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Decoupling of Product and Production Development in Flexible Production Environments
Available online at www.sciencedirect.com
ScienceDirect Procedia CIRP 60 (2017) 548 – 553
27th CIRP Design 2017
Decoupling of product and production development in flexible production environments Iris Gräßlera, Alexander Pöhlera*, Julian Hentzea a
Heinz Nixdorf Insitute, Paderborn University, Fuerstenallee 11, 33102 Paderborn, Germany
* Corresponding author. Tel.: +49-5251-60-6262; fax: +49-5251-60-6268. E-mail address: [email protected]
Abstract The integration of production development in product development methodologies is one of the most promising current research topics for shortening time-to-market of development projects. In flexible production environments new products shall be produced by the adaption of the existing production system. The characteristics of production system adaption differs substantially from a new development of a production system. This paper analyzes effects of flexible production environments on integrative development methodologies and how to match inconsistencies in a united approach. The focus was placed on simplifications of established methodologies and a new approach considering these simplifications is presented. © Published by Elsevier B.V. This 2017The TheAuthors. Authors. Published by Elsevier B.V.is an open access article under the CC BY-NC-ND license ©2017 (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of the scientific committee of the 27th CIRP Design Conference. Peer-review under responsibility of the scientific committee of the 27th CIRP Design Conference Keywords: integrative product development; production development; Cyber Physical Production Systems; flexible production environments; integrative product development
1. Introduction To meet the demand of a steadily decreasing time to market, a reduction of development time is required. The simultaneous development of product and production system is a promising approach to enhance already optimized development procedures. Additionally parallel design of product and production system enables a close coordination to prevent extensive changes due to neglected production restrictions. For simultaneous development approaches, a strong interconnection between the development of product and production is required. Therefore procedure models already try to integrate the production into the product generation process [1]. This paper deals with the impact of flexible production environments, mainly caused by the implementation of Cyber Physical Production Systems (CPPS), on the linkage of product with production development. The paper describes an approach that takes into account the market changes as well as the new range of possibilities of CPPS. Nowadays much effort is used in order to connect production and product development and create a production, which is tailored for future products. The implementation of CPPS enables possibilities to automate the
interface between production and product development and therefore redesign the mutual development. The changes in cooperation between development and production and the effects on target products are explained in detail. 2. Interconnection between product and production development in product engineering methodologies Established product engineering methodologies usually include procedures for production system development or at least the specification of the production process. Common engineering procedures like Pahl et al. [2] and the VDI guideline 2221 (Systematic approach to the development and design of technical systems and products) [3] do not emphasize explicit phases of production system development. These approaches consider the product development procedure as a concluded iterative sequence. Neither the integration nor the consideration of restrictions or feedback of the assigned production system in an early phase of the product development are explicitly emphasized. Considerations regarding the envisioned manufacturing process however are included. The procedure shown in the VDI 2221 for example
2212-8271 © 2017 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of the scientific committee of the 27th CIRP Design Conference doi:10.1016/j.procir.2017.01.040
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ends with the elaboration of production and utilization information. This includes the description of the production process by working plans, bill of materials and operating instructions. The production system development, respectively the adaption of manufacturing means are regarded as downstream processes, which are executed by the production planning department. In section 4 it is shown, that this kind of procedure is still a common approach in industrial practice. The VDI 2206, “Development methodology for mechatronic systems” [4] and the 3-cycle-model of Product Design [5] are considering restrictions of the production system at an early phase of the product development and also integrate elements of production system development into the product development procedure in a simultaneous manner. The VDI 2206 [4] outlines the parallel design of product and production. Models of product and production shall support this integrative approach. Following the V-cycles, product and production systems are specified and lead to in series producible products with affiliated production systems. Summarized the VDI 2206 concludes that the integration of different product development domains must also include the integration of their production systems. The described iterative character of VDI 2206’s development approach for the production of mechatronic systems is shown in figure 1.
Research, product discovery
Development and design Production planning and factory design
Product and product generation process
Fig. 2. Production development process of [6]
Based on consultations and agreements with and assumptions of the other domain, development of both is realized. This procedure originates from the functional division of product and production development into two separate departments. This kind of procedure can lead to a deficient interconnection between production and product development. It is possible to create a product, which cannot be produced, respectively a production which cannot produce the developed products. Planning of layout and process chains
consultation
consultation
Discovery, conceptual design
Development
Production life cycle
Building and ramp-up
Production
Usage
Product life cycle Expiration
Fig. 3. Common interconnection between product and production life cycle
Most established product development/engineering procedures, like [11, 12, 13, 14, 15] do not consider the integration of production in detail or see it as downstream processes. The state of the art of integrative development is described in the following subsections. Two characteristic approaches for the interconnection between product and production are introduced as examples. Fig. 1. . Iterative procedure of an integrated development approach for mechatronic systems [4].
Several production development methodologies [6,7,8,9] describe the product development from the production perspective. The interconnection between product and production development in these procedures are characterized as "integrated", "parallelized" and "simultaneous". Observed more closely, the interconnection is limited to the final phase of product development, where simultaneously the product development is completed and a concept for the production is derived. In figure 2 the process model of the VDI 4499 (Digital Factory) is shown. This figure also illustrates the consecutive elements of this approach. The conceptual design of production is started before the product development process is finished. Another interconnection between product development and production is presented in figure 3. The production system development cycle is based on Westkämper [10], the product development cycle on the VDI 2221 [3]. Product and production development follow independent procedures and are not necessarily interconnected.
