an integrated control loop for winding at multi-spindle winding systems based on electronic devices with programmable controllers and sensors (Fig. 7, [11]). Tolerances of the bobbin geometry and especially of the wire diameters lead to different ohmic resistances at the respective spindles. Measuring the wire diameters by laser scan micrometers and the actual wound up length of each coil by incremental length measuring devices allows the on-line adjustment of the tensile force for each tensioner to in¯uence the resistance and to minimize the tolerances of all parallel produced coils. This leads to a better quality and a higher output due to the reduction of rejects. During manufacturing of printed circuit boards onserting, that means connecting the components with the board, is one of the most important process steps. In general, two different onserting technologies can be distinguished: the through hole technology (THT) and the surface mount technology (SMT). The use of surface mount devices (SMD) favors an
K. Feldmann, H. Rottbauer / Journal of Materials Processing Technology 107 (2000) 319±329
Fig. 5. Trends towards new assembly structures characterized by more subassembly both in automotive and electronics industry.
Fig. 6. Hierarchical control loops in assembly.
323
324
K. Feldmann, H. Rottbauer / Journal of Materials Processing Technology 107 (2000) 319±329
Fig. 7. Rationalization of assembly by electronic devices.
automated assembly, because the components can be easily onserted on the printed circuit board in comparison to the THT. Additionally the concentration of higher functional density in subsystems enables the reduction of process steps (Fig. 8). On the basis of technological innovations especially in microelectronics, the introduction of the SMT has lead to an enormous change of the respective assembly systems. The assembly of high precision components like ®ne-pitch results in high requirements on the accuracy of onserting machines. For the compensation of disturbances of the assembly processes due to geometric variations in the size of the electronic components an image processing system can be integrated in onserting machines. This is a further example of ef®cient assembly solutions based on electronically controlled systems. Fig. 9 shows the development of the assembly structure in the case of telephone devices. A look at the production costs indicates that the material costs are already dominating 80%. Concerning the material costs, the share of electronics is 50%, whereas the value of the integrated circuits amounts to 25%. Two conclusions can be drawn
in the ®eld of electronically determined products: ®rstly, the integration of electronics and housing becomes decisive for function and assembly task, and secondly, the purchase conditions for semiconductors become decisive for product prices. The assembly of microelectronics and mechanical housings is in¯uenced by a further technological innovation: the direct integration of the electronic circuit into a molded product housing. The molded interconnect devices (MID) technology aims at the integration of electrical and mechanical functions in almost any shape of planes. MID, therefore, enables totally new functions and supports the further miniaturization of products [12]. Fig. 9 also illustrates the CAD conception and kinematic simulation of an onserting machine for three-dimensional component placement developed at the Institute for Manufacturing Automation and Production Systems, University of Erlangen±Nuremberg. Further applications can be expected both for devices of telecommunications and consumer electronics and for the important ®eld of automotive electronics. Examples for the application of MID in the automotive industry are shown in Fig. 10.
K. Feldmann, H. Rottbauer / Journal of Materials Processing Technology 107 (2000) 319±329
325
Fig. 8. SMD assembly systems for ®ne-pitch and high-volume tasks.
The integrative MID technology also leads to new concepts in the previous division of labor of electronic board assembly and the later assembly into a device. When integrating electrical and mechanical functions, the whole value adding chain from injection molding through structuring to electronic and mechanical assembly must be signi®cantly re-engineered, too.
5. Global networking Today's paradigms for manufacturing require an holistic view of the value adding chain. The disadvantages of breaking up the value adding chain and distributing the single functions globally can be compensated by models and tools supporting an integrated process optimization. Examples for
Fig. 9. In¯uence of microelectronics on the assembly structure of electronic devices.
