special issue paper 451 digital manufacturing: history ... · digital manufacturing: history,...

Digital manufacturing historyperspectives and outlookG Chryssolouris D Mavrikios N Papakostas D Mourtzis G Michalos and K Georgoulias

Department of Mechanical Engineering and Aeronautics University of Patras Patras Greece

The manuscript was received on 23 May 2008 and was accepted after revision for publication on 20 June 2008

DOI 10124309544054JEM1241

Abstract Digital manufacturing has been considered over the last decade as a highly promis-ing set of technologies for reducing product development times and cost as well as for addres-sing the need for customization increased product quality and faster response to the marketThis paper describes the evolution of information technology systems in manufacturing outlin-ing their characteristics and the challenges to be addressed in the future Together with the digi-tal manufacturing and factory concepts the technologies considered in this paper includecomputer-aided design engineering process planning and manufacturing product data andlife-cycle management simulation and virtual reality automation process control shopfloorscheduling decision support decision making manufacturing resource planning enterpriseresource planning logistics supply chain management and e-commerce systems These tech-nologies are discussed in the context of the digital factory and manufacturing concepts

Keywords information technology computer-integrated manufacturing computer-aideddesign computer-aided engineering computer-aided manufacturing

1 INTRODUCTION

The need for reduced development time together withthe growing demand for more customer-orientedproduct variants have led to the next generation ofinformation technology (IT) systems in manufactur-ing Manufacturing organizations strive to integratetheir business functions and departments with newsystems in an enterprise database following a unifiedenterprise view [1] These systems are based on thedigital factorymanufacturing concept according towhich production data management systems andsimulation technologies are jointly used for optimiz-ing manufacturing before starting the productionand supporting the ramp-up phases [2] Digital manu-facturing would allow for first the shortening ofdevelopment time and cost second the integrationof knowledge coming from different manufacturingprocesses and departments third the decentralizedmanufacturing of the increasing variety of parts andproducts in numerous production sites and fourththe focusing of manufacturing organizations on their

core competences working efficiently with other com-panies and suppliers on the basis of effective IT-basedcooperative engineering

The evolution of IT in manufacturing is describedin the next section Recent developments and thedigital manufacturing concept are then discussedfollowed by the conclusions regarding the pers-pectives and the outlook of digital manufacturing inthe future

2 IT IN MANUFACTURING

Over the past few decades the extensive use of IT inmanufacturing has allowed these technologies toreach the stage of maturity The benefits of the newtools have been thoroughly examined and their effi-ciency in many applications has been proven Theirapplication ranges from simple machining applica-tions to manufacturing planning and control sup-port From the early years of the introduction ofnumerical control and all the way to machiningcentres manufacturing cells and flexible systemscosts and increased power have been the mainadvantages of IT [3] An example of the introductionof IT in the manufacturing world is the concept of

Corresponding author Department of Mechanical Engineer-

ing and Aeronautics University of Patras University Campus

Rio Patras 26500 Greece email mourtzislmsmechupatrasgr

JEM1241 IMechE 2009 Proc IMechE Vol 223 Part B J Engineering Manufacture

SPECIAL ISSUE PAPER 451

computer-integrated manufacturing (CIM) This con-cept was introduced in the late 1980s favouring theenhancement of performance efficiency operationalflexibility product quality responsive behaviour tomarket differentiations and time to market How-ever the full strategic advantage of information tech-nologies was poorly understood at that time andcould not be exploited to its full extent [3]

The inventory control and material requirementsplanning (MRP) systems were introduced in the1960s and 1970s respectively Such systems werefurther enhanced with the integration of tools cap-able of providing capacity and sales planning func-tionalities together with scheduling capabilities andforecasting tools The result was the introduction ofthe closed-loop- MRP [4] Nevertheless the advancesin microprocessor technology the advent of theinternet era the standardization of software inter-faces the wide acceptance of formal techniques forsoftware design and development and the maturityof certain software products (relational databasemanagement systems and computer-aided design(CAD) systems for instance) paved the way for facil-itating the integration among diverse software appli-cations [1] The evolution of information systemsover the last decade has played a crucial role in theadoption of new information technologies in theenvironment of manufacturing systems [5]

21 Computer-aided technologies

CAD is considered among the technologies that haveboosted productivity allowing faster time to marketfor the product and dramatically reducing the timerequired for product development Although the firstCAD applications were inherently difficult to useowing to the text-based input systems and the extre-mely slow computational equipment their succes-sors have become more than necessary in todayrsquosmanufacturing companies regardless of their sizeAffordable solutions offering a modern photorea-listic graphical user interface are nowadays avai-lable in the market Functionalities of such systemsintegrate finite element analysis (FEA) kinematicsanalysis dynamic analysis and full simulation ofgeometrical properties including texture and mech-anical properties of materials The CAD systemshave become indispensable to todayrsquos manufacturingfirms because of their strong integration withadvanced manufacturing techniques CAD modelsare often considered sufficient for the production ofthe parts since they can be used for generating thecode required to drive the machines for the pro-duction of the part Rapid prototyping is an exampleof such a technology

Process planning activities determine the neces-sary manufacturing processes and their sequence in

order to produce a given part economically and com-petitively [1] Towards this direction the computer-aided process planning (CAPP) systems have beenused for the generation of consistent process plansand are considered as being essential componentsof the CIM environments [6] Denkena et al [7] pro-posed a holistic component manufacturing processplanning model based on an integrated approachcombining technological and business considera-tions in order to form the basis for developingimproved decision support and knowledge manage-ment capabilities to enhance available CAPP solu-tions Kim and Duffie [8] introduced a discretedynamic model design and have analysed the controlalgorithms for closed-loop process planning controlthat improve response to disturbances such as rushorders and periodic fluctuations in capacity In theirwork Azab and ElMaraghy [9] presented a novelsemigenerative mathematical model for reconfigur-ing macrolevel process plans In the same work it isclaimed that reconfigurable process planning is animportant enabler of changeability for evolvingproducts and systems Finally Ueda et al [10] intro-duced a new simultaneous process planning andscheduling method of solving dilemmas posed bysituations where a process plan and a productionschedule conflict using evolutionary artificial neuralnetworks based on emergent synthesis

