Effect of cutting parameters on surface quality in ductile cutting of KDP crystal using self-developed micro PCD ball end mill

Micro-milling is widely accepted as the most promising approach to repair the micro-defects on the KH2PO4 (KDP) surface. In order to get excellent surface quality of workpiece, the ductile cutting of KDP crystal should be achieved. Compared to plastic materials (e.g., metals), the ductile cutting of KDP crystal is more sensitive to the geometrical parameters of tools and cutting parameters, as a result of the soft brittle properties of KDP crystal. In this work, the variable regularity of peak to valley (P-V) value of cutting force on cutting parameters was obtained through simulations, which was matched well with the results obtained from the single-factor experiments using the self-designed micro polycrystalline diamond (PCD) ball end mill. Meanwhile, the ductile cutting parameters of KDP crystal were also obtained through the single-factor experiments. Then, the orthogonal experiments were explored which reveal that the axial depth of cut and the feed speed had maximal and minimal influences on the roughness value R (a), respectively. Moreover, the optimal cutting parameters which are the spindle speed (7 x 10(4) r/min), axial depth of cut (0.5 mu m), and feed speed (30 mm/min) were also gained. At last, the optimal cutting parameters obtained above which were used in the repairing experiments were proved to be good cutting parameters because the good surface quality of repairing outlines was achieved; meanwhile, the repairing performance of self-developed micro PCD ball end mill was also verified.