2.1. Simultaneous development As already mentioned, many product and production engineering methodologies include simultaneous development elements of product and production. The VDI 2206 for example describes a parallelization between product and production development, but does not present a precise procedure model. A detailed elaboration is shown by Vielhaber [16], who compares the interconnection of different procedures and develops an integrated product and production development process model. This integrated process model is an enhancement of the procedure shown figure 3. Whereas the connections between product and production planning in figure 3 are loose and not structurally defined, Vielhaber creates fixed bonds. Vielhaber proposes a synchronization between the product and production process. The synchronization is not seen as a model-based joint development, but more as links through harmonized milestones and joint analysis activities. This synchronization shall improve the cooperation between
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development and production and prevent strategical planning mistakes. There are quite a few other approaches for the simultaneous development of product and production, e.g. [17, 18, 19] which share a similar view.
2.2. Integrative model-based development of product and production system The model-based integration of production into product development mentioned in this subsection is a current research subject related to Systems Engineering. It goes far beyond approaches like simultaneous engineering, where cycles of product and production development are overlapping. During the product development models of both, product and production system are used for the simultaneous development of the production system. Models used for engineering production systems are for example requirement models, models for production processes, resource models and design models of the production system. These models share properties with the models of the product and therefore enable an integrated approach. The 3-cycle-model of Gausemeier [5], is the only procedure model, which really includes such a kind of integrated approach of product and production development. In [1] this integrative development of product and production system is described. The conceptual design of product and production system are performed simultaneously through the description of partial models for the product and the production system. The product and production system conceptual design are shown as parallel tasks. Through interactions between the product and production system design, restrictions for the product design shall be identified and after the specification of the product the production system is designed. The 3-cyclemodel includes interconnections between both: conceptual design and concretization of product and production system. The process flow of production system design is subsequent to the product design. In particular, each of the steps are consecutive. Nevertheless, the objective of this design methodology is to create one coherent system with different partial models of product and production system. In detail the explicit procedure for the simultaneous design of product and production system is described in [20]. The integrative part is the simultaneous model-based design of product and production system. The idea of Gausemeier is to simultaneously develop the production system concept through the description of for example process sequence, resources and production system shape. The product concept shall include environment, application scenarios, functions, active structure, behaviour and product shape. Requirements are defined for both, product and production system. These partial models are related to each other and enable a coherent system description. Based on these models the subsequent design and engineering of both, product and production system development can be executed. [20]
3. Impact of CPPS on product and production development Product concepts are significantly determined by the assigned manufacturing processes. Based on restrictions and possibilities of assigned manufacturing technologies products are developed. The selection of the production technology strongly influences the product development and therefore the product itself. New production technologies, such as Cyber Physical Production Systems, and new forms of inter-company collaboration, such as ad-hoc value creation networks, provide new possibilities to widen the range of usable manufacturing technologies and to shift the timepoint of selecting the used technology backwards. [21] This paper points out the impact of CPPS on the connection between product and production system development. In the following subsections the impact of CPPS on existing procedure models is examined.
3.1. Cyber Physical Production Systems (CPPS) A CPPS consists of linked, collaborating Cyber-Physical Production Devices (CPPD). A CPPD is an embedded system which has an additional networking interface to communicate with other CPPDs. Its task is to control or observe physical production processes by sensors and react by actors. Due to the connection of multiple CPPDs, the data exchange among them and connections to superordinate collaboration platforms [23], CPPS can gain holistic information on their given tasks. A main difference between CPPS and existing production systems is the improved ability to gather and process the information. This improved information processing enables an embedded cognition and artificial intelligence of CPPS, which is normally associated with the self-control of production systems. CPPS offer a higher flexibility due to self-X abilities [22] and usage of generic manufacturing and operation technologies. CPPS provide possibilities for a self-controlling production, where production orders with yet undefined production processes can be deployed on the basis of various product information. A joint semantic description serves for the derivation of required information for the production process. All necessary information needs to be derivable from this semantic description. This includes for example: material properties, geometry, joints, function surface, etc. Mainly there are two consequences of the interconnection between product and production through the implementation of CPPS. Production systems will find a way to produce the product themselves. The production process does not need to be completely specified, instead a joint semantic model suffices for the automatic deployment of production orders. This kind of deployment is limited to generic manufacturing technologies like additive manufacturing and machining. The automatic execution of tool supported manufacturing technologies like injection molding will not be possible without the prior engineering and fabrication of the tool.
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CPPS enable, but also demand flexibility. The usage of CPPS is limited to flexible processes, which can be adapted and changed. CPPS linked research fields like mass customization, decentralized production control and orchestration of production processes need flexible production systems and processes. Therefore the implementation and development of CPPS demand a certain level of flexibility of associated processes and technologies.
3.2. Consequences on procedures The empowerment of production systems to automatically execute different production jobs based on model-descriptions without the complete specification of the production process chain questions the integrative development of the production process. The idea of CPPS inherits, that for the execution of production orders only a semantic model is needed. [24] This semantic model serves as a description for the finished part and as a basis for deriving the assigned production process. The production shall execute itself and deduced production jobs shall automatically be deployed on different machines. Whereas today a production job with assigned handling procedure is needed for every involved machine, in future this assignment will not be necessary. If production jobs can be automatically created and executed without the specification of the production process, production development of this process will not be necessary any more.
