J Intell Manuf (2008) 19:689–700 DOI 10.1007/s10845-008-0120-6
Modeling workflow activities for collaborative process planning with product lifecycle management tools H. R. Siller · A. Estruch · C. Vila · J. V. Abellan · F. Romero
Published online: 14 June 2008 © Springer Science+Business Media, LLC 2008
Abstract Process planning activities are critical in manufacturing distributed environments where different companies need to collaborate in product development. In this work, we propose a workflow model for a collaborative process planning environment in which original equipment manufacturer and suppliers companies interact with the help of Product Lifecycle Management and CAD/CAM tools. The proposed workflow model establishes the different activities, the information flows and the different stages that must be followed by all the participants. A pilot implementation has been made in order to validate the model in a realistic industrial scenario. Keywords Collaborative process planning · Product lifecycle management · Extended enterprise · Workflow management Introduction Process planning, which is called Computer-Aided Process Planning (CAPP) when it is supported by software applications, is the procedure or set of procedures that take engineering drawings, lists of materials and other specifications as input in order to identify and select the processes, resources, sequences of operations and parameters needed to convert raw materials into finished products (Kulvatunyou H. R. Siller Centre for Innovation in Design and Technology, Technológico de Monterrey, Garza Sada 2501 Sur, Monterrey 64700, Mexico e-mail:
[email protected] A. Estruch · C. Vila (B) · J. V. Abellan · F. Romero Department of Industrial Systems Engineering and Design, Universitat Jaume I, Av. Vicent Sos Baynat s/n, 12071 Castellón, Spain e-mail:
[email protected]
et al. 2004). Currently available CAPP tools incorporate reasoning mechanisms and knowledge bases that help process planning, but they do not integrate easily with other functions in the enterprise, such budgeting, production scheduling, quality control, purchasing and other enterprise functions (Denkena et al. 2007). This integration is critical in enterprises that need to collaborate with other enterprises to reduce the development cycle of their products in order to successfully be competitive in the global market. The entire network of collaborating enterprises, from supplier to end-use customers, which have a long term agreement, can be defined as Extended Enterprise. The purpose of this integration is to achieve a competitive advantage by maintaining a distributed cooperation across the entire organization. In the age of the Extended Enterprise, the swift expansion of the Internet provides the infrastructure by which information can be made simultaneously available to all those involved in planning manufacturing processes, that is to say, designers, planners, production managers, shop floor workers and so forth. Yet, before this situation can be accomplished the following problems will need to be overcome (Ahn et al. 2001): • Even the most experienced designers cannot know the exact capacities of the processes used by the enterprises responsible for manufacturing the product. • Nowadays, Computer-Aided Design (CAD) tools enable designers to produce sophisticated geometric parts that must then be examined and, later, modified by manufacturing engineers to ensure trouble-free manufacturing; this results in longer product development cycle times. • The commercial Computer-Aided Manufacturing (CAM) systems used by process designers and planners can be different. Internet-based manufacturing needs to overcome this heterogeneous software environment.
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These problems can be solved by distributed, adaptable, open and intelligent process planning systems within a collaborative environment. In addition to the computer requirements it must satisfy, a collaborative process planning system should also help users to draw up process plans at their different levels of detail. These levels, according to some authors (Ahn et al. 2001; Chan et al. 1998), are known as meta-planning, macro-planning and micro-planning. Metaplanning is performed to determine the manufacturing process and the machines that fit the shape, size, quality and cost requirements of the parts that have been designed. In macroplanning the equipment is selected, the minimum number of set-ups needed to manufacture the part is determined and the sequence of operations is established. Micro-planning is concerned with determining the tools to be used, the tool paths they have to follow during the manufacturing process (e.g. machining process) and the parameters associated to shop floor operations so that productivity, quality of the parts and manufacturing costs can be optimised. The work presented in this paper, is focused in a frequent Extended Enterprise scenario where exists one enterprise, that requires to assign manufacturing contracts to those geographically distributed enterprises capable to satisfy quality, costs and delivery requirements. Furthermore, it is common that the selected manufacturing enterprise requires planning its manufacturing processes in a collaborative way, in order to incorporate the shop floor personnel knowledge for giving process plan efficiency and robustness. To achieve this purpose, it is needed to identify all collaborative activities and information flows (product data, quotations, manufacturing process plans, etc.), and to integrate them into a Computer Supported Collaborative Work (CSCW) infrastructure that allows all the communication and coordination. This paper reviews recent research papers that describes web-based computer systems which supports collaborative process planning, either multi-agent systems (MAS) or systems which allow human cooperation. After the literature review, interactions required for the meta-, macro- and microdistributed process planning, have been identified and the technological infrastructure capable of integrate such distributed environment has been acknowledged. We propose a reference workflow model for representing the activities and interactions identified, and we have applied the proposed workflow in a case study with the support of a CAD/CAM/PLM (Product Lifecycle Management) tool, as a feasible CSCW framework for the implementation of future CAPP applications. This practical industrial solution should take advantage of the capabilities of PLM systems for managing the integrated Knowledge Information and Data (KID) regarding product design, manufacturing process and production capabilities, specifically for collaborative process planning tasks.