326
K. Feldmann, H. Rottbauer / Journal of Materials Processing Technology 107 (2000) 319±329
Fig. 10. Examples for the application of MID in the automotive industry (source: MIDIS).
this are multimedia applications based on new developments in information technology and the concept of virtual manufacturing building on simulation technology. The diffusion of systems such as electronic data interchange (EDI) and integrated service digital network (ISDN) allow a more ef®cient communication and information exchange (Fig. 11). Distributed and decentralized manufacturing involves the problem of locally optimized and isolated applications as well as incompatibilities of process and system. To ensure synergy potentials and to stabilize the productivity of the distributed assembly plants an intensive communication and data exchange within the network of business units is vital. New information technologies provide correct information and incentives required for the coordination of ef®cient global production networks. The coordination of a network of transplants dispersed throughout the world provides an operating ¯exibility that adds value to the ®rm. From that point of view a decisive improvement of the conditions for global production networks has turned up again under the in¯uence of microelectronics with the new possibilities of telecommunication. Processing programs developed world-
wide can be used in all production sites by means of direct computer guidance (Fig. 12). The rising complexity of machines and their world-wide application lead to an increasing importance of remote diagnosis. Therefore, at the Institute for Manufacturing Automation and Production Systems, University of Erlangen±Nuremberg, a computer-aided remote diagnosis system based on Internet technologies has been developed (Fig. 13). The remote diagnosis system is designed for the installation on the machine manufacturer's WWW-server being world-wide accessible both for the operator and the expert. On the server the essential components and features of the system are installed, as they are the information system with the description of the failure-cause-structures for a type of onserting system, the knowledge-based diagnostic strategies as well as the multimedia means of communication. The hierarchical graded strategies are made for fault recovery using in parallel the competence of the operator and the expert. With the developed remote diagnosis system for onserting machines from a central control center the diagnosis of the assembly systems is coordinated. In this way, it becomes
K. Feldmann, H. Rottbauer / Journal of Materials Processing Technology 107 (2000) 319±329
327
Fig. 11. The new possibilities of electronic communication also favor ef®cient global production networks.
possible to transmit the management of a project in the global production network following the times of day. The competition resulting of technological innovations, serious changes in world politics and general economic ¯uctuations have caused a dynamic change in production engineering as hardly ever before. The displacement of
assembly plants into the target markets and/or countries with low labor costs is taking place on a large scale. There are ®rst lasting signs for the restructuring of research and education in manufacturing, too. Especially the production research, particularly the product determining assembly technology, requires a feedback of experiences
Fig. 12. On-line control, supervision and visualization of ¯exible production systems via internet [13].
328
K. Feldmann, H. Rottbauer / Journal of Materials Processing Technology 107 (2000) 319±329
Fig. 13. Structure of the remote diagnosis system for onserting machines with hierarchically graded strategies for diagnosis [14].
Fig. 14. Possible changes in research and education caused by the trend towards globally distributed assembly.
from realized solutions. In this context presently two controversial ideas are discussed (Fig. 14). On the one hand, research and education in production engineering follows production or on the other hand, development and education are successfully positioned detached from the plants and the experienced closed loop control system can be preserved with innovative possibilities of telecommunication.
6. Conclusion Advances in technology and shifting market requirements are the root of the new dynamics shaping corporate management, communications, and production systems. These trends suggest that the global corporations of the future will evolve into networks of decentralized manufacturing plants
K. Feldmann, H. Rottbauer / Journal of Materials Processing Technology 107 (2000) 319±329
headquartered in the world's largest and most sophisticated regional markets. References [1] J.D. Goldhar, D. Lei, The shape of twenty-®rst century global manufacturing, J. Business Strategy 3 (4) (1991) 37±41. [2] C. Verter, M. Dincer, An integrated evaluation of facility location, capacity acquisition and technology selection for designing global manufacturing strategies, Eur. J. Oper. Res. 60 (1992) 1±18. [3] G.P. Pisano, S.C. Wheelwright, High-Tech R&D, Harvard Business Rev. 9 (10) (1995) 93±105. [4] H.K. ToÈnshoff, E. Metzel, H.S. Park, A knowledge-based system for automated assembly planning, Ann. CIRP 41 (1) (1992) 19±24. [5] T. Arai, K. Yamaba, N. Koyachi, Robot assembly scheme in intelligent manufacturing system, in: Proceedings of the 24th International Symposium on Industrial Robots, 1993, pp. 161±168. [6] K. Feldmann, H. Rottbauer, N. Roth, Relevance of assembly in global manufacturing, Ann. CIRP 45 (2) (1996) 545±552.
