Investigation of novel low pressure lapping technology on aluminium moulds

Aluminium is a popular material widely used in ultra-precision machining processes [1]. In this work, a novel ultra-precision lapping method was developed to remove the tool marks on an aluminum mould machined by Single Point Diamond Turning (SPDT). In SPDT process, tool marks are inevitably generated during the process, and these marks can affect the surface roughness and degrade the optical performance by generating distortion or scattering. However, conventional ultra-precision polishing methods cannot be applied to soft metals like aluminium and brass because it will scratch the machined surface. Therefore, a special lapping method was investigated by using a strand of hair to do lapping. The Taguchi method was used to determine the optimal parameters for the lapping process. Spectral Analysis was carried out to investigate the lapping performance. The results show the new lapping method has a good performance in lapping soft material.