Comparison of fly cutting and transverse planing for micropyramid array machining on nickel phosphorus plating

Nickel phosphorus (Ni-P) is a promising plating material for the moulds used in the precision glass moulding (PGM) of micropyramid structure components. A transverse planing method for machining Ni-P moulds with a micropyramid array pattern is analysed. Notable defects, including chippings and burrs, are observed on the exit and entry parts, respectively. The defect-forming mechanisms are analysed, and it is confirmed that a large cutting thickness and chip interference in non-free cutting tend to be the most effective methods for eliminating defects. Based on the above analysis, the diamond fly-cutting method is introduced into the micropyramid array Ni-P mould fabrication process. The advantage of the diamond fly-cutting method is revealed through comparison with the transverse planing method. To establish a contrast to the transverse planing method and evaluate the machining quality of the structure in the diamond fly cutting, a maximum effective cutting thickness of the remaining surface is proposed based on theoretical analysis. Finally, an experimental setup of ultraprecision fly cutting is established, and an ultraprecision micropyramid array is fabricated on nickel phosphorus plating.