INTERNATIONAL DESIGN CONERENCE - DESIGN 008 Dbrvik - Cratia, May -, 008. ON THE DEVELOPMENT O MODULAR PRODUCT STRUCTURES: A DIERENTIATED APPROACH C. Blees ad D. Krase Keywrds: mdlarizati, assembly seqece, iterfaces, assembly pririty chart. Itrdcti I recet years may idstries have itrdced mdlarized prdct strctres t cpe with risig demad fr cstmized prdcts ad icreasig reqiremets ccerig lead times, csts ad qality. Amg thers the aircraft idstry makes icreasig se f sch mdlarized prdct strctres [Whitey 004]. I this applicati especially the aircraft iterir is a very prmisig field as the iterirs ca be fd i a high variety ad their fial assembly is e f the mst labris parts f the prdcti prcess. The methdlgies spprtig the develpmet f mdlar prdct strctres are basically cmpsed f three steps, which have bee prpsed first by [Pimmler/Eppiger 4]:. Decmpsiti f the system it fctial r physical elemets. Dcmetati f the iteractis betwee the elemets. Clsterig f the elemets it mdles Accrdig t Pimmler ad Eppiger, fr the decmpsiti it has t be csidered if it is a vel r a icremetal desig. r a vel desig fctial elemets are defied i the stage f cceptal desig ad are develped i mre detail i the gig desig prcess [Pahl/Beitz 007]. I the mre likely case f a icremetal desig mst f the physical elemets f the prdct, the cmpets, are already kw. Sbseqet t the decmpsiti the fctial-techical ad prdct-strategic iteractis betwee the elemets are mapped ad this basis mdles are derived. Hwever, as a reslt f the mltitde f techical-fctial ad prdct-strategic iteractis this becmes a very cmplex apprach. Therefre, i this paper the apprach is made t develp a methdlgy that eables a separate csiderati f the mst relevat perspectives f mdlarizati. O the e had this eables the redcti f the cmplexity ad the ther had this makes it pssible t spprt the differet perspectives i a mre apprpriate way. At the begiig f this paper the tw mst cmm methdlgies fr mdlarizati are briefly described. Secdly, the apprach f the develpmet f a mdlar prdct frm differet perspectives is preseted. ially, the develpmet f mdlar prdcts frm the mafactrig ad assembly perspective is preseted which has already bee prepared mre i detail.. Desig methdlgies fr mdlarizati r the develpmet f mdlar prdct strctres especially the appraches made by [Pimmler/Eppiger 4] ad [Erix 8] are imprtat. Pimmler ad Eppiger fcs the develpmet f mdles by mappig f techical-fctial iteractis betwee cmpets. Therefre they adapt the Desig Strctre Matrix (DSM) f [Steward 8]. I the DSM the cmpets are ppsed t each ther ad their iteractis are aalyzed. This is de by idetifyig DESIGN METHODS 0
the type f iteracti ad by givig each iteracti a scre. The iteracti types are: spatial, eergy, ifrmati ad materials. r the evalati f the iteractis a scale f (reqired), (desired), 0 (idifferet), - (desired) ad - (detrimetal) is prvided. A example f a desig strctre matrix is illstrated i figre. After the evalati f iteractis, clsterig the elemets it chks ca develp mdles. Clsterig ca be achieved by srtig clms ad rws. The idea is t cmbie the iteractis predmiatly withi the chks ad t miimize the iteracti betwee the chks. r this prpse the athrs sggest the se f algrithms. A B C D E G H I J K L M N O P Radiatr Egie a Heater Cre Heater Hses Cdeser Cmpressr Evapratr Case Evapratr Cre Accmlatr Refrigirati Ctrls Air Ctrls Sesrs Cmmad Distribti Actatrs Blwer Ctrller Blwer Mtr A B C D E G H I J K L M N O P - - - - - - - - Mdle driver Desig & Develpmet Variace Mafactrig Qality Prchase After