Computer-aided engineering (CAE) systems areused to reduce the level of hardware prototypingduring product development and to improve theunderstanding of the system [11] The CAE systemssupport a large number of engineering research fieldsincluding fluid mechanics (computational fluidmechanics) dynamics (simulation of machines andmechanisms) mechanics of materials (FEA) thermo-dynamics and robotics For instance Brinksmeieret al [12] conducted an extensive survey on theadvances in the simulation of grinding processestogether with a series of models that can be imple-mented in simulation systems

Following the development of the CAD systems theconcept of computer-aided manufacturing (CAM)was born The great step towards the implementationof CAM systems was the introduction of computernumerical control (CNC) Apart from the fact thatthis new technology has brought about a revolutionin manufacturing systems by enabling mass produc-tion and greater flexibility [13] it has also enabledthe direct link between the three-dimensional (3D)CADmodel and its production Newman and Nassehi[14] proposed a universal manufacturing platform forCNC machining where the applications of variouscomputer-aided systems (CAx) applications canseamlessly exchange information The proposed plat-form is based on the standard STEP-NC In additionstandardization of programming languages for these

Proc IMechE Vol 223 Part B J Engineering Manufacture JEM1241 IMechE 2009

452 G Chryssolouris D Mavrikios N Papakostas D Mourtzis G Michalos and K Georgoulias

machines (GampM code and APT) leads solution devel-opers to integrate an automatic code generation intheir applications From that point on CAD andCAM systems have been developed allowing for partdesign and production simulation Engineers havethe ability to visualize both the part and the produc-tion process to verify the quality of the product andthen physically to perform the manufacturing pro-cess with minimum error probability

Other systems such as computer-aided quality [15]systems have also started to emerge and to becomepart of the engineering workflow Product data man-agement (PDM) and product life-cycle management(PLM) systems on the other hand allow for perform-ing a variety of data management tasks includingvaulting workflow life-cycle product structure andview and change management PDM systems areclaimed to be able to integrate and manage all ap-plications information and processes that define aproduct from design tomanufacture to end-user sup-port PDM systems are frequently used for controllinginformation files documents and work processesand are required to design build support distributeandmaintain products Typical product-related infor-mation includes geometry engineering drawingsproject plans part files assembly diagrams productspecifications numerical control machine-tool pro-grams analysis results correspondence bill of mate-rial and engineering change orders

PLM is an integrated information-driven approachto all aspects of a productrsquos life cycle from its designinception through its manufacture deployment andmaintenance to finally its removal from service andits final disposal Some of the benefits reported bythe usage of PLM involve the reduced time to marketimproved product quality reduced prototyping costssavings through the reuse of original data featuresfor product optimization and reduced waste and sav-ings through the complete integration of engineeringworkflows These systems are theoretically supposedto tie everything together allowing engineering man-ufacturing marketing and outside suppliers andchannel partners to coordinate activities

Technically speaking todayrsquos PDM and PLM sys-tems mainly focus on the administration of computerfiles without however having much access to theactual content of these files Instead the CAD sys-tems are used for developing product modelssince geometry data constitute the major part of theproduct-defining characteristics [16] On the otherhand PLM systems often include a mature collabora-tive product design domain and aim at encompass-ing design and management of the manufacturingprocesses and digital manufacturing the latter repre-senting a strategic and important milestone in theadvancement of PLM Digital manufacturing hasarrived as a technology and discipline within PLM

that provides a comprehensive approach for thedevelopment implementation and validation ofall elements of the manufacturing process which isforeseen by researchers and engineers to be oneof the primary competitive differentiators formanufacturers

In todayrsquos state of the art the PDM and PLM solu-tions in one of the most complex industrial domainsthe automotive industry use concepts such as thegenerative template a solution aiming to reducedesign cycle time in several development processesby employing computer models to incorporate com-ponent and knowledge rules that reflect design prac-tice and past experience In the templates variouselements included in product design are combinedThe templates are then reused either by the sameteam project or company or through the extendedenterprise by way of exchanges between originalequipment manufacturers (OEM) and suppliersThis components-based approach accelerates andsimplifies the design

During the design of a new product or process it isessential that all the knowledge and experience avail-able (either on the product or process design) gainedthrough time can be accessed easily and rapidly Thiscan be achieved with the use of archetypes and tem-plates A process archetype is a way of classifyingstandard solutions that do not need any furtherdevelopment so that they can be available whenevernecessary within a very short time Archetypes canalso include information on newly developed innova-tive processes that have been assessed for their effi-ciency in order for any implementation risks to beminimized in case the application of this process isunder consideration

22 Manufacturing control

Manufacturers will base their future controller selec-tion on factors such as adherence to open industrystandards multi-control discipline functionalitytechnical feasibility cost-effectiveness ease of inte-gration and maintainability More importantlyembedded systems and small-footprint industrial-strength operating systems will gradually change theprevailing architecture by merging robust hardwarewith open control Integration of control systemswith CAD and CAM and scheduling systems as wellas real-time control based on the distributed net-working between sensors and control devices [17]currently constitute key research topics For instanceElMaraghy et al [18] developed a methodology ofcompensating for machining errors aimed at maxi-mizing conformance to tolerance specificationsbefore the final cuts are made

New developments in the use of wireless tech-nologies on the shopfloor such as radiofrequency


Digital manufacturing history perspectives and outlook 453

identification (RFID) as a part of automated identifi-cation systems involve retrieving the identity ofobjects and monitoring items moving through themanufacturing supply chain which enable accurateand timely identification information [19] Morerecently the installation of wireless technologies onthe shopfloor such as RFID global system for mobilecommunications (GSM) and 80211 has been a newIT application area on the industrial shopfloor [20]However the integration of wireless IT technologiesat an automotive shopfloor level is often preventedbecause of the demanding industrial requirementsnamely immunity to interference security and highdegree of availability

On the other hand in the automotive assembly ITis applicable to a series of processes such as pro-duction order control production monitoringsequence planning vehicle identification qualitymanagement maintenance management and mate-rial control [21]

