Now showing 1 - 10 of 73
  • Publication
    Application of Generic CAD Models for Supporting Feature Based Assembly Process Planning
    ( 2018)
    Kardos, C.
    ;
    Vancza, J.
    The paper discusses a novel geometric reasoning method that supports the definition of assembly sequence planning models departing from the CAD models of the parts involved. Specifically, by means of the presented algorithms that use a so-called collision point cloud approach one can determine the precise disassembly directions of parts having complex polygon mesh models. This information can be applied when defining assembly planning models both for suggesting precedence constraints as well as parameters for assembly operations. The presented heuristic algorithm was able to overcome certain shortcomings of earlier methods working with polygon mesh representations, and proved to be successful both in handling abstract and real-life industrial use cases. Working examples from both categories are presented in the paper.
  • Publication
    An integrated framework for design, management and operation of reconfigurable assembly systems
    ( 2018)
    Manzini, M.
    ;
    Unglert, J.
    ;
    Gyulai, D.
    ;
    Colledani, M.
    ;
    Jauregui-Becker, J.M.
    ;
    Monostori, L.
    ;
    Urgo, M.
    Manufacturing has to cope with the continuously increasing variety of products, change of volumes and shortening product life cycles. These trends also affect the automotive sector: the frequent introduction of new models, materials and assembly technologies put the suppliers of make-to-order parts under pressure. In this context, the design of assembly systems and their management are of paramount importance for the companies' competitiveness. In this paper, we propose an approach for the design and reconfiguration of modular assembly systems through the integration of different computational tools addressing the design of the system, the optimization of the layout, the planning of reconfiguration actions as well as production planning. Integrating these computational tools and iterating through the resulting workflow and feedback allow to consider the outcomes and dependencies of alternative decision sequences holistically with the objective of an effective and efficient approach to production system design and management. The viability of the approach is demonstrated through the application to an automotive case study.
  • Publication
    Supply chains robustness: Challenges and opportunities
    ( 2018)
    Monostori, J.
    Nowadays robustness of supply chains, i.e. their ability to cope with external and internal disruptions and disturbances, gains more and more importance. The paper puts the topic into a broader scope, i.e. it also highlights the concept of robustness in other disciplines (especially in biology) and at the different levels of manufacturing. The main risks of supply chain operations together with some fundamental risk mitigation strategies are summarized. Measures of structural and operational robustness of supply chains are introduced, and the concept of a framework for evaluating supply chains robustness, complexity and efficiency is described in short. Challenges and opportunities related to the increase of robustness are outlined in the paper, with special emphasis on those which arise in the cyber-physical era.
  • Publication
    Capacity management of modular assembly systems
    ( 2017)
    Gyulai, D.
    ;
    Monostori, L.
    Companies handling large product portfolio often face challenges that stem from market dynamics. Therefore, in production management, efficient planning approaches are required that are able to cope with the variability of the order stream to maintain the desired rate of production. Modular assembly systems offer a flexible approach to react to these changes, however, there is no all-encompassing methodology yet to support long and medium term capacity management of these systems. The paper introduces a novel method for the management of product variety in assembly systems, by applying a new conceptual framework that supports the periodic revision of the capacity allocation and determines the proper system configuration. The framework has a hierarchical structure to support the capacity and production planning of the modular assembly systems both on the long and medium term horizons. On the higher level, a system configuration problem is solved to assign the product families to dedicated, flexible or reconfigurable resources, considering the uncertainty of the demand volumes. The lower level in the hierarchy ensures the cost optimal production planning of the system by optimizing the lot sizes as well as the required number of resources. The efficiency of the proposed methodology is demonstrated through the results of an industrial case study from the automotive sector.
  • Publication
    Robust production planning and control for multi-stage systems with flexible final assembly lines
    ( 2017)
    Gyulai, D.
    ;
    Pfeiffer, A.
    ;
    Monostori, L.
    Production planning of final assembly systems is a challenging task, as the often fluctuating order volumes require flexible solutions. Besides, the calculated plans need to be robust against the process-level disturbances and stochastic nature of some parameters like manual processing times or machine availability. In the paper, a simulation-based optimisation method is proposed that utilises lower level shop floor data to calculate robust production plans for final assembly lines of a flexible, multi-stage production system. In order to minimise the idle times when executing the plans, the capacity control that specifies the proper operatorâtask assignments is also determined. The analysed multi-stage system is operated with a pull strategy, which means that the production at the final assembly lines generates demands for the preceding stages providing the assembled components.
