Development of a modular and reconfigurable manufacturing system - method and industry case

Transcription

1 THE 4 th STUDENT SYMPOSIUM ON MECHANICAL AND MANUFACTURING ENGINEERING Development of a modular and reconfigurable manufacturing system - method and industry case B. Martinez Bort, C. Meldgaard Thomsen, M. Dimitrov Delev Department of Mechanical and Manufacturing Engineering, Aalborg University Fibigerstraede 16, DK-9220 Aalborg East, Denmark cmth12@student.aau.dk, Web page: Abstract As a part of the initiative Industrie 4.0 manufacturing companies and as educational institutions desire more knowledge on the field of designing a Modular and reconfigurable manufacturing system. This paper suggest a method for developing such a system. The method provide different system viewpoints that are used in four iterative loops. The method is applied in a research case for a large Danish manufacturing company. The effects of applying a modular production system is investigated trough a discrete event simulation study. The methods is found useful and the simulation study reveal a good potential in such a manufacturing system. Keywords: Industry 4.0, Modular Production System(MPS), Scalable production, Flexible Manufacturing Systems (FMS), Manufacturing development, FESTO-MPS 1. Introduction As the incipient implementing of initiatives as Industrie 4.0/Smart Factory has become more urgent there is an increasing need for practical experience on implementing the different aspects of the Industry 4.0. One aspect is modular productions systems(mps) which play a key role in the wide term Industry 4.0. The initiative is referenced to as the fourth industrial revolution where the three preceding are the Mechanisation, Assembly line and Electronics and IT [1]. The fourth revolution is contrary to the others driven by a change in society and increasing demand of customized products [2]where MPS is seen as one of the answers to this demand. Other alternative manufacturing paradigms that deal with the same problem are Reconfigurable Manufacturing Systems (RMS) and Scalable Manufacturing Systems (SMS). RMS provides a manufacturing set-up with a high level of respondency which is demanded on a rapidly changing market. The paradigm of Scalable Manufacturing Systems provides different ways of scaling the production capacity by rearranging or adding modular production units. The three mentioned paradigms are strongly related to each other and can be translated to three general Key Performance Indicators (KPI) that will be used throughout this project. To gain experience in designing a modular and reconfigurable manufacturing system, Aalborg University has invested in a Cyber-Physical System from the German company FESTO. The system consist of a number of conveying modules that are easy reconfigurable. The system designed in this project is based on the available FESTO modules. 2. Methodology To structure the development of the MPS a methodology research is conducted. The research found a number of different methods where non are found suitable for the given problem. A new method that fit the purpose of this project is conducted. 2.1 Previous work The term MPS is introduced in the 90s [10] as a consequence of a demand for shorter product life-cycle and increasing competition, nevertheless the thoughts were applied earlier [11]. Ever since methods for developing a MPS are suggested [12] in this work a method for developing a modular architecture suggested by [6] is used. [6] is in some extent inspired by the method from [4], which has been widely used in the industry through the last decade. From [6] four steps describing the relations between requirements and all the way to Unit or Organ are applied. The steps are Manufacturing Requirements, Transformation Process, Functional Elements and Units/Organ. The requirement in the first step is determined by the specific product or products, 1

2 if the intention is to merge to production lines. In the second step the production or assembly process is transformed, and in the third step the transformed process is grouped into functional elements, which is directly related to the fourth step where each unit or organ is designed. In the work of implementing a suitable method for developing a modular production system, in the later described industry case, problems concerning the information in different levels of the manufacturing system occurred. It appears that most methods, specially the methods concerning product development, often work on only one level. [8] describe a manufacturing system system in six levels and links it to six corresponding levels of a product. The six corresponding levels are Network/Product portfolio, Factory/Product Group, Segment/Product Instance, System/Part Group, Cell/Part Instance and last Station/Part Element in this project the two last levels are considered. [6] deals with the development of system architectures defined as "fundamental concepts or properties of a system en its environment embodied in its system, relationships, and in the principles of its design and evolution" [13] on the other hand a platform is defined by [14] as "A product platform is a set of subsystems and interfaces that form a common structure from which a stream of derivative products can be efficiently developed and produced.". Steen K. Hansen has created a Five Layer Platform Model, from a products view point, for internal use at the Danish pump manufacture Grundfos, this model is further developed by [3]. The Revised Five Layer Platform Model incorporate a production viewpoint based on the conceptual architecture description in [13] which is intentionally developed for software development further argues [15] for its application in production systems. The Revised Five Layer Platform Model is presented in [3] by six platform viewpoint moreover describe [9] the same model with five layers where the two first viewpoints is merged. The five corresponding viewpoints presented in [9] are Product/Production system, Domain Platform, Core Platform, Core Technology and Core Function. In this project the two view points Core Platform and Domain Platform are adopted respectively to an "Abstract" viewpoint and a "Concrete" viewpoint distinguished by a high and low abstraction level. sets the foundation for the development method created for this project. Fig. 1 Holistic Platform Architecture model - by Jacob Bossen 2.2 MPS development spiral During the work of finding a suitable method for developing a MPS for a manufacturing company (described late in section 3) it has been difficult to find one single method which provides a convenient way to design such a system. This problem led to the development of a new method which uses the previously described methodologies. Inspired by The spiral model[16] known from risk driven software development and The Four View Platform Spiral presented in [3] a development spiral is established, see figure 2. The development spiral consist of four sections which corresponds to the four steps described by [6] moreover the loops corresponds to the four different viewpoint marked with coloured circles in figure 1. This method provides a clear system viewpoint for each loop and, thereby, helps to include the right amount of information when specifying the requirements and defining the final Unit or Organ in the end of each loop. The development spiral works as an iterative process where a system concept is suggested in the end of each loop. The presented different levels and the mentioned platform viewpoints set the foundation for the Holistic Platform Architecture model presented in figure 1 which 2