23 Simulation

Computer simulation has become one of the mostwidely used techniques in manufacturing systemsdesign enabling decision makers and engineers toinvestigate the complexity of their systems and theway that changes in the systemrsquos configuration or inthe operational policies may affect the performanceof the system or organization [22]

Simulation models are categorized into staticdynamic continuous discrete deterministic andstochastic Since the late 1980s simulation softwarepackages have been providing visualization capabil-ities including animation and graphical user interac-tion features Computer simulation offers the greatadvantage of studying and statistically analysingwhatndashif scenarios thus reducing overall time andcost required for taking decisions based on the sys-tem behaviour Simulation systems are often inte-grated with other IT systems such as CAx FEAproduction planning and optimization systems

While factory digital mock-up (DMU) softwareallows manufacturing engineers to visualize the pro-duction process via a computer which allows for anoverview of the factory operations for a particularmanufacturing job the discrete event simulation(DES) helps engineers to focus closely on each indivi-dual operation DES may help decision making in theearly phases (conceptual design and prestudy) onevaluating and improving several aspects of theassembly process such as location and size of theinventory buffers the evaluation of a change in pro-duct volume or mix and throughput analysis [23]

An extension to simulation technology (the virtualreality (VR) technology) has enabled engineers tobecome immersed in virtual models and to interact

with them Activities supported by VR involve factorylayout planning operation training testing andprocess control and validation [24 25]

Other applications include the verification ofhuman-related factors in assembly processes byemploying desktop three-dimensional simulationtechniques replacing the human operator with ananthropometrical articulated representation of ahuman being called a lsquomannequinrsquo [26]

24 Enterprise resource planning andoptimization

Enterprise resource planning (ERP) systems attemptto integrate all data and processes of an organizationinto a unified system A typical ERP system will usemultiple components of computer software and hard-ware to achieve the integration A key ingredient ofmost ERP systems is the use of a unified database tostore data for the various system modules ERP hasbeen associated with quite a broad spectrum of defi-nitions and applications over the last decades [27]

The manufacturing resources planning (MRP II)systems apart from incorporating the financialaccounting and management systems have beenfurther expanded to incorporate all resource plan-ning and business processes of the entire enterpriseincluding areas such as human resources projectmanagement product design materials and capa-city planning [4]

The elimination of incorrect information and dataredundancy the standardization of business unitinterfaces the confrontation of global access andsecurity issues [4] and the exact modelling of busi-ness processes have all become part of the list ofobjectives to be fulfilled by an ERP system Largeimplementation costs high failure risks tremendousdemands on corporate time and resources [4] andcomplex and often painful business process adjust-ments are the main concerns pertaining to an ERPimplementation Considering the current trend inthe manufacturing world for maximizing their com-munication and collaboration the ERP system func-tionality has also been extended with supply chainmanagement solutions [28]

The ERP systems often incorporate optimizationcapabilities for cost and time savings virtually fromevery manufacturing process Indicative examplesinvolve cases from simple optimization problemsshopfloor scheduling and production planning totodayrsquos complex decision-making problems [29 30]Monostori et al [31] have proposed a scheduling sys-tem capable of real-time production control Thissystem receives feedback from the daily productionthrough the integration of information coming fromthe process quality and production monitoring sub-systems The system is able to monitor deviations



and problems of the manufacturing system and tosuggest possible alternatives for handling them

A new generation of factory control algorithms hasrecently appeared in literature known as lsquoagentbasedrsquo In Sauersrsquo [32] work a software agent technol-ogy is discussed and proposed as the middlewarebetween the different software application compo-nents on a shopfloor Agents are a promising technol-ogy for industrial application because they are basedupon distributed architecture however issues suchas synchronization interfacing agents and data con-sistency among agents impose difficulties on theirpractical application [23]

3 RECENT DEVELOPMENTS

31 Academic research

Recent developments in digital manufacturing maybe categorized into two major groups The develop-ments of the first group have followed a bottom-upapproach considering digital manufacturing andextending its concepts within a wider frameworkeg the digital factory or enterprise The devel-opments of the second group have followed a top-down approach considering the technologies in sup-port of individual aspects of digital manufacturingeg e-collaboration and simulation

According to the Verein Deutscher Ingenieure thedigital factory includes models methods and toolsfor the sustainable support of factory planning andfactory operations It includes processes based onlinked digital models connected with the productmodel [33] At a theoretical level several researchershave contributed to the definition of the digital fac-tory vision and suggested how this vision could beimplemented in reality (Fig 1) [34] Data and modelsintegration has been a core research activity to sup-port implementation The introduction of consistentdata structures for improving the integration ofdigital product design and assembly planning andconsequently supporting a continuous data exchangehas been investigated in the literature [35] Similaractivities have focused on the definition of semanticcorrelations between the models distributed as wellas the associated databases and the introduction ofappropriate modelling conventions [33] On topof these developments a number of methodologiesfor computer-supported co-operative developmentengineering within a digital factory frameworkhave been published Some researchers further sug-gested software architectures for relationship man-agement and the secure exchange of data [36]

The new concept of digital enterprise technology(DET) has also been recently introduced as thecollection of systems and methods for the digitalmodelling of the global product development and

Fig 1 The vision of the digital factory [34]



realization process in the context of life-cyclemanagement [37] As such it embodies the tech-nological means of applying digital manufacturingto the distributed manufacturing enterpriseDET is implemented by a synthesis of technologiesand the systems of five main technical areas theDET lsquocornerstonesrsquo corresponding to the design ofproduct process factory technologies for ensuringthe conformance of the digital environment with thereal one and the design of the enterprise On thebasis of the DET framework a new methodologyhas been suggested that focuses on developing novelmethods and tools for aggregate modelling knowl-edge management and test on validation planningto lsquobridgersquo the gap that exists between conceptualproduct design and the organization of the corre-sponding manufacturing and business operations(Fig 2) [38]