Cloud Resources
Apps Business Processes
Data
Finished order
Requirements
Product Development Process
Planning
Design
Integration
Testing
Joint semantic model Order initiation
Production Process
Fig. 4. Development procedure in CPPS-environments
Figure 4 shows an exemplary development procedure in CPPS-environments. The product development concludes with a semantic model to describe the product and required production properties. Afterwards the product can be deployed in the production automatically. This deployment is done via cloud-services. The agent-based order processing, as one cloud-service, is connected with all necessary information and instances to execute the order. The assigned agents choose suitable systems through decision rules. Until the semantic description of the product, all processes are executed on office level, afterwards they are automatically deployed on the shop floor. The joint semantic model serves as interconnection between product and production system. A major influence of CPPS is the decoupling of production restrictions from the product development process. CPPS and inter-company collaborations open up possibilities regarding manufacturing technologies and order execution. Therefore current existing strong dependencies between available production technologies and possibilities of product creation
can be detached. The current focus of product engineering to develop in-house-producible products will lose in influence due to this increased flexibility and additional manufacturing options. Current endeavours to combine product and production development are contrary to current engineering individualization trends in CPPS-environments. A holistic approach to create a production system, which suits one product is not appropriate for automatically choosing suitable production systems. In the following subsection a new procedure model for product and production development in CPPS-environments is presented.
3.3. Procedure model for product and production development in CPPS-environments The semantic model description in CPPS-environments as interconnection between product development and production will decouple the product development with its execution. The automatic deployment of production orders does not require an adaption of production development for each developed product. It will be the task of the production management to provide a generic production base for a broad deployment of different products. Therefore this procedure model and the integrated modelling of production process will not be necessary. It is going to be important that the production can interpret the description of the product and subsequently produce it. The objective of production conception is going to shift from serving as development for one specified product to developing a broad base of possibilities. The individualization of products supports this new procedure. Whereas the shortening of product development is desirable to fulfil customer needs at any time and to adapt to changing circumstances, the shortening of the production life cycle requests major investments. Also product lifecycles are normally shorter than production lifecycles. Therefore a decoupling of product and production development is necessary and the objective of production development is to be versatile to meet arising challenges of increasing complexity, interdisciplinary and new production technologies. The production process however is going to be an existential part of the product. The joint semantic description requires a holistic description of features and therefore of production information of the developed product. The design of the production system should not be a part of this and completely decoupled. The main task of the production will be to deliver a flexible manufacturing environment where diverse production tasks can be deployed. However it will not be possible to create a flexible, generic production base for all manufacturing technologies. Due to sensitive intellectual property or envisaged production technologies (like tool binding manufacturing technologies), parts of production processes are still going to be product specific and therefore cannot be part of the semantic model and need to be described and developed separately. These parts
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needs to be developed especially for the envisaged production process. Figure 5 shows a procedure adapted to this circumstance. The start for product development is normally a promising product idea (for non-request-based development) or a customer request. During conceptual design crucial parts, for which a specific production systems needs to be designed, need to be identified. The identification is mainly based on the following factors: x Choose of production technology according to quality (e.g. tolerances), quantity, material and costs. If a specified production technology is chosen the production system (e.g. tooling, jig, handling device …) needs to be developed simultaneously with the product. For these technologies, similar to subsection 2.2 models shall be used for an integrative development of product and production system. x Often production technologies are used as unique selling propositions with individual intellectual property or knowledge, which should be used explicitly for the production of the part. Therefore the normal selection decision making of the production system respectively the manufacturing technology should not be used. For specified parts the product development process is not going to change. The production should be designed simultaneously to the product, similar to the description in subsection 2.2. All generic processes are not going to need this kind of procedure and can be deployed directly. Therefore the deployment of the production process itself is going to be with constraints. Parts of the process are going to be executed in specified and other parts in generic production systems. initiation
Product development
Production process
Engineered product (specified)
Conception of production
Production system (specified)
Engineering Methodology and Engineering Sensitive Management Engineeredd Intellectual Property
Production development
yes
Promising product idea
or specified technono logy
Produced product
Production system (generic)
product (generic)
planning
Feedback, dback, k restrictions ictions
Production Management control execution
Fig. 5. Implementable procedure model for CPPS-environments.
