A manufacturing framework for capability-based product-service systems design

Vijaykumar, Annamalai Vasantha Gokula et al. Article A manufacturing framework for capability-based productservice systems design Journal of Remanufacturing Provided in Cooperation with: Springer Nature Suggested Citation: Vijaykumar, Annamalai Vasantha Gokula et al. (2013) : A manufacturing framework for capability-based product-service systems design, Journal of Remanufacturing, ISSN 2210-4690, Springer, Heidelberg, Vol. 3, pp. 1-32, https://doi.org/10.1186/2210-4690-3-8 This Version is available at: https://hdl.handle.net/10419/155485 Standard-Nutzungsbedingungen: Die Dokumente auf EconStor dürfen zu eigenen wissenschaftlichen Zwecken und zum Privatgebrauch gespeichert und kopiert werden. Sie dürfen die Dokumente nicht für öffentliche oder kommerzielle Zwecke vervielfältigen, öffentlich ausstellen, öffentlich zugänglich machen, vertreiben oder anderweitig nutzen. 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If the documents have been made available under an Open Content Licence (especially Creative Commons Licences), you may exercise further usage rights as specified in the indicated licence. http://creativecommons.org/licenses/by/2.0/ RESEARCH Open Access A manufacturing framework for capability-based product-service systems design Gokula Vijaykumar Annamalai Vasantha 1 , Hitoshi Komoto 2 , Romana Hussain 3 , Rajkumar Roy 4* , Tetsuo Tomiyama 4 , Steve Evans 5 , Ashutosh Tiwari 4 and Stewart Williams 6 * Correspondence: [email protected] 4 Manufacturing and Materials Department, Cranfield University, Cranfield, Bedfordshire MK43 0AL, UK Full list of author information is available at the end of the article Abstract Manufacturers aim to design product-service systems (PSS) which integrate services with products to attain sustained competitive advantage from a life cycle perspective. PSS design should be customised solutions which are aligned to integrated stakeholders' capabilities, a subject which the extant literature has not sufficiently addressed. This paper proposes a systematic framework for the PSS solution provider to address this aim and operationalizes this through software developed for PSS design which models stakeholders' individual activities and simulates their occurrences depending on their relations. The framework stresses that integrated stakeholders' capabilities define continuing ability to generate a desired operational outcome for the customers. The paper reports a PSS design case for a laser system manufacturer and then applies the framework to it. The industrial experts' views on this framework reveal that it helps to develop PSS design from a holistic systems approach which facilitates a change in the designer's mindset from a product-centric to a systems-centric. The level of trust and transparency required for this framework is argued to be absent in most industrial sectors, being one of the foremost limitations for implementation of PSS. Keywords: Product-service system; Design; Framework; Simulation; Representation Background Particularly in the light of recent economic downturns, manufacturers require alternative strategies to cope with globalization and reduced profit margins, and for retaining and attracting customers. One promising approach in helping manufacturers to achieve these objectives is product-service systems (PSS). This approach facilitates manufacturers in bundling products and services together to create a sustained competitive advantage. It aims at providing more value by fostering the optimal use of resources which can be sustained for both consumption and production. Major advantages for the PSS solution provider include prolonged and strategic relationships with the customer and product/service improvements based on the improved understanding of customer needs. However, Neely's [1] findings from the analyses of a large industrial database were that designing, implementing and managing PSS is a huge challenge to the provider as there are distinct possibilities of economic downturns. A review of current PSS literature [2] reveals that the theories and methodologies to aid the design of PSS are still in their initial stages of development, and substantial © 2013 Vasantha et al.; licensee Springer. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Vasantha et al. Journal of Remanufacturing 2013, 3:8 http://www.journalofremanufacturing.com/content/3/1/8 research is required to develop a practical PSS design methodology along with supporting tools. Also, from the interviews which were conducted with 15 industrial maintenance experts of large technical systems such as aerospace engines and related systems, naval ships, land vehicle systems, trains and trucks, our understanding is that, currently, PSS conceptual design in practice is ad hoc (fairly intuitive) and lacks a systematic approach in allowing heterogeneous (tangible and intangible characteristics) aspects to be reflected within the PSS design process. The interaction of the stakeholders in the design process and the unique characteristics of products, services, networks of players as well as the supporting infrastructure [3] which are involved in the design of PSS all demand new theories, methodologies, tools and techniques. The aim of our research is the formal development of a PSS design framework for the PSS solution provider to create customised PSS designs aligned to integrated stakeholders' capabilities. The proposed PSS framework has a view to developing PSS designs to support long-term business solutions from a capability viewpoint whilst stressing the development of additional value to customers by fostering the optimal use of integrated stakeholders' resources. A framework has been developed to address gaps identified in the literature. The framework encompasses a systems thinking perspective, which aims to improve