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Development of new concepts and software tools for the optimization of manual assembly systems
Development of new concepts and software tools for the optimization of man ual assem bly systems K Felhann (l), S. Junker Institute fw ManufacturingAutmation and Production Systems, University of ErlangewNuremberg,Germany
Abstmd Due to grrming numbers of differing products and mriannts, assembly systems with optifired manual w w k h t i o n s hiwe become M efficient alternative to hi#& autmated but less flexible production systems. Especially in the final stage of the product assembly, the flembillty of human enployees enables them to meed the requirements for assembling various products and changng volumes. In wder to create hi#ly efficient production systems biased on human work, it is necessary to develop innmahe cmcepts for the desigr and wgimktion of manual assembly mctures. Another majw issue is the development of sohiare tools allowing the facillty planner to simulate and optifire the conplebe desigr of the assembly &ucture such as the matterial flrm or manual workstations, e.g. with respect to ergonmics, befwe construction. These requirements hiwe led to a cmprehensive research hmewwk fw manual assembly systems. Keywwds: Assembly, Flexible Manufachrring System, Simulation
1 INTROWCTlON The transition of m h e b sbuchrres towards a custmerfowsed market has led to significant changes in the requirements of assembly systems. M e r e a s wstomers' needs could be easily satisfied with high batch sire produced standard products a few years ago, t&y% bryers demand a wide h e b y of products, optifired fw their indvidual needs. The consequence of this development for the manufacturer is the increased i m m c e of flembillty in the production s e w . Therefore, flembillty and agillty are key issues fw realizing efficient and mpetitive production systems [ l ] . Further biasic requirements for cmpetitive assembly systems indude a high level of e c m m i c efficiency as well as appropriate wganization methods and assembly techndoges [2]. Especially in malC and medumsized c m p n i e s , this high level of flembillty can be achieved through the use of manual assembly systems. This fwm of assembly combines a low inv-ent risk with a hi# level of adapbbillty and productiwty. However, mast manual assembly systems still hiwe the potential to be opbmized. In addtion to efficient techniques fw planning and designing human biased systems, the infwmation and k n d e d g e management of enployees plays a majw role in manual assembly systems [3]. Furthermwe, factws such as the wganization of employees and the introduction of modular assembly systems offer further possibilities fw increasing the efficiency of enployee related manufacturing systems. 2 MonvAnoN AND ERCONOMCS The m& inpmtiant a&iantiage of manual assembly &uctures is their capbilty to be quickly adapted to changing products and m h e b situations. A very i m m t precondition for this purpase is the cooperativeness and willingness of the wwkers to acmpl and support the required changng processes. Beside other issues (figure l ) , the encwmgement and pesewation of employee m o h t i o n is the biasic requirement for the successful operation of manual assembly systems. One majw factw that encwmges wwker m o h t i o n is the delegation of responsibillty to the enployee. The wgimktion of work within a tern, for i n h c e , provides
each wwker with the passibillty to perform and accmplish assembly tasks a-rdng to their indvidual skills and k n d e d g e . This ensures that in an ideal case, enployees are neither ove-ined nw unchallenged and thus are able to reach their indvidual achievement potential. A! the same time, dependng on the conplexlty of the bmsfened responsibilities, such errployee cooperation requires social and emotional conpebences in addition to the necessary assembly skills [4]. The introduction of teamwwk offers the wwkers a number of benehts. These indude an improved work atmosphere, diversified wwk cmtents as well as a higher selC confidence and sense of responsibility. On the other hand the c m p n y profits frm the increased workfwce contentnmnt and the more efficient utilization of enployee potential. Furthermwe, the introduction of tearwork has pasitive effects on the conpliance with hi# qualty standards and addtionally leads to high producbvlty and flexibility.
Figure 1: Effects on the productiwty of manual assembly systems
In addtion to the enrichment of work contents, perfwmanmrelated payment struchrres and flexible wwking h w r s represent efficient tods fw increasing motivation and productivlty. F l d b l e Iabwr time also constitutes a yeat chance fw cd-siaving, permitting short-notice adamtion of productive capacity to the actual demand. In contrasf financial incentives stimulate the employees to monitor their wwk and conply with high quallty and productiwty hndards.
related with the workers willingness to perform their duties is the design of manual wwkplaces that consider the demands of human bodies under wwk condtions as well as physical -ins. By the prwision of ergonmic wwkhtions, the wwkfwce has no need to waste effort on poshrre corrections, brt is able to concentrate its prmer on value addng processes. The a h h g e s of ergonmic desigred wwkhtions and processes are reduced numbers of employees away sick as well as further enhancement to wwker motivation [q. For this reason, the men classic types of wastage defined by Toy& have to be extended with an eiath, the wastage emerging frm wwking procedures that can adversely affect health [q,
m.