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[7] S.E. Fawcett, Strategic logistics in co-ordinated global manufacturing success, Int. J. Prod. Res. 30 (1992) 1081±1099. [8] J. Milberg, Manufacturing in the US Ð a challenge for German manufacturing technology, VDMA (1995) 9±22. [9] G. Boothroyd, Product design for manufacture and assembly, Computer-Aided Design 26 (1994) 505±520. [10] K. Feldmann, B. MuÈller, T. Haselmann, Automated assembly of lightweight automotive components, Ann. CIRP 48 (1) (1999) 9±12. [11] K. Feldmann, K. Wolf, Computer based planning of coil winding processes for improvements in ef®ciency and quality, in: Proceedings of the Electrical Manufacturing and Coil Winding, 1996, pp. 299± 305. [12] K. Feldmann, A. Brand, Analytical and experimental research on assembly systems for molded interconnection devices (3D-MID), Ann. CIRP 43 (1) (1994) 15±18. [13] K. Feldmann, S. Krimi, Alternative placement systems for threedimensional circuit boards, Ann. CIRP 47 (1) (1998) 23±25. [14] K. Feldmann, J. GoÈhringer, Multimedia system for remote diagnosis of complex placement machines, AC'98, in: Proceedings of the V International Conference on Monitoring and Automatic Supervision in Manufacturing, Warsaw, 1998.
Electronically networked assembly systems for global manufacturing K. Feldmann*, H. Rottbauer Institute for Manufacturing Automation and Production Systems, University of Erlangen±Nuremberg, 91058 Erlangen, Germany
Abstract In industrial production engineering a radical structural change is taking place. The developments in microelectronics, the data and communication technology as well as the fast evolving markets result in changing requirements for the productivity, ¯exibility and availability of assembly systems. The ¯exibility of future assembly systems is not only a question of technology but is determined by a holistic view of the value adding chain. The application of electronics is a key factor for achieving and maintaining competitiveness in the major economic ®elds. The impact of electronics on different steps in the value adding chain will be discussed exemplarily in the ®eld of electronic assembly. # 2000 Elsevier Science B.V. All rights reserved. Keywords: Assembly; Globalization; Flexible manufacturing
1. Introduction Today's competitive environment is characterized by an intensive competition resulting from market saturation and increasing demands for a customer-orientated production. Additionally, technological innovations have in¯uence on the competitive environment. These facts have dramatically altered the character of manufacturing. Meeting the customer's demands requires a high degree of ¯exibility, lowcost/low-volume manufacturing skills and short delivery times [1]. So, production and thereby manufacturing performance have gained signi®cant increase and are conceived as a strategic weapon for both achieving and maintaining competitiveness [2]. Especially in high-tech markets, where product technology is rapidly evolving, manufacturing process innovation is becoming an increasingly critical capability for product innovation [3]. To meet the requirements of today's markets, new paths must be trodden both in organizational methods and in manufacturing and automation technology. 2. Challenges to assembly in global manufacturing Rationalization of assembly is still technologically impeded by high product variety and the various in¯uences resulting from the manufacturing tolerances of the parts to * Corresponding author. Tel.: 49-9131-85-27569; fax: 49-9131-3025-28. E-mail addresses: [email protected] (K. Feldmann), [email protected] (H. Rottbauer).