overall PSS design on a system level and avoid sub-optimized solution towards any single activity across the whole life cycle-including remanufacturing. Therefore, this work did not focus specifically on the remanufacturing phase. To help PSS designers' model and simulate PSS designs, a framework has been implemented in a software environment. Service CAD integrated with a life cycle simulator (ISCL) [4] has been chosen because it provides both modelling and simulation facilities. A simulation facility is used to quantitatively evaluate the performance of the PSS designs regarding the requirements. This paper is structured into seven sections detailing: the gaps identified in the literature, understanding industrial challenges in PSS development, defining the constituents of PSS design, a step-by-step illustration of the proposed framework, application of the proposed framework to an industrial laser system case study, academic and industrial experts' views on this framework, and conclusions with future directions of research. Figure 1 illustrates the structure of the paper with the research methodology description. Figure 1 Structure of the paper with the research methodology description. Vasantha et al. Journal of Remanufacturing 2013, 3:8 Page 2 of 32 http://www.journalofremanufacturing.com/content/3/1/8 Related PSS design research In this paper, four state-of-the-art methodologies which have been proposed for PSS design are reviewed: Komoto and Tomiyama [4,5] proposed a method to design and analyze business models of manufacturers by focusing on the variations of services in product life cycles (e.g. rental, sharing, maintenance and upgrade services, and pay-per-function sales). The business models are modelled using Service CAD and are quantitatively analyzed using a life cycle simulation technique [6]. Sakao and Shimomura [7] and Shimomura et al. [8,9] developed Service Explorer for service engineering to design products with a higher added value from enhanced services. Service Explorer is also a Service CAD software which employs discrete event simulation methods for the evaluation of PSS design. The scope of evaluation is different from the sequence of activities of customers in a specific service environment (e.g. restaurants) [9] to those of the activities of manufacturers and users of products during their entire life cycle [4]. Maussang et al. [10] presented a PSS design model to assist engineers in the joint development of physical products and interacting services to generate more added value. Alonso-Rasgado et al. [11] and AlonsoRasgado and Thompson [12] proposed a total care design process to develop innovative offerings consisting of hardware and services integrated to provide complete functional performance. Compared to other methodologies in the literature, these four methodologies are detailed, demonstrated through industrial examples, published in refereed journals and widely discussed in the literature. Table 1 compares four state-of-the-art PSS design methodologies with reference to six characteristics. The chosen six characteristics are important for discussion based on which the proposed framework is developed and nurtured. Table 1 illustrates the differences between the approaches proposed in the literature and aids to identify the literature gaps. This table shows that all of the authors define PSS in terms of increasing the value of hardware (functional entities that carry out the elementary functions of the system) by focusing on services (entities that will ensure the smooth functioning of the whole system). Some of the aforementioned methods can deal with capabilities of stakeholders as parameters of PSS models employed in their methods. However, they do not provide specific methods or guidelines for PSS design based on the measurement, control and increase of capabilities. Furthermore, a common problem in PSS definition is the usage of different terms to define constituents of PSS. Various terms such as environment, activity, provider, receiver, channel, content, receiver state parameter (RSP), agent, and relationship among RSPs, function, entity and attribute parameters can create confusion and misunderstanding with regards to defining and communicating PSS design amongst research and industrial practitioners - a simple and unified PSS definition illustrating its constituents is required. Also, a PSS design representation technique should be commonly accepted to implement and develop a computer-supported PSS design platform for the effective evaluation of PSS performance and the capture and reuse of PSS design knowledge. The next section summarizes the industrial challenges in the PSS development. Industrial challenges in designing PSS This section summarizes the challenges which have been observed by the experts in business and maintenance of several providers of large, technical, capital-intensive and sensored product-service systems. Specifically, these are challenges observed in Vasantha et al. Journal of Remanufacturing 2013, 3:8 Page 3 of 32 http://www.journalofremanufacturing.com/content/3/1/8 Table 1 Comparison of state-of-the-art PSS design methodologies Characteristics of the proposed methods Komoto and Tomiyama [4,5] Shimomura et al. [7-9] Maussang et al. [10] Alonso-Rasgado et al. [11,12] PSS definition A set of services in the life cycle of products, whose characteristics are customized with respect to the services Service/product engineering as a discipline seeking to increase the value of artefacts by focusing on service PSS are composed of physical objects and service units that relate to each other Total care products as integrated systems comprising hardware and support services Aim Support the design and analysis of integration of services with a product life cycle and the identification of the characteristics of products Focuses on service engineering to design products