From a technological point of view new frame-works for distributed digital manufacturing haveappeared on the scene Recent developments focuson a new generation of decentralized factory controlalgorithms known as lsquoagent basedrsquo A software agentfirst is a self-directed object second has its ownvalue systems and a means of communicating withother such objects and third continuously acts onits own initiative [39] A system of such agents calleda multi-agent system consists of a group of identicalor complementary agents that act together Agent-based systems encompassing real-time and decen-tralized manufacturing decision-making capabilitieshave been reported [40] In such a system eachagent as a software application instance is respon-sible for monitoring a specific set of resourcesnamely machines buffers or labour that belong to a

production system and for generating local alterna-tives upon the occurrence of an event such as amachine breakdown Web-based multi-agent systemframeworks have also been proposed to facilitatecollaborative product development and productionamong geographically distributed functional agentsusing digitalized information (Fig 3) [41] The pro-posed system covers product design manufactur-ability evaluation process planning scheduling andreal-time production monitoring

The advances in DMU simulation technologiesduring the 1990s were the key stone for theemergence of VR and human simulation in digitalmanufacturing These advances have led to new fra-meworks that integrate product process resourceknowledge and simulation models within the DMUenvironment [42]

The VR technology has recently gained major inter-est and has been applied to several fields related todigital manufacturing research and developmentVirtual manufacturing is one of the first fields thatattracted researchersrsquo interest A number of VR-basedenvironments have been demonstrated providingdesktop andor immersive functionality for processanalysis and training in such processes as machiningassembly and welding [25 43] Virtual assemblysimulation systems focusing on digital shipbuildingand marine industries incorporating advanced simu-lation functionalities (crane operability block erec-tion simulation in virtual dock etc) have also beenintroduced by Kim et al [44] Human motion simula-tion for integrating human aspects in simulationenvironments has been another key field of interest(Fig 4) Several methodologies for modelling themotion of digital mannequins on the basis of realhuman data have been presented Furthermore ana-lysing the motion with respect to several ergonomicaspects such as discomfort have been reported[28 30 45]

Collaborative design in digital environments isanother emerging research and development fieldThe development of shared virtual environmentshas enabled dispersed actors to share and visualizedata to interact realistically as well as to make deci-sions in the context of product and process designactivities over the web [46] Research activities havebeen also launched for the definition and imple-mentation of VR- and augmented-reality-based col-laborative manufacturing environments which areapplicable to human-oriented production systems[47 48]

32 Industrial practices and activities

In industrial practice digital manufacturing aims at aconsistent and comprehensive use of digital methodsFig 2 The DET cornerstones [38]



of planning and validation from product develop-ment to production and facility planning

The Accessible Information Technology (AIT)Initiative and its offspring projects launched duringthe 1990s by the automotive and aerospace industryin Europe have been pioneering in driving digitalmanufacturing advances aiming at increasing thecompetitiveness of industry through the use ofadvanced information technology in design andmanufacturing [49] On that basis the automotiveindustry still drives today a number of relevant devel-opments in digital manufacturing

In BMW the three series at Leipzig has beenBMWrsquos best launch ever as they achieved 50 percent fewer faults per vehicle and have recorded far

better process capability measures than in the pastbecause of the use of the simulation of productionprocesses at a very early stage of design [50]Similarly General Motors has utilized a three-dimensional workcell simulation (iGRIP) providedby digital enterprise lean manufacturing interactiveapplication (DELMIA) allowing the engineers to gen-erate three-dimensional simulations and to translatemodels created in other commercially availablepackages During 2002 Opel utilized DELMIA forthe simulation of the production process of its Vectramodel allowing for a very fast production launch [51]Finally computer-aided three-dimensional interac-tive application (CATIA) machining simulation toolshave given manufacturing experts at Daimler achance to test virtually the lsquochoreographyrsquo for theproduction of parts ensuring that the finished pro-duct will meet precise design expectations

At Volvo DES has been used as a tool for continu-ous process verification in industrial system devel-opment [52] BMW and DaimlerChrysler are alsoamong the users of similar applications [53] GeneralMotors has used DES in several case studies and hasdemonstrated the ability of using simulation for opti-mizing resources and identifying constraints [54]Ford has also been using computer simulation insome form or other for designing and operating itsengine manufacturing facilities since the mid-1980sCase studies in advanced manufacturing engineeringfor a powertrain at DaimlerChrysler have identifiedvirtual modelling as an emerging technology forautomotive process planners [55]

Fig 4 Human simulation in digital manufacturing envir-onments [29]

Fig 3 A web-based multi-agent system framework [41]



The method of digital planning validation (DPV)has recently gained some interest (Fig 5) [56] Basedon a validation process running in parallel to that ofdigital planning the DPV method developed byDaimlerChrysler consists of both the continuouschecking of digital planning results as well as the pro-cess reviews at certain points in time the so-calledprocess days During the process days the currentplanning states are validated through geometricalchecks of the assemblies the simulation of processesor detailed examinations of layouts The DPV methodis based on the DMU techniques and simulation Inanalogy to the product DMU for the product devel-opment can be regarded as a kind of process DMUof production planning within the digital factory

The so-called virtual process week is another rele-vant method applied to BMW working practices[57] This method addresses the assessment of theassembly planning by a group of people responsiblefor the process Based on the product structurevisualization scenes are created By using the groupfunction of visualization the system parts are shownsubsequently according to the assembly plan Theparticipants use eight criteria to assess the operationAll results are documented in a database online Inthe end statistical evaluations of the database showwhere operations have to be clarified in more detailor where the geometry of parts will have to bechanged because of bottlenecks during the onlineoperation

New methods and technologies for virtual assem-bly in the digital factory have been investigated byVolvo DaimlerChrysler Fiat and Ford in the contextof the Eu Integrated Project lsquoMyCarrsquo driven by Volvo

and Laboratory for Manufacturing Systems and Auto-mation University of Patras [58] The OEMs are seek-ing novel approaches to achieving an improvementin the data communication and to providing a foun-dational IT CAx architecture that enables the varioustools to interoperate seamlessly and the processes tobe managed efficiently Digital validation of produc-tion of body-in-white and assembly as well as simula-tion for virtual ramp-up of production cells and linesincluding virtual commissioning are investigatedThe human simulation of manual automated andmixed processes for improving the consideration ofhuman factors is another topic of major research

4 DIGITAL MANUFACTURING OUTLOOK

The speed-up of a manufacturing process consists oftwo aspects one is the speed-up of product devel-opment to reduce development lead time and theother is that of production to reduce productionlead time [59]