3 PUNNING MANUAL ASS-Y STRUCTURES In wder to ensure a fast and reliable production rimpup, the enployees' special requirements concerning the manufacturing equipment have to be taken into account within the planning and desigr shge. As a result of the effectiveness of t&y% cmputer-aided simulation tools, failures in the technologcal and ewnorrrical planning can be prevented at an early stage [El. Modern simulation tools prwide the passibillty of conputer biased modelling, visualization and simulation of c m p l e x production &uchrres. Currently, bdh logical and physical conshints can be considered in a virtual model of an assembly system. The aim of this technology is the kndedgebased validation of dfferent assembly &uctures. The cmputer-biased m p r i s o n of variws l q m t s enables the planner to predct passible bottlenecks w failure sMIrces in the planning stage (figure 2).
The simulation of human wwkers' motions in a virtual manufacturing environment is another significant feature for the process of planning manual assembly sbuchrres. The s o k e based analysis of assembly wwk contents and the deterrrrination of corresponding fwces and twques in adrance allows M early opbrrrlation of the assembly process. In addition, a m w r r e n t analyas of the wwkers poshrre allrms the dassifidion of a process' ergonmic characteristics per fraction of time (figure 3). Thus, the user has the oppwtunlty to optirrrLe the laywt of a worksbhon with respect to ergonmic aspects in M early planning phase. Furthemwe, the simulation of human workers allrms M estimation of the assembly times expected fw the real production. This has a special effect on the desigr of c m p l e x production mchrres since it enables the planner to fwesee the achimmble productivity dependng on the number o f w w k h t i o n s [q.
Figure 3: Ergonmic analysis providesjoint-related details about the q e c t e d physical stress
Another innovative trend within the simulation technology field are the current developments in the arm of Internet biased simulations, the smcalled 'web based desigr simulation". wlth the provision of on-line simulatim capabilities together with piarts and conponents libraries, the user, e.g. a system desigrer, CM conduct initial testing and analysis withmt the need to invest in expensive simulation tools. An accwdn& opbrrrled, web biased simulation tool CM result in sigrificant c& reductions. The application of this web technology gives prticularly small and mediumsized c m p n i e s the opportunlty to use simulation systems as efficient planning tools.
4 Figure 2: Inproving the efficiency of manual assembly systems with virtual manufacturing
The soitware supported planning of assembly system l q m t s and wwkstation desigrs allrms the arrangement of comnercial as well as user specific system elements w modules within the virtual factmy. On the one hand these models m s i s t of both a q u h b l e and n m adjustable gemeQical data, which are required fw correct visualization. On the other hand, each model includes information describing the logcal conshints with other virtual system modules. The models of the individual conponents can nrm be arranged, either manually or in M interactive way, within the faallty accwdng to the planners' demands. Based on this virtual assembly system models fw the simulation of logistics, simulation of ergonorrrics and discrede went simulations can be derived. Furthermore, two w more &uctural l q m t s with dffering technical and econorrric aspects CM be mmluated. Parts lists, price lists, gemebical dmensions or the w e i a t of the designed device are only a few examples of the w i w s infwmation provided by such a sirnulation.
MOWLAR A S E m L Y SYSTEMS
As prwiwsly described, manual production can be a highly efficient shtegy fw the realization of markedWiented assembly m c h r r e s . Beside the human abillty to conply to changng demands of variable duties and wwk contents, lasting flexibillty g i n s can be achieved by using suitable manufachrring equipment fw i n h n c e stepwise upgradeable assembly systems (figure 4). A considerable d s a h h g e of conventional assembly &uctures is that they are oRen desigred to meed special requirements, i.e. the upper limit of the estimated production volume. The lack of flembillty of such facilities concerning variable demand situations prevents their short-term, econorrrical adaptation of producbvlty accwdng to the actual marked condtions. Since the beak-wen point of such assembly systems is bed, a prerequisite fw making a p o M is to exceed a wen rrrinimum production volume [ 1o]. The flexibility of modern assembly systems offered today oRen suffers frm the lack of adaptability regarding variws issues, such as possibilities to quickly conply to changing demands or shortened product life cydes [q. For this reason, a modular assembly system has been
developed at the Institute fw Manufacturing Automation and Production Systems (FAPS) to meed in particular the requirements of highly flexible, manual assembly struchrres. The major g d of this project was to create lowcost devices that are especially desigred to meed the specific requirementsof manual wwkstations.
