Available online at ScienceDirect. Procedia CIRP 17 (2014 )

Transcription

1 Avalable onlne at ScenceDrect Proceda CIRP 7 (204 ) arety Management n Manufacturng. Proceedngs of the 47th CIRP Conference on Manufacturng Systems Performance measurement of modular product platforms G. Schuh, S. Rudolf, T. ogels * Laboratory for Machne Tools and Producton Engneerng (WZL) RWTH Aachen Unversty, Stenbachstraße 9, Aachen, Germany * Correspondng author. Tel.: +49-(0) ; fax: +49-(0) E-mal address: t.vogels@wzl.rwth-aachen.de Abstract It s a vtal ssue for producng companes n hgh wage countres to maxmze economes of scale and economes of scope smultaneously. Many companes nowadays use a modular product platform approach to solve ths dlemma. The preservaton of the modular product platform over the lfecycle s one of the central success factors of ths strategy. Therefore, a performance measurement system for modular product platforms s descrbed n ths paper. The approach s based on three steps to evaluate the performance of a modular product platform. In the frst step the company-specfc objectves for the modular product platform are defned and weghted. Afterwards relevant performance fgures are dentfed and ntegrated nto a balanced scorecard model, whch s developed for the performance measurement of modular product platforms. At last an evaluaton s done, whch performance ndcators can be obtaned automatcally by usng data from dfferent IT-systems. 204 Elsever B.. Ths s an open access artcle under the CC BY-NC-ND lcense 204 The Authors. Publshed by Elsever B.. Selecton ( and peer-revew under responsblty of the Internatonal Scentfc Commttee of The 47th CIRP Conference on Manufacturng Systems Selecton n and the peer-revew person of the under Conference responsblty Char Professor of the Internatonal Hoda ElMaraghy. Scentfc Commttee of The 47th CIRP Conference on Manufacturng Systems n the person of the Conference Char Professor Hoda ElMaraghy Keywords: Performance measurement; Standardzaton; Modular product platform. Introducton and motvaton Due to saturated markets and growng competton especally from Asan compettors, producng companes n hgh wage countres need to solve the dlemma between economes of scale and economes of scope. Therefore, they have to offer nnovatve and ndvdual products wth reasonable prces whch sut the needs of customers worldwde [e.g., 2, 3]. One approach to solve ths dlemma s the development of modular product platforms [e.g. 3, 4, 5]. Two man challenges have to be solved to successfully mplement modular product platforms: Frstly, a modular product platform needs to be developed ntally, whch requres a reorganzaton of product development processes as well as a consderaton of the whole value chan. Secondly, the conservaton of the modular product platform over the lfecycle has to be ensured wthout lmtng the ablty for nnovaton. [4, 5, 6, 7] The followng paper ntroduces a methodology facng the second challenge. Therefore, an approach to develop a performance measurement system for modular product platforms s descrbed n ths paper. A man task of the approach s to enable companes to track the fulfllment of gven objectves n dfferent dmensons,.e. not only fnancal dmensons but also producton aspects. In case of modular product platforms t s of specal mportance to evaluate product changes over the lfetmecycle of the platform to conserve the developed structure. In many cases product varety ncreases sgnfcantly over the lfecycle and therefore decreases economes of scale. 2. Exstng approaches addressng the performance measurement of modular product platforms Accordng to Rechmann [8] the structure of controllng s generally bult up from fve dmensons: Controllng targets Elsever B.. Ths s an open access artcle under the CC BY-NC-ND lcense ( Selecton and peer-revew under responsblty of the Internatonal Scentfc Commttee of The 47th CIRP Conference on Manufacturng Systems n the person of the Conference Char Professor Hoda ElMaraghy do:0.06/j.procr

2 G. Schuh et al. / Proceda CIRP 7 ( 204 ) Controllng tasks Controllng concepton Controllng system Controllng nsttuton Glech [9] defnes performance measurement as a part of controllng, so that the structure can also be used for the concepton of the performance measurement of modular product platforms. Classcal controllng s focused on fnancal aspects [8]. There are varous approaches whch focus on the evaluaton of the fnancal aspects of modular product platforms or complexty n general [e.g. 5, 7, 2, 24, 25]. However, these approaches do not address all dmensons of the value chan whch are affected by the mplementaton of a modular product platform. Especally benefts whch are hard to measure n fnancal fgures or not assessable at all have to be consdered [0, 2]. Therefore dfferent approaches use key performance ndcators and key fgures to