Criteria for Machinability Evaluation of Compacted Graphite Iron Materials Design and Production Planning Perspective on Cylinder Block Manufacturing

Sammanfattning: The Swedish truck industry is looking for new material solutions to achieve lighter engines with increased strength to meet customer demands and to fulfil the new regulations for more environmentally friendly trucks. This could be achieved by increasing the peak pressure in the cylinders. Consequently, a more efficient combustion is obtained and the exhaust lowered. This, however, exposes the engine to higher loads and material physical properties must therefore be enhanced. One material that could meet these demands is Compacted Graphite Iron (CGI). Its mechanical and physical properties make it ideal as cylinder block material, though there are drawbacks concerning its machinability as compared to other materials that are commonly used for the same purpose. Knowledge about machining of the material and its machinability is consequently inadequate.The main goal of this thesis is to identify and investigate the effect of the major factors and their individual contributions on CGI machining process behaviour. When the relationship between the fundamental features; machinability, material microstructure, and material physical properties, are revealed, the CGI material can be optimized, both regarding the manufacturing process and design requirements. The basic understanding of this is developed mainly through experimental analysis as, e.g., machining experiments and material characterization.The machining model presented in this thesis demonstrates the influence of material and process parameters on CGI machinability. It highlights machinability from both design and production planning perspectives. Another important objective of the thesis is an inverse thermo?mechanical FE model for intermittent machining of CGI. Here, experimental results obtained from a developed simulated milling method are used as input data, both to calibrate and validate the model. With these models, a deeper understanding is obtained regarding the way to achieve a stable process, which is the basis for future optimization procedures. The models can therefore be used as a foundation for the optimization of CGI component manufacturing.