availability of relevant assembly knowhow fw all current products and also for thase that are actually not in production anymore. In gened, t&y% infwmation management systems that are located in the production area cmsist of a wieby of dfferenf self-whining and function-wiented modules. The prwision of production data is oRen realized with wder-related forms, on which every work step has to be noted and sigred. Additionally, many workstations dsplay hard copied infwmation abwt processrelevant issues. The major problem of such a shared data management system is the dah a h i n i h t i o n , since there is no passitility fw pwfwming quick and conpanywide updates. Furthemwe there is no opbon for the worker to adoldedge in-ctions w report problems from the assembly area hack to the adrrrinisthve level.
Figure 4: AdMing the productMty to the demand with stepwise upgradeable, modular assembly systems The basic element of the dweloped concept is a standardized wwkplace module, which CM be modified to conply with variws assembly requirements. On the one hand, this can be achieved by mwnting different kinds of function-dented workspace modules on M integrated interface fmmwwk. On the other hand, a workstation can be quiddy and easily adapted to changng requirements by the integation of addtional expansion elements, e.g. t d holders or bmes fw parts dsposition. To implement a material flrm that meeds the requirements of the dfferent h g e s during the stepwise expansion of the manual assembly system, a wide variety of standardized bimsfer modules is available. The user can hereby select manual w automated modules or a combination of bdh. A special f e d r e of the systems' struchrre is the strict classification of the conponents in intelligent and unintelligent units. This suppwts the realization of cost-efficient sbuchrres, for i n h n c e in the start-up phase. The capacity of the production system can be easily adapted to changing demands throughwt the product's lifecyde, e.g. by incwpmting further workstiations or M automated material flrm. The great advantage of this concept is the option to delay invesment until it is required, e.g. as a result of M increase in demand. From the cmpanies' view, this is preferable as this approach minirrrLes the risk of inmrect financial decisions. In addition, the design of the developed system was kept very simple in order to enable the assembly employees to conduct modfications on their rmn [ill.
cam1
PROVIDING INFORMTION AT THE WORK STATION Another field of research that still offers a high level of optimization potential is the provision of assembly kndedge. The steadily accelerating evolution of changng processes concerning product variants, hatchsires and production numbers requires innmtive solutions fw information contrd with respect to different marked situations. Beside the development of efficient processes fw both production and logstics, infwmation management provides a significant potential fw lasting productivity increases. By providng infwmation such as assembly insbuctions, parts lists, qualty data or test in-ctions at the workstiation, the worker CM be supported while performing assembly hsks (figure 5). The production of spare parts is another issue that can be handled using wwkhtion-integrated infwmation techndoges. An im-t precondition therefwe is the
Figure 5: h h flrm in wwker information systems
The worker information system called IM@GE+, which was developed at FAPS, offers a suitable solution for workstiatiowintegiated informatiow and dah provision. The system, which consists of a hasic module, CM be extended with addtional, function-dented modules. These CM be fw instance for the prwision of product infwmation, workstation management or quality management. Furthemre, the IM@GE+basic module allrms the worker information system to be connected to other third party applications (figure 6). The productionrelevant information is stwed in a central dabbase, whase ahini&ation and access c m t r d is also integrated in the IM@GE+ hasic module.
5
Figure 6: Sbuchrre of a modular desigred wwker infwmation system The connection of the individual workstations to the worker infwmation system is realized by the c m p i e s ' inbimed. Depending on the authwization level of the user, dfferent levels of infwmation and functions are available. This ensures that only authorized users are able to manipulate the stored dab. The interaction of the employee with the electronic system hkes place via a conputer screen, where an ergonorrric designed humanmachineinterface guides him t h r w a w i w s menus.
In the production area, the infwmation is displayed on a dare free flat screen that is integated into the workstation. In wder to aqust the level of information, multi-meda techniques can be applied to present the required depth of information with respect to the users skill level. F w instance, a h i a l y skilled worker requires only a sinple dowmenhtion of assemblyrelevant factors, whereas his or her inexperienced new colleague is in need of mwe d h i l e d information. The type of data prwided mnges from simple p r t s lists w pichrred assembly manuals to short video sequences of the respective hsks. Furthermwe the w w k h t i o n related infwmation management system enables the individual allocation of tasks.
caused by unhealthy wwk poshrres. On the other hand, the conpimy p r o k from c& reductions and increased produchlty. The addtionid fldbillty within the manual production can by achieved by the use of sukable, highly flexible modular assembly systems. Furthermore, the increasing dstribution of electronic infwmation management devices such as the IM@GE+ system presented offer high potentials f w productMty improvements. Therefwe, the introduction of such nem and innovative technologies enables the continuous improvement of the efficiency of manual production systems. However, h i a l y motivated and skilful human wwkers will still remain the dederrrrining factor of hrture manual production systems.