evaluate and optmze complexty [e.g. 0,, 2, 20 22, 23]. Especally the balanced Scorecard s frequently used [3] as performance measurement system to evaluate and track the long term strategy. From the above mentoned approaches only one focusses on the performance measurement of modular products n specal. Junge [0] uses a modular balanced scorecard approach to control modular product famles n the automotve sector. He defnes the four felds: fnance, producton, development and marketng/sales. In accordance to the last three felds Schuh et. al [5] defne three areas for an ntegratve assessment model and add a fourth feld to the model: the supply chan. The defned felds of acton of other works [, 2] correspond wth the mentoned works. However, these approaches are not developed for the contnuous performance measurement of modular product platforms. Especally the ease of use s not focused n the descrbed approaches. Therefore, the followng approach focuses on the development of key fgures whch can be created automatcally by usng data from IT-systems and should be applcable for manufacturng companes from dfferent branches. 3. Performance measurement of modular product platforms The approach s based on three steps to evaluate the performance of modular product platforms. In the frst step the company-specfc objectves for the modular product platform are defned and weghted based on the three generc objectves for a modular product platform: tme, costs and flexblty [4]. Target conflcts between partal objectves are dentfed and a prortzaton, to avod uncontrolled decsons, s done. Afterwards the partal objectves are structured n a system of objectves. In the second step relevant performance fgures are dentfed or newly developed, where needed. The performance fgures are ntegrated nto a balanced scorecard model, whch s developed for the performance measurement of modular product platforms. Dependng on the company specfc system of objectves, a sub-set of the dentfed performance fgures has to be chosen. Due to the effort, whch s needed to collect the data for the performance fgures, the mplementaton of many scentfc valdated performance measurement systems fal n realty [9]. Therefore, an evaluaton s done n step three, whch performance ndcators can be obtaned automatcally by usng data from dfferent IT-systems. If the needed data for chosen performance ndcators s not avalable, alternatve solutons are derved. On the other hand the need to adapt and augment the avalable data from IT-systems wll be dscussed and solutons wll be descrbed. (see fg. ) Fg. : Concepton of a performance measurement system for modular product platforms 3.. System of objectves The three generc objectves of modular platforms are: Shorter tme to market Cost reducton and Hgher flexblty (varety) for customer requrements Modular platforms should fulfll all three objectves at the same tme but n realty each company has a dfferent focus: e.g. mass producers focus more on cost savngs n the producton area, whle small seres producers focus more on customer specfc solutons and therefore flexblty and varety. ery nnovatve companes e.g. n the feld of electro motors are manly nterested n a shorter tme to market snce ths s ther unque sellng pont. Therefore, the three objectves need to be weghted accordng to the company specfc strategy. The objectves can be detaled nto partal objectves, whch enable the companes to derve practcal measures. These partal objectves agan need to be weghted. In combnaton wth the weghtng factor for the shorter tme to market, each partal objectve gets an overall weghtng factor. The targets presented below are an example for machnery and plant engneerng companes. Partal objectves for a shorter tme to market are e.g.: Reducton of development tme Reducton of teratons n the prototype testng Reducton of ramp-up tme Partal objectves for cost reducton are: Less effort for part mantenance by reduced part numbers Reducton of nvestment for tools and machnes Reducton of stored materal

3 268 G. Schuh et al. / Proceda CIRP 7 ( 204 ) Reducton of assembly and manufacturng tme by standardzaton Reducton of assembly errors Partal objectves for hgher flexblty for customer requrements: Quck adjustments for customer specfc requrements Fulfllment of customer requrements Shorter delvery tme The nterdependences between the partal objectves can be vsualzed n a cause and effect network. Target conflcts can be solved n advance by the weghtng factor for each partal objectve. The weghng factors can be ether developed n workshops based on expert knowledge or by analytcal methods (e.g. analytcal herarchy process AHP, utlty analyss). Anyway, the results should be dscussed wth all relevant stakeholders lke development, product management, producton etc Performance fgures and balanced scorecard The performance measurement of modular product platforms demands the fulfllment of specfc requrements.. At frst they need to be related to the system of objectves. Therefore, the objectves namely reducton of tme to market, reducton of costs by economes of scale and fulfllment of customer requrements should be evaluated by the key fgures. 