sales cti carrier Carry-ver Techlgy psh Prdct Plaig Differet Specificati Stylig Cmm Uit Prcess/Orgaisati Separate Testig Black-bx egieerig Service/Maiteace Upgradig Recyclig Weight f Driver vertically smmarized: Mdle cadidates Wire cllectr Cver Grip Wire & ctact Switch ilter Bag Chassis Electric mtr a 4 7 7 5 7 6 7 Leged: Spatial: S E :Eergy = Strg driver () = Medim driver () = Sme driver () Ifrmati: I M :Materials igre. The Desig Strctre Matrix accrdig t [Pimmler/Eppiger 4] ad the Mdle Idicati Matrix accrdig t [Erix 8] Erix ses his methd, Mdlar cti Deplymet (MD), fr the develpmet f mdlar prdct strctres. The MD-methd is sbdivided i the steps clarificati f reqiremets, selecti f techical sltis, geerati f mdlar ccepts, evalati f mdlar ccepts ad imprvemets f mdlar ccepts. The mai part f the MD is the geerati f mdlar ccepts sig the Mdle Idicati Matrix (MIM). I the MIM prdct-strategic iteractis betwee cmpets ad s-called mdle drivers are idicated. A example f a MIM is shw i figre. The mdle drivers frm the fields f desig ad develpmet (carry-ver, techlgy psh, prdct plaig), variace (differet specificati, stylig), mafactrig (cmm it, prcess/rgaizati), qality (separate testig), prchase (black-bx egieerig) ad after sales (service/maiteace, pgradig, recyclig) are reass fr cmpets t becme part f a mdle. The iteractis betwee the mdle drivers ad the cmpets are evalated by experts ad classified by vales frm 0 ( driver) t, ad (strg driver). r bildig the mdles the cmpets with the highest rakig are sed as basis. I the gig prcess frther cmpets with a similar evalati patter are added t these basic cmpets. With this techiqe several mdlarized prdct strctres ca be develped. I the fllwig step f the MD methdlgy the mdlar ccepts are evalated. irst it is csidered, whether a assembly-friedly prdct strctre ca be realized sig a hambrger assembly r base-part assembly. I the ext step the ccepts are rated with respect t develpmet (lead time i develpmet, develpmet csts, develpmet capacity), assembly (prdct csts, system csts, lead time, qality) ad after sales (variat flexibility, service/pgradig, recyclig). With this evalati e ccept is chse ad frther detailed i a fial step. r this Erix refers t the established DX methdlgies.. Apprach fr a differetiated methdlgy fr mdlarizati rm the applicati f the methdlgies f Pimmler/Eppiger ad Erix i the field f aircraft iterirs it was realized that the mltitde f iteractis betwee the cmpets trs mdlarizati it a very cmplex task. Oe majr reas fr this cmplexity is that all perspectives 0 DESIGN METHODS
f mdlarizati have t be csidered at the same time. Therefre i this paper the apprach f a separate develpmet f mdles accrdig t the mai perspectives is sggested. A examiati f the similarities ad iterdepedecies betwee the mdle drivers has already bee realized by [Stake 000]. He sggests a grpig f the drivers i prdct family plaig related drivers ad drivers related t fctial prity. I additi he allcates the drivers f the first grp t the characteristics degree f cmmality ad time ad the drivers f the secd grp t the characteristics lcati f effrt ad prdct life cycle. The resltig represetati is shw i figre. r the derivati f the mst relevat perspectives f mdlarizati this classificati is sed as a basis. Mdle drivers related t prdct family plaig: Mdle drivers related t fctial prity: Time Preset tre Techlgy psh Plaed desig chages Differet specificati Stylig Carry ver Cmm it Prdct life cycle Early Late Recyclig Service / Maiteace Upgradig Separate testig