7 ACKNOWLEDCMNT The authws wish to thank all those cdleagues who sent infwmation material and documentation abwt their wwk. 8
Figure 7: Benefits frm worker information systems The use of wwker infwmation systems within manual assembly &uctures offers the pdential for gem increasing produchlty and flexibillty. A majw precondition is the indvidually scaleable depth of infwmation as well as the demonstrative display of conplex designs and procedures. This supports the worker during both the l e m i n g and the assembly process with respect to their qualification and individual assembly knrmhow. Also, the passibillty to receive immedate worker feedback leads to a sigrificant reduction in production rejects and inproves the quallty of the manufactured goods (figure 7). Furthermore, there is a very large potential fw mtionalization cmceming the creation and updating of printed doeuments. Other positive effects include improvements in tidiness and deanness at the w w k h t i o n s due to the nowutilization of ppers and printwts. In addition to the abovementioned aspects that CM drectly lead to cost reductions and finanaal gains, electronic information systems also prwide mimy now finanad adrantages. The provision of current and correct information to the enploy- leads to conpetitive advantages. Furthermwe, the customer is shown that the m n p ~ is y r e d i n g lean production and handles its technical and locjstic processes as well as it implements lean information mctures. C m p r e d with conventional tods, the abillty to hande high numbers of product variants as well as conplex product struchrres hrms M electronic wwker information system into the perfect management tool for flexible production systems. Another p a s h e effect is the enrichment of assembly duties due to the support of an electronic infwmation device. This leads to an increase in the significance of manual assembly systems and thus promotes the wwker motivation [12].
6 WIMYANDOU~OOK To sum up, the application of nem concepts and soitware tods offers a hi# potential f w manual assembly systems. A c m p r i s o n of selected assembly m c t u r e simulations allrms the early predction of the ideal system design. An addtionid a h n t a g e is the passibillty to simulate human wwkers within a virtual manufachrring environment. The main beneMs from this research wwk are on the one hand the lrmer risk of long term injuries
REFERENCES
[ l ] h i , T., Aiyima, Y., Mae& Y., Sugi, M., Ota, J., 2m0, Agle Assembly System by "Plug and Produce", Annals ofthe CIRP, 4W1:1-4 [2] Feldmann, K., Slrna, S., Mol, Highly flexible Assembly - Scope and Justification, Annals of the CIRP, 5012:489498 [3] Kjellberg, A , Wememan, A,, 2m0, Business Innovation - Innmtive Terns, Cmpetence Brokers and Beehive Sbuctures - in a Suhinable Work Organisation, Annals of the CIRP, 4W1:355
358 [4] Kjellberg, A,, 1999, Teams - W a f s Next? F r m Fmgnentation and Consawmess to Responsiveness by Cmpetence Management fw Modular Manufachrring Learning, Annals of the CIRP, 4812:599609 [5] Bullinger, H.J., 1999, E r g m m i e - Rodukt- und Arbeitsplakgestdhrng, B. G.Teubner SMtgart [6] Regber, H., Zimmermann, K, 2m1, Change Management in der Roduktion - Rozesse efibient verbessern im T e r n , Verlag Moderne Industrie Krug, S., 2Mx), Robuste und p r o h b l e Monhgeshtegien in der Automobilruliefererindustrie, Auslegung und BeQieb flexibler Montagesysteme, Seminar VDC Bildungswerk, Forth [El Klauke, S., 2m0, Besser p l s p r~t Kosten ~ Softwarebods in der Monhgeplanung, Seminar VDC Bildungswerk, Forth
m
[9l Sutanto, A, 2M)2, Planning and simulation of fldble assembly systems in the virtual manufacturing environmenf Proceedngs of the I S M 2M)Z PTC Berlin [lo] Kwen, Y., Heisel, U. Jovane, F., Mwiwaki, T., Pritschrm, G.,Ulsoy, G.,Van Brussel, H., 1999, Reconfigumble Manufacturing Systems, Annals of the CIRP, 4W2527-540 [ i l l Felhann, K., Slrna, S., Junker, S., 2002, Mit marktorientierten Sbuukturen zur effiienten Monhge, wt Werkhttstechnik online [12] Felhann, K, S l a m , S., L M ~ , S., 2002, Mkarbeiterkonpebenz in der Monhge rit multimedalen Infwmationssystemen steigem, wt Werkstattstechnik online
Abstmd Due to grrming numbers of differing products and mriannts, assembly systems with optifired manual w w k h t i o n s hiwe become M efficient alternative to hi#& autmated but less flexible production systems. Especially in the final stage of the product assembly, the flembillty of human enployees enables them to meed the requirements for assembling various products and changng volumes. In wder to create hi#ly efficient production systems biased on human work, it is necessary to develop innmahe cmcepts for the desigr and wgimktion of manual assembly mctures. Another majw issue is the development of sohiare tools allowing the facillty planner to simulate and optifire the conplebe desigr of the assembly &ucture such as the matterial flrm or manual workstations, e.g. with respect to ergonmics, befwe construction. These requirements hiwe led to a cmprehensive research hmewwk fw manual assembly systems. Keywwds: Assembly, Flexible Manufachrring System, Simulation