2. Furthermore the automated creaton of the key fgures s of the utmost mportance lke explaned n chapter. Ths requrement wll be dscussed n chapter The thrd requrement for the key fgures s the contnuous evaluaton of the modular product platform. Snce the performance measurement should be done on a regular bass, only key fgures whch can be created and compared at dfferent tmes should be used. 4. Snce the modular product platform has an mpact on the whole value chan, t s mportant to control all relevant areas. The effects of modular product platforms affect the whole value chan [e.g. 3, 4, 5]. Therefore, all areas of the value chan need to be consdered. Schuh et. al [5] developed an ntegratve assessment model for complexty based on the theores of Malk [6] and Kaser [7] whereby complexty can be dfferentated nto nternal and external complexty. The second dmenson they used s descrbed by Wendahl and Scholtsek [8] and dvdes complexty nto a product and a producton type. In addton Junge [0] uses n hs balanced scorecard concept the fnancal aspect for the controllng of modular product platforms. These fve dmensons are used as consttutve framework for the performance measurement of modular product platforms (see fg. 2). The requred key fgures have to be derved for each company based on the specfc system of objectves. The key fgures presented below are an example of machnery and plant engneerng companes. There are dfferent key fgures whch apply to the dfferent company specfc targets. However the chosen key fgures were dscussed wth experts from all relevant felds and chosen wth regard to ther ease of use for the mentoned companes. Note that there mght be other better suted key fgures for companes wth a dfferent background. Product program Supply Chan Fnance Product archtecture Producton Fg. 2 Consttutve framework for the performance measurement of modular product platforms In the feld of Product Program there are four key fgures whch are shown n table. Table : Key fgures for the feld Product Program Dmenson and Equaton ProductSalesBalanceIndex(PSBI),2580% PSBI OA ProductPlatformRange(PPP) PPP PPR POA Externalarety(E) mv, must can mv, x x m m E m Explanablty atpontofsale (EF PoS ) n EF PoS n OA PRODUCTPROGRAM, exp l OA Overall number of sold varants 80% Number of sold varants, whch made 80% of the revenues X mv,must m Num. of oblgatory varants of module m X mv,can m Num. of optonal varants of module m K K Prohbted combnatons n between modules OA Overall number of sold varants,expl Number of sold varants, whch made 80% of the revenues n Number sales persons The Product-Sales-Balance-Index [] gves an overvew over the dstrbuton between standard and exotc models. Ths key fgure s related to the objectve of quck customer specfc adjustments. The Product Platform Range (PPP) gves an overvew how many products can be sold based on the platform n comparson to the overall sold products. Ths key fgure s related to the objectve of offerng more varants wthn the platform. The External arety [0] gves an overvew how many standard modules are used for a varant and how many optonal modules are used. Ths key fgure refers to two objectves: to offer more varants and to reduce the part mantenance effort. At last the explanablty at Pont of Sale [2] gves an overvew how good the offered varants can be explaned and therefore sold by sales persons. Ths refers to the target of offerng more varants. The derved key fgures for the machnery and plant branch n the feld Product Archtecture are shown n table 2. The Flexblty [2] gves an overvew of how the dstrbuton of components s set between standard components and exotc components. Ths refers to the objectves n the two areas cost P OA P PP Overall number of sold products Number of sold varants of the product platform

4 G. Schuh et al. / Proceda CIRP 7 ( 204 ) reducton and shorter tme to market. The Commonalty Index [] ndcates how much costs are deduced by specal parts. Ths refers to cost reducton n the development and manufacturng of parts. The Cycle-Tme-Effcency [0] gves an overvew of the needed development tme for specal varants and therefore refers to the objectves reducton of development, prototype testng and ramp-up tme. The Interface-Effcency-Index [] gves an overvew of the number of nterfaces. It s related to the objectves reducton of assembly tme and reducton of assembly errors. Table 2: Key fgures for the feld Product Archtecture PRODUCTARCHITECTURE Dmenson and Equaton Flexblty(FPA) U j Sales volume realzed wth varant j U stand, Realzed sales volume