3 Fig. 2 Development spiral 3. Industry Case The industry case is made in cooperation with a large Danish manufacturing company. The company experiences, like many others manufacturing companies, problems with a poor utilization of their equipment and shorter life cycles of their products, giving an increasing need for shorter changeover time and a more scalable manufacturing system. The company considers implementing a Reconfigurable Manufacturing System (RMS) to accommodate the need for shorter changeover time and, therefore, wants to gain knowledge about how to implement a Modular Production system (MPS) and how such a system is capable of scaling the production capacity. The company manufactures products in a large variety of sizes and price range. Previously, projects within the company have studied grouping the different products into Domains both from a product viewpoint and a production viewpoint. The focus of this project has been to manufacture two very different products from the same domain. The two products have similar sizes and similarities in how they are manufactured, however, the two products have different shapes and components. It is believed that by selecting two different products from the same domain further works of implementing other products from same domain will be straight forward. The project has not aimed at designing a manufacturing line capable of producing two different products on the same. Instead, the aim has been to design two new manufacturing lines that have as many parts in common as possible and simultaneously consider decreasing the changeover time from one product to another. 3.1 Loop 1 The first loop have an "abstract" viewpoint on cell level (see green circle(1) in figure 1) which means that the abstraction level is high. The Requirements for first loop states that process flow of the two products should remain the same (investigating alternative manufacturing procedures are out of the scope of this project). Three general process categories are established; Handling, Value Adding Process (VAP) and Test. In the third section of the loop, Transform process, the process flow is transformed to a high abstraction level, where it is not distinctness between which part that is processed but only the process itself in its simplest form. After the process flow is transformed for both products it is revealed that there are a number of common shared processes. Moreover, the different processes are categorized in the three general process categories. This categorization leads to an abstract manufacturing line concept only existing on the three different general process categories arranged so as to follow the initial process flow. 3.2 Loop 2 In the second loop, the abstraction level is lower and the viewpoint is defined as a "concrete" cell-level viewpoint. The Requirements are now more concrete on designing a modular production system. The requirements in loop 2 are strongly inspired by [5] which suggests certain factors that should be considered when designing a modular product. The factors have been rewritten to suite a production system and afterwards applied as requirements. In the Transform process each process task is grouped based on the task and what part it handles. At this viewpoint the shape and size of the part is not considered. Based on the grouping, common process tasks are defined equally to the first loop but it now takes the part it has to handle into consideration. It is derived that most of the handling processes are very similarly when considering the basic task. Based on basic requirements to the task the different process tasks are grouped. Most of the VAPs are specialized for the specific product and, thereby not candidate to be combined with each other. Last in Units the final modules are defined with process tasks it should fulfil. 3.3 Loop 3 Loop 3 represents the "abstract" view of Station level. This high abstraction level viewpoint corresponds to a conceptual viewpoint. The aim for loop 3 is to define the technologies and present a conceptual model of the handling modules specified in loop 2. First the basic theoretical requirement is listed for each handling 3

4 task. The requirements are examined by plotting them respectively to each other and clusters of requirements for the different tasks are identified. The clusters define the tasks that the module fulfilling the clusterrequirement should take care of. The handling tasks are separated into five functional elements that are required for the handling process. The five functional elements is Manipulator, Gripper, Gripper mounting device, Platform for manipulator and Pallet. The technologies for each functional element are chosen by listing different possible solutions up against the requirements. The chosen technologies set the foundation for the conceptual handling model consisting of a stationary but moveable platform, an articular robot with a revolving griping tool holding more dedicated grippers. 3.4 Loop 4 The fourth loop is the last loop in the development spiral and the viewpoint is concrete, and all necessary information is included. The purpose of the last loop is to specify the conceptual handling module from loop 3. The Requirements is based on details about the parts that have to be handled. The evaluated details are Dimensions, Weight, Material and Surface. Different concrete solutions from different providers of articulated robot, platforms and grippers are listed and evaluated in respect to the requirements set by each part. In Units the final suggestion for the handling module is presented together with a BOM for the module. 3.5 Evaluation of concept To evaluate the concept of a modular and reconfigurable production system a simulation study is conducted. The simulation is established by following the seven-step approach for conducting a successful simulation study suggested by [17]. The seven steps are as follow 1. Formulate the problem, 2. Collect information/data and Construct Conceptual Model, 3. Is the Conceptual Model Valid?, 4. Program the Model, 5. Is the Program Model Valid, 6. Design, Conduct and Analyze Experiments and last 7. Document and present the simulation. The simulation focuses on the gernal Key Performance Indicators (KPI) Takt time and Produktion Capacity for that reason the problem is formulated as a discrete event simulation. The process times used in the simulation are based on process times for current similar manufacturing systems and thereby do not represent the actual system that is simulated. The stochastic process times is described by a triangular random distribution going to right t [18]. The conceptual model based on the current manufacturing system is designed and compared with the existing manufacturing system. The simulation model is programmed by using the discrete event simulation program Arena from Rockwell Automation which provide a GUI were logic boxes is connected [19]. The simulation study investigates four different configurations of the six different modules for each manufacturing line Simulation results Based on the results from the simulation, it is concluded that the modular production system is highly scalable and relatively easily capable of achieving production capacity similarly with the current dedicated manufacturing system. Fig. 3 Scaling of production capacity of product 1 Fig. 4 Scaling of production capacity of product 2 4. Conclusion The aim of this project was to design a modular and reconfigurable manufacturing system where two different products were considered. The purpose of the project has never been to design a system capable of producing both products at the same time. For that reason, the focus has been on three general KPI - Flexibility, Scalability, Modularity. To fulfil the 4