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State of the art of collaborative process planning In a geographically dispersed manufacturing environment, it is needed not only a Web-based tool for collaboration, but also a framework that enables the integration and coordination of product development activities and the exchange of information between entities (expert applications or individuals). In the case of Extended Enterprise different tier suppliers collaborate within the common communication infrastructure provided by the Original Equipment Manufacturer (OEM) (Fig. 1). For tier 1 suppliers the collaboration must be stronger in order to achieve product requirements but, occasionally, with new product introduction, OEMs allow bids from other companies that work in different Extended Enterprises. In this scenario the definition of the manufacturing plan becomes a key issue. Specifically, in the field of process planning, the state-ofthe-art presents several research papers and academic prototypes diversified in terms of functionalities, communication protocols, programming languages and data structured representations. The following paragraphs include a chronological review of some of those recent works that report Web-based systems and methodologies of collaborative meta-, macro- and micro-process planning, most of them oriented to machining processes. Van Zeir created a computer system for distributed process planning called Blackboard. Here, several expert modules perform specific process planning tasks that range from process and machine assignation to the sequencing of operations and tool selection. The system generates graphs (Generic Petri Nets), called Non-Linear Process Plans, which are made available to users by means of a graphic interface. The process plans that are thus generated can then be handled and modified by users, according to their own experience and skills (Van Zeir et al. 1998). Chan proposed a tool called Computer Oriented Materials, Processes and Apparatus Selection System that helps designers to identify potential manufacturing problems in the early stages of the development cycle of a product; it also helps them organise in one coherent plan all the heterogeneous technological processes involved in manufacturing (Chan et al. 1998). The system, which was developed in the form of a meta-planner, provides essential information about production costs, cycle times and product quality for different candidate processes by a series of modules that receive the design information and analyse it according to the restraints of each technological process stored in databases. Tu proposed a CAPP framework for developing process plans in virtual one-of-a-kind manufacturing environment. It includes reference architecture, an incremental process planning (IPP) method, an optimal/rational cost analysis model
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Fig. 1 Collaboration through supply chain
and a database of the partner’s resources. The framework was implemented for concurrently designing and manufacturing a steel frame of a rail station (Tu et al. 2000). Zhao presented a process planning system (CoCAPP), which utilizes cooperative and coordination mechanisms built into distributed agents with their own expert systems. Each agent has knowledge contained in databases, analytical algorithms and conflict resolution rules for constructing feasible process plans (Zhao et al. 2000). Ahn created an Internet-based design and manufacturing (CAD/CAM) tool, called CyberCut, which allows the generation, by a destructive solid geometry approach (DSG), of 3D prismatic parts, from the basic machining specifications. Thus, in the design stage, the user can suggest what processes, operations, sequences and tools will be used in the actual manufacturing process (Ahn et al. 2001). Wang presented an approach for distributed process planning based on the use of function blocks, which encapsulate complete process plans for their execution in open CNC controllers. The process plans are generated by a multi-agent negotiation implemented with Knowledge Query Manipulation Language (KQML) protocol (Wang et al. 2003). Kulvatunyou described a framework for integrating collaborative process planning in which collaborative manufacturing is divided into two parts—the “design house” and the “manufacturing side”. These two divisions exchange information by means of hierarchical graphs and Unified Modeling Language (UML) models which represent the process requirements and alternatives. In this same work a prototype