by standard n F varant PA U j U sta nd, n Number of standard varants CommonaltyIndex(CI) MC sngle,pl Amount of manufacturng costs for specal parts of the product lne CI MC s ngle, PL MC OA,PL Amount of manufacturng costs for MCOA, PL PL PL all parts of the product lne RuD CycleTmeEffcency(CEC) t m R&D-tme for varant v RuD t v= R&D-tme for bass varant v= RuD RuD CEC t v OA tv OA Overall number of varants v2 InterfaceEffcencyIndex(IEI) M Overall number of modules of a product lne M IEI X Number of Interfaces of the X modules of a product lne In the feld Supply Chan the followng key fgures are dentfed for the machnery and plant ndustry (see table 3). Table 3: Key fgures for the feld Supply Chan Dmenson and Equaton SourcngaretyIndex(SI) LT, M SI NT, M alueaddindex(ai) MCFF, PL AI MCOA, PL Supplychancaptaleffcency(KE SC ) U T KESC max( ;0) T Supplychaneffectveness(KG SC ) q q LGSC M FQ, M OA, SUPPLYCHAIN MC FF,PL Manufacturng costs for bought-n part MC OA,PL Overall manufacturng costs for all parts of a product lne M FQ, M OA, q Quantty delvered on tme n perod Overall quantty ordered n perod Number of sub-perods wthn perod The Sourcng arety Index [] gves the relaton between number of supplers and number of parts. Ths key fgure s related to the objectve reducton of assembly errors, snce the suppler varety s a man factor for assembly errors n the current state. The alue-add-index [] gves the relaton between costs for bought-n parts and manufacturng parts. It s related to the objectves reducton of development tme and reducton of assembly tme. The Supply chan captal effcency [2] gves an overvew of how much money s bound for stored parts and creates a relaton to the overall revenues. Ths key fgure s related to the objectve reducton of stored materal. The last key fgure n ths feld s the Supply chan effectveness [2] whch gves an overvew over L T,M N T,M t U t Number of dfferent suppler for the used parts Number of dfferent parts Avg. value of nventores related to consdered product program Revenues generated by consdered product program n underlyng perod the orders delvered n tme and therefore s coupled wth the objectve shorter delvery tme. In the feld of producton the followng four key fgures can be used (see table 4). The Process commonalty [2] gves an overvew of the standardzaton of processes and s therefore related wth the objectve reducton of manufacturng tme. The same apples for the key fgure Resource utlzaton. The key fgure Dfferentaton-Pont- Index [] gves an overvew how many assembly varants exst n each assembly step. It s related to the objectves reducton of ramp-up tme, reducton of stored materal and reducton of assembly errors. At the same tme t s related to the objectve of quck adjustment for customer requrements. The Manufacturng Platform Effcency [0] gves an overvew over the nvestment for a specfc varant n comparson to basc varants. Ths key fgure s related to the objectve reducton of nvestment for tools and machnes. Table 4: Key fgures for the feld Producton Dmenson and Equaton Processcommonalty(PK PS ) r r PK PS 2 Rmax p Resourceutlzaton(A PS ) o A PS T o t DfferentatonPontIndex(DPI) n DPI n OA ManufacturngPlatformEffcency(MPE) P P MPE Iv Iv v2 PRODUCTION r R max p T t OA n IP v IP v= Overall number of process steps Investment n producton for varant v Absolute nvestment n producton for the bass varant v = Total amount of varants The last fle s the feld fnance. The key fgures are not drectly related to the gven objectves but they gve an overvew how successful the modular product platform s. The key fgures are shown n table 5. Table 5: Key fgures for the feld Fnance Dmenson and Equaton NetPresentalue(NP) T CFt NP t t 0 PlatformRevenue(PR) PR X v p v v PrceCostRato(PCR) pv PCR PC OA v kv The frst key fgure Net-Present-alue [0] gves an overvew over the cash flow n relaton to the defned return rate of the modular product platform. The Platform-Revenue [0] gves an overvew over the sales of each varant and allows therefore to dentfy standard products and exotc products. The Prce-Cost-Rato [0] gves the relaton of prce o FINANCE X v p v OA p PC v k v Number of used process sequences Theoretcal max. of sequences Overall number of resources Duraton of underlyng perod Process tme of resource wthn tme span Number of avalable resources Number of assembly varants n process step Overall number of product varants CF t Net-Cash-Flow n perod t Requred rate of return T Lfespan of a modular platform product Sales quantty for varant v Prce for varant v Overall number of varants Prce for varant v Prme costs for varant v