  • Publication
    Cyber-physical manufacturing in the light of Professor Kanji Ueda's Legacy
    ( 2017)
    Vancza, J.
    ;
    Monostori, L.
    Cyber-physical manufacturing, i.e., the formerly never seen integration of the physical and virtual worlds in the manufacturing domain is considered the substance of the 4th industrial revolution. Much of the changes deemed now revolutionary are originated in a long and converging progress of manufacturing science and technology, as well as of computer science, information and communication technologies. One of the pioneers and influential thinkers of production engineering who paved the way towards cyber-physical manufacturing was unquestionably Professor Kanji Ueda (1946-2015). With this paper the authors would like to pay a tribute to his achievements, by highlighting his main contributions not only to the advancement of production engineering and industrial technology but also to the sustainability of our society.
  • Publication
    Simulation model study for manufacturing effectiveness evaluation in crowdsourced manufacturing
    ( 2017)
    Kaihara, T.
    ;
    Katsumura, Y.
    ;
    Suginishi, Y.
    ;
    Kadar, B.
    Crowdsourced manufacturing, a new type of manufacturing in which companies share their manufacturing resources depending on their demand and capacity, is discussed in one of the main ideas of Industry 4.0 concept. According to this, companies share their resource information and can find an outsourcing company when they need specific or extra resources. In this study, we have developed a simulation model of crowdsourced manufacturing with a resource model and an agent-based negotiation algorithm to evaluate manufacturing effectiveness based on delivery and machine usage. According to a combination and balance of business style, the delivery rate changes with the saturation point which depends on resource commonality.
  • Publication
    Decision support solutions for factory and network logistics operations
    ( 2017)
    Ilie-Zudor, E.
    ;
    Kemény, Z.
    ;
    Pfeiffer, A.
    ;
    Monostori, L.
    The paper examines the relationship of decision levels, performance measures and modelling and decision support approaches through the example of two implemented decision support systems for manufacturing and logistics application fields. Aside from highlighting the relevance of decision support for making industrial networks fit for emerging challenges, the relevance of the two presented EU FP7 projects VFF and ADVANCE to the Factories of the Future vision is shown. A discussion of the two projects outlines future research, with particular focus on challenges that arise from integration across levels of the decision hierarchy, within an organisationally heterogeneous network.
  • Publication
    Artificial neural network based tool condition monitoring in micro mechanical peck drilling using thrust force signals
    ( 2017)
    Patra, K.
    ;
    Jha, A.K.
    ;
    Szalay, T.
    ;
    Ranjan, J.
    ;
    Monostori, L.
    Micro scale machining process monitoring is one of the key issues in highly precision manufacturing. Monitoring of machining operation not only reduces the need of expert operators but also reduces the chances of unexpected tool breakage which may damage the work piece. In the present study, the tool wear of the micro drill and thrust force have been studied during the peck drilling operation of AISI P20 tool steel workpiece. Variations of tool wear with drilled hole number at different cutting conditions were investigated. Similarly, the variations of thrust force during different steps of peck drilling were investigated with the increasing number of holes at different feed and cutting speed values. Artificial neural network (ANN) model was developed to fuse thrust force, cutting speed, spindle speed and feed parameters to predict the drilled hole number. It has been shown that the error of hole number prediction using a neural network model is less than that using a r egression model. The prediction of drilled hole number for new test data using ANN model is also in good agreement to experimentally obtained drilled hole number.
  • Publication
    Decomposition approach to optimal feature-based assembly planning
    ( 2017)
    Kardos, C.
    ;
    Kovacs, A.
    ;
    Vancza, J.
    The paper proposes a generic approach to assembly planning where individual tasks, with detailed technological content specified by features, must be combined into an optimal assembly plan subject to technological and geometric constraints. To cope with the complexity and variety of the constraints that refer to the overall assembly process, Benders decomposition is applied. The macro-level master problem looks for the optimal sequencing and resource assignment of the tasks, while sub-problem modules ensure plan feasibility on the micro-level from aspects of technology, fixturing, tooling, and collision. Constraints are also dynamically generated for the master problem. The approach is demonstrated in automotive assembly.