The production development process itself is going to be divided into providing a broad generic base and developing specific production systems for envisaged tasks. [9] describes this kind of manufacturing strategy as versatile factory. 4. Investigation of practical effects To evaluate the consequences of the implementation of CPPS for practical development procedures, an extermination at three companies was made. Their current product and production development processes were investigated and possible changes through the implementation of CPPS were estimated. Company A is a medium sized electrical component company, Company B is a lager automotive supplier, Company C is a smaller mechanical engineering company. All investigated companies use some kinds of stage gate processes
to manage the product and production system development. Company A produces and sells highly individual components. For nearly every order the components are somehow customized. This means that there are a lot of design changes during the product development. The production process whatsoever does not change so much. The basic structure of the components are identical and just the dimensioning and execution are adjusted. Nevertheless injection molds, diecasting, assembly devices and test devices have to be adapted, respectively newly developed for most new products. The development of manufacturing means is the last part of the product development process and consumes usually 3 to 12 months and does not start before the product is completely designed. The manufacturing means are engineered by the production department. Elements of simultaneous engineering are not included in this procedure. The tooling engineering is initiated through meetings with the product development department. The actual design process though is not initiated before the product development is concluded and all required product information are transferred. To examine practical effects of the implementation of CPPS on the production, the production process of five standard parts were examined. The extermination showed, that just two die casting production processes need a specified production process, because of the necessary tooling. All other processes (on average 7 production processes) can be generalized. An analysis of product development projects showed, that delays and problems mostly occurred in processing specified production development processes. The presented development procedure would help identifying these processes and therefore enable the implementation of prevention measures. The second industrial implementation of a product development procedure was examined at a larger automotive supplier. Its stage gate process is way more comprehensive and project manager spend a lot of their work maintaining the documentation and synchronizing the different project tasks. Similar to company A the production-related departments are just informed about current development projects and are involved in the way to feedback restrictions and information about limitations and the timeline of the production system development. Company B produces mass products with large quantities. For the production of the components mostly specified production processes are used, which are greatly adapted for the envisaged product. Due to these great adaptions the implementation of generic manufacturing technologies is questionable. The leeway for automatically executing production processes is limited. Company C is a small mechanical engineering company with less than 200 employees. The product development is sometimes coordinated and executed by one responsible project manager. The production consist of generic production systems, like milling and turning machines, which are not specified for developed products. Mostly clamping and assembly devices are adapted, respectively developed for specific products. In this kind of production, the introduction
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of CPPS could support optimizing procedure and control schematics. Existing approaches for the integrative design of product and production system are not used in any of these companies. The production and product development procedures of all companies are comparable. A high specialization of production processes questions the implementation of CPPS, because key advantages like flexibility and self-controlling cannot be used for this kind of processes. Therefore the implementation of flexible manufacturing technologies could greatly improve procedures at company A and C. A lot of their parts are milled, assembled, turned and stamped, which all could be automated, respectively integrated in CPPS-environments. In contrast, an implementation at company B will not affect existing procedures due to the high specialization of the production processes. CPPS enable a direct production without the development of the production process. 5. Conclusion and outlook CPPS will have a major impact on production system and product engineering. The examination showed, that the idea of automatic deployment and execution without production development will not be possible due to a majority of specific product-related manufacturing technologies. Currently in industrial practice production development does not include integrative development procedures. The implementation of CPPS will have a major effect on these procedures, because without integrative product and production procedures the advantages of new production technologies will have a significant less effect on time to market. Therefore especially model-based development is a promising approach, which should be included in production development for specific manufacturing technologies, which cannot be implemented in CPPS. All production processes, which can be implemented in CPPS-environments can be decoupled from product engineering. The semantic model of the part serves as an interface between product development and production. Because of the automatic deployment and generic, flexible production processes an explicit development of these production systems will not be necessary. The implementation of CPPS will lead to a differentiation in an early phase of product development. At some point a decision about an execution in a CPPS-environment has to be taken. The investigation showed, that CPPS will have extensive effects on current procedures and that its implementation is going to need a huge adaption of applied product and production procedures. References [1] Gausemeier, J., Lanza, G., & Lindemann, U. (2012). Produkte und Produktionssysteme integrativ konzipieren: Modellbildung und Analyse in der frühen Phase der Produktentstehung. München: Hanser Verlag. [2] Feldhusen, J., & Grote, K.-H. (. (2012). Pahl/Beitz Konstruktionslehre: Methoden und anwendung erfolgreicher. [S.l.]: Springer. [3] VDI 2221 (Mai 1993). Düsseldorf: Verein Deutscher Ingenieure. [4] VDI 2206 (2004). Düsseldorf: Verein Deutscher Ingenieure.
[5]