In parallel the quality and manufacturing cost ofthe final product are determined again in both thedesign and production phases This demonstratesthat there is a significant need for a bridge to be builtbetween the production of development and thereal production digital manufacturing aims to playthis part

Years ago both FEA and computer-aided machin-ing were the true lsquoblack artsrsquo of manufacturing Withproducts that devolved out of high-end academicresearch these software products often neededhighly trained highly scientific minds and a deep

Fig 5 Digital manufacturing links product development production planning and facility planning [56]



and healthy bank account In the 1990s both FEAand computer-aided machining suddenly becameaffordable and usable even on the shopfloor FEAintegrated with mainstream design products hasmeant that most testing and analysis can be con-ducted quickly and with reliable results Now anengineer can find out much earlier in the process ifa design has any flaws and then can eradicate themquickly The recent technology improvements aremaking digital manufacturing real to many andmany companies are using pieces of digital manufac-turing without realizing it [60]

Nevertheless digital manufacturing needs to befurther exploited in order to close the gap betweenthe product definition (configuration of componentsand required manufacturing processes) and theactual manufacturing production activities withinthe enterprise [61] Simulation and VR can now beused in order to significantly reduce costs and timeto market Manufacturing is only 30 per cent of theproduct development cost but the remaining 70 percent is locked during the design phase of new pro-duct development [62]

Based on responses from industry Dalton-Taggart[60] defined digital manufacturing as lsquothe ability todescribe every aspect of the design-to-manufactureprocess digitally ndash using tools that include digitaldesign CAD office documents PLM systems ana-lysis software simulation CAM software and so onrsquoThe concept is that the passage of data from onedepartment or discipline to another should be seam-less so that the data created are immediately reusablein a different discipline Several benefits can thenbe derived By exploiting digital manufacturingmanufacturing enterprises expect to achieve thefollowing [61]

(a) shortened product development(b) early validation of manufacturing processes(c) faster production ramp-up(d) faster time to market(e) reduced manufacturing costs(f) improved product quality(g) enhanced product knowledge dissemination(h) reduction in errors(i) increase in flexibility

The industries that benefit the most from utilizingthese methodologies are those with capital-intensivemanufacturing and those with very complex productsbut very low production even single-unit productionFor the capital intensive manufacturers the returnof investment is calculated on the basis of thedecrease in the time to market by 30ndash50 per centdue to efficient concurrent engineering reducingthe product cost by 10ndash25 per cent through multipleiterations of design for manufacturing and designfor assembly and reducing the costly engineering

changes to product design and production toolingduring launch by 80ndash90 per cent [63] Organiza-tional issues including technical teams and efficientproduct change management constitute an impor-tant challenge which has already started to beinvestigated [64]

Enterprises already exploiting these benefits areshowing great potential for future growth Daimler-Chrysler General Motors Boeing and LockheedMartin have publicly declared that digital technolo-gies have saved them millions of dollars in just afew years Similar savings have been realized in thesemiconductor industry [63] Further research effortis however required to be able to simulate theassembly process fully and to avoid costly installa-tions and lengthy start-up periods This is becausedigital simulation and planning of assembly pro-cesses are based on various enabling technologiessuch as immersive VR collaborative virtual designand digital human simulation for manual assemblysystem and ergonomic assessments [23]

In digital manufacturing the ambiguity of tacitknowledge in manufacturing should be eliminatedthoroughly and the tacit knowledge should be trans-formed into tangible knowledge namely numericalvalues andor equations and finally into digital values[59] This is expected to minimize the productionperformance diversities frequently observed betweenglobally distributed production sites of extendedenterprises

Since up to 60 per cent of the value of automobilesand fighter aircraft are sourced from suppliers thedigital manufacturing environment must be accessibleacross the supply chain to support todayrsquos business-to-business method [63] The spreading of the internetand the software technologies that arise from it providethe means for the globalization of the services offered[65] Modern information technology can support thecommunication among the various nodes of theextended production network but then systematicdata management becomes critical Optimized datamanagement is required through all the stages of digi-tal manufacturing for its efficient exercise Three-dimensional design data can result in huge data filesGigabytes of information in one or two filesmeanmas-sive wait times the inability actually to send themanywhere and a huge barrier to digital manufactur-ing However the acceptance of XML as a communi-cation format and the development of additionalformats (such as XVL JT and U3D) provide veryhigh compression without a loss of information [60]

In the new manufacturing paradigm suggested byManufuture for the year 2020 digital manufacturingis defined as a key research area for the implementa-tion of the knowledge-based factory of the future Itwill be a key element in product and process know-ledge acquisition helping to translate from implicit



to explicit knowledge Additionally it is driven by theapplication and standardization of the informationand communication technologies and the increasingdemand for the efficiency of operations in globalnetworks [66] The tools of future engineering andmanagement of manufacturing are digital and dis-tributed The identified research priorities includethe development of integrated tools for industrialengineering and adaptation of manufacturing takinginto account the configurability or partial autonomyof systems the development of a standard datamodel of factories and the management of factorydata including open networks of engineering andreal-time management of manufacturing data [67]

5 CONCLUSIONS

Digital manufacturing incorporates technologies forthe virtual representation of factories buildingsresources machine systems equipment labour staffand their skills as well as for the closer integrationof product and process development through model-ling and simulation

Closing the gap between the product definitionand the actual manufacturing production activitieswithin the enterprise fully transforming tacit manu-facturing knowledge into tangible and finally digitalknowledge optimizing data management and devel-oping standard models are some key priorities

ACKNOWLEDGEMENTS

This work has been partially supported by the Inte-grated Projects lsquoFlexible assembly processes for thecar of the third millennium ndash MyCarrsquo (FP6-2004-NMP-NI-4-026631) and lsquoMulti-functional Materialsand related production technologies integrated intothe automotive industry of the future ndash FUTURArsquo(FP6-2004-NMP-NI-4-026621) funded by theEuropean Commission

REFERENCES

1 Chryssolouris G Manufacturing systems ndash theory andpractice 2nd edition 2006 (Springer-Verlag New York)

2 Westkamper E Strategic development of factoriesunder the influence of emergent technologies CIRPAnn 2007 56(1) 419ndash422