5 270 G. Schuh et al. / Proceda CIRP 7 ( 204 ) to costs for the modular platform and allows to track the proftablty. The key fgures wll be collected n regular ntervals. The development over tme can be shown and also need for acton can be dentfed by usng statstcal methods lke control charts. Ths enables the companes to measure the performance of the modular product platform and enables them to dentfy felds of acton e.g. n the area of producton. The nterpretaton of each value should be conducted n order to the strategc long-term targets. The controllng of the development of each key fgures allows to dentfy trends or dfferences between the as-s and should-be value and allows an early dentfcaton and defnton of countermeasures. To better compare the dfferent values and aggregate them nto one comprehensve KPI t s useful to standardze the values of each key fgure from 0. The aggregaton nto a sngle comprehensve KPI s one focus of further research Avalable data n IT-systems For the ease of use of the performance measurement t s of the utmost mportance, that all relevant key fgures can be created wth very low or wthout effort and that the results can be repeatedly created and compared. Therefore, the needed data should be delvered automatcally by the exstng ITsystems. Nowadays the IT-landscape s very heterogeneous [9] and conssts of many dfferent systems. Egner [9] descrbes four levels of a state of the art PLM (Product- Lfecycle-Management) system: author tools lke CAD, CAM or Offce where the data s created are assgned to the lowest level. On the second level so called TDM (Team-Data- Management) systems where the data from the author tools s handled are aggregated. The thrd level s the so called PLM backbone. The data gets transferred from the dfferent TDM systems nto ths backbone and s aggregated over all dfferent systems and functons. Functons lke confguraton management, change management and smulaton should be done on ths level. The last level s the ERP (Enterprse Resource plannng) system where the actual plannng of producton, purchasng, logstcs and so on should be done [9]. For the performance measurement of modular product platforms t s necessary to consder data from all four levels dependng on the chosen key fgures. However, n the ndustry ths IT archtecture s often made up of many dfferent systems and the synchronzaton between these systems s nowadays often problematc and the structure s very company specfc. Therefore, t s necessary to check for each set of key fgures, whch data s avalable and n whch IT-system. If the data s not avalable n the IT-systems there are dfferent ways to handle the problem. At frst t should be examned, f there are dfferent key fgures avalable, whch gve a smlar nformaton based on dfferent data. In the example for the machnery and plant companes the chosen key fgure for the product commonalty cannot be created automatcally. The reason s that t s not possble to dentfy automatcally the parts whch are only used for a specfc product. Therefore, a dfferent key fgure for evaluaton of the commonalty n the product can be used [2]: CI A k k k: Number of overall components w : alue of component of overall value of product archtecture Abs : Sales of component Abs ges : Overall sales In the mentoned example the number of overall components can be delvered by the PDM system, whle the cost value of each component and the sales fgures of the specfc components and the overall sales fgures can be delvered by the ERP system. Therefore, the requrement of automated data preparaton s fulflled. If there s no other key fgure avalable whch delvers the same data, t can be consdered to create a new key fgure based on the data avalable n the IT-systems. Important for ths bottom up approach s the fulfllment of the objectves whch are related to the orgnal key fgure. The second way to solve the problem s to adjust the ITsystems to make the needed data avalable. Ths step usually creates more effort than the change of key fgures, hence the frst opton should be consdered at frst. However, there mght exst some cases where no alternatve key fgure s avalable or where t s useful to have the nformaton n the IT-systems. In the example for the machnery and plant branch the DPI was such a key fgure. To evaluate the dfferentaton pont n the producton t s necessary to dentfy the number of assembly varants for each producton step. Therefore, t was necessary to structure the producton process nto several steps and mplement a logc to mplement the nformaton n the PDM system. Afterwards each product varant got an assembly varant assgned for each of the defned producton steps. Ths enables the PDM system to delver the needed data for the key fgure DPI. All key fgures were checked n ths manner and got lnked to the IT-systems whch contan the needed data. The shown adaptons gve an example how the key fgures and ITsystems can be adjusted to fulfll the requrement of automated data preparaton. 4. Concluson Abs w Abs ges In order to measure the performance of modular product platforms t s necessary to develop a controllng system whch consders the company specfc objectves, allows an automated data creaton for the ease of use, consders the effects on the whole value chan and can be used contnuously over the lfecycle. Therefore, a method to derve a company specfc performance measurement system s presented n ths paper. The development s based on three steps. At frst the objectves of the modular product platform need to be dentfed and afterwards structured n a system of objectves. In the second step the objectves need to be lnked to key fgures whch allow an evaluaton of the objectves. The key fgures are mplemented n a consttutve framework. In the thrd step the automated creaton of the requred data for the

