An investigation into tooling requirements and strategies for FMS operation

A study of the minimum tooling requirements and strategies for efficient operation of Flexible Manufacturing Systems, FMS's, in Assembly set Production, ASP, i.e production in sets of parts to completely assemble one or more product units, is presented in this research work. The main investigating tool is a simulation model. With this model the tool groups to be loaded into machines and fixtured pallet requirements were studied in conjunction with two scheduling rules. One is a FCFS rule and the other is a new rule, called MRPAS, which schedules work on the basis of the number of parts still unfinished belonging to an Assembly Set. The results of the research work show that ASP can be efficiently carried out in FMS's. However this requires that a good system set-up and adequate operating strategies are used. In particular appropriate tooling levels and good tooling configurations,TC's, i.e. combinations of tools in groups to be loaded into the machines, must be established to achieve high FMS performance. Tooling combination and duplication heuristic rules and the simulation model can be used for achieving this aim. The heuristic approach is shown to be necessary due to the impossibility, in a reasonable time, of evaluating the performance of FMS's under the large number of alternative tooling configurations which are possible. The level of fixtured pallets used can also have a great influence on system performance. Appropriate levels of these resources to operate FMS's for given TC's can be established using the methodology developed in this work. It is also important that good scheduling rules are used. In the cases studied, the MRPAS rule produces the best performance expressed as the combination of FMS utilization and production of complete assembly sets. Moreover a very small assembly set batch size, ASBS, i.e. number of AS released together into the FMS, is likely to be preferable. In the cases studied an ASBS of one performed best overall

Simulation modelling software approaches to manufacturing problems

Increased competition in many industries has resulted in a greater emphasis on developing and using advanced manufacturing systems to improve productivity and reduce costs. The complexity and dynamic behaviour of such systems, make simulation modelling one of the most popular methods to facilitate the design and assess operating strategies of these systems. The growing need for the use of simulation is reflected by a growth in the number of simulation languages and data-driven simulators in the software market. This thesis investigates which characteristics typical manufacturing simulators possess, and how the user requirements can be better fulfilled. For the purpose of software evaluation, a case study has been carried out on a real manufacturing system. Several simulation models of an automated system for electrostatic powder coating have been developed using different simulators. In addition to the evaluation of these simulators, a comprehensive evaluation framework has been developed to facilitate selection of simulation software for modelling manufacturing systems. Different hierarchies of evaluation criteria have been established for different software purposes. In particular, the criteria that have to be satisfied for users in education differ from those for users in industry. A survey has also been conducted involving a number of users of software for manufacturing simulation. The purpose of the survey was to investigate users' opinions about simulation software, and the features that they desire to be incorporated in simulation software. A methodology for simulation software selection is also derived. It consists of guidelines related to the actions to be taken and factors to be considered during the evaluation and selection of simulation software. On the basis of all the findings, proposals on how manufacturing simulators can be improved are made, both for use in education and in industry. These software improvements should result in a reduction in the amount of time and effort needed for simulation model development, and therefore make simulation more beneficial

A control strategy for promoting shop-floor stability

This research aimed to study real-time shop floor control problem in a manufacturing environment with dual resource (machine and labour), under impact of machine breakdowns. In this study, a multiperspective (order and resource perspectives) control strategy is proposed to improve effectiveness of dispatching procedure for promoting shop floor stability. In this control strategy, both order and resource related factors have been taken into account according to information on direct upstream and succeeding workcentres. A simulated manufacturing environment has been developed as a platform for testing and analysing performances of the proposed control strategy. A series of experiments have been carried out in a variety of system settings and conditions in the simulated manufacturing environment. The experiments have shown that the proposed control strategy outperformed the ODD (Earliest Operation Due Date) rule in hostile environments, which have been described by high level of shop load and/or high intensity of machine breakdowns. In hostile environments, the proposed control strategy has given best performance when overtime was not used, and given promising results in reduction of overtime cost when overtime was used to compensate for capacity loss. Further direction of research is also suggested

Integrated knowledge-based hierarchical modelling of manufacturing organizations

The objective of this thesis is to research into an integrated knowledge-based simulation method, which combines the capability of knowledge based simulation and a structured analysis method, for the design and analysis of complex and hierarchical manufacturing organizations. This means manufacturing organizations analysed according to this methodology can manage the tactical and operational planning as well as the direct operation of shop floor. [Continues.