be joined [4]. As a result considerable disturbance rates are leading to a reduced availability of the assembly systems and a delay of the assembly operations [5]. This complicates an ef®cient automation and consolidates considerations for a displacement of assembly plants into lower cost regions. Additionally, assembly is in¯uenced by innovative developments in the manufacturing of parts like surface technology or connecting technology, which can have essential in¯uence on the assembly structures. This effect is also reinforced by the in¯uence of microelectronics on the product design and the manufacturing structure as well as by the global communication possibilities. Within the framework of assembly rationalization electronics almost has a double effect (Fig. 1, [6]). In the ®rst step, ef®cient assembly solutions can be built up by electronically controlled systems with programmable controllers and sensors. In a second step, the assembly task can be completely substituted with an electronically provided function. Examples are the substitution of electromechanical ¯uorescent lamp starters with an electronic solution or on a long-term basis, the substitution of the technically complex letter-sorting installations with purely electronic communication via global computer networks. The substitution of electromechanical solutions with electronic functional carriers does not only reduce assembly expenditure. Additionally, electronics production can be automated more ef®ciently. In many cases the functionality and thus the customer bene®t can be expanded by the transition to entirely electronic solutions. The high signi®cance of assembly to a company's success is given by its function and quality determining in¯uence on
0924-0136/00/$ ± see front matter # 2000 Elsevier Science B.V. All rights reserved. PII: S 0 9 2 4 - 0 1 3 6 ( 0 0 ) 0 0 6 7 4 - 9
320
K. Feldmann, H. Rottbauer / Journal of Materials Processing Technology 107 (2000) 319±329
Fig. 1. The impact of electronics on rationalization and substitution of assembly.
the product at the end of the direct production chain (Fig. 2). Due to the fast changing market and production conditions the role and the design of the individual functions within the entire value adding chain are also changing. Facing the
customer's demands, the after sales or service function, for example, is becoming increasingly important for a company's success. More and more customers wish to make the availability of the product a part of the purchasing contract.
Fig. 2. Changing role and signi®cance of assembly in the value adding chain.
K. Feldmann, H. Rottbauer / Journal of Materials Processing Technology 107 (2000) 319±329
Due to the fact that assembly is the last step in the value adding chain towards customers, the set-up of local assembly plants is one of the ®rst steps of globalization. Two generic global manufacturing strategies have evolved and have been widely implemented in recent years [7]: the factor-input strategy has a primary objective, the enhancement of a ®rm's competitive position through the acquisition and use of the best low-cost or high-quality mix of factor inputs available. In contrast, the market-access strategy focuses on increasing the ®rm's access to foreign markets by the local set-up of manufacturing and assembly plants. With regard to site selection for assembly plants two major strategies can be identi®ed [6]: assembly follows the markets, and/or assembly is being transferred to national economies in pursuit of lower production costs (Fig. 3). In the triad US, Japan and Europe there are grave differences of labor costs compared to those of the respective neighboring states. These cost differences lead partly to the relocation of prefabrication, so that the function determining assembly further remains in the country of origin with more favorable costs. Another strategy is the arrangement of assembly plants in the new target markets. There is a whole range of considerations favoring in-market assembly. In addition to a quicker market-speci®c access to customers and suppliers these include local content requirements of the target countries, currency ¯uctuations and the opportunity to develop new operating methods on the basis of local technical and organizational developments [8].
321
3. Change of assembly technology The manufacturing process in industry is characterized by growing complexity, which has its origin in the globalization of the markets, the customer demands for systems instead of single products and the introduction of new materials and technologies. Designing a product for the ease of assembly using the design for manufacture and assembly (DFMA) methodology leads to a reduced number of variants and parts, higher quality, shorter time-to-market, lower inventory and few suppliers and makes a signi®cant contribution to the reduction of complexity in assembly [9]. The in¯uence of the different branches and product structures is more evident in the range of assembly technology than in prefabrication. In general, for all industries four fundamental solutions in assembly design can be distinguished (Fig. 4): manual assembly at small batch sizes is opposed by automated serial assembly. Thus the introduction of ¯exible assembly systems is reinforced. Again, these ¯exible automated assembly systems offer two alternatives. The integration of NC-axes increases the ¯exibility of conventional automats, whereas the introduction of robot solutions is aimed at opening up further assembly tasks for an ef®cient automation. There have been many technological responses to the global demand for a large product variety coupled with short delivery times. In this context the concept of human integrated production systems is gaining ground. The intention here is to allow the human
Fig. 3. Decentralization of assembly plants following the markets and labor costs.