Gausemeier, J., & Plass, C. (2014). Zukunftsorientierte Unternehmensgestaltung: Strategien, Geschäftsprozesse und IT-Systeme für die Produktion von morgen, München: Hanser. [6] VDI 4499, 2008. Düsseldorf 2008. [7] Wiendahl, H.-P., Nyhuis, P., & Reichardt, J. (2014). Handbuch Fabrikplanung: Konzept, Gestaltung und Umsetzung wandlungsfähiger Produktionsstätten, München [u.a.]: Hanser. [8] Bellgran, M., & Säfsten, K. (2010). Production development: Design and operation of production systems. London: Springer. [9] Grundig, C.-G. (2015). Fabrikplanung: Planungssystematik - Methoden Anwendungen (5., aktualisierte Aufl.). München: Hanser. [10] Westkämper, E., Constantinescu, C., and Hummel, V. New Paradigm in Manufacturing Engineering: Factory Life Cycle. In Production Engineering 2006 (pp. 143–146). [11] Isermann, R. (2007). Mechatronische Systeme: Grundlagen (2., vollständig neu bearb. Aufl.). Berlin: Springer-Verlag Berlin and Heidelberg. [12] Lindemann, U. (2007). Methodische Entwicklung technischer Produkte: Methoden flexibel und situationsgerecht anwenden (2., bearb. Aufl.). VDI. Berlin: Springer. [13] Eversheim, W., & Schuh, G. (2005). Integrierte Produkt- und Prozessgestaltung (1. Aufl.). VDI. Berlin: Springer. [14] Albers, A., & Braun, A. (2011). A generalized framework to comapps and to support complex product engineering processes. International Journal of Product Management, 15, 6–25. [15] Bender, K. (2005). Embedded Systems: Qualitätsorientierte Entwickung (1. Aufl.). Berlin: Springer. [16] Michael Vielhaber, Pascal Stoffels. (2014) Product Development vs. Production Development. In Procedia CIRP 21 (pp. 252–257). [17] Achim Kampker, Günther Schuh, Peter Burggräf, Christoph Nowacki, Mateusz Swist. Cost innovations by integrative product and production development. In CIRP Annals - Manufacturing Technology 61 (2012) (pp. 431–434). [18] Brandis, R. (2014). Systematik für die integrative Konzipierung der Montage auf Basis der Prinziplösung mechatronischer Systeme. HNIVerlagsschriftenreihe: Bd. 325. Paderborn [19] Ehrlenspiel, K., & Meerkamm, H. (2013). Integrierte Produktentwicklung: Denkabläufe, Methodeneinsatz, Zusammenarbeit (5., überarb. und erw. Aufl. München: Hanser. [20] J. Gausemeier, R.Dumitrescu, S.Kahl, D.Nordsiek (2011). Integrative development of product and production system for mechatronic products. In Robotics and Computer-Integrated Manufacturing 27 (2011) 772–778 (pp. 772–778). [21] Acatech. (2012). Cyber-Physical Systems: Innovationsmotoren für Mobilität, Gesundheit, Energie und Produktion. Acatech BEZIEHT POSITION. Dordrecht: Springer. [22] Königs, S. F. (2013). Konzeption und Realisierung einer Methode zur templategestützten Systementwicklung (Dissertation). TU Berlin, Berlin. [23] D. Mourtzis, E. Vlachou, (2016), "Cloud-based Cyber-Physical Systems and Quality of Services", TQM Emerald Journal, Volume 28, Issue 6 [24] Höme, S., Grützner, J., Hadlich, T., Diedrich, C., Schnäpp, D., Arndt, S., Schnieder, E. (2015). Semantic Industry: Herausforderungen auf dem Weg zur rechnergestützten Informationsverarbeitung der Industrie 4.0. at Automatisierungstechnik, 2015, Vol.63(2), pp.74-86 De Gruyter Oldenbourg
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ScienceDirect Procedia CIRP 60 (2017) 548 – 553
27th CIRP Design 2017
Decoupling of product and production development in flexible production environments Iris Gräßlera, Alexander Pöhlera*, Julian Hentzea a
Heinz Nixdorf Insitute, Paderborn University, Fuerstenallee 11, 33102 Paderborn, Germany
* Corresponding author. Tel.: +49-5251-60-6262; fax: +49-5251-60-6268. E-mail address: [email protected]
Abstract The integration of production development in product development methodologies is one of the most promising current research topics for shortening time-to-market of development projects. In flexible production environments new products shall be produced by the adaption of the existing production system. The characteristics of production system adaption differs substantially from a new development of a production system. This paper analyzes effects of flexible production environments on integrative development methodologies and how to match inconsistencies in a united approach. The focus was placed on simplifications of established methodologies and a new approach considering these simplifications is presented. © Published by Elsevier B.V. This 2017The TheAuthors. Authors. Published by Elsevier B.V.is an open access article under the CC BY-NC-ND license ©2017 (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of the scientific committee of the 27th CIRP Design Conference. Peer-review under responsibility of the scientific committee of the 27th CIRP Design Conference Keywords: integrative product development; production development; Cyber Physical Production Systems; flexible production environments; integrative product development
1. Introduction To meet the demand of a steadily decreasing time to market, a reduction of development time is required. The simultaneous development of product and production system is a promising approach to enhance already optimized development procedures. Additionally parallel design of product and production system enables a close coordination to prevent extensive changes due to neglected production restrictions. For simultaneous development approaches, a strong interconnection between the development of product and production is required. Therefore procedure models already try to integrate the production into the product generation process [1]. This paper deals with the impact of flexible production environments, mainly caused by the implementation of Cyber Physical Production Systems (CPPS), on the linkage of product with production development. The paper describes an approach that takes into account the market changes as well as the new range of possibilities of CPPS. Nowadays much effort is used in order to connect production and product development and create a production, which is tailored for future products. The implementation of CPPS enables possibilities to automate the
interface between production and product development and therefore redesign the mutual development. The changes in cooperation between development and production and the effects on target products are explained in detail. 2. Interconnection between product and production development in product engineering methodologies Established product engineering methodologies usually include procedures for production system development or at least the specification of the production process. Common engineering procedures like Pahl et al. [2] and the VDI guideline 2221 (Systematic approach to the development and design of technical systems and products) [3] do not emphasize explicit phases of production system development. These approaches consider the product development procedure as a concluded iterative sequence. Neither the integration nor the consideration of restrictions or feedback of the assigned production system in an early phase of the product development are explicitly emphasized. Considerations regarding the envisioned manufacturing process however are included. The procedure shown in the VDI 2221 for example
2212-8271 © 2017 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of the scientific committee of the 27th CIRP Design Conference doi:10.1016/j.procir.2017.01.040
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Iris Gräßler et al. / Procedia CIRP 60 (2017) 548 – 553
ends with the elaboration of production and utilization information. This includes the description of the production process by working plans, bill of materials and operating instructions. The production system development, respectively the adaption of manufacturing means are regarded as downstream processes, which are executed by the production planning department. In section 4 it is shown, that this kind of procedure is still a common approach in industrial practice. The VDI 2206, “Development methodology for mechatronic systems” [4] and the 3-cycle-model of Product Design [5] are considering restrictions of the production system at an early phase of the product development and also integrate elements of production system development into the product development procedure in a simultaneous manner. The VDI 2206 [4] outlines the parallel design of product and production. Models of product and production shall support this integrative approach. Following the V-cycles, product and production systems are specified and lead to in series producible products with affiliated production systems. Summarized the VDI 2206 concludes that the integration of different product development domains must also include the integration of their production systems. The described iterative character of VDI 2206’s development approach for the production of mechatronic systems is shown in figure 1.