Prcess / rgaisati Strategic spplier Lw High Degree f cmmality Iteral Lcati f effrt Exteral igre. Grpig f mdle drivers accrdig t [Stake 000] All mdle drivers Stake has assiged t the grp f prdct family plaig have very strg iterdepedecies, ad as a reslt they d t allw a separate csiderati. Therefre, the drivers techlgy psh, plaed desig chages, differet specificati, stylig, carry ver ad cmm it remai tgether i the prdct plaig perspective. The iterdepedecies f the drivers i the secd grp are less strg. Ths, the drivers ca be adjied t three differet perspectives. The first perspective is the prchase perspective which csists slely f the driver strategic spplier. The secd e is the mafactrig ad assembly perspective. Beeath the driver prcess/rgaizati the driver separate testig has bee added as testig is e f the majr tasks f assembly [Adrease 88]. The remaiig drivers recyclig, service/maiteace ad pgradig are added t the after sales perspective. Hwever, a frther decmpsiti f the after sales perspective shld still be csidered if particlarly high reqiremets ccerig recyclig r maiteace have t be satisfied by the prdct. O the basis f these csideratis a differetiated prceedig fr the develpmet f mdlar prdcts ca be derived. I figre the mai steps f sch a apprach are preseted. At the begiig the gals f the mdlarizati have t be clarified. These cld be the variats reqested by the prdct plaig r the reqiremets ccerig after sales aspects. Sbseqetly, the actal mdlarizati prcess takes place. At the begiig the prdct is decmpsed it its cmpets. This decmpsiti is the basis fr the fllwig mdlarizati accrdig t the fr perspectives that have bee derived befre. The apprach f a mafactrig ad assembly rieted prceedig is preseted i the ext chapter while the develpmet f adapted prceedigs fr the remaiig perspectives will be part f the ftre wrk. Ccldig the ccepts made frm differet perspectives have t be cmbied it the fial mdlar prdct strctre. Therefre it has t be examied whether differet mdlar ccepts ca be cexistet i the prdct r t. I the latter case a decisi i favr f e ccept has t be made. The water filter f a aircraft galley is a gd example t shw idepedet perspectives f mdlarizati. rm the maiteace perspective the water filter has t be a separate mdle i rder t allw a easy replacemet. I additi the assembly perspective reqires the itegrati f the water filter i the lwer mdle f the galley t miimize the mber f assembly steps i the fial assembly lie. I this example the differet ccepts ca be cexistet i the prdct witht cflictig with each ther. DESIGN METHODS 0
4 5 Gemetrie Verwedg der Stadard-Sitzschiee Verwedg eies dreifache Zgblzes Überbrückg des Abstads zwische Rahme d Sitzschiee Kiematik Verchieblichkeit der Galley i der Sitzschiee bei gelöstem Halter ermögliche Verchieblichkeit des Halters i der tere Rahmestrktr der SPICE-Galley Verstellweg zm Tlerazasgleich i x-richtg sx -4,00 4,00 mm 4 Verstellweg zm Tlerazasgleich i y-richtg sy -4,00 4,00 mm 5 Verstellweg zm Tlerazasgleich i z-richtg sz -4,00 4,00 mm Kräfte Maximale Kraft i x-richtg x max kn Maximale Kraft i y-richtg y max kn Maximale Kraft i z-richtg z max kn Mtage Schelle Mtage ermögliche W Bi ACU Light Iserts acet Hadle Sik E t Mdltreiber w i c k l g & K P r s d t e r k ti k gv ti a ri g a & z P Q r a d Eli it k ä ti kt Aa f tf e r - S a l Se s m mm e d l cectig elemets reqired tls reqired plg cectis clamp ad sap cectis qick-discects ktie Gebläse Überahme vm Vrgäger Techlgiesprg Prdktplag Variiere de A frderge Stylig