Modelling and experimental analysis of the effects of tool wear, minimum chip thickness and micro tool geometry on the surface roughness in micro-end-milling

"Tool wear, minimum chip thickness and micro tool geometry are found to have a significant influence on the surface roughness through experimental analysis of the micro-end-milling process. To address these issues, a surface roughness model is developed and validated in this present work. Firstly, experimental analysis for the tool wear and surface roughness was performed based on the micro-end-milling experiments of OFHC Copper by using 0.1 mm diameter micro endmills with a miniaturized machine tool. The cutting velocity and material removal volume are found to have a great effect on the tool wear, which will in turn affect the surface roughness significantly. Then, a trajectory-based surface roughness model for micro-end-milling is proposed and proven capable of capturing the minimum chip thickness, micro tool geometry and process parameters. Finally, based on this model, a surface roughness model with tool wear effect is developed by taking the material removal volume and cutting velocity into account and is experimentally validated. This model accurately predicts the surface roughness variation with tool wear progress and provides the means for further process design and optimization studies of the micro-end-milling process."