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  • Lund 2004-02-12 Institute of Packaging Logistics Supervisor Mats Johnsson

    A Simulation Program for Forecasts of Production at Tetra Pak Packaging

    Material AB in Lund Master Thesis by Dan Lennartsson & Peter Mnsson

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    Preface This master thesis was carried out as the final project of our Master of Science education in Mechanical Engineering at Lund Institute of Technology. The project was performed in cooperation with Tetra Pak Packaging Material AB in Lund. We would like to express our sincere thanks to our supervisor at the Institute of Packaging Logistics, Mats Johnsson, and our supervisors at Tetra Pak, Christine Thern, Ulf Johnsson and Ulf Lindberg for support during this project. We would also like to thank Ola Johansson and Daniel Hellstrm at the Institute of Packaging Logistics for helpful information, and Jeanette Hansen at Tetra Pak for bringing us data files needed for this project. Thanks also to all the employees at Tetra Pak for helping us with our questions. Lund, 2004-02-12 Dan Lennartsson Peter Mnsson

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    Abstract Tetra Pak Packaging Material AB (TPPM) is the division within the Tetra Pak concern that produces the packaging material that later on will be used for liquid products. There are 63 TPPM plants in the world, and the factory in Lund is one of the largest with its 325 employees. It is also the TPPM factory that manufactures the most varied set of packages. There are nine producing machines, divided into three machine groups: printing machines, laminating machines and slitting machines. The department of planning at TPPM plans the orders with the help of a program called ProPlanner. What they lack is a tool to predict the lead times of the planned orders and the capacity of every machine during a specific period of time. This tool should complement the ProPlanner. To solve the problem we decided to make a simulation program. The reason we did so is that there are so many random events that affect the production so it is hard to calculate forecasts by using a deterministic method. The software we used is called AutoMod and it is a simulation program especially made for simulations of production and materials handling. After having studied the processes of production at TPPM, we structured the simulation program and collected the data needed for the program. The parameters used were:

    Set Up times for the machines MTTR (Mean Time To Repair) MTBF (Mean Time Between Failure) Run speed for the different orders in the different machine groups Planned stops in the machines Stops during weekends in the different machines

    An important thing for this project was that the user interface of the simulation program must be user-friendly. All parameters must be possible to change and to do this we have created an easy-to-use Excel interface integrated with the simulation program. The output from the simulation is also displayed in this interface. The reliability of the output gets higher if more than one run for every simulation is made. It is possible to do 1-100 runs, and tests of the program showed that at least 30 runs should be made to get an accurate result. The simulation program will help the personnel at the department of planning at TPPM. They can control if the lead times of the orders, as they are planned, will exceed the predetermined due date and if the capacity of the machines are enough. As all results from the simulation program are forecasts, there are no guarantees that the future will look exactly as the forecasts. If no dramatic events will occur in the production line, though, the program will give a good general view of the production in the near future.

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    Table of Contents 1 Introduction .........................................................................................7

    1.1 Background ..............................................................................................................7 1.2 Problem ....................................................................................................................7 1.3 Objectives.................................................................................................................7 1.4 Delimitations............................................................................................................8 1.5 Target group ............................................................................................................8 1.6 Company description...............................................................................................8

    2 Description of the production planning process at TPPM ................9 2.1 The production.........................................................................................................9 2.2 The planning process ............................................................................................10 2.3 ProPlanner.............................................................................................................10

    3 Methodology.......................................................................................11 3.1 Collecting information ..........................................................................................11 3.2 Measurements ........................................................................................................12 3.3 Simulation as a tool...............................................................................................13 3.4 Our working process .............................................................................................13

    4 Theory ................................................................................................17 4.1 Simulation ..............................................................................................................17 4.2 When simulation is a good tool ............................................................................17 4.3 An example of simulation......................................................................................18 4.4 Where simulation could be a good tool ...............................................................18 4.5 Terms used within simulation ...............................................................................19 4.6 Advantages and disadvantages of simulation......................................................20 4.7 Phases in a Simulation Project.............................................................................21 4.8 Statistical models...................................................................................................24 4.9 Distributions ..........................................................................................................24 4.10 Statistical tests .......................................................................................................29 4.11 Planning and scheduling.......................................................................................30

    5 Compilation of Data...........................................................................33 5.1 Collection of Data .................................................................................................33 5.2 Set Up .....................................................................................................................34 5.3 Unplanned Stops....................................................................................................34

    6 Analysis of Data .................................................................................35 6.1 Set Up .....................................................................................................................35 6.2 Unplanned Stops....................................................................................................36 6.3 Running times ........................................................................................................37 6.4 Discussion around the analysis ............................................................................38

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    7 Description of the Simulation Program............................................39 7.1 The construction of the simulation program .......................................................39 7.2 Variables ................................................................................................................39 7.3 The program ..........................................................................................................40

    8 Conclusions ........................................................................................43

    9 References ..........................................................................................45 9.1 Literature ...............................................................................................................45 9.2 Electronic Sources.................................................................................................45 9.3 Interviews ...............................................................................................................46 9.4 Publications ...........................................................................................................46

    Appendix A ...............................................................................................47

    Appendix B ...............................................................................................51

    Appendix C ...............................................................................................55

    Appendix D ...............................................................................................59

    Appendix E ....................................................

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