3 Cagliano R and Spina G Advanced manufacturingtechnologies and strategically flexible production J OpsMgmt 2003 18 169ndash190

4 Umble E J Haft R R and Umble M M Enterpriseresource planning Implementation procedures and cri-tical success factors Eur J Opl Res 2003 146 241ndash257

5 Birchfield G Advanced process control optimizationand information technology in the hydrocarbon

processing industries ndash the past present and future

Aspen Technology Inc Cambridge Massachusetts

2002 available from httpwwwaspentechcompubli-

cation_filesAdvanced_Process_Controlpdf6 Cay F and Chassapis C An IT view on perspectives of

computer aided process planning research Computers

Industry 1997 34 307ndash3377 Denkena B Shpitalni M Kowalski P Molcho Z

and Zipori Y Knowledge management in process plan-

ning CIRP Ann 2007 56(1) 175ndash1808 Kim J-H and Duffie N A Backlog control design for

a closed loop PPC system CIRP Ann 2004 53(1)

357ndash3609 Azab A and ElMaraghy H A Mathematical modelling

for reconfigurable process planning CIRP Ann 2007

56(1) 467ndash47210 Ueda K Fujii N and Inoue R An emergent synthesis

approach to simultaneous process planning and sche-

duling CIRP Ann 2007 56(1) 463ndash46611 King G S Jones R P and Simner D A good practice

model for implementation of computer-aided engineer-

ing analysis in product development J Engng Des

2003 14(3) 315ndash33112 Brinksmeier E Aurich J C Govekar E Heinzel C

Hoffmeister H W Klocke F Peters J Rentsch R

Stephenson D J Uhlmann E Weinert K and

Wittmann M Advances in modelling and simulation

of grinding processes CIRP Ann 2006 55(2) 667ndash69613 Yeung M K Intelligent process-planning system or

optimal CNC programming ndash a step towards complete

automation of CNC programming Integrated Mfg

Systems 2003 14(7) 593ndash59814 Newman S T and Nassehi A Universal manufac-

turing platform for CNC machining CIRP Ann 2007

56(1) 459ndash46215 Mbang S and Haasis S Automation of the computer-

aided design ndash computer-aided quality assurance pro-

cess chain in car body engineering Int J Prod Res

2004 42(17) 3675ndash368916 Weber C Werner H and Deubel T A different view

on product data managementproduct life-cycle man-

agement and its future potentials J Engng Des 2003

14(4) 447ndash46417 Ranky P G A real-time manufacturing assembly sys-

tem performance evaluation and control model with

integrated sensory feedback processing and visualiza-

tion Assembly Automn 2004 24(2) 162ndash16718 ElMaraghy H A Barari A and Knopf G K Inte-

grated inspection and machining planning for maxi-

mum conformance to design tolerances CIRP Ann

2004 53(1) 411ndash41619 McFarlane D Auto ID systems and intelligent manu-

facturing control Engng Applic Artif Intell 2003 16

365ndash37620 Egea-Lopez E Martinez-Sala A Vales-Alonso J

Garcia-Haro J and Malgosa-Sanahuja J Wireless

communications deployment in industry a review of

issues options and technologies Computers Industry

2005 56(1) 29ndash53



21 Makris S Michalos G Papakostas N andChryssolouris G Automotive assembly technologies

performance and limitations In Proceedings of the

40th CIRP International Seminar on Manufacturing

systems Liverpool UK MayndashJune 2007 CDndashROM22 Baldwin L P Eldabi T Hlupic V and Irani Z

Enhancing simulation software for use in manufac-

turing Logistics Inf Mgmt 2000 13(5) 263ndash27023 Papakostas N Makris S Alexopoulos K Mavrikios

D Stournaras A and Chryssolouris GModern auto-

motive assembly technologies status and outlook In

Proceedings of the First CIRP International Seminar on

Assembly systems Stuttgart Germany 2006 pp 39ndash44

(Fraunhofer IRB Verlag Stuttgart)24 Xu Z Zhao Z and Baines RW Constructing virtual

environments for manufacturing simulation Int J

Prod Res 2000 38(17) 4171ndash419125 Chryssolouris G Mavrikios D Fragos D Karabatsou

V and Pistiolis K A novel virtual experimentation

approach to planning and training for manufacturing

processes ndash the virtual machine shop Int J Computer

Integrated Mfg 2002 15(3) 214ndash22126 Chryssolouris G Mavrikios D Fragos D and

Karabatsou V A virtual reality-based experimentation

environment for the verification of human-related

factors in assembly processes J Robotics Computer-

Integrated Mfg 2000 16(4) 267ndash27627 Jacobs F R and Bendoly E Enterprise resource plan-

ning Developments and directions for operations man-

agement research Eur J Opl Res 2003 146 233ndash24028 Chryssolouris G Makris S Xanthakis V and

Mourtzis D Towards the Internet-based supply chain

management for the ship repair industry Int J Compu-

ter Integrated Mfg 2004 17(1) 45ndash5729 Chryssolouris G Papakostas N and Mourtzis D

A decision-making approach for nesting scheduling a

textile case Int J Prod Res 2000 38(17) 4555ndash456430 Chryssolouris G Papakostas N and Mourtzis D

Refinery short-term scheduling with tank farm inven-

tory and distillation management an integrated simu-

lation-based approach Eur J Opl Res 2005 166 812ndash

82731 Monostori L Kadar B Pfeiffer A and Karnok D

Solution approaches to real-time control of customized

mass production CIRP Ann 2007 56(1) 431ndash43432 Sauer OModern production monitoring in automotive

plants In Proceedings of the FISITA 2004 World Auto-

motive Congress Barcelona Spain 23ndash27 May 2004

(Fraunhofer Institut fur Informations- und Datenverar-

beitung IITB Karlsrube) available from httpwww

brainguidededatapublicationsPDFpub5298pdf33 Wenzel S Jessen U and Bernhard J Classifications

and conventions structure the handling of models

within the digital factory Computers Industry 2005

56 334ndash34634 Bracht U and Masurat T The digital factory

between vision and reality Computers Industry 2005

56 325ndash33335 Bley H and Franke C Integration of product design

and assembly planning in the digital factory CIRP

Ann 53(1) 25ndash30

36 Woerner J and Woern H A security architecture inte-grated co-operative engineering platform for organised

model exchange in a digital factory environment

Computers Industry 2005 56 347ndash36037 Maropoulos P G Digital enterprise technology ndash

defining perspectives and research priorities Int J

Computer Integrated Mfg 2003 16(7ndash8) 467ndash47838 Maropoulos P G Rogers B C Chapman P McKay

