Assessment of Machine tool flexibility in a Production system

Abstract: This project aims to present machine tool characteristics which may induce limiting factors in terms of flexibility. The aim is also to present a current state description of the machine tools in the production system regarding their characteristics in terms of quantifiable results. This refers to visual presentation in the form of graphs of the distribution of these characteristics among the different machine tools. A literature study was conducted to attain knowledge of machine tools and how the literature defines machine tool flexibility. Based on this, the flexibility parameters were identified. The result illustrates the current state description of the machine tools found in Volvo truck’s factory in Köping. These machine tools are lathe machines, machine centers, gear cutting machines and grinding machines. The result presents a percentage breakdown for each parameter for each of the machine types regarding the number of machines which possess a specific characteristic. The result displayed various cases of data missing. In many cases only a small percentage of data was missing, thus this result should be a sufficient representation of the situation. Meanwhile in other cases more data was missing and it leads to the result being less accurate. Overall, the acquired data in most cases should be sufficient to provide a current state description of the machines in the factory. There is no clear definition of flexibility referenced by the literature, hence it is difficult to conduct a quantitative evaluation. Moreover, there are many parameters presented in this work which emphasizes the multidimensional complexity of the problem. The parameters presented in this project directly influence the type of operations required, geometrical complexity of the workpiece, number of setups and size of workpiece which the machine is capable of handling. The machines have been grouped into the four categories mentioned above. This was done to reduce the complexity of the problem, hence not investigating each sub-category of machine (for example hobbing, skiving, etc.) The work has chosen not to group the machines based on the article they process as this would require additional knowledge of the layout and flow of material in the factory. The chosen approach will provide more of a generic visualization. A method has been developed to present a current state description of a manufacturing system regarding machine tool flexibility and how they can be evaluated. This process includes data collection and documentation of machines tools for the flexibility parameters. Hence, it can be presented how the machines within each machine type possess a specific attribute in terms of numbers or fit within a certain interval. The purpose is to present visual results of the data to illustrate for the reader the distribution of the machine characteristics for each of the machine types and parameters.