Gleichteil Przess Separate Prüfg Zlieferer Wartg A früstg Recyclig 4 Wertg: 7 7 5 7 6 7 ilter Risig assembly effrts cectig elemets ad/r tls reqired cectig pis cable ties pipe clamps simple screw cectis Chassis Betel ilter Schalter Gehäse Kabel Griff special prcesses ecessary screw cectis that eed t be adjsted cectis that eed t be sealed cable jits witht plg Galley assembly Galley assembly Galley Galley assembly Galley assembly Galley I ctrast t the abve example the hadrail mted at the bttm f the hat rack shws a cflict f the perspectives prdct plaig ad prchase. rm the prdct plaig pit f view hadrail ad hat rack shld t be itegrated i e mdle as the hat rack is a cmm it while the hadrail ca vary i terms f clr ad shape. Bt, at the same time it is aspired t prchase a stadardized hat rack mdle with all attached parts frm a spplier. I this case a strategy has t be develped i rder t vercme this cflict. If the gals f prdct plaig are weighted higher, the hadrail cld be separated frm the hat rack mdle. Ctrariwise the had rail cld be stadardized ad itegrated i the hat rack mdle. Thereby the differetiated csiderati f the perspectives f mdlarizati spprts a attetive dealig with the cflictig gals i prdct develpmet. Develpmet f mdlar ccepts Clarificati f the gals f the mdlarizati Prdct plaig Prchase Sythesis f mdlar prdct strctres Decmpsiti f the system Mafactrig/assembly After sales igre. Apprach fr a differetiated develpmet f mdlar prdct strctres 4. Mdlarizati frm a mafactrig ad assembly perspective Mdlar prdct strctres are fdametally imprtat fr the assembly as mst f the degrees f freedm that ca be sed fr assembly plaig are determied by the prdct strctre. Therefre the prdcti perspective has t be itegrated it the desig phase. I figre 4 the apprach f a mafactrig ad assembly rieted develpmet f mdlar prdct strctres is tlied. Iitial Mdle Iterface Graph (MIG) Iterative imprvemets Cmpets Adapted Mdle Idicati Matrix (MIM) Elektrmtr Abdeckg Kabeltrmmel Mdle Mdle 4 Mdle Mdle Mdlarized Mdle Iterface Graph (MIG) A A A A8 A6 A7 A A A4 A0 A5 Assembly Pririty Chart Mdlar prdct strctre Iterfaces igre 4. Mdlarizati frm a mafactrig ad assembly perspective r the develpmet f a prdcti-rieted mdlarizati the essetial ipts are the cmpets, the iitial prdct strctre ad kwledge f the iterfaces. While i the case f a icremetal desig the cmpets sally ca be take frm the parts list, the decmpsed prdct strctre has t be mapped t tlie the iitial state. Therefre the Mdle Iterface Graph (MIG) has bee develped. A example is give i figre 5. Here the cmpets are mapped apprximately t their gemetrical psiti the graph. The iterfaces are represeted by lies betwee the cmpets with differet drawig styles r clrs accrdig their type (strctral, pwer-trasmittig etc.) tgether with ipts ad tpts. This illstrati gives a clear visalizati f the iitial prdct strctre icldig the iterfaces. r validati the MIG has already bee applied sccessflly t the majr systems f aircraft iterirs (galley, lavatry, hat racks, persal service chael ad paels). 04 DESIGN METHODS