with a higher added value from enhanced services Assists engineers in the joint development of physical products and interacting services to generate more added value Develop innovative offerings consisting of hardware and services integrated to provide complete functional performance The first step Define goal(s) and quality as specified by product users Define the state change of the receiver Customer expectations, needs and specifications involved in the whole life cycle Business ambitions of the client PSS variables Stakeholders in a product life cycle and the activities (e.g. production, use and services) RSP, sequential chain of agents, relationships among RSPs, function, entity and attribute parameters External functional representation, specifications of the physical elements Customer's business needs, business solutions, clearer view of the hardware and/or services PSS design representation technique A graph description based on service formulation Business process markup language, service blueprint Scenarios and FBD No representation technique is mentioned Evaluation of PSS designs Life cycle simulation considering multi-objectives (e.g. economic and environmental) AHP, Dematel and Petri nets (discrete event simulation) No evaluation approach proposed Business case validation and evaluation of alternatives RSP, receiver state parameter; FBD, functional block diagram; AHP, analytic hierarchy process. Vasantha et al. Journal of Remanufacturing 2013, 3:8 Page 4 of 32 http://www.journalofremanufacturing.com/content/3/1/8 maintenance planning. The maintenance experts were interviewed to understand engineering services issues because maintenance service occupy nearly three quarters of acquisition and support costs as compared to other aftermarket services [13]. Semistructured interviews were held with five companies: aerospace engines and related systems, naval ships, land vehicle systems as well as, trains and trucks. Overall, manufacturers generally lack the competence to address the challenges of PSS-type contracts. The reasons for this situation are listed below: Customers now have higher expectations from manufacturers. Product-orientated manufacturers tend to be product-centric and so do not have the mindset to develop and deliver PSS. There tends to be very few technical employees of manufacturers interacting with customers. Customer issues could take months or years to be resolved if they are to be addressed by services. Current PSS design methodologies tend to be ad hoc and tend not to start with the business case. The design of the product and service is not completely performed simultaneously and maintenance is mostly an afterthought; only slight modifications to the product are considered following a decision to create a PSS. Manufacturers tend not to perform enough modelling to fully understand maintenance activities sufficiently to undertake PSS-type contracts. There is a lack of high-level strategic decisions to, for example, trade-off between design, maintenance and supply network solutions for the efficiency of the overall solution. A common understanding of PSS-type contracts is lacking across teams. The framing of competitive maintenance offerings is a challenge. Most importantly, the consideration of value-added benefits to customers and a suitable operative model between stakeholders to ensure the throughput of inputs as well as reasonable profits tends to be lacking. These challenges present obstacles to the design of PSS solutions offered by these companies. As a result of an investigation of the state-of-the-art methodologies and challenges in designing PSS in the literature, we have framed the following research questions to be answered in this paper: What constitutes PSS design? (This question intends to define characteristics and properties of the system). How can customised PSS solutions be designed to be aligned to integrated stakeholders' capabilities? The next section discusses our definition and constituents of PSS design. What constitutes PSS design? PSS design aligned to integrated stakeholders' capabilities is mandatory to achieve a viable and sustained solution for an intended duration. A capability can be defined as the continuing ability to generate a desired operational outcome [14]. The definition of Vasantha et al. Journal of Remanufacturing 2013, 3:8 Page 5 of 32 http://www.journalofremanufacturing.com/content/3/1/8 capability exemplifies how the joint capability of all the stakeholders could achieve the desired outcome required by the PSS customer and for the PSS provider to design economically sustainable PSS. Considering capabilities as a core element, we defined PSS design as a process to synthesize and create sustained functional behaviour through tangible products and intangible services. Sustained functional behaviour represents the degree to which a system can continuously achieve its purpose by adapting its capabilities. To represent sustained functional behaviour, an activity-based modelling approach is proposed (Figure 2). An activity could be defined as an action incorporated or influenced in the customer's system. The activity-based modelling approach is in-line with the definition of the PSS design processes provided by Komoto and Tomiyama [4], in which designers define the activity to meet a specified goal and quality, and also define environment as being the circumstance within which that activity is realized. Furthermore, Matzen [15] and Tan [16] emphasized activity systems in modelling PSS development. Tan focused on customer activity cycles whereas Matzen viewed activity systems with a broader and general view encompassing both customer and company activities. Both Matzen and Tan conceptualized PSS solutions by considering artefact-, activityand actor-based domains with slight differences. In this work, capability is mapped through resources, competences, responsibilities