Influence of MEKP Content and Milling Parameters on the Surface Roughness of Polyester-Based Materials Used in Automotive Applications

İngilizce (OpenAlex)

In industrial fields such as automotive and machinery manufacturing, the surface quality of polymer-based materials after machining is of great importance for functional performance, assembly accuracy, and service life. In this study, the surface roughness behavior of polyester-based samples containing different proportions of MEKP hardener after milling was experimentally investigated. In the experiments, two different polyester samples prepared with 1% and 2% MEKP addition by weight were machined on a CNC milling machine at different speeds, feed rates, and depths of cut. The surface quality after milling was evaluated using the mean surface roughness (Ra) parameter. The results obtained showed that the MEKP ratio and cutting parameters have a significant effect on surface roughness. Overall, it was determined that samples containing 1% MEKP exhibited lower or similar Ra values compared to samples containing 2% MEKP. This was attributed to the fact that increasing the MEKP ratio increases cross-linking density, making the material more brittle and negatively affecting machinability. Increasing the spindle speed had a surface roughness-reducing effect under all cutting conditions, and smoother surfaces were obtained, especially at medium and high-speed levels, thanks to more stable cutting conditions. In contrast, increasing the feed rate and depth of cut significantly increased the surface roughness. Increased cutting forces at high feed rates and large depths of cut led to increased surface tearing and micro-fractures, especially in the harder and more brittle samples containing 2% MEKP. However, it was observed that these negative effects were partially suppressed at high spindle speeds. Overall, the study results show that polyester-based materials with a low MEKP ratio offer better machinability and lower surface roughness in milling operations. Furthermore, it was concluded that the surface quality of polyester-based parts used in industrial applications such as automotive and machine manufacturing can be improved by selecting appropriate cutting parameters.