application was implemented that uses the Java programming language and the data representation language Extensible Mark-up Language (XML) to ensure information portability (Kulvatunyou et al. 2004). Chung addressed the issue of selecting machines and tools under a Web-based manufacturing environment. To ensure efficiency and functionality, they developed a selection tool using MySQL databases, Java Applets and a Virtual Reality Modeling Language (VRML) browser (Chung and Peng 2004). Sormaz created a process plan model prototype (named IMPlanner) for distributed manufacturing planning activities. It relies on existing CAD/CAM applications and proprietary CAPP software, and it has been implemented with Java and XML languages (Sormaz et al. 2004). You applied the ISO 10303 (STEP, STandard for Exchange of Product Model Data) standard and Java J2EE specification, to implement a process planning platform for selecting machining operations, machines and tools, based on EXPRESS-G (object-oriented information modeling) models of the geometric characteristics of the parts to be machined (You and Lin 2005). Feng developed a prototype of a MAS that helps the user select the technological processes required to manufacture a part and the associated resources. This system is based on a platform with a knowledge base which captures design factors and classifies them in several machining features. It also integrates heterogeneous CAD, CAM and CAPP applications, databases and mathematical tools. Designers, process
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planners and manufacturing engineers can access it by means of Web-based heterogeneous tools (Feng 2005). Nassehi examined the application of artificial intelligence techniques, as well as collaborative MASs, to design a prototype of an object-oriented process planning system, called MAS for CAPP. This system focuses on prismatic parts and uses the STEP-NC standards (ISO 14649 and ISO 10303) (Nassehi et al. 2006). Cecil developed a collaborative Internet-based system to perform some of the process planning activities carried out between the partners in a Virtual Enterprise, based on the use of an object request broker (ORB). The distributed resources include feature identification modules, STL (stereo-lithography) files and software objects for choosing and sequencing processes, generating setups, selecting machines and tools, and also include a machining cost analysis agent (Cecil et al. 2006). Guerra-Zubiaga designed a manufacturing model to ensure management and storage of facility information and knowledge related to processes and resources. They developed an experimental system for the model validation using UML modeling language, Object Store databases and Visual C++ programming environment (Guerra-Zubiaga and Young 2007). Mahesh proposed a framework for a Web-based MAS (WebMAS) based on a communication over the Internet via KQML messaging. Each agent possesses unique capabilities and a knowledge base for performing different activities like manufacturing evaluation; process planning, scheduling and real-time production monitoring (Mahesh et al. 2007). Peng proposed a networked virtual manufacturing system for SMEs (Small and Medium Enterprises) in which distributed users share CAD models in a virtual reality environment and contribute to the development of process plans with the
aid of a system named VCAPP, implemented in Java and using VRML (Peng et al. 2007). The Table 1 shows the main technological characteristics (standards and Information Technology) of each reviewed work including the different process planning levels covered. Other works that complement this literature review include state-of-the-art about Web-based manufacturing and collaborative systems (Yang and Xue 2003; Li and Qiu 2006), in which they identify future trends of development issues like integration, security, flexibility and interoperability. Although the above mentioned works have established the roadmap for the next generation commercial tools, most of them are not ready for commercial off-the-shelf (COTS) industrial implementation. This problem was addressed by Denkena et al. (2007) who described a holistic component manufacturing process planning model based on an integrated approach combining technological and business considerations. In the same research, after a survey of process planning in SMEs (Small and Medium Enterprises), they pointed out three main topics to solve: • Contrary to CAD/CAM technologies CAPP is not yet implemented in industry • Management of infrastructure knowledge is lacking, and • Digital information is transferred from designer to manufacturer but there is not feedback from manufacturer to designer. As a conclusion, they suggest the applicability of PLM systems as the KID backbone to support CAD/CAPP/CAM systems for improving design and process planning productivity and profitability. These tools have reached maturity, and are well developed and implemented in industry, providing an
Table 1 Summary of the state-of-the-art of collaborative process planning Author
Prototype
Standards used
Information technology resources
Process planning level Meta Macro Micro
(Van Zeir et al. 1998) Blackboard – – (Chan et al. 1998) Compass – – (Tu et al. 2000) IPP CSG/Brep, STEP – (Zhao et al. 2000) CoCAPP – ABE Tool Kit, KQML, Visual C++ (Ahn et al. 2001) Cybercut DSG Java (Wang et al. 2003) DPP STEP, IEC-61499, KQML Java (Kulvatunyou et al. 2004) IPPD/RIOS UML, XML Java (Chung and Peng 2004) WTMSS VRML, DXF Java, MySQL (Sormaz et al. 2004) IMPlanner XML Java (You and Lin 2005) – STEP J2EE (Feng 2005) – XML ProTool Kit, CORBA, C, Java, Oracle, Matlab (Nassehi et al. 2006) MASCAPP UML, OMT, STEP-NC Java, Object store (2006) CHOLA STL CORBA, C++, Java (Guerra-Zubiaga and Young 2007) MKM UML Object Store, Visual C++ (Mahesh et al. 2007) WebMAS KQML JATLite, MySQL, Java (Peng et al. 2007) VCAPP VRML Java, LDAP, MS-Access