K R and Bramall D C A novel digital enterprise

technology framework for the distributed development

and validation of complex products CIRP Ann 52(1)

389ndash39239 Baker A A survey of factory control algorithms chat

can be implemented in a multi-agent Hetararchy

dispatching scheduling and pull J Mfg Systems 1998

17(4) 297ndash32040 Papakostas N Mourtzis D Bechrakis K

Chryssolouris G Doukas D and Doyle R A flexible

agent based framework for manufacturing decision

making In Proceedings of the Conference on

Flexible Automation and Intelligent Manufacturing

(FAIM99) Tilburg The Netherlands 23ndash25 June 1999

pp 789ndash800 (Begell House Inc Redding Connecticut)41 Mahesh M Ong SK Nee A Y C Fuh J Y H and

Zhang Y F Towards a generic distributed and col-

laborative digital manufacturing Robotics Computer-

Integrated Mfg 2007 23(3) 267ndash27542 Mavrikios D and Chryssolouris G Digital mock-up

process simulation In Proceedings of the Third Aero-

days Conference Nouvelle Revue drsquoAeronautique et

drsquoAstronautique Toulouse France 1998 vol 2

pp 29ndash33 (Elsevier Paris)43 Mavrikios D Karabatsou V Fragos D and

Chryssolouris G A prototype virtual reality based

demonstrator for immersive and interactive simulation

of welding processes Int J Computer Integrated Mfg

2006 19(3) 294ndash30044 Kim H Lee K J Park H J Park J B and Jang S K

Applying digital manufacturing technology to ship

production and the maritime environment Integrated

Mfg Systems 2002 13(5) 295ndash30545 Alexopoulos K Mavrikios D Pappas M Ntelis E

and Chryssolouris GMulti-criteria upper body human

motion adaptation Int J Computer Integrated Mfg

2007 20(1) 57ndash7046 Pappas M Karabatsou V Mavrikios D and

Chryssolouris G Development of a web-based colla-

boration platform for manufacturing product and pro-

cess design evaluation using virtual reality techniques

Int J Computer Integrated Mfg 2006 19(8) 805ndash81447 DiFac digital factory for human oriented production

system Report Project FP6-2005-IST-5-035079 2006

available from httpdifacitiacnritDownloadDiFac_

report_edited_DTC_31052006pdf48 Mavrikios D Pappas M Karabatsou V and

Chryssolouris G A new concept for collaborative

product and process design within a human-oriented

collaborative manufacturing environment In the future

of product development Proceedings of the 17th

CIRP Design Conference (Ed F-L Krause) 2007

pp 301ndash310 (Springer-Verlag London)



49 EC DG INFSOC Preliminary assessment of the AITinitiative Report European Commission Enlargement

Directorate-General Information Society 2001 available

from ftpftpcordiseuropaeupubistdocska2aitas

sessmentfinal20010308pdf50 Kochan A BMW innovates at new Leipzig assembly

plant Assembly Automn 2006 26(2) 111ndash11451 DELMIA 3D simulations help speed up launch of the

opel vectra plant Robotics online 2002 available from

httpwwwroboticsonlinecompublicarticlesdetails

cfmidfrac1488652 Klingstam P Using simulation techniques for continu-

ous process Verification in industrial system develop-

ment In Proceedings of the 2000 Winter Simulation

Conference (Eds J A Joines R R Barton K Kang and

P A Fishwick) Orlando Florida USA 10ndash13 December

2000 vol 2 pp 1315ndash1321 (IEEE New York)53 Heinicke UM and Hickman A Eliminate bottlenecks

with integrated analysis tools in eM-plant In Proceed-

ings of the 2000 Winter Simulation Conference (Eds

J A Joines R R Barton K Kang and P A Fishwick)

Orlando Florida USA 10ndash13 December 2000 vol 1

pp 229ndash231 (IEEE New York)54 Patel V Ashby J andMa JDiscrete event simulation

in automotive final process system In Proceedings

of the 2002 Winter Simulation Conference (Eds E

Yucesan C-H Chen J L Snowdon and J M Charnes)

San Diego California USA 8ndash11 December 2002 vol 1

pp 1030ndash1034 (IEEE New York)55 Hetem V Integrating capacity simulation into process

planning In Proceedings of the 2001 Winter Simu-

lation Conference (Eds B A Peters J S Smith D J

Medeiros and M W Rohrer) Arlington Virginia USA

9ndash12 December 2001 vol 1 pp 1470ndash1472 (IEEE

New York)56 Woehlke G and Schiller E Digital planning validation

in automotive industry Computers Industry 2005 56

393ndash40557 Grandl R Virtual process week in the experimental

vehicle build at BMW AG Robotics Computer Integrated

Mfg 2001 17 65ndash71

58 MyCar Flexible assembly processes for the car of thethird millennium Portal of the Eu Integrated ProjectlsquoMyCarrsquo Report Project FP6-2004-NMP-NI-4-026631-2 2006 available from httpwwwmycar-projecteu

59 Seino T Ikeda Y Kinoshita M Suzuki T andAtsumi K The impact of digital manufacturing ontechnology management Mgmt Engng Technol 20011 31ndash32

60 Dalton-Taggart R The move to digital manufacturingManufacturing Center 2005 accessed 30 August 2007available from httpwwwmanufacturingcentercomtoolingarchives04050405move_to_digitalasp

61 Miller E and MacKrell J Digital manufacturingmoving the design into production CIMdata 2006accessed 6 September 2007 available from httpwwwcimdatacompublicationsarticle06ndash1_moving_designhtml

62 Pasha A Digital manufacturing drives PLM adoptionExpress computer 2003 accessed 7 September 2007available from httpwwwexpresscomputeronlinecom20031110focus01shtml