undertaken and outcomes. Inputs to a particular activity are mapped through customer needs and precedence activities' outcomes. Other influential parameters on an activity are enforced through an environmental variable. In Figure 2, the coloured boxes represent modification incorporated in the existing system. We propose in this work that a network of seven parameters, namely activities,customer needs,environmental influences,resources,competences,responsibilities,inputs (precedence activities'outcomes) and outcomes, are sufficient to model PSS design. We have chosen these familiar and simpler terminologies for easy acceptance within industrial practitioners. These parameters map the required information for mapping products, services, processes and interactions of all the elements involved within the system. Figure 2 Representation of PSS design constituents (coloured boxes represent modification to the existing system). Vasantha et al. Journal of Remanufacturing 2013, 3:8 Page 6 of 32 http://www.journalofremanufacturing.com/content/3/1/8 Mapping of these parameters helps to understand the gaps within the current customer's system (PSS user) and aids the development of innovative PSS designs to satisfy customer business needs. The derivation of these parameters in PSS design is presented in the proposed framework. The framework is detailed step by step in the next section. A capability-based PSS design framework The proposed framework aims to support manufacturers in designing customeradjusted PSS designs which are aligned to stakeholders' capabilities. The core principles supporting this framework to realize this aim are as follows: Gap analysis: Identification of value addition required in the customer's system (PSS user) by understanding their needs through assessing customer's business activities and constructing relative key performance indicators [17]. This initial step lays a foundation to develop customised solutions. Generation of new and/or re-designs of integrated product and service solutions along with conditions and consequences of each design. These designs take into consideration the partial substitution of product and service shares over the life cycle. Responsibility assignment which considers the capabilities of all the stakeholders involved at various levels: activity, object (resources), and parameter (competences). This assignment enables the derivation of innovative function-, availabilityor result-oriented business models. Synthesis-generated solutions in each gap to improve the overall PSS design on a system level and avoid a sub-optimized solution towards any of single activity, stressing the importance of resource effectiveness. Standard representation of PSS designs is required for effective communication across all the stakeholders. These core principles are structured into 10 steps in the proposed framework (Figure 3). The steps mentioned in this framework are highly inter-dependent, and feedback loops exist between every step. The following sub-sections describe each step individually and detail the course of action involved. Step 1: understand customer needs The first step in deriving customer needs from their complete business activities and existing systems is not taken into consideration in most of the PSS methodologies; commonly, customer needs are deemed to be the requirements of products and services. Note that the term ‘customer’represents the PSS user throughout this framework. Figure 4 illustrates a typical product-centric life cycle. The product life cycle within the customer's business process only partly covers operation. Although the consideration of the product life cycle improves the understanding of what is required of products and services, extra value could be offered by considering the customer's goals as revealed by their business processes (Figure 4). Moreover, understanding the customer's business processes reveals the ‘need behind the need’[18] of the customer that has to be fulfilled. Tan [16] has emphasized that PSS solutions may be conceptualized by considering the product life phase, customer activities and actor network. Vasantha et al. Journal of Remanufacturing 2013, 3:8 Page 7 of 32 http://www.journalofremanufacturing.com/content/3/1/8 Figure 4 illustrates the point that it is the consideration of the capabilities that are required to use a product that presents opportunities to add value. Identifying and understanding the customer's overall needs should therefore be the foremost step in the design process. Once the overall customer needs have been identified by focusing on their business processes, the next step would be to identify the current capabilities of the customer. Step 2: identify existing capabilities and resources of the customer Identifying the customer's needs is followed by understanding of the customer's existing capabilities. Such an understanding helps to develop designs which are more aligned to their capabilities. A capability can be defined as the continuing ability to generate a desired operational outcome [14]. Capabilities can be realized through people, processes, tools and technology [19]. It should be noted that these elements are highly coupled and should be visualized together. Integration of these elements will be facilitated if the customer's activities are identified and the efficiency of each activity is measured. For this reason, capabilities should be mapped depicting their outcomes and the reasons for deficiency. Some of the parameters to assess each activity could be performance, time taken, reliability, responsiveness, expense and quality [20,21]. Such analyses will highlight the gaps within the customer capabilities that need to be filled by a PSS design. In the next step, in-depth analyses of existing products and services are performed to ascertain the degree to which the needs can be addressed. Step 