Modeling of multi-scale material removal in centrifugal superfinishing

Abstract

Centrifugal superfinishing (CSF) is a non-conventional mass finishing technology that achieves nano-level surface roughness on workpieces. However, due to the complexity and multi-scale characteristics, there is limited in-depth research on the effects of different processing parameters on finishing efficiency and surface quality. To address this, a multi-scale material removal theoretical model based on Hertz contact and fluid dynamics theory was developed. The Hertz contact theory is employed to describe the effect of abrasives on material removal in the microscopic process, while the fluid dynamics theory is utilized to analyze the relationship between macroscopic flow stress p_d, relative velocity v, and media velocity flow field. Additionally, the intrinsic relationship between macroscopic flow stress p_d and microscopic contact stress p_n is analyzed based on the force characteristics of individual dry medium. Different parameters were considered in the model, including abrasive size d_a, polishing paste ratio c_a, dry media size d_p, revolution speed N, and loading amount c_p. A series of simulation and finishing experiments were conducted to validate this model and the mechanisms of material removal and surface roughness evolution were revealed by microscopic morphology features and contact stress distributions. The results indicate that the effects of abrasive size d_a and polishing paste ratio c_a on MRR and surface roughness are primarily reflected in the Hertz contact depth h_a and the number of active abrasives at the microscopic scale. In contrast, the effects of dry media size d_p, revolution speed N, and loading amount c_p on MRR and surface roughness are associated with the normal contact force F_N and the number of contacts N_c at the microscopic scale, as well as flow stress p_d and contact probability at the macroscopic scale. Additionally, these parameters also influence the relative velocity. The developed model provides a theoretical reference for optimizing the CSF technology.