6 G. Schuh et al. / Proceda CIRP 7 ( 204 ) dentfed key fgures s ensured. Therefore, the companes need to check f the needed data s avalable n ther ITsystems. If they are not avalable there are two approaches to tackle the problem: the adapton or change of the key fgures based on the avalable data or the adapton of the data avalable n the IT-systems. The paper shows examples from the machnery and plant producton branch to gve an dea how the development of a performance measurement of modular product platforms can be done. Acknowledgements The presented results have been developed at the WZL and have been valdated wth dfferent companes n the machnery and plant ndustry. The author's sncere thanks go to the companes who supported n the verfcaton of the performance measurement model. References [] ElMaraghy, W.H., Urbanc, R.J., 2003, Modellng of Manufacturng Systems Complexty, Annals of the CIRP, 52/: [2] Schuh, Arnoscht, Bohl, Nußbaum. Integratve asssessment and confguraton of producton systems. In: Crp Annals Manufacturng Technology 60; 20. P [3] ElMaraghy, H. ()a, Schuh, G. () b, ElMaraghy, W. ()c, Pller, F. d, Schönsleben, P. (2)e,Tseng, M. ()f, Bernard, A. (). Product arety Management. In: Crp Annals - ol , p [4] Martn, M.., 999, Desgn for arety, A Methodology for Developng Product Platform Archtectures, Dssertaton Stanford Unversty. [5] Schuh, G., Arnoscht, J., Rudolf, S., 200, Integrated development of modular product platforms, PICMET 200. [6] Ercsson, A., Erxon, G., 999, Controllng Desgn arants Modular Product Platforms, SME, p [7] Smpson, T.W., Maer, J.R.A., Mstree, F., 200, Product platform desgn: method and applcaton, Sprnger. [8] Rechmann. Controllng mt Kennzahlen und Management-Tools (Controllng wth key fgures and management tools), 2006, p. 2. [9] Glech, R., Qutt, A., Görner, A., 20, Performance Measurement Konzepte, Fallstuden und Grundschema für de Praxs (Performance Measurement concepts, case studes and base structure for ndustral use), Franz ahlen, München, p [0] Junge, M., 2004, Controllng modularer Produktfamlen n der Automoblndustre (Controllng of modular product famles n the automotve sector), Gabler, p [] Rennekamp, M., 203, Methode zur Bewertung des Komplextätsgrades von Unternehmen (Methodology to evaluate the complexty of companes), Dssertaton RWTH Aachen. [2] Nußbaum, C.L., 20, Modell zur Bewertung des Wrkungsgrads von Produktkomplextät (Model to evaluate the effcency of product complexty), Dssertaton RWTH Aachen. [3] Kaplan, R.S., Norton, B.P., 992, The Balanced Scorecard Measures that drve performance, Harvard Busness Revew, p [4] Pfefer, T., Schmtt, R., 200, Qualtätsmanagement: Strategen, Methoden, Technken (Qualty management, strateges, methods and methods), Hanser, p.2-6. [5] Schuh, G., 2005, Produktkomplextät managen (Managng product complexty), Sprnger. [6] Malk, F., 2000, Systemsches Management (Systematc management), 2nd ed., Haupt, Bern. [7] Kaser, A., 995, Integrertes arantenmanagement mt Hlfe der Prozesskostenrechnung (Integrated varant management by use of complexty costs), Dssertaton Unverstät St. Gallen. [8] Wendahl, H.-P., Scholtssek, P., 994, Management and Control of Complexty n Manufacturng, Annals of the CIRP, 43/2: [9] Egner, Stelzer. Product Lfecycle Management, Sprnger, p [20] Blecker, T., Abdelkaf, N., Kaluza, B., Fredrch, G., Controllng varetynduced complexty n mass customsaton: a key metrcs-based approach, In: Int. J. Mass Customsaton, ol., Nos. 2/3, [2] Webb, G.S., 20, Product varety: An nvestgaton nto ts revenue, cost, and proft, Mchgan State Unversty: Unted States -- Mchgan. [22] Caesar, C., 99, Kostenorenterte Gestaltungsmethodk für varantenreche Serenprodukte (Cost orented methodology for seres products wth many varants), Dssertaton RWTH Aachen. [23] Suh, E. S., de Weck, O. L., Flexble Product Platforms: framework and case study. In: Research n Engneerng Desgn, 8. Jg., Nr. 2, 2007, S [24] Lee, L., Tang, C., Modellng the Costs and Benefts of Delayed Product Dfferentaton. In: Management Scence, (): p [25] Sedenschwarz,W., 993, Target Costng: Marktorentertes Zelkostenmanagement (Target Costng: market orented cost management), München.