Research, product discovery
Development and design Production planning and factory design
Product and product generation process
Fig. 2. Production development process of [6]
Based on consultations and agreements with and assumptions of the other domain, development of both is realized. This procedure originates from the functional division of product and production development into two separate departments. This kind of procedure can lead to a deficient interconnection between production and product development. It is possible to create a product, which cannot be produced, respectively a production which cannot produce the developed products. Planning of layout and process chains
consultation
consultation
Discovery, conceptual design
Development
Production life cycle
Building and ramp-up
Production
Usage
Product life cycle Expiration
Fig. 3. Common interconnection between product and production life cycle
Most established product development/engineering procedures, like [11, 12, 13, 14, 15] do not consider the integration of production in detail or see it as downstream processes. The state of the art of integrative development is described in the following subsections. Two characteristic approaches for the interconnection between product and production are introduced as examples. Fig. 1. . Iterative procedure of an integrated development approach for mechatronic systems [4].
Several production development methodologies [6,7,8,9] describe the product development from the production perspective. The interconnection between product and production development in these procedures are characterized as "integrated", "parallelized" and "simultaneous". Observed more closely, the interconnection is limited to the final phase of product development, where simultaneously the product development is completed and a concept for the production is derived. In figure 2 the process model of the VDI 4499 (Digital Factory) is shown. This figure also illustrates the consecutive elements of this approach. The conceptual design of production is started before the product development process is finished. Another interconnection between product development and production is presented in figure 3. The production system development cycle is based on Westkämper [10], the product development cycle on the VDI 2221 [3]. Product and production development follow independent procedures and are not necessarily interconnected.
2.1. Simultaneous development As already mentioned, many product and production engineering methodologies include simultaneous development elements of product and production. The VDI 2206 for example describes a parallelization between product and production development, but does not present a precise procedure model. A detailed elaboration is shown by Vielhaber [16], who compares the interconnection of different procedures and develops an integrated product and production development process model. This integrated process model is an enhancement of the procedure shown figure 3. Whereas the connections between product and production planning in figure 3 are loose and not structurally defined, Vielhaber creates fixed bonds. Vielhaber proposes a synchronization between the product and production process. The synchronization is not seen as a model-based joint development, but more as links through harmonized milestones and joint analysis activities. This synchronization shall improve the cooperation between
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development and production and prevent strategical planning mistakes. There are quite a few other approaches for the simultaneous development of product and production, e.g. [17, 18, 19] which share a similar view.
2.2. Integrative model-based development of product and production system The model-based integration of production into product development mentioned in this subsection is a current research subject related to Systems Engineering. It goes far beyond approaches like simultaneous engineering, where cycles of product and production development are overlapping. During the product development models of both, product and production system are used for the simultaneous development of the production system. Models used for engineering production systems are for example requirement models, models for production processes, resource models and design models of the production system. These models share properties with the models of the product and therefore enable an integrated approach. The 3-cycle-model of Gausemeier [5], is the only procedure model, which really includes such a kind of integrated approach of product and production development. In [1] this integrative development of product and production system is described. The conceptual design of product and production system are performed simultaneously through the description of partial models for the product and the production system. The product and production system conceptual design are shown as parallel tasks. Through interactions between the product and production system design, restrictions for the product design shall be identified and after the specification of the product the production system is designed. The 3-cyclemodel includes interconnections between both: conceptual design and concretization of product and production system. The process flow of production system design is subsequent to the product design. In particular, each of the steps are consecutive. Nevertheless, the objective of this design methodology is to create one coherent system with different partial models of product and production system. In detail the explicit procedure for the simultaneous design of product and production system is described in [20]. The integrative part is the simultaneous model-based design of product and production system. The idea of Gausemeier is to simultaneously develop the production system concept through the description of for example process sequence, resources and production system shape. The product concept shall include environment, application scenarios, functions, active structure, behaviour and product shape. Requirements are defined for both, product and production system. These partial models are related to each other and enable a coherent system description. Based on these models the subsequent design and engineering of both, product and production system development can be executed. [20]
3. Impact of CPPS on product and production development Product concepts are significantly determined by the assigned manufacturing processes. Based on restrictions and possibilities of assigned manufacturing technologies products are developed. The selection of the production technology strongly influences the product development and therefore the product itself. New production technologies, such as Cyber Physical Production Systems, and new forms of inter-company collaboration, such as ad-hoc value creation networks, provide new possibilities to widen the range of usable manufacturing technologies and to shift the timepoint of selecting the used technology backwards. [21] This paper points out the impact of CPPS on the connection between product and production system development. In the following subsections the impact of CPPS on existing procedure models is examined.