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infrastructure for collaborating in product development activities. The developers of PLM systems are presently embedding Workflow Management Systems (WFMS), which provide the ability to script a business process, providing a flowchart to show the current state of the process and often an “inbox” for participants to receive notifications about tasks assigned to them (Maropoulos et al. 2006). Workflow systems have their roots in CSCW systems and are oriented to towards coordinating tasks executed by both human and software systems (Madhusudan 2005). After the literature review, and once studying all the interactions required by collaborative process planning, we propose a workflow model for enabling collaboration among different process planners who are distributed across an Extended Enterprise. This model constitutes the starting point of a valid PLM implementation and provides a framework for the integration of future CAPP applications, which must be developed with state-of-the-art technologies and standards.
PLM and workflow management The entire product lifecycle consists of a set of processes, which are functions or tasks to create, transform, and deliver products. The difficulty in managing these processes is not only the modelling, designing, integrating, automating, monitoring and optimizing them, but also the capability to support levels of collaboration to improve efficiency and effectiveness throughout the entire product lifecycle (Ming et al. 2005). Therefore, appropriate CSCW technology solutions are imperatively required to facilitate the implementation and deployment of PLM systems to benefit industrial application. This section provides an overview of the main characteristics that these solutions must have. PLM systems overview PLM systems are groupware technologies used for the storage, organization and sharing of product-related data and for the coordination of the activities of a distributed team in the deployment of all products’ lifecycle processes like project and portfolio management, product design, manufacturing planning and process design, supply production, client service, recycling and all related activities (Fig. 2) (Contero and Vila 2004). The most immediate forerunners of PLM tools are PDM (Product Data Management) systems, which are designed for use as engineering databases, storing information such as CAD drawings, CAE (Computer-Aided Engineering) analysis, CAM processes and textual documents. Nowadays PLM systems must offer the following capabilities for managing the Product’s Lifecycle:
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Project Management Procurement investments
Design/Engineering
Manufacturing Plan Marketing Sales Client services Production Deliveries CLIENTS
Plant/Process SUPPLIERS
Fig. 2 Product lifecycle management
A. Product data vault and document management. This is the core functionality of the system and it offers a secure, controlled storage for all the data and meta-data (attributes for the product data). B. Product data and structure management. According to Van den Hamer and Lepoter (Van den Hamer and Lepoeter 1996), the management of product data can be divided into five orthogonal dimensions: Versions, views, hierarchies, status and variants. Each dimension plays an important role in the product structure data management, like carry out the iterative nature of product design, the representation of different detail levels, the division into assemblies, sub-assemblies and parts, and so forth. C. Data classification and retrieval. These functions make it possible to define attributes for the product data. Authorised users can perform searches that use these metadata for information retrieval. D. Notifications. These are essential for enabling the collaborative environment in which the users can be notified about tasks and engineering changes. Communication can be possible with the system’s messaging functions or with interfaced external e-mail applications. E. Data sharing. This function allows authorised users to extract documents from the vault so that they can work with them in their private workspace. Once the tasks or modifications have been completed, the documents can be uploaded back to the shared data vault to make changes visible to other users. F. Data exchange. This is essential when working in a heterogeneous environment where different applications generate files in different formats. Here it becomes necessary to use of standardized formats to represent CAD models, such as STEP and IGES (Initial Graphics Exchange Specification), and to represent other documents. G. Pre-visualisation. This function enables global access and allows the user to pre-visualise CAD documents with the help of Web-based light-weight applications, that lately use file formats like VRML, X3D, JT Open and