322
K. Feldmann, H. Rottbauer / Journal of Materials Processing Technology 107 (2000) 319±329
Fig. 4. The basic technological alternatives in assembly.
operator to be vital participant in the future computer integrated manufacturing systems. This has also an impact on the design of assembly systems. Prevalent drivers for assembly rationalization are changes in the product structure and the in¯uence of electronics. A common approach from car assembly up to the assembly in the electronics industry is the stronger concentration on higher functional density in subsystems (Fig. 5). In car assembly this means preassembling of complex units like doors or cockpits, in electronics this means circuit design with few, but highly integrated circuits. In the following, new potentials for the automation of assembly are shown exemplarily in the case of the assembly of large lightweight components. At the Institute for Manufacturing Automation and Production Systems, University of Erlangen±Nuremberg, failure-tolerant assembly systems are developed to detect deviations of the process in¯uencing parameters and to deduce extended strategies for compensation of ¯uctuations [10]. Preliminary analysis showed that close part tolerances are often caused by the insuf®cient error tolerances of automated assembly systems and not necessarily by high qualitative demands on the ®nal products. Fig. 6 shows the approach of hierarchical internal system control loops in combination with assembly spanned coordination of assembly, manufacturing and design. The major goal to achieve with this approach is to create robust, shortened process sequences in order to increase assembly quality and to reduce costs of production.
4. Rationalization and substitution of assembly by electronics As mentioned before the use of electronics in the broad range of assembly tasks leads in different ways to ef®cient assembly solutions. In the following the rationalization effect of electronics will be shown in the ®eld of electrical engineering in the whole range from coil winding technology up to the assembly of electronic devices. An example of the rationalization in assembly by electronics is the realization of an integrated control loop for winding at multi-spindle winding systems based on electronic devices with programmable controllers and sensors (Fig. 7, [11]). Tolerances of the bobbin geometry and especially of the wire diameters lead to different ohmic resistances at the respective spindles. Measuring the wire diameters by laser scan micrometers and the actual wound up length of each coil by incremental length measuring devices allows the on-line adjustment of the tensile force for each tensioner to in¯uence the resistance and to minimize the tolerances of all parallel produced coils. This leads to a better quality and a higher output due to the reduction of rejects. During manufacturing of printed circuit boards onserting, that means connecting the components with the board, is one of the most important process steps. In general, two different onserting technologies can be distinguished: the through hole technology (THT) and the surface mount technology (SMT). The use of surface mount devices (SMD) favors an
K. Feldmann, H. Rottbauer / Journal of Materials Processing Technology 107 (2000) 319±329
Fig. 5. Trends towards new assembly structures characterized by more subassembly both in automotive and electronics industry.
Fig. 6. Hierarchical control loops in assembly.
323
324
K. Feldmann, H. Rottbauer / Journal of Materials Processing Technology 107 (2000) 319±329
Fig. 7. Rationalization of assembly by electronic devices.
automated assembly, because the components can be easily onserted on the printed circuit board in comparison to the THT. Additionally the concentration of higher functional density in subsystems enables the reduction of process steps (Fig. 8). On the basis of technological innovations especially in microelectronics, the introduction of the SMT has lead to an enormous change of the respective assembly systems. The assembly of high precision components like ®ne-pitch results in high requirements on the accuracy of onserting machines. For the compensation of disturbances of the assembly processes due to geometric variations in the size of the electronic components an image processing system can be integrated in onserting machines. This is a further example of ef®cient assembly solutions based on electronically controlled systems. Fig. 9 shows the development of the assembly structure in the case of telephone devices. A look at the production costs indicates that the material costs are already dominating 80%. Concerning the material costs, the share of electronics is 50%, whereas the value of the integrated circuits amounts to 25%. Two conclusions can be drawn
in the ®eld of electronically determined products: ®rstly, the integration of electronics and housing becomes decisive for function and assembly task, and secondly, the purchase conditions for semiconductors become decisive for product prices. The assembly of microelectronics and mechanical housings is in¯uenced by a further technological innovation: the direct integration of the electronic circuit into a molded product housing. The molded interconnect devices (MID) technology aims at the integration of electrical and mechanical functions in almost any shape of planes. MID, therefore, enables totally new functions and supports the further miniaturization of products [12]. Fig. 9 also illustrates the CAD conception and kinematic simulation of an onserting machine for three-dimensional component placement developed at the Institute for Manufacturing Automation and Production Systems, University of Erlangen±Nuremberg. Further applications can be expected both for devices of telecommunications and consumer electronics and for the important ®eld of automotive electronics. Examples for the application of MID in the automotive industry are shown in Fig. 10.