3.1. Cyber Physical Production Systems (CPPS) A CPPS consists of linked, collaborating Cyber-Physical Production Devices (CPPD). A CPPD is an embedded system which has an additional networking interface to communicate with other CPPDs. Its task is to control or observe physical production processes by sensors and react by actors. Due to the connection of multiple CPPDs, the data exchange among them and connections to superordinate collaboration platforms [23], CPPS can gain holistic information on their given tasks. A main difference between CPPS and existing production systems is the improved ability to gather and process the information. This improved information processing enables an embedded cognition and artificial intelligence of CPPS, which is normally associated with the self-control of production systems. CPPS offer a higher flexibility due to self-X abilities [22] and usage of generic manufacturing and operation technologies. CPPS provide possibilities for a self-controlling production, where production orders with yet undefined production processes can be deployed on the basis of various product information. A joint semantic description serves for the derivation of required information for the production process. All necessary information needs to be derivable from this semantic description. This includes for example: material properties, geometry, joints, function surface, etc. Mainly there are two consequences of the interconnection between product and production through the implementation of CPPS. Production systems will find a way to produce the product themselves. The production process does not need to be completely specified, instead a joint semantic model suffices for the automatic deployment of production orders. This kind of deployment is limited to generic manufacturing technologies like additive manufacturing and machining. The automatic execution of tool supported manufacturing technologies like injection molding will not be possible without the prior engineering and fabrication of the tool.
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CPPS enable, but also demand flexibility. The usage of CPPS is limited to flexible processes, which can be adapted and changed. CPPS linked research fields like mass customization, decentralized production control and orchestration of production processes need flexible production systems and processes. Therefore the implementation and development of CPPS demand a certain level of flexibility of associated processes and technologies.
3.2. Consequences on procedures The empowerment of production systems to automatically execute different production jobs based on model-descriptions without the complete specification of the production process chain questions the integrative development of the production process. The idea of CPPS inherits, that for the execution of production orders only a semantic model is needed. [24] This semantic model serves as a description for the finished part and as a basis for deriving the assigned production process. The production shall execute itself and deduced production jobs shall automatically be deployed on different machines. Whereas today a production job with assigned handling procedure is needed for every involved machine, in future this assignment will not be necessary. If production jobs can be automatically created and executed without the specification of the production process, production development of this process will not be necessary any more.
Cloud Resources
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Fig. 4. Development procedure in CPPS-environments
Figure 4 shows an exemplary development procedure in CPPS-environments. The product development concludes with a semantic model to describe the product and required production properties. Afterwards the product can be deployed in the production automatically. This deployment is done via cloud-services. The agent-based order processing, as one cloud-service, is connected with all necessary information and instances to execute the order. The assigned agents choose suitable systems through decision rules. Until the semantic description of the product, all processes are executed on office level, afterwards they are automatically deployed on the shop floor. The joint semantic model serves as interconnection between product and production system. A major influence of CPPS is the decoupling of production restrictions from the product development process. CPPS and inter-company collaborations open up possibilities regarding manufacturing technologies and order execution. Therefore current existing strong dependencies between available production technologies and possibilities of product creation
can be detached. The current focus of product engineering to develop in-house-producible products will lose in influence due to this increased flexibility and additional manufacturing options. Current endeavours to combine product and production development are contrary to current engineering individualization trends in CPPS-environments. A holistic approach to create a production system, which suits one product is not appropriate for automatically choosing suitable production systems. In the following subsection a new procedure model for product and production development in CPPS-environments is presented.
3.3. Procedure model for product and production development in CPPS-environments The semantic model description in CPPS-environments as interconnection between product development and production will decouple the product development with its execution. The automatic deployment of production orders does not require an adaption of production development for each developed product. It will be the task of the production management to provide a generic production base for a broad deployment of different products. Therefore this procedure model and the integrated modelling of production process will not be necessary. It is going to be important that the production can interpret the description of the product and subsequently produce it. The objective of production conception is going to shift from serving as development for one specified product to developing a broad base of possibilities. The individualization of products supports this new procedure. Whereas the shortening of product development is desirable to fulfil customer needs at any time and to adapt to changing circumstances, the shortening of the production life cycle requests major investments. Also product lifecycles are normally shorter than production lifecycles. Therefore a decoupling of product and production development is necessary and the objective of production development is to be versatile to meet arising challenges of increasing complexity, interdisciplinary and new production technologies. The production process however is going to be an existential part of the product. The joint semantic description requires a holistic description of features and therefore of production information of the developed product. The design of the production system should not be a part of this and completely decoupled. The main task of the production will be to deliver a flexible manufacturing environment where diverse production tasks can be deployed. However it will not be possible to create a flexible, generic production base for all manufacturing technologies. Due to sensitive intellectual property or envisaged production technologies (like tool binding manufacturing technologies), parts of production processes are still going to be product specific and therefore cannot be part of the semantic model and need to be described and developed separately. These parts
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needs to be developed especially for the envisaged production process. Figure 5 shows a procedure adapted to this circumstance. The start for product development is normally a promising product idea (for non-request-based development) or a customer request. During conceptual design crucial parts, for which a specific production systems needs to be designed, need to be identified. The identification is mainly based on the following factors: x Choose of production technology according to quality (e.g. tolerances), quantity, material and costs. If a specified production technology is chosen the production system (e.g. tooling, jig, handling device …) needs to be developed simultaneously with the product. For these technologies, similar to subsection 2.2 models shall be used for an integrative development of product and production system. x Often production technologies are used as unique selling propositions with individual intellectual property or knowledge, which should be used explicitly for the production of the part. Therefore the normal selection decision making of the production system respectively the manufacturing technology should not be used. For specified parts the product development process is not going to change. The production should be designed simultaneously to the product, similar to the description in subsection 2.2. All generic processes are not going to need this kind of procedure and can be deployed directly. Therefore the deployment of the production process itself is going to be with constraints. Parts of the process are going to be executed in specified and other parts in generic production systems. initiation
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Fig. 5. Implementable procedure model for CPPS-environments.