1 INTROWCTlON The transition of m h e b sbuchrres towards a custmerfowsed market has led to significant changes in the requirements of assembly systems. M e r e a s wstomers' needs could be easily satisfied with high batch sire produced standard products a few years ago, t&y% bryers demand a wide h e b y of products, optifired fw their indvidual needs. The consequence of this development for the manufacturer is the increased i m m c e of flembillty in the production s e w . Therefore, flembillty and agillty are key issues fw realizing efficient and mpetitive production systems [ l ] . Further biasic requirements for cmpetitive assembly systems indude a high level of e c m m i c efficiency as well as appropriate wganization methods and assembly techndoges [2]. Especially in malC and medumsized c m p n i e s , this high level of flembillty can be achieved through the use of manual assembly systems. This fwm of assembly combines a low inv-ent risk with a hi# level of adapbbillty and productiwty. However, mast manual assembly systems still hiwe the potential to be opbmized. In addtion to efficient techniques fw planning and designing human biased systems, the infwmation and k n d e d g e management of enployees plays a majw role in manual assembly systems [3]. Furthermwe, factws such as the wganization of employees and the introduction of modular assembly systems offer further possibilities fw increasing the efficiency of enployee related manufacturing systems. 2 MonvAnoN AND ERCONOMCS The m& inpmtiant a&iantiage of manual assembly &uctures is their capbilty to be quickly adapted to changing products and m h e b situations. A very i m m t precondition for this purpase is the cooperativeness and willingness of the wwkers to acmpl and support the required changng processes. Beside other issues (figure l ) , the encwmgement and pesewation of employee m o h t i o n is the biasic requirement for the successful operation of manual assembly systems. One majw factw that encwmges wwker m o h t i o n is the delegation of responsibillty to the enployee. The wgimktion of work within a tern, for i n h c e , provides
each wwker with the passibillty to perform and accmplish assembly tasks a-rdng to their indvidual skills and k n d e d g e . This ensures that in an ideal case, enployees are neither ove-ined nw unchallenged and thus are able to reach their indvidual achievement potential. A! the same time, dependng on the conplexlty of the bmsfened responsibilities, such errployee cooperation requires social and emotional conpebences in addition to the necessary assembly skills [4]. The introduction of teamwwk offers the wwkers a number of benehts. These indude an improved work atmosphere, diversified wwk cmtents as well as a higher selC confidence and sense of responsibility. On the other hand the c m p n y profits frm the increased workfwce contentnmnt and the more efficient utilization of enployee potential. Furthermwe, the introduction of tearwork has pasitive effects on the conpliance with hi# qualty standards and addtionally leads to high producbvlty and flexibility.
Figure 1: Effects on the productiwty of manual assembly systems
In addtion to the enrichment of work contents, perfwmanmrelated payment struchrres and flexible wwking h w r s represent efficient tods fw increasing motivation and productivlty. F l d b l e Iabwr time also constitutes a yeat chance fw cd-siaving, permitting short-notice adamtion of productive capacity to the actual demand. In contrasf financial incentives stimulate the employees to monitor their wwk and conply with high quallty and productiwty hndards.
related with the workers willingness to perform their duties is the design of manual wwkplaces that consider the demands of human bodies under wwk condtions as well as physical -ins. By the prwision of ergonmic wwkhtions, the wwkfwce has no need to waste effort on poshrre corrections, brt is able to concentrate its prmer on value addng processes. The a h h g e s of ergonmic desigred wwkhtions and processes are reduced numbers of employees away sick as well as further enhancement to wwker motivation [q. For this reason, the men classic types of wastage defined by Toy& have to be extended with an eiath, the wastage emerging frm wwking procedures that can adversely affect health [q,
m.