K. Feldmann, H. Rottbauer / Journal of Materials Processing Technology 107 (2000) 319±329
325
Fig. 8. SMD assembly systems for ®ne-pitch and high-volume tasks.
The integrative MID technology also leads to new concepts in the previous division of labor of electronic board assembly and the later assembly into a device. When integrating electrical and mechanical functions, the whole value adding chain from injection molding through structuring to electronic and mechanical assembly must be signi®cantly re-engineered, too.
5. Global networking Today's paradigms for manufacturing require an holistic view of the value adding chain. The disadvantages of breaking up the value adding chain and distributing the single functions globally can be compensated by models and tools supporting an integrated process optimization. Examples for
Fig. 9. In¯uence of microelectronics on the assembly structure of electronic devices.
326
K. Feldmann, H. Rottbauer / Journal of Materials Processing Technology 107 (2000) 319±329
Fig. 10. Examples for the application of MID in the automotive industry (source: MIDIS).
this are multimedia applications based on new developments in information technology and the concept of virtual manufacturing building on simulation technology. The diffusion of systems such as electronic data interchange (EDI) and integrated service digital network (ISDN) allow a more ef®cient communication and information exchange (Fig. 11). Distributed and decentralized manufacturing involves the problem of locally optimized and isolated applications as well as incompatibilities of process and system. To ensure synergy potentials and to stabilize the productivity of the distributed assembly plants an intensive communication and data exchange within the network of business units is vital. New information technologies provide correct information and incentives required for the coordination of ef®cient global production networks. The coordination of a network of transplants dispersed throughout the world provides an operating ¯exibility that adds value to the ®rm. From that point of view a decisive improvement of the conditions for global production networks has turned up again under the in¯uence of microelectronics with the new possibilities of telecommunication. Processing programs developed world-
wide can be used in all production sites by means of direct computer guidance (Fig. 12). The rising complexity of machines and their world-wide application lead to an increasing importance of remote diagnosis. Therefore, at the Institute for Manufacturing Automation and Production Systems, University of Erlangen±Nuremberg, a computer-aided remote diagnosis system based on Internet technologies has been developed (Fig. 13). The remote diagnosis system is designed for the installation on the machine manufacturer's WWW-server being world-wide accessible both for the operator and the expert. On the server the essential components and features of the system are installed, as they are the information system with the description of the failure-cause-structures for a type of onserting system, the knowledge-based diagnostic strategies as well as the multimedia means of communication. The hierarchical graded strategies are made for fault recovery using in parallel the competence of the operator and the expert. With the developed remote diagnosis system for onserting machines from a central control center the diagnosis of the assembly systems is coordinated. In this way, it becomes
K. Feldmann, H. Rottbauer / Journal of Materials Processing Technology 107 (2000) 319±329
327
Fig. 11. The new possibilities of electronic communication also favor ef®cient global production networks.
possible to transmit the management of a project in the global production network following the times of day. The competition resulting of technological innovations, serious changes in world politics and general economic ¯uctuations have caused a dynamic change in production engineering as hardly ever before. The displacement of
assembly plants into the target markets and/or countries with low labor costs is taking place on a large scale. There are ®rst lasting signs for the restructuring of research and education in manufacturing, too. Especially the production research, particularly the product determining assembly technology, requires a feedback of experiences
Fig. 12. On-line control, supervision and visualization of ¯exible production systems via internet [13].
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Fig. 13. Structure of the remote diagnosis system for onserting machines with hierarchically graded strategies for diagnosis [14].
Fig. 14. Possible changes in research and education caused by the trend towards globally distributed assembly.
from realized solutions. In this context presently two controversial ideas are discussed (Fig. 14). On the one hand, research and education in production engineering follows production or on the other hand, development and education are successfully positioned detached from the plants and the experienced closed loop control system can be preserved with innovative possibilities of telecommunication.
6. Conclusion Advances in technology and shifting market requirements are the root of the new dynamics shaping corporate management, communications, and production systems. These trends suggest that the global corporations of the future will evolve into networks of decentralized manufacturing plants
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