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U3D among other open XML enabled 3D file formats (Subrahmanian et al. 2005). H. Lifecycle Management. This functionality allows the possibility to define lifecycle for documents and rules for transitions between product development stages. Also provides the possibilities to track the document history and to access control according to lifecycle stage. I. Process management. This capability allows defining and monitoring processes like engineering changes and approval processes. The processes must be modeled as workflows (concept to be approached later in this paper), including all necessary actions or steps, and the resources and information required to perform them. PLM tools must have an embedded workflow engine that launch and monitor its execution. However, to get the most competitive advantages in the modern dynamic global manufacturing era, there is still a big gap between increasing demands from industrial companies and available solutions from vendors. The lacks in PLM software include real time design to manufacturing collaboration; supply chain and lifecycle efficiency, knowledge management, links with ERP (Enterprise Resource Planning) systems and the generic use of standards (Gao et al. 2003; Ming et al. 2005). Most of PLM implementations are centred in the management of initial stages of product development, like conceptual design, detailed design and prototyping, usually performed inside only one organization. Moreover, cooperation between process planners and manufacturers is more common than between process planners and designers (Denkena et al. 2007). Therefore, it is required that complete implementations cover later stages of product development, like process planning and manufacturing resources management, in which interact the different partners of an Extended Enterprise. This paper is focused in exploit the workflow approach for modeling this scenario and for its implementation on a workflow capable PLM tool. Workflow modeling approach The term workflow is defined as the automation of a business process in the course of which documents, information or tasks move from one participant to another in order to perform some action, in accordance with a set of procedure rules (WfMC 1999). There are several emerging industry standards and technologies related to Workflows and Business Process Management. The Business Process Execution Language for Web Services (BPEL) (WS-BPEL 2006) is emerging as a de facto standard for implementing business processes on top of Web services technology. Numerous workflow platforms support the execution of BPEL processes. However, BPEL modeling
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tools do not have the adequate level of abstraction required to make them usable during analysis and design phases of high complexity processes like collaborative product design and manufacturing. On the other hand, the Business Process Modeling Notation (BPMN) (BPMI 2004) has attracted the attention of business analyst and system architects as a language for defining business process blueprints for subsequent implantation. The BPMN is a graph-oriented language in which control and action nodes can be connected almost arbitrarily. Also supported by numerous modeling tools, none of these can directly execute BPMN models, because they require the translation of BPMN to BPEL. Workflow technology has found its place into mainstream application development tools, application integration middleware, and in packaged applications for customization. This last is crucial to the success of a PLM implementation, and deals with the complexity and heterogeneity of existing relationships among all participants in the collaborative environment in which a PLM system must be implemented.
Methodology for collaborative process planning: a case study This section presents the methodology for a PLM implementation as the KID backbone for the collaborative process planning in a specific Extended Enterprise, where one OEM and different tiers suppliers exist. It is necessary in such scenario to satisfy the following requirements: • The personnel of the OEM involved in searching available tier 1 suppliers for manufacturing a part previously designed, need to perform some basic process planning tasks, for guaranteeing the manufacturability and for selecting the best supplier from the directory of existing suppliers. • It is imperative that managers of the tier 1 suppliers extract product information from a shared repository and perform rough process planning tasks aided by process planners, for elaborating a concise quotation. • The personnel of the selected supplier, who perform detailed process planning tasks, need to develop them collaboratively with shop floor personnel in order to incorporate the operating parameters in accordance to the best performance in terms of productivity, quality and economics. The proposed methodology consists in three mainstays: Workflow Modeling and Lifecycle Phases Identification, IT (Information Technology) Basic Requirements, and Implementation. In the following sections these mainstays are described comprehensively.