3 PUNNING MANUAL ASS-Y STRUCTURES In wder to ensure a fast and reliable production rimpup, the enployees' special requirements concerning the manufacturing equipment have to be taken into account within the planning and desigr shge. As a result of the effectiveness of t&y% cmputer-aided simulation tools, failures in the technologcal and ewnorrrical planning can be prevented at an early stage [El. Modern simulation tools prwide the passibillty of conputer biased modelling, visualization and simulation of c m p l e x production &uchrres. Currently, bdh logical and physical conshints can be considered in a virtual model of an assembly system. The aim of this technology is the kndedgebased validation of dfferent assembly &uctures. The cmputer-biased m p r i s o n of variws l q m t s enables the planner to predct passible bottlenecks w failure sMIrces in the planning stage (figure 2).
The simulation of human wwkers' motions in a virtual manufacturing environment is another significant feature for the process of planning manual assembly sbuchrres. The s o k e based analysis of assembly wwk contents and the deterrrrination of corresponding fwces and twques in adrance allows M early opbrrrlation of the assembly process. In addition, a m w r r e n t analyas of the wwkers poshrre allrms the dassifidion of a process' ergonmic characteristics per fraction of time (figure 3). Thus, the user has the oppwtunlty to optirrrLe the laywt of a worksbhon with respect to ergonmic aspects in M early planning phase. Furthemwe, the simulation of human workers allrms M estimation of the assembly times expected fw the real production. This has a special effect on the desigr of c m p l e x production mchrres since it enables the planner to fwesee the achimmble productivity dependng on the number o f w w k h t i o n s [q.
Figure 3: Ergonmic analysis providesjoint-related details about the q e c t e d physical stress
Another innovative trend within the simulation technology field are the current developments in the arm of Internet biased simulations, the smcalled 'web based desigr simulation". wlth the provision of on-line simulatim capabilities together with piarts and conponents libraries, the user, e.g. a system desigrer, CM conduct initial testing and analysis withmt the need to invest in expensive simulation tools. An accwdn& opbrrrled, web biased simulation tool CM result in sigrificant c& reductions. The application of this web technology gives prticularly small and mediumsized c m p n i e s the opportunlty to use simulation systems as efficient planning tools.
4 Figure 2: Inproving the efficiency of manual assembly systems with virtual manufacturing
The soitware supported planning of assembly system l q m t s and wwkstation desigrs allrms the arrangement of comnercial as well as user specific system elements w modules within the virtual factmy. On the one hand these models m s i s t of both a q u h b l e and n m adjustable gemeQical data, which are required fw correct visualization. On the other hand, each model includes information describing the logcal conshints with other virtual system modules. The models of the individual conponents can nrm be arranged, either manually or in M interactive way, within the faallty accwdng to the planners' demands. Based on this virtual assembly system models fw the simulation of logistics, simulation of ergonorrrics and discrede went simulations can be derived. Furthermore, two w more &uctural l q m t s with dffering technical and econorrric aspects CM be mmluated. Parts lists, price lists, gemebical dmensions or the w e i a t of the designed device are only a few examples of the w i w s infwmation provided by such a sirnulation.
MOWLAR A S E m L Y SYSTEMS
As prwiwsly described, manual production can be a highly efficient shtegy fw the realization of markedWiented assembly m c h r r e s . Beside the human abillty to conply to changng demands of variable duties and wwk contents, lasting flexibillty g i n s can be achieved by using suitable manufachrring equipment fw i n h n c e stepwise upgradeable assembly systems (figure 4). A considerable d s a h h g e of conventional assembly &uctures is that they are oRen desigred to meed special requirements, i.e. the upper limit of the estimated production volume. The lack of flembillty of such facilities concerning variable demand situations prevents their short-term, econorrrical adaptation of producbvlty accwdng to the actual marked condtions. Since the beak-wen point of such assembly systems is bed, a prerequisite fw making a p o M is to exceed a wen rrrinimum production volume [ 1o]. The flexibility of modern assembly systems offered today oRen suffers frm the lack of adaptability regarding variws issues, such as possibilities to quickly conply to changing demands or shortened product life cydes [q. For this reason, a modular assembly system has been
developed at the Institute fw Manufacturing Automation and Production Systems (FAPS) to meed in particular the requirements of highly flexible, manual assembly struchrres. The major g d of this project was to create lowcost devices that are especially desigred to meed the specific requirementsof manual wwkstations.
availability of relevant assembly knowhow fw all current products and also for thase that are actually not in production anymore. In gened, t&y% infwmation management systems that are located in the production area cmsist of a wieby of dfferenf self-whining and function-wiented modules. The prwision of production data is oRen realized with wder-related forms, on which every work step has to be noted and sigred. Additionally, many workstations dsplay hard copied infwmation abwt processrelevant issues. The major problem of such a shared data management system is the dah a h i n i h t i o n , since there is no passitility fw pwfwming quick and conpanywide updates. Furthemwe there is no opbon for the worker to adoldedge in-ctions w report problems from the assembly area hack to the adrrrinisthve level.