3: identify current status of products and services The identification of existing products and services (whether they are on the market or just being developed) that could help to address the identified customer needs is Figure 3 The proposed capability-based PSS design framework. Vasantha et al. Journal of Remanufacturing 2013, 3:8 Page 8 of 32 http://www.journalofremanufacturing.com/content/3/1/8 Standard process modelling and simulation approaches are not encouraged in this work because the PSS domain requires a specialized software environment defining its own terminologies and incorporating specific methods to support development. It helps to develop and integrate PSS research knowledge generation and understanding into a specific platform for wider uses and support tools evaluation. Although there is significant scope for improvements, from the authors' opinion, ISCL is a mature, reliable and accessible PSS software which well integrates modelling and simulation modules. Finally, the software is currently in the public domain and is actively supported by the developers, which is an incentive for industries to use it in practice. Before describing the case study, the PSS modelling method employed in ISCL is briefly explained. A PSS-based business model in ISCL consists of activities, scenes and entities which are described along with their attributes (what the entity owns) and specifications (what the entity aims are) (Figure 6). Scenes represent partial states of the service environment as defined by the attribute values of entities. Activities treat scenes as the execution condition and change the value of attributes and realize specifications. As shown, these elements have several ports that are connected with lines. These lines have 11 different relations between elements instantiated during life cycle simulation. Figure 7 illustrates these links, and Table 4 shows the meanings (for details of the modelling method and grammar of the simulation codes, please refer to [24] and the user manual on the supporting website [25], respectively). Designers can create these elements on the canvas of ISCL and also move, inspect and delete these elements on the canvas. Step 1: understanding customer needs The laser systems under consideration in this case study are mature products as are the laser processes which are structured and mostly inbuilt to the system. The customers are laser job shop owners who procure laser systems from the original equipment manufacturer and supply semi-finished goods to the end product manufacturer. Figure 8 illustrates stakeholders' map of the laser system case study. As the laser job shops have many years of experience in this field, they are able to precisely specify their requirements of laser-cutting systems. The transaction type between the laser system manufacturer and the laser job shop customer is business-to-business. The semistructured interviews with the laser job shops revealed the importance of the need behind the need, experiences, required state change and business ambitions of the laser Figure 6 Elements in a business model on ISCL. Vasantha et al. Journal of Remanufacturing 2013, 3:8 Page 15 of 32 http://www.journalofremanufacturing.com/content/3/1/8 job shop. We developed a PSS customer needs specifications of the laser system by using overall equipment effectiveness which is a multiplication of availability, performance and quality. The required values are mapped to be: Overall equipment effectiveness (A×P×Q), 50% to 60% Availability (Mean time between failure (MTBF) / (MTBF + Mean time to repair (MTTR)), 85% to 95% Performance (Working speed / Designed speed), 55% to 65% Quality (Good units within tolerance / Total units produced), 95% to 99% Laser system usage period, 5 years At this point, ISCL supports the designer to define the specifications of the users of laser systems as well as the attributes of the laser systems, which are identified at this step. Figure 9 details the specifications and the attributes of the laser systems with examples. In Figure 9a, three entities: ‘Manufacturer’,‘LaserSystem’and ‘User’, are shown. The model includes an activity ‘Use’to deliver ‘Function’as a specification targeted by User. LaserSystem already includes the overall equipment effectiveness specification and the relevant attributes such as MTBF and MTTR. The value of these attributes can be individually calculated with respect to each instance of LaserSystem during the life cycle simulation. Figure 9b shows the objectives of the model, which are statistical values obtained as a result of life cycle simulation. For instance, ‘AvrOEE’is the average overall equipment effectiveness of all laser systems in the market with respect to Figure 7 Relations in a business model on ISCL (please read Table 4 for link description). Table 4 Definition of relations in a business model on ISCL in relation to Figure 7 Figure 7link number Element 1 Element 2 Meaning 1 Scene Entity Scene includes all instances of Entity 2 Scene Attribute Entity instances included in Scene are specified by the value of Attribute 3 Activity Scene Scene is regarded as the execution condition of Activity 4 Activity Entity Activity creates instances of Entity 5 Activity Entity Activity deletes instances of Entity 6 Activity Scene Activity refers to (calls) an instance of Entity specified by Scene 7 Activity Attribute Activity gets the value of Attribute 8 Activity Attribute Activity assigns the value of Attribute 9 Activity Specification Specification is realized as a result of execution of Activity 10 Activity Specification Specification is evaluated during the execution of Activity 11 Specification Attribute The value of Specification is related with Attribute Vasantha et al. Journal of Remanufacturing 2013, 3:8 Page 16 of 32 http://www.journalofremanufacturing.com/content/3/1/8 simulation time, which is defined with the