Connecting rod’s manufacturing improvements and process planning : Tolerance chain analysis and training material

Abstract: Process planning includes the series of activities to design the process to transform the blank into the finished manufactured part. There is no specific method to create an optimum process plan and the results highly depend on the experience of the process planner. Besides, the high competitiveness among the companies demands a very high quality keeping costs as low as possible. This thesis has been focused on the study of the connecting rod manufacturing process. The analysis of the Scania’ line together with a benchmark among different leading companies on the connecting rod manufacturing has been undertaken. As tolerance chain analysis is an essential activity in process planning for geometry assurance, a tolerance chains study based on Monte Carlo simulations for the connecting rod line has been performed to develop improved manufacturing solutions to lower costs and increase quality. The code created for this simulation calculates the deviation of the different measures due to the accumulation of in-process tolerances. Apart from this tolerance chain analysis, other additional improvements have been suggested based on theoretical studies. Finally, the development of a training material with an example to introduce new process planners to feasible process planning approaches has been performed. Three main outcomes have been obtained from this thesis. Firstly, a new methodology to deal with tolerance stackups has provided an advanced analysis tool to assess the suitability of new improvements and optimize the manufacturing process. Secondly, a comprehensive analysis of the connecting rod manufacturing has led to many ideas to improve the current process. These ideas have been mainly related to machining sequence, machine tool and new technologies for machining. Thirdly, a didactic training material in process planning has been successfully developed and tested for future educative purposes in Scania.