Microgroove machining on crystalline nickel phosphide plating by single-point diamond cutting

Electroless nickel phosphide (Ni–P) plating is used as a new mold material to fabricate microgrooves on glass molding process because of its excellent mechanical properties and machinability. Amorphous Ni–P will be crystallized at high temperature during the glass molding process. Crystalline Ni–P plating leads to mold deformation, which may reduce the mold accuracy and shorten the service life. In this study, the amorphous plating is heated to its annealing temperature at nearly 600 °C to make it transform to crystalline state in advance. Thus, the hardness of the plating increased from 614 to 941 HV; the deformation of the mold with crystalline plating similar to glass molding condition is removed by ultraprecision turning. Finally, microgrooves are fabricated on crystalline Ni–P plating. In the experiments, matrices with amorphous plating and crystalline plating are used in microgroove machining on an ultraprecision machine. Subsequently, machined form accuracy and surface quality for the two plating layers are compared. Under the condition of different cutting speeds, the surface roughness of the crystalline Ni–P plating distributed in the interval of about 60 nm; the amorphous Ni–P plating distributed in the interval of about 80 nm correspondingly. The results proved that the microgrooves machined on the crystalline plating exhibited better performance than its amorphous counterpart.