window in Figure 9c. At this moment, the dynamic behaviour of laser systems such as physical deterioration has not been defined yet. In the next step, to understand whether required needs levels are achievable through existing customer's capabilities, they are noted. Step 2: identification of the existing capabilities and resources of the laser job shop To understand the laser job shop's capabilities, currently performed activities are mapped with resources, outcomes and the reasons for deficiency. The important tasks which are mapped include machine calibration, CAD file preparation, identification of process parameters, material preparation, work piece (un)loading, work piece alignment, machining operation, daily and planned maintenance, repair work, and material Figure 8 Stakeholders' map of the laser system case study. Figure 9 Modelled attributes of laser systems and their objectives in ISCL. (a) Entities of the model. (b) Objectives of the model. (c) Average overall equipment effectiveness. Vasantha et al. Journal of Remanufacturing 2013, 3:8 Page 17 of 32 http://www.journalofremanufacturing.com/content/3/1/8 and gas procurement. Some of the activities to map the laser job shop's capabilities are detailed in Table 5. The complete list of activities and the respective status of each helps us to understand the capability gaps of laser job shops. Along with these gaps, current products and services are assessed in the next step. Step 3: identify current status of laser systems and services A laser system is an assemblage of a laser generator unit, beam delivery system, beam manipulation system, motion system, process monitoring system and a control system (Figure 10). The key performance indicators (KPIs) for these systems are failure rate, repair time, degradation rate, redundancy and reliability. Mapping these KPIs to the sub-systems shows that beam delivery and beam manipulation systems have to be improved. Identifying root causes through discussions with the experts revealed that mirror misalignment, laser instability, variation within suppliers, operator's error and a mismatch in cooling needs could be possible problems to be addressed. Mapping the KPIs of services (frequency, number of technicians available, time consumed, spare parts and tools availability, and location) with provided services (training, planned maintenance, technical assistance and repair activity) revealed several potential improvement areas like the operator's knowledge of the machine, complexity regarding the different shapes to be machined, constraints in space requirements, the probability of making mistakes being high and escalated expense of module replacement. In this study, there was restriction to collect required industrial data. Therefore, the current scenario was simulated through data collected from the interviews. If data could have been available, ISCL supports to import these data through .CSV format. From the interviews, it was revealed that the overall equipment effectiveness at the required level is not maintained and, in particular, that performance should be improved. At this point, ISCL supports the designer in adding other necessary elements to describe the current design. The refined model (Figure 11) includes new activities, entities and attributes so that the model can represent the current design. For instance, ‘Fail (ure)Rate’,‘Deg(radation)Rate’and ‘Rep(air)Rate’are added as attributes of LaserSystem, which influence the degradation in terms of the availability, performance and quality. Furthermore, ‘Engineer’and ‘Operator’are treated as the entities of the current design. Their ‘Skill’also influences the degradation and its recovery through activities ‘Repair’ and ‘Maintenance’. By supplying codes specific to each activity, the model becomes the input of life cycle simulation. For instance, Figure 12a shows the codes specific to an activity Repair. These codes are used to automatically create links between the model elements as shown in Figure 12b, which is helpful to the designer in debugging these codes. An explanation of coding as the input to life cycle simulation is beyond the Table 5 Mapping existing capabilities of laser job shops Activities Resources Outcomes Reasons Machine calibration Limited skills. One employee Trial and error Not having enough understanding of the machine. The system is partially protected by the manufacturer Work piece loading/unloading Manual process. Two unskilled employees Time-consuming Automated machine unavailable Vasantha et al. Journal of Remanufacturing 2013, 3:8 Page 18 of 32 http://www.journalofremanufacturing.com/content/3/1/8 scope of this paper. Figure 13 shows the simulation result of the current design, the average overall equipment effectiveness with respect to simulation time. At this stage, the simulation results are partly based on fictive parameter values, which should be specified in the design process. The gaps identified in these first three steps facilitate generation of PSS designs in steps as described in the following sections. Step 4: identification of new designs required to satisfy the needs at every level From steps 2 to 3, 10 activities have been identified for improvement. Within the 10 activities, 18 problems are observed. Through group brainstorming with the researchers, 54 designs have been generated. From the perspectives of adding and modifying activities, enriching the laser systems through support systems and focusing on specific parameters helped to generate many designs. These designs have been checked and rated by the researchers in preference with the feasibility scope. The highlighted circles in Figure 14 are some of the preferred designs. In order to add these designs in ISCL, corresponding model elements should be added to the model to represent the current design. Alternatively, corresponding model elements can be separately modelled