The production development process itself is going to be divided into providing a broad generic base and developing specific production systems for envisaged tasks. [9] describes this kind of manufacturing strategy as versatile factory. 4. Investigation of practical effects To evaluate the consequences of the implementation of CPPS for practical development procedures, an extermination at three companies was made. Their current product and production development processes were investigated and possible changes through the implementation of CPPS were estimated. Company A is a medium sized electrical component company, Company B is a lager automotive supplier, Company C is a smaller mechanical engineering company. All investigated companies use some kinds of stage gate processes
to manage the product and production system development. Company A produces and sells highly individual components. For nearly every order the components are somehow customized. This means that there are a lot of design changes during the product development. The production process whatsoever does not change so much. The basic structure of the components are identical and just the dimensioning and execution are adjusted. Nevertheless injection molds, diecasting, assembly devices and test devices have to be adapted, respectively newly developed for most new products. The development of manufacturing means is the last part of the product development process and consumes usually 3 to 12 months and does not start before the product is completely designed. The manufacturing means are engineered by the production department. Elements of simultaneous engineering are not included in this procedure. The tooling engineering is initiated through meetings with the product development department. The actual design process though is not initiated before the product development is concluded and all required product information are transferred. To examine practical effects of the implementation of CPPS on the production, the production process of five standard parts were examined. The extermination showed, that just two die casting production processes need a specified production process, because of the necessary tooling. All other processes (on average 7 production processes) can be generalized. An analysis of product development projects showed, that delays and problems mostly occurred in processing specified production development processes. The presented development procedure would help identifying these processes and therefore enable the implementation of prevention measures. The second industrial implementation of a product development procedure was examined at a larger automotive supplier. Its stage gate process is way more comprehensive and project manager spend a lot of their work maintaining the documentation and synchronizing the different project tasks. Similar to company A the production-related departments are just informed about current development projects and are involved in the way to feedback restrictions and information about limitations and the timeline of the production system development. Company B produces mass products with large quantities. For the production of the components mostly specified production processes are used, which are greatly adapted for the envisaged product. Due to these great adaptions the implementation of generic manufacturing technologies is questionable. The leeway for automatically executing production processes is limited. Company C is a small mechanical engineering company with less than 200 employees. The product development is sometimes coordinated and executed by one responsible project manager. The production consist of generic production systems, like milling and turning machines, which are not specified for developed products. Mostly clamping and assembly devices are adapted, respectively developed for specific products. In this kind of production, the introduction
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of CPPS could support optimizing procedure and control schematics. Existing approaches for the integrative design of product and production system are not used in any of these companies. The production and product development procedures of all companies are comparable. A high specialization of production processes questions the implementation of CPPS, because key advantages like flexibility and self-controlling cannot be used for this kind of processes. Therefore the implementation of flexible manufacturing technologies could greatly improve procedures at company A and C. A lot of their parts are milled, assembled, turned and stamped, which all could be automated, respectively integrated in CPPS-environments. In contrast, an implementation at company B will not affect existing procedures due to the high specialization of the production processes. CPPS enable a direct production without the development of the production process. 5. Conclusion and outlook CPPS will have a major impact on production system and product engineering. The examination showed, that the idea of automatic deployment and execution without production development will not be possible due to a majority of specific product-related manufacturing technologies. Currently in industrial practice production development does not include integrative development procedures. The implementation of CPPS will have a major effect on these procedures, because without integrative product and production procedures the advantages of new production technologies will have a significant less effect on time to market. Therefore especially model-based development is a promising approach, which should be included in production development for specific manufacturing technologies, which cannot be implemented in CPPS. All production processes, which can be implemented in CPPS-environments can be decoupled from product engineering. The semantic model of the part serves as an interface between product development and production. Because of the automatic deployment and generic, flexible production processes an explicit development of these production systems will not be necessary. The implementation of CPPS will lead to a differentiation in an early phase of product development. At some point a decision about an execution in a CPPS-environment has to be taken. The investigation showed, that CPPS will have extensive effects on current procedures and that its implementation is going to need a huge adaption of applied product and production procedures. References [1] Gausemeier, J., Lanza, G., & Lindemann, U. (2012). Produkte und Produktionssysteme integrativ konzipieren: Modellbildung und Analyse in der frühen Phase der Produktentstehung. München: Hanser Verlag. [2] Feldhusen, J., & Grote, K.-H. (. (2012). Pahl/Beitz Konstruktionslehre: Methoden und anwendung erfolgreicher. [S.l.]: Springer. [3] VDI 2221 (Mai 1993). Düsseldorf: Verein Deutscher Ingenieure. [4] VDI 2206 (2004). Düsseldorf: Verein Deutscher Ingenieure.
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