63 Brown RG Driving digital manufacturing to realityIn Proceedings of the 2000 Winter Simulation Con-ference Orlando Florida USA 10ndash13 December 2000vol 1 pp 224ndash228 (IEEE New York)

64 Scholz-Reiter B Krohne F Leng B and Hohns HTechnical product change teams an organizationalconcept for increasing the efficiency and effectivenessof technical product changes during ramp-up phasesInt J Prod Res 2007 45(7) 1631ndash1642

65 Chryssolouris G Makris S Xanthakis V andKonstantinis V An XML based implementation of thevalue added chain in manufacturing a ship repair casestudy CIRP J Mfg Systems 2003 32(6) 507ndash511

66 Westkamper E Digital enterprise technology digitalmanufacturing in the global era 2007 (Springer-Verlag New York)

67 Manufuture ndashEu European Commission ManufuturePlatform Strategic Research Agenda Assuring the futureof manufacturing in Europe Report Manufuture Plat-form High-Level Group Brussels Belgium September2006



computer-integrated manufacturing (CIM) This con-cept was introduced in the late 1980s favouring theenhancement of performance efficiency operationalflexibility product quality responsive behaviour tomarket differentiations and time to market How-ever the full strategic advantage of information tech-nologies was poorly understood at that time andcould not be exploited to its full extent [3]

The inventory control and material requirementsplanning (MRP) systems were introduced in the1960s and 1970s respectively Such systems werefurther enhanced with the integration of tools cap-able of providing capacity and sales planning func-tionalities together with scheduling capabilities andforecasting tools The result was the introduction ofthe closed-loop- MRP [4] Nevertheless the advancesin microprocessor technology the advent of theinternet era the standardization of software inter-faces the wide acceptance of formal techniques forsoftware design and development and the maturityof certain software products (relational databasemanagement systems and computer-aided design(CAD) systems for instance) paved the way for facil-itating the integration among diverse software appli-cations [1] The evolution of information systemsover the last decade has played a crucial role in theadoption of new information technologies in theenvironment of manufacturing systems [5]

21 Computer-aided technologies

CAD is considered among the technologies that haveboosted productivity allowing faster time to marketfor the product and dramatically reducing the timerequired for product development Although the firstCAD applications were inherently difficult to useowing to the text-based input systems and the extre-mely slow computational equipment their succes-sors have become more than necessary in todayrsquosmanufacturing companies regardless of their sizeAffordable solutions offering a modern photorea-listic graphical user interface are nowadays avai-lable in the market Functionalities of such systemsintegrate finite element analysis (FEA) kinematicsanalysis dynamic analysis and full simulation ofgeometrical properties including texture and mech-anical properties of materials The CAD systemshave become indispensable to todayrsquos manufacturingfirms because of their strong integration withadvanced manufacturing techniques CAD modelsare often considered sufficient for the production ofthe parts since they can be used for generating thecode required to drive the machines for the pro-duction of the part Rapid prototyping is an exampleof such a technology

Process planning activities determine the neces-sary manufacturing processes and their sequence in

order to produce a given part economically and com-petitively [1] Towards this direction the computer-aided process planning (CAPP) systems have beenused for the generation of consistent process plansand are considered as being essential componentsof the CIM environments [6] Denkena et al [7] pro-posed a holistic component manufacturing processplanning model based on an integrated approachcombining technological and business considera-tions in order to form the basis for developingimproved decision support and knowledge manage-ment capabilities to enhance available CAPP solu-tions Kim and Duffie [8] introduced a discretedynamic model design and have analysed the controlalgorithms for closed-loop process planning controlthat improve response to disturbances such as rushorders and periodic fluctuations in capacity In theirwork Azab and ElMaraghy [9] presented a novelsemigenerative mathematical model for reconfigur-ing macrolevel process plans In the same work it isclaimed that reconfigurable process planning is animportant enabler of changeability for evolvingproducts and systems Finally Ueda et al [10] intro-duced a new simultaneous process planning andscheduling method of solving dilemmas posed bysituations where a process plan and a productionschedule conflict using evolutionary artificial neuralnetworks based on emergent synthesis

Computer-aided engineering (CAE) systems areused to reduce the level of hardware prototypingduring product development and to improve theunderstanding of the system [11] The CAE systemssupport a large number of engineering research fieldsincluding fluid mechanics (computational fluidmechanics) dynamics (simulation of machines andmechanisms) mechanics of materials (FEA) thermo-dynamics and robotics For instance Brinksmeieret al [12] conducted an extensive survey on theadvances in the simulation of grinding processestogether with a series of models that can be imple-mented in simulation systems

Following the development of the CAD systems theconcept of computer-aided manufacturing (CAM)was born The great step towards the implementationof CAM systems was the introduction of computernumerical control (CNC) Apart from the fact thatthis new technology has brought about a revolutionin manufacturing systems by enabling mass produc-tion and greater flexibility [13] it has also enabledthe direct link between the three-dimensional (3D)CADmodel and its production Newman and Nassehi[14] proposed a universal manufacturing platform forCNC machining where the applications of variouscomputer-aided systems (CAx) applications canseamlessly exchange information The proposed plat-form is based on the standard STEP-NC In additionstandardization of programming languages for these

















23 Simulation



































































5 CONCLUSIONS



ACKNOWLEDGEMENTS


REFERENCES

















































2005 56(1) 29ndash53
















































Ann 53(1) 25ndash30


















































































Mfg 2001 17 65ndash71



























23 Simulation



































































5 CONCLUSIONS



ACKNOWLEDGEMENTS


REFERENCES

















































2005 56(1) 29ndash53
















































Ann 53(1) 25ndash30


















































































Mfg 2001 17 65ndash71


































































5 CONCLUSIONS



ACKNOWLEDGEMENTS


REFERENCES

















































2005 56(1) 29ndash53
















































Ann 53(1) 25ndash30


















































































Mfg 2001 17 65ndash71


























































Ann 53(1) 25ndash30


















































































Mfg 2001 17 65ndash71












































Mfg 2001 17 65ndash71













special issue paper 451 digital manufacturing: history ... · digital manufacturing: history,...

Documents