and stored in the knowledge base of ISCL. The stored model elements are instantiated Figure 10 Laser system. (a) Laser unit (IPG YLR-8000). (b) Optical head. (c) Monitoring system. (d) Robot motion system. Vasantha et al. Journal of Remanufacturing 2013, 3:8 Page 19 of 32 http://www.journalofremanufacturing.com/content/3/1/8 Figure 11 Modelling the current design in ISCL. Vasantha et al. Journal of Remanufacturing 2013, 3:8 Page 20 of 32 http://www.journalofremanufacturing.com/content/3/1/8 Figure 12 The detail of an activity repair in the current design. (a) Codes specific to an activity Repair. (b) Links between the model elements. Vasantha et al. Journal of Remanufacturing 2013, 3:8 Page 21 of 32 http://www.journalofremanufacturing.com/content/3/1/8 when necessary. Furthermore, the formalization of this step can be useful for ISCL to automatically synthesize new designs using the knowledge base. The subsequent steps help to develop and assess these designs. Step 5: identify conditions and consequences of each design Steps 5 and 6 are jointly discussed in the next section due to greater continuity between them. Step 6: identify (additional) capabilities required to develop new designs Even though preferred designs are highlighted in the previous step, the potential of every design is identified by specifying conditions and consequences. The conditions are mainly specified through the frequency and complexity of the activities, laser system usage period and patterns, required skills, parameters values, man-days required and the condition of the laser system. The consequences of each of the proposed designs are expressed in terms of the impact on availability, performance and quality to set the overall equipment effectiveness and incurred costs. The generated conditions Figure 13 The simulation results of the current situation. Figure 14 Representation of generated designs for two problems in the concern activity. Vasantha et al. Journal of Remanufacturing 2013, 3:8 Page 22 of 32 http://www.journalofremanufacturing.com/content/3/1/8 and consequences have been evaluated by the heuristic judgements of two experts. From the conditions and consequences, the capabilities required by each design are derived. Table 6 illustrates the conditions, consequences, capabilities, resources and control variables derived for new designs which have been generated. Conditions and consequences are inherent processes in ISCL. Support should be developed to highlight the new capabilities achieved, and the additional resources should be incorporated in the PSS laser system modelling. Developing new integrated business models between the laser job shop, the manufacturer and suppliers through the alignment of capabilities for each design will be the next step. Step 7: understand and specify responsibilities of the stakeholders Responsibilities have to be assigned precisely between the laser job shop, the manufacturer and suppliers (based on the identified required resources) for the capability shift to occur to satisfy the proposed design and eventually to satisfy the required level of overall equipment effectiveness. These assignments are precisely defined either at the level of activities, objects or parameters. Based on inputs of preferences and views from the laser job shops and manufacturers, various possibilities of responsibility assignment are generated. The outcome of such a PSS design process has stark impact upon business model generation. Table 7 illustrates responsibilities aligned within a new design generated. Using ISCL, such responsibilities are defined by selecting appropriate entities (such as Manufacturer) as the service provider of specific activities. This assignment results in modification of financial flow. In some cases, the expected service may not be realized in life cycle simulation, because some entities may not satisfy the conditions to provide the expected service (such as the level of Skill of Engineer). Synthesizing designs generated for 18 problems through responsibility alignment is the next step. Step 8: group different combinations of designs to satisfy customer needs To satisfy the required overall equipment effectiveness levels throughout the usage period, a wide variety of designs are generated by synthesizing the designs identified for each gap. The synthesis process is systematically carried out through Taguchi's factorial method. The control variables identified in each design in step 6 are used to vary values to generate multiple options within each design. Table 8 details the combinations possible across four activities. In Table 8, the four columns explain the chosen four activities (in which gaps exist in the current system) to be addressed in PSS designs. The six cells in each column explain two solutions with three improvement levels each (based on Taguchi's factorial method) to fill the gap in each activity. Similar to step 4, the automatic synthesis of the new design by combining model elements stored in the knowledge base including these activities can be implemented in ISCL. Currently, ISCL supports the automatic synthesis process, when the conditions and consequences of added activities are defined and these activities solely influence the state of a single entity with a hierarchical structure. For instance, [4] shows a procedure implemented in ISCL to generate possible functional upgrading services combined with repair services for medical equipment systems. The next step evaluates combinations to understand the satisfaction of required overall equipment effectiveness levels. Vasantha et al. Journal of Remanufacturing 2013, 3:8 Page 23 of 32 http://www.journalofremanufacturing.com/content/3/1/8 Table 6 Outcomes from steps 5 and 6 for the derived new design Solutions Conditions Consequences at each time Capability shift Resources Control variables Technical assistance to set efficient process