Improving the quality of automobile lighting parts produced by plastic injection by Taguchi method

In this thesis, it is aimed to improve the plastic injection process parameters of the lighting parts produced in an automotive supplier industry. In order to prevent getting yellow and bluing quality problems after injection in the parts, the Taguchi method which is one of the commonly used design of experiment method, was used. Seven factors which are packing time (sn), packing pressure (Pa), cooling time (sn), mold surface temperature (°C), furnace temperature (°C), injection speed (m/s), and manifold temperature (°C), are discussed. Experiments were created using the Taguchi method L27 orthogonal array, and the change on the color difference was measured with an optical sphere measuring device. As a result of the optimization and subsequent verification experiments with Taguchi method, it was observed that optimum factor values were reached, which minimized the color change on the parts. It was determined that manifold temperature (°C) and furnace temperature (°C) were the most important factors affecting the responses, while packing pressure (Pa) and injection speed (m/sn) were the least important factors affecting the responses.