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Fig. 3 Exploded View of parts of a mould for forming ceramic tiles
Workflow modeling and lifecycle phases identification The specific Extended Enterprise chosen for the case study is dedicated to the manufacture of moulds for ceramic tiles. Within this context three geographically distributed companies interact. One of them (A) is the OEM of the mould products, and the other two (B and C) are tier 1 members of the supply chain providing parts for the moulds, more specifically, parts that require certain machining operations (see Fig. 3). With the aim of enabling a proper collaboration, a standard product data file (STEP AP214, for example) is needed containing and specifying all product details and features such as geometry, dimensions, material, dimensional and geometrical tolerances and surface finish. This file with a meta-plan document can be used by tentative suppliers to prepare the manufacturing plan. Suppliers should prepare, with their own CAD/CAM resources, a document containing all the process plan details like machine, operations, sequences, fixtures, tools, tool paths and process parameters. Figure 4 shows the BPMN workflow model used for representing the running of tasks that must be carry out for the collaborative process planning, required in this set of enterprises. The workflow can be explained as follows: in Enterprise A the design team performs conceptual and detailed design after a study of client’s requirements. After the 3D modeling of the product, the model should be available in a shared data vault classified in a product family with a standard format. Then, the purchasing department team reviews the manufacturability of the design and use the 3D model to create a
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manufacturing requirements file that must contain the process plan at the meta-planning level (selection of technological processes, type of machines, thermal treatments, and so forth). Once the manufacturing process has been specified, it will be available in text document to engineering managers at Enterprises B and C, who elaborate a manufacturing quotation in response of a previous proposal request. In order to elaborate a concise quotation including costs and delivery times estimations, each manager must develop a macro plan, and also a rough micro plan, aided by each technical department staff, containing set-ups, operations, sequence of operations, and tools to be used. Once a quotation has been approved by Enterprise A, a member of the process planning team in the enterprise selected for the contract (B or C), must undertake the final micro-plan (including tool paths), and it must be developed in a collaborative way with shop floor personnel. They examine part requirements and the process plan, for determining the real operating conditions according to the performance and the capacity of the process. The micro-planner of the selected supplier technical department adds the changes (in the form of machining parameters) into the final process plan and sends it to the shop floor in G-code. At this point, the collaborative process planning will be finished and the related files, in supplier proprietary formats, will be saved in the repository private area so that they can be retrieved for further process plans for similar parts. In order to track the document history during the process planning activities defined above and to delimit the transition between these activities, it is necessary to determine the different stages of the lifecycle of the process planning documents, showed in the top ribbon of the BPMN model in Fig. 4. This is also necessary for establishing access permissions to the personnel involved in each stage. For this particular case study the stages established are: Design, Manufacturing Proposal, Quotation, Planning and Manufacturing. Design stage refers only to the activities in which the design team and the purchasing department of the OEM must verify the manufacturability of the product. It is important to consider this stage as the beginning of the whole process planning activities. Manufacturing Proposal is the stage in which the process planning document will be created and the meta-plan will be elaborated before sending quotation requests to the suppliers. Once these quotation requests are received by the technical department in Enterprise B and C, the Quotation stage will be initiated, in which the process planning document is accessed and modified by suppliers’ engineering managers in order to elaborate the quotation. The Planning stage will begin after the contract assignation, either with Enterprise B or C, and it should be finished when the G-codes are generated. Finally, the Manufacturing stage is considered as the stage where the process planning document’s lifecycle ends.