parameters Laser parts (new shape and size parts) Man-days, +0.2 (24-h day); performance, +0.5%; quality, +1%; set (overall equipment effectiveness (laser system)); total cost, +£50 Efficient process parameters irrespective of varying shapes and sizes To employ an additional three technical employees to support process query Frequency of new shapes and sizes, technical employees, number of queries Vasantha et al. Journal of Remanufacturing 2013, 3:8 Page 24 of 32 http://www.journalofremanufacturing.com/content/3/1/8 PSS to help meet customer goals. A capability-based approach generates a wide variety of PSS designs which are intended to produce sustained functional behaviour in the proposed system to achieve its purpose continuously and create an innovative value addition for the customer. It encourages a broader customer business perspective in designing PSS as compared to the traditional approach where the functional availability of products is considered given their deterioration during the use stage. Details of a capability map of the customer's processes help to pinpoint the focus areas for PSS development. It stresses the capability shift and mix between products and services and also between stakeholders in order to develop feasible and enduring PSS designs. The framework emphasizes the importance of taking into account the preferences and views of the stakeholders and the apposite alignment of responsibilities. Organized feedback loops between the various steps aid PSS design modelling and performance evaluation. The framework facilitates the exploration of a wide variety of designs by synthesizing designs that have been identified for various gaps. The generation and evaluation of designs are well structured in the framework. The results of the simulation using ISCL provide good insights into PSS designs. We believe that this framework would facilitate and structure the interactions between the customer, manufacturer and supplier. It also helps in understanding the capabilities of the stakeholders and aids an understanding of the value of PSS designs as appreciated by the customer. The representation of PSS designs through extended IDEF0 was found to be useful in providing a common understanding among the stakeholders. The application of this framework to a real industrial laser system case study helps to demonstrate the benefits of the framework. This demonstration also helps refine the framework based on the few observed limitations such as the inputs collected and the features in the modelling technique. The demonstration of the framework along with ISCL highlights the important features of ISCL and the modules to be developed to enhance design support. In particular, support for design generation through standardized PSS ontology and the synthesis of different designs generated through Taguchi's factorial method would prove to be especially helpful for PSS designers. Additionally, the implementation of this framework using a step-by-step approach in software could greatly facilitate the design process by decreasing information load on PSS designers. An effective mechanism is required to support PSS designers to specify the conditions and consequences of each development design which are vital inputs for PSS simulation. Since the underpinning expectation that PSS will have a lower environmental impact is yet to be proven, the impact of PSS designs on environmental benefits should be studied separately. There is ongoing work in applying this framework to various case studies which involve other case companies who are in the process of refining the development of their PSS designs. Competing interests The authors declare that they have no competing interests. Authors' contributions GVAV carried out understanding industrial challenges, framework development, case study development, framework evaluation and manuscript preparation. HK participated in the framework development, Service CAD integration with the framework and manuscript preparation. RH participated in understanding industrial challenges and assisted in the framework development, case study development and framework evaluation. RR was the principal investigator of this project and assisted in all the phases of the work especially on the framework development and framework evaluation. TT supported in Service CAD integration with the framework. SE and AT participated in the framework development and framework evaluation. SW supported in the laser case study development and framework evaluation. All authors read and approved the final manuscript. Vasantha et al. Journal of Remanufacturing 2013, 3:8 Page 31 of 32 http://www.journalofremanufacturing.com/content/3/1/8 Acknowledgements This research was funded by the Cranfield Innovative Manufacturing Research Centre (EPSRC Grant EP/E001874/1) as part of the research project ‘Capability based conceptual PSS design’. Author details 1 Design, Manufacture and Engineering Management, University of Strathclyde, Glasgow G1 1XQ, UK. 2 Advanced Manufacturing Research Institute, National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8564, Japan. 3 School of Engineering, Cranfield University, Cranfield, Bedfordshire MK43 0AL, UK. 4 Manufacturing and Materials Department, Cranfield University, Cranfield, Bedfordshire MK43 0AL, UK. 5 Institute for Manufacturing, University of Cambridge, Cambridge CB3 0FS, UK. 6 Welding Engineering and Laser Processing Centre, Cranfield University, Cranfield, Bedfordshire MK43 0AL, UK. Received: 10 April 2013 Accepted: 13 August 2013 Published: 23 August 2013 References 1. Neely, A: Exploring the financial consequences of the servitization of manufacturing. Operation Management Research 1, 103–118 (2008) 2. Annamalai Vasantha, GV, Roy, R, Lelah, A, Brissaud, D: A review of product–service systems design methodologies. J. Eng. 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