Simulation project at Tetra Pak

Sammanfattning: This work has been done for Tetra Pak Distribution (TPD) at the Department of Engineering Logistic at the Lund Institute of Technology. My task was mainly to create a set of simulation models based on the Tetra Pak Distribution Lines. These models are going to be used by TPD to try to analyse the effect of the accumulation systems on the line efficiency. The inputs for the models are failure rate specifications. Main Time Between Failure (MTBF) and Main Time to Repair (MTTR) are required as well as some monetary data (profit per package and cost of the accumulation system). The output information from the models is line efficiency, number of packages produced and value of this missed production (always by comparing different models). By getting this information, payback time of each accumulation system in each condition can be calculated. Nowadays simulation software offers great possibilities to the companies for creating computers models that work exactly as the real system, whichever this system would be. These simulation techniques would be used in many fields at one company. It could be used to represent production lines, as in this case, but it can also be used for new products, machines or services development. And not only for development but also for old lines or products improvement. In this global world and market in which development and service times have been drastically reduced, simulation is a very powerful tool to decrease these cycles. It would help because using this, a modeller can easily and fast change many parameters of the simulation model, and then get the results without wasting time and money in preliminary designs and test. With this Automod Simulation Software, models can achieve a great realistic appearance because of the 3-D graphic animation. Due to that they can be used as a marketing tool for the customers and it is easier for everyone to understand how they work. An Excel Visual Basic macro has been created. It acts as a user interface and allows an easy and fast communication between the models and the final user. This is necessary because the user is not familiar with the simulation software and at the same time, the models are not static. Some input is required. Some parameters (MTBF and MTTR) should be specified and changed to get results in different situations and analyse them. Sixteen different models have been developed to cover quite a big range of the new machines and filling lines market by Tetra Pak Distribution nowadays. The important thing in here is to be able to compare results from the same kind of line (same standard line) but with different accumulation system. This can test many different line situations. Defining the failure rate of each machine (MTBF) and the time it is going to be down (MTTR) as statistical distributions allows the user to test a great range of possibilities. The use of statistical distribution adds certain randomness to the models, but if correct distributions are chosen, average results from the model should be the same as the real system ones. It is possible to compare models results and see with is the line efficiency gain (in number of packages produced) when adding an accumulation system. It is important to run always first one of the standard lines without accumulation system with a set of parameters. Obtain the results and then run the same standard line with an accumulation system and with the same parameters. It is possible to do like this with all the accumulation systems and obtain results from all of them. Then, the analysis of these results is not an easy task. Many parameters affect the outputs and some knowledge about the inputs and how they affect the models behaviour are needed. This is something for the people at TPD.