Galley Lavatry Hatracks ad Persal Service Chael Dr Paels Clig it Bi acet Sik Light Iserts Hadle Tilet cver Lights Waste bx Left Dr Right Dr Had- ilter Cver Cver Ne lamp PSU-rails Water system (aisle- ad hld wall-side) Cver Plate Tilet it Ld- Air Smke speaker extracti detecti Illmiati Air tlet Air tlet Oxyge mask Service cabiet Ctrl pael Service cabiet cver Illmiati Hadhld Left rame Cver Exit Sig Illmiati Upper rame Cver Upper Dr Cver Hadhld Wash table Wash table cver Mirrr lsh lap btt Lwer Dr Cver lr pa xyge spacer lights sigs Scree air bx Escape Slide Dr Hige Cver Cati. Cver Right rame Cver Hadhld Illmiati Escape Slide Cver Strctral Pwer Ifrmati resh Water Waste Water Vacm resh air Exhast air Ipt Otpt igre 5. Mdle Iterface Graph (MIG) fr a galley ad frther aircraft iterir systems rthermre, the iterfaces ad their desig are f vital imprtace. rm the assembly pit f view especially the resltig lead time is the crcial factr. Therefre, a classificati f iterfaces based their assembly effrt is implemeted. I the first class iterfaces are smmarized that ca be assembled witht tls ad separate fasteers. Iterfaces that reqire tls ad/r separate fasteers are assiged t the secd class. The third ad last class ctais iterfaces that reqire additial prcedres sch as adjstmets r sealig f split-lies. Table shws cmm iterfaces kw frm the field f aircraft iterirs. I fact, this apprach reqires a ew classificati fr every differet type f prdct, bt ce a framewrk has bee cmpiled it is easy t assig ather iterface t e f the classes. Table. Classificati f cmm iterfaces frm the field f aircraft iterirs Risig assembly effrts separate fasteers reqired tls reqired plg cectis click ad sap cectis qick-discects separate fasteers ad/r tls reqired cectig pis cable ties pipe clamps simple screw cectis special prcedres ecessary screw cectis that eed t be adjsted cectis that eed t be sealed cable jits witht plg I the prpsed prceedig the Mdle Iteracti Matrix is sed agai fr the actal deplymet f mdlar ccepts. Hwever, t spprt the mafactrig ad assembly perspective the mdle drivers have t be adapted accrdigly. O the basis f Erix ad [Blliger 86] a adapted set f drivers has bee cmpiled: Wrk ctet: the cmpet has sitable wrk ctet fr a grp. Skills: special skills are reqired t assemble the cmpet. Lead time: the assembly f this cmpet has a especially lg lead-time. Atmati: the cmpet ca be assembled atmatically. Tls: special tls are reqired t assemble the cmpet. DESIGN METHODS 05
Separate testig: the cmpet shld be tested separately. Prcess: the cmpet reqires a special prcess. Hadlig: the cmpet reqires a special hadlig. Strage: the cmpet shld be stred i a particlar way. A frther adaptati f the set f drivers is ecessary i every applicati. I the case f the mdlarizati f a aircraft cabi the driver size has bee added t itrdce the reqiremet that the itegrati f cmpets ad mdles has t be accmplished thrgh the passeger dr. O the ther had sme mdle drivers have bee remved. The adapted MIM sed i this applicati is shw i figre 5. Cmpet Mdle driver Iserts Light acet Sik Drai valve Drai valve hadle Bi Clig it Water filter Ilet valve Size Hadlig Assembly Separate Testig Prcess Lead time Weight f Driver vertically smmarized: 6 7 0 7 Mdle cadidates = Strg driver () = Medim driver () = Sme driver () igre 6. The adapted MIM cmpleted fr a aircraft galley I the ext step all ipts are cmbied. The mdlar ccepts pited t by the adapted MIM are examied. r this prpse the Mdle Iterface Graph is sed agai. The MIG gives the simple represetati f the prdct strctre that is ecessary t csider the give spatial adjacecy reqiremets. I additi the lie weights f the iterfaces are chse accrdig t their assembly effrts. I figre 7 the iitial ad the mdlarized MIG are preseted fr the example f a aircraft galley. Bi Clig it Iitial Mdle Iterface Graph acet Sik Light Iserts Hadle ilter Mdlarized Mdle Iterface Graph Isert (M) Clig it M4 Upper galley (M) Lwer galley (M) Strctral Pwer Ifrmati resh