Figure 4: AdMing the productMty to the demand with stepwise upgradeable, modular assembly systems The basic element of the dweloped concept is a standardized wwkplace module, which CM be modified to conply with variws assembly requirements. On the one hand, this can be achieved by mwnting different kinds of function-dented workspace modules on M integrated interface fmmwwk. On the other hand, a workstation can be quiddy and easily adapted to changng requirements by the integation of addtional expansion elements, e.g. t d holders or bmes fw parts dsposition. To implement a material flrm that meeds the requirements of the dfferent h g e s during the stepwise expansion of the manual assembly system, a wide variety of standardized bimsfer modules is available. The user can hereby select manual w automated modules or a combination of bdh. A special f e d r e of the systems' struchrre is the strict classification of the conponents in intelligent and unintelligent units. This suppwts the realization of cost-efficient sbuchrres, for i n h n c e in the start-up phase. The capacity of the production system can be easily adapted to changing demands throughwt the product's lifecyde, e.g. by incwpmting further workstiations or M automated material flrm. The great advantage of this concept is the option to delay invesment until it is required, e.g. as a result of M increase in demand. From the cmpanies' view, this is preferable as this approach minirrrLes the risk of inmrect financial decisions. In addition, the design of the developed system was kept very simple in order to enable the assembly employees to conduct modfications on their rmn [ill.
cam1
PROVIDING INFORMTION AT THE WORK STATION Another field of research that still offers a high level of optimization potential is the provision of assembly kndedge. The steadily accelerating evolution of changng processes concerning product variants, hatchsires and production numbers requires innmtive solutions fw information contrd with respect to different marked situations. Beside the development of efficient processes fw both production and logstics, infwmation management provides a significant potential fw lasting productivity increases. By providng infwmation such as assembly insbuctions, parts lists, qualty data or test in-ctions at the workstiation, the worker CM be supported while performing assembly hsks (figure 5). The production of spare parts is another issue that can be handled using wwkhtion-integrated infwmation techndoges. An im-t precondition therefwe is the
Figure 5: h h flrm in wwker information systems
The worker information system called IM@GE+, which was developed at FAPS, offers a suitable solution for workstiatiowintegiated informatiow and dah provision. The system, which consists of a hasic module, CM be extended with addtional, function-dented modules. These CM be fw instance for the prwision of product infwmation, workstation management or quality management. Furthemre, the IM@GE+basic module allrms the worker information system to be connected to other third party applications (figure 6). The productionrelevant information is stwed in a central dabbase, whase ahini&ation and access c m t r d is also integrated in the IM@GE+ hasic module.
5
Figure 6: Sbuchrre of a modular desigred wwker infwmation system The connection of the individual workstations to the worker infwmation system is realized by the c m p i e s ' inbimed. Depending on the authwization level of the user, dfferent levels of infwmation and functions are available. This ensures that only authorized users are able to manipulate the stored dab. The interaction of the employee with the electronic system hkes place via a conputer screen, where an ergonorrric designed humanmachineinterface guides him t h r w a w i w s menus.
In the production area, the infwmation is displayed on a dare free flat screen that is integated into the workstation. In wder to aqust the level of information, multi-meda techniques can be applied to present the required depth of information with respect to the users skill level. F w instance, a h i a l y skilled worker requires only a sinple dowmenhtion of assemblyrelevant factors, whereas his or her inexperienced new colleague is in need of mwe d h i l e d information. The type of data prwided mnges from simple p r t s lists w pichrred assembly manuals to short video sequences of the respective hsks. Furthermwe the w w k h t i o n related infwmation management system enables the individual allocation of tasks.
caused by unhealthy wwk poshrres. On the other hand, the conpimy p r o k from c& reductions and increased produchlty. The addtionid fldbillty within the manual production can by achieved by the use of sukable, highly flexible modular assembly systems. Furthermore, the increasing dstribution of electronic infwmation management devices such as the IM@GE+ system presented offer high potentials f w productMty improvements. Therefwe, the introduction of such nem and innovative technologies enables the continuous improvement of the efficiency of manual production systems. However, h i a l y motivated and skilful human wwkers will still remain the dederrrrining factor of hrture manual production systems.