Modelling and optimisation of Turkish Army 5th level renovation maintenance system via simulation

Ankara : The Department of Industrial Engineering and the Institute of Engineering and Sciences of Bilkent Univ., 2000.Thesis (Master's) -- Bilkent University, 2000.Includes bibliographical references leaves 104-106.Logistics is the application of time and space factors to war. It is the economics of warfare, and it comprises, in the broadest sense, the three big M's of warfare; material, movement, and maintenance. This thesis employing the simulation tool as an effective vehicle for defining the path from competitive concepts to real word solutions, modelling Turkish Army's 5 Level Renovation System and bringing up ways of optimisation. Steady state performances of the renovation unit are measured. Different types of configurations are tested and their advantages and disadvantages are discussed.Tütüncüoğlu, Reşat AliM.S

Generic proposals to increase productivity using discrete-event simulation for Ford Motor Company

The research project was carried out in conjunction with Ford Motor Company and Cranfield University. This research project has demonstrated partial fulfilment of the requirements for the Master Degree of Science. The project uses discrete simulation techniques to carry out experimentation with an aim of developing generic solutions to increase productivity and output of manufacturing transfer lines within the Ford group. In this highly competitive era for manufacturing where the profit margins tighten each year, Ford and other automotive companies are striving to ensure they produce products that are not only desirable to the consumer but also profitable. Every year senior management at Ford expect an increase in output for each line. This means that investigations must be carried out using simulation to formulate generic ideas and proposals to optimise and increase the output of a number of machining lines. Increasing manufacturing outputs reduces the unit cost per part; therefore there is an increase on the profit margin for each unit sold. Based on the experimental data collected from the research project, three manufacturing lines have been optimised to maximise their productivity. The solutions were then developed into business cases which were produced in line with Ford’s strict investment criteria and as a result each of the three lines should have its annual output increased by more than 5%, with a pay back period of under a year for the required capital investment. A generic solution was found which can potentially optimise any manufacturing line in the Ford Motor Company, providing large increases in annual output to Ford’s manufacturing lines. These solutions will help Ford to maximise its profit contribution per unit sold, securing its place as a leading global automotive manufacturer.MRe

Scheduling and control in the batch process industry using hybrid knowledge based simulation

This thesis relates to the area of short term scheduling and control in batch process plants. A batch process plant consists of individual plant items linked by a pipe network through which product is routed. The structure of the network and the valve arrangements which control the routing severely constrains the availability of plant items for configuration in routes when a plant is operating. Current approaches to short term scheduling contain simplifying assumptions which ignore these constraints and this leads to unrealistic and infeasible schedules. The work undertaken investigates the use of techniques from the areas of Artificial Intelligence (AI) and Discrete Event Simulation (DES) in order to overcome these simplifying assumptions and develop good schedules which can be implemented in a plant. The main divisions of work cover a number of areas. The development of a representation scheme for batch plant networks, and procedures for reasoning about the constraints imposed by their structure to infer the actual availability of plant items for routing purposes at any time. The development of a dynamic rule-based route configuration procedure which takes into account the constraints on plant item availability. The development of an activity scheduling framework for batch plants based on this. The development of a dynamic simulation model to take account of finite capacity constraints in a batch plant. The integration of these elements in a hybrid structure to make best use of the techniques available from the areas of AI and DES. The representation scheme and procedures developed for reasoning about the constraints in a plant network enable the simplifying assumptions of other approaches to be overcome so that the system can produce good feasible schedules. The hybrid structure is a practical one to take for implementation and enables the best use of techniques from AI and DES

Real-time simulation of advanced manufacturing systems

A project report submitted to the Faculty of Engineering. University of the Witwatersrand, Johannesburg, in Partial fulfilment of the requirements for the. degree of Master of Science in Engineering, Johannesburg. 1991In order to analyse and optimize the design and Operation of Advanced Manufacturing Systems (AMS) various simulation techniques are currently in use. However, these methods are' generally inflexible and are used off-line in this project report, a modular, modelling approach is adopted to investigate the requirements of shop floor device models which operate in real-time. The models when connected together, simulate the Operation of the AMS. A suitable technique for the development of these models is proposed. A simulation architecture to support the models is discussed. It is intended that the models are connected on-line to the AMS control system via a local Area Network (LAN). [Advantages and - applications of this approach to AMS simulation are discussed.MT201