<p>Understanding the formation mechanisms in copper substrate lapping processes is of importance for the improvement of surface quality by the optimization of lapping plate design and machining parameters. In this study, formation mechanisms of surface integrity for the lapping of copper are investigated by the numerical simulation of single grit scratching. The numerical simulation models of single grit scratching without and with overlap were developed. A new method for the single grit high-speed scratching test was proposed for the first time. The high-speed single grit scratching tests were implemented based on the self-developed equipment to verify the accuracy of the numerical simulation model. The average relative error between the simulated and experimental scratching forces was 5.84%, which proved the high accuracy of simulation models. Then the surface integrity of copper during the lapping process was study based on single grit scratching simulation from the aspect of material side flow ratio, specific scratching energy and residual stress. It was found that the side flow ratio was 1 for the single grit scratching without overlap, which means that no material was removed and that there is a positive correlation between scratch distance and side flow ratio for the single grit scratching with overlap. The results also depicted that the specific scratching energy decreases with the rise of scratching velocity and that the specific energy decreases with the increase of scratching depth, which is called “size effect”. The analysis of scratch induced residual stress presented that the decreases of the scratching depth and scratch distance is beneficial to obtain the residual stress with compression state.</p>