Surface Quality Evaluation in Orthogonal Turn-Milling Based on Box-Counting Method for Image Fractal Dimension Estimation

Turn-milling is a relatively new cutting process combining the both advantages of turning and milling, during which the tool and the workpiece rotate simultaneously. Due to the small axial cutting force, turn-milling is especially suitable for the machining of miniature parts. Usually, the surface quality is characterized by roughness, but the size of miniature parts is difficult to meet the requirements of the sampling length, which will have a huge influence on the characterization results. This paper introduces the box-counting method for image fractal dimension estimation to evaluate the surface quality of miniature parts during orthogonal turn-milling. The fractal dimension is an independent parameter for scale, which is not influenced by the sampling length. The effect of cutting parameters on surface quality of miniature parts during turn-milling is also studied.