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Fig. 4 Proposed BPMN workflow for collaborative process planning
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Description of the information technology infrastructure The main functional requirements and the technological infrastructure needed for the implementation of a PLM system, capable to enable the collaborative environment described above, are shown in Fig. 5. The CSCW Information Technology platform that enables communication among partners must have a shared Web Application Server, which should contain at least components for managing Product Data, Lifecycle, Document, Workflows and Visualisation Services. To support collaborative data storage and retrieval, it must have a shared file vault repository and connectivity with other enterprise databases. On the other hand, the collaborative platform clients must have connectivity with the server through web browsers and CAD/CAM tools with integrated plug-ins to access and modifying the shared data. The Web-based communication between clients and the server must deal with the use of common communication standards like HTTP/S, SOAP (Simple Object Access Protocol), XML, WSDL (Web Service Description Language), RMI (Remote Method Invocation) and CORBA (Common Object Request Broker Architecture). Also, the platform must be enabled for the exchange of pre-arranged standardized formats like STEP, IGES, DXF, STL, VRML, and other design, manufacturing and office document formats. By the use of standardized communication protocols and interchange formats, this platform must be ready to offer interoperability with external systems like CAPP and other CAx, ERP, SCM
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(Supply Chain Management) and MES (Manufacturing Execution Systems). Finally, other important issue to be accomplished by the platform is the security management, in the communication level and in the user authentication level. In the former level, encrypting protocols must be used to avoid security attacks like for example packet sniffing. In the last level, directory services are needed for providing user information that can be used for authentication purposes, like for example LDAP (Light-weight Directory Access Protocol).
Implementation issues As a validation of the proposed workflow model a pilot implementation project has been developed with the help of a commercial PLM tool (Windchill from PTC) available in our industrial environment. This tool, according to a literature review (Liu and Xu 2001; Ming et al. 2005; Subrahmanian et al. 2005), accomplishes in a basic manner the CSCW requirements described previously for a practical collaborative process planning. The specific PLM tool architecture is based in the following components: an application server developed in Java programming language, Oracle 9iR2 database, Apache Web server and the Tomcat Servlet engine for providing the needed service to clients through a Web browser. Although the system clients (OEM and suppliers) can work with any CAD/ CAM tool, because they can import the part in a standard
Fig. 5 Collaborative process environment and shared IT platform required
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Fig. 6 Workflow deployment within a PLM tool
Fig. 7 Simulation of the machining of a mould part and its final process plan
format, for this pilot Pro-Engineer CAD/CAM tool and web browsers have been used. Even though Windchill does not support BPMN standard, it has been relatively easy to develop a model with the proprietary workflow modelling tool (Fig. 6) from the original proposed model. The embedded workflow engine allows execution and monitoring of all the activities performed by each
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participant in the different stages of the process planning’s lifecycle. During the pilot of a ceramic tile mould, participants have tested the collaborative environment using different product data formats, specifically STEP AP214 and IGES, in order to achieve some interoperability requirements. The standard file was used by the participants within each CAM tool to create
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the collaborative process plan. Figure 7 shows the part, the final process plan and the tool path generated.
Conclusions The workflow model outlined in this work should be taken into account as a guide to help achieving the orderly execution of activities and information flow during the collaborative manufacturing activities of process planning that could involve several companies of an Extended Enterprise. The literature review has been valuable to detect future interoperability trends between CAPP and PLM systems. The approach of establishing a collaborative manufacturing environment can be technically achieved thanks to the CSCW groupware tools and the consolidation of the concept of Extended Enterprise. Companies belonging to a Supply Chain should exploit these tools in order to cooperate in the product development process, shortening lifecycles of new products introduction to market. Nevertheless, they must consider manufacturing planning activities as one of the key product development stages, taking especial attention when it must be done abroad or it should be outsourced. In this case collaborative engineering ought to be transferred to effective process planning activities beyond the frontiers of the company and complementing the concurrent design. It is important to point out that PLM tools need to interoperate with CAPP systems in order to set up the bridge between concurrent product design and collaborative manufacturing within product lifecycle. It is expected to work in the direction of integrating not only CAD/CAM tools in PLM systems but also CAPP tools because PLM must act as a backbone to provide all the required product information to other applications. Therefore future research should integrate next generation CAPP systems with PLM tools through automated workflows that will enable the embedded execution of CAPP applications for an entirely automated collaborative process planning. Acknowledgements This research was funded by the Fundación Caja Castelló-Bancaixa and the Universitat Jaume I through the project entitled “Integration of Process Planning, Execution and Control of High Speed Machining in Collaborative Engineering Environment. Application to Ceramic Tiles Moulds Manufacturing.” We are also grateful for support from the European Union’s Alβan Programme of Scholarships for Latin America, grant number E04D030982MX. Disclaimer: Certain commercial software systems are identified in this paper in order to facilitate understanding. Such identification does not imply that this software systems are necessarily the best available for the purpose.
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