An investigation of acoustic emission to monitoring flat lapping with non-replenished slurry

Lapping is a precision manufacturing process. However, the material removal rate and surface roughness show significant variation between trials for repeated experiments and, thus, the repeatability of the results depends on the machine operator’s skill. Acoustic emission (AE) seems to be capable of monitoring the process. Therefore, an understanding of AE generation during lapping is important to predict the performance of the grains and hence the lapping results. Based on a theoretical analysis and experimental results collected during flat lapping, the AE signal was investigated for the situation when slurry is supplied without replenishment. The experiments were carried out with a wireless rotating AE sensor mounted in the middle of the lapping plate. Three parameters related to the AE curve are proposed to monitor the process. The influence of process parameters (lapping pressure, velocity, average grain size, concentration of grains in lapping compound and the number of conditioning rings) on the characteristics of the AE curve was investigated