5 KPIs and by considering the process flow and the specific FESTO system it has been chosen to design six different modules for each manufacturing line. Some of the modules are shared between the two manufacturing lines and thereby add a level of flexibility in the production. By adding more of the same modules a simulation study has proven that the production capacity is scalable by ordering the modules differently. Acknowledgement The authors of this work gratefully acknowledge the help from Bjørn Langland and Jakob Stepping Pedersen for the job as external supervisor and for providing different viewpoints of the problem and necessary information. References [1] S. I. Shafiqa, C. Sanina, E. Szczerbickib, and C. Toroc, Virtual engineering object / virtual engineering process: A specialized form of cyber physical system for industrie 4.0, in Procedia Computer Science (60, ed.), pp , Elsevier B.V., [2] G. Schuh, T. Potente, C. Wesch-Potente, A. R. Weber, and J.-P. Prote, Collaboration mechanisms to increase productivity in the context of industrie 4.0, in Robust Manufacturing Conference (RoMaC 2014) (19, ed.), pp , Procedia CIRP, Elsevier B.V., [3] D. G. H. Sørensen, Co-development of architectures & platforms - exploration of a method for platform co-development, Master s thesis, Aalborg University - Department of Mechanical and Manufacturing Engineering, Fibigerstræde 16 DK-9220 Aalborg Ø, Is under a NDA. [4] A. Ericsson and G. Erixon, Controlling Desig Variants - Modular Product Platforms. Society of Manufacturing Engineers, 2nd ed., [5] K. T. Ulrich and S. D. Eppinger, Product Design and Development. 121 Avenue of the Americas, New York, NY 10020: McGraw-Hill, 5 ed., [6] S. N. Joergensen, Developing Modular Manufacturing System Architectures - The Foundation to Volume Benefits and Manufacturing System Changeability and Responsiveness. PhD thesis, Department of Mechanical and Manufacturing Engineering, Aalborg University, Fibigerstræde 16 DK-9220 Aalborg Ø, Special Report No. 94. [7] S. N. Joergensen, C. Schou, and O. Madsen, Developing modular manufacturing architectures an industrial case report, 5th International Conference on Changeable, Agile, Reconfigurable and Virtual Production (CARV2013), Munich, Germany 2013, [8] H. EIMaraghy and H. P. Wiendahl, Changeability - an introduction, in Changeable and Reconfigurable Manufacturing Systems (H. A. EIMaragy, ed.), ch. 1, pp. 3 24, Springer-Verlag London Limited, [9] J. Bossen, M. Bejlegaard, D. G. H. Sørensen, T. D. Brunoe, and K. Nielsen, Production platforming - practical experience and implications. To be published by Elsevier, [10] G. G. Rogers and L. Bottaci, Modular productions systems: a new manufacturing paradigm, Journal of Intelligent Manufacturing, no. 8, pp , [11] P. Voho and J. Heilala, Modular production system concept for a water tap assembly, Computers & Electrical Engineering, vol. 18, no. 1, pp , [12] A. Jose and M. Tollenaere, Modular and platform methods for product family design: Literature analysis, Jornal of Intelligent Manufacturing, no. 16, pp , [13] ISO/IEC/IEEE, Systems and software engineering - architecture description, ISO ISO/IEC/IEEE 42010:2011(E), International Organization for Standardization, Geneva, Switzerland, [14] M. H. Meyer and A. P. Lehnerd, Power of Product Platforms - Building Value and Cost Leaderships Avenue of the Americas - New York, NY 10020: The Free Press, [15] A. D. Jepsen, Architecture Descriptions - A Constribution to Modeling of Production System Architecture. PhD thesis, DTU Mechanical Engineering, DCAMM Special Report; No. S186. [16] B. W. Boehm, A spiral model of software development and enhancement, TRW Defense Systems Group, [17] A. M. Law, How to conduct a successful simulation study, in Proceedings of the

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