A rigid conformal (RC) lap can smooth mid-spatial-frequency (MSF) errors,which are naturally smaller than the tool size,while still removing large-scale errors in a short time.However,the RC-lap smoothing efficiency performance is poorer than expected,and existing smoothing models cannot explicitly specify the methods to improve this efficiency.We presented an explicit time-dependent smoothing evaluation model that contained specific smoothing parameters directly derived from the parametric smoothing model and the Preston equation.Based on the time-dependent model,we proposed a strategy to improve the RC-lap smoothing efficiency,which incorporated the theoretical model,tool optimization,and efficiency limit determination.Two sets of smoothing experiments were performed to demonstrate the smoothing efficiency achieved using the time-dependent smoothing model.A high,theory-like tool influence function and a limiting tool speed of 300 RPM were obtained.