7 ACKNOWLEDCMNT The authws wish to thank all those cdleagues who sent infwmation material and documentation abwt their wwk. 8
Figure 7: Benefits frm worker information systems The use of wwker infwmation systems within manual assembly &uctures offers the pdential for gem increasing produchlty and flexibillty. A majw precondition is the indvidually scaleable depth of infwmation as well as the demonstrative display of conplex designs and procedures. This supports the worker during both the l e m i n g and the assembly process with respect to their qualification and individual assembly knrmhow. Also, the passibillty to receive immedate worker feedback leads to a sigrificant reduction in production rejects and inproves the quallty of the manufactured goods (figure 7). Furthermore, there is a very large potential fw mtionalization cmceming the creation and updating of printed doeuments. Other positive effects include improvements in tidiness and deanness at the w w k h t i o n s due to the nowutilization of ppers and printwts. In addition to the abovementioned aspects that CM drectly lead to cost reductions and finanaal gains, electronic information systems also prwide mimy now finanad adrantages. The provision of current and correct information to the enploy- leads to conpetitive advantages. Furthermwe, the customer is shown that the m n p ~ is y r e d i n g lean production and handles its technical and locjstic processes as well as it implements lean information mctures. C m p r e d with conventional tods, the abillty to hande high numbers of product variants as well as conplex product struchrres hrms M electronic wwker information system into the perfect management tool for flexible production systems. Another p a s h e effect is the enrichment of assembly duties due to the support of an electronic infwmation device. This leads to an increase in the significance of manual assembly systems and thus promotes the wwker motivation [12].
6 WIMYANDOU~OOK To sum up, the application of nem concepts and soitware tods offers a hi# potential f w manual assembly systems. A c m p r i s o n of selected assembly m c t u r e simulations allrms the early predction of the ideal system design. An addtionid a h n t a g e is the passibillty to simulate human wwkers within a virtual manufachrring environment. The main beneMs from this research wwk are on the one hand the lrmer risk of long term injuries
REFERENCES
[ l ] h i , T., Aiyima, Y., Mae& Y., Sugi, M., Ota, J., 2m0, Agle Assembly System by "Plug and Produce", Annals ofthe CIRP, 4W1:1-4 [2] Feldmann, K., Slrna, S., Mol, Highly flexible Assembly - Scope and Justification, Annals of the CIRP, 5012:489498 [3] Kjellberg, A , Wememan, A,, 2m0, Business Innovation - Innmtive Terns, Cmpetence Brokers and Beehive Sbuctures - in a Suhinable Work Organisation, Annals of the CIRP, 4W1:355
358 [4] Kjellberg, A,, 1999, Teams - W a f s Next? F r m Fmgnentation and Consawmess to Responsiveness by Cmpetence Management fw Modular Manufachrring Learning, Annals of the CIRP, 4812:599609 [5] Bullinger, H.J., 1999, E r g m m i e - Rodukt- und Arbeitsplakgestdhrng, B. G.Teubner SMtgart [6] Regber, H., Zimmermann, K, 2m1, Change Management in der Roduktion - Rozesse efibient verbessern im T e r n , Verlag Moderne Industrie Krug, S., 2Mx), Robuste und p r o h b l e Monhgeshtegien in der Automobilruliefererindustrie, Auslegung und BeQieb flexibler Montagesysteme, Seminar VDC Bildungswerk, Forth [El Klauke, S., 2m0, Besser p l s p r~t Kosten ~ Softwarebods in der Monhgeplanung, Seminar VDC Bildungswerk, Forth
m
[9l Sutanto, A, 2M)2, Planning and simulation of fldble assembly systems in the virtual manufacturing environmenf Proceedngs of the I S M 2M)Z PTC Berlin [lo] Kwen, Y., Heisel, U. Jovane, F., Mwiwaki, T., Pritschrm, G.,Ulsoy, G.,Van Brussel, H., 1999, Reconfigumble Manufacturing Systems, Annals of the CIRP, 4W2527-540 [ i l l Felhann, K., Slrna, S., Junker, S., 2002, Mit marktorientierten Sbuukturen zur effiienten Monhge, wt Werkhttstechnik online [12] Felhann, K, S l a m , S., L M ~ , S., 2002, Mkarbeiterkonpebenz in der Monhge rit multimedalen Infwmationssystemen steigem, wt Werkstattstechnik online