Water Waste Water Ipt Otpt High assembly effrts Medim assembly effrts Little assembly effrts igre 7. Mdle Iterface Graph (MIG) fr a aircraft galley The last step f the prpsed prceedig is the evalati f the resltig assembly seqece. r this the assembly pririty chart is sed. A assembly pririty chart is a etwrk pla where ecessary assembly tasks are represeted as des ad their iterdepedecies by cecti lies. The des are pltted at the earliest pit f time where the execti is pssible, while the cecti lies ed at the latest pssible pit f execti. igre 6 shws a rgh assembly pririty chart fr a aircraft galley. 06 DESIGN METHODS
A A A A4 A5 A6 A7 A8 A A0 A A: jiig f strctral iterface M/M A: cectig f fresh water iterface M/M A: jiig f strctral iterface M/M4 A4: cectig f pwer iterface M/M4 A5: cectig f ifrmati iterface M/M4 A6: psitiig f galley i aircraft A7: jiig f strctral iterface M/aircraft A8: cectig f fresh water iterface M/aircraft A: cectig f waste water iterface M/aircraft A0: iserti f iserts M/M A: fctial check igre 8. Assembly pririty chart fr the fial assembly f a aircraft galley The assembly pririty chart is the basis fr the evalati f the mdlarized prdct strctre i terms f lead time, wrkshp rgaizati etc.. If the reslts are t satisfyig, a iterative imprvemet f the prdct strctre is reqired. 5. Cclsi This paper explais why itegrated appraches f develpig mdlar prdct strctres lead t a very cmplex task. T vercme this difficlty a prceedig is prpsed which is based a differetiated csiderati f the prdct plaig, prchase, mafactrig ad assembly ad after sales perspective. rthermre, the develpmet f mdlar prdcts frm a mafactrig ad assembly perspective has bee discssed. A adapted Mdle Idicati Matrix ad the Mdle Iterface Graph have bee preseted. I additi the classificati f iterfaces ccerig their assemblability ad the itegrati f the assembly pririty chart have bee prpsed. This methdlgy has already bee applied t aircraft iterirs ad will be frther detailed i ftre applicatis. Besides the mafactrig ad assembly perspective the remaiig perspectives eed t be frther examied. Hece, a majr part f the ftre wrk will be the develpmet f adapted methdlgies fr these perspectives algside with the mre precise csiderati f their iterdepedecies. Refereces Adrease, M. M., "Desig fr Assembly", Spriger Verlag Ld, UK, 88. Blliger, H.J., "Systematische Mtageplag, Hadbch für die Praxis", Carl Haser Verlag Müche, Germay, 86. Erix, G., Mdlar fcti deplymet: a methd fr prdct mdlarisati, The Ryal Istitte f Techlgy, Departmet f Mafactrig Systems, Assembly Systems Divisi, Stckhlm, 8. Pahl,G. Beitz,W., "Egieerig Desig", Spriger Verlag Berli, Germay, 007. Pimmler, T. U.; Eppiger, S. D., "Itegrati aalysis f prdct decmpsitis", Prceedigs f the ASME 6 th Iteratial Cferece Desig Thery ad Methdlgy, Mieaplis, 4, pp. 4-5. Stake, R., O cceptal develpmet f mdlar prdcts, The Ryal Istitte f Techlgy, Departmet f Prdcti Egieerig, Divisi f Assembly Systems, Stckhlm, 000. Steward, D., The Desig Strctre System: A Methd fr Maagig the Desig f Cmplex Systems, IEEE Trasactis Egieerig Maagemet, EM-8, N., 8, pp. 7-74. Whitey, D.E., Mechaical Assemblies, Oxfrd Uiversity Press New Yrk, 004. DESIGN METHODS 07
Dipl.-Ig. Christph Blees Scietific Assistat Hambrg Uiversity f Techlgy, Istitte fr Prdct Develpmet ad Mechaical Egieerig Desig Prf. Dr.-Ig. D. Krase Deickestraße 7 (Gebäde L), 07 Hambrg, Germay Tel.: +4 (0)40-4878-784 ax.: +4 (0)40-4878-6 Email: christph.blees@thh.de URL: http://www.thh.de/pkt 08 DESIGN METHODS