Polisher density into Preston equation

For the polishing process, Preston (1927) [1] proposed wear, h, is proportional to the work given by a frictional force, ffr, on the glass. He assumed ffr does not depend on relative velocity, v, between the glass and the tool. Téllez et al. (2007) [2] found frictional force depends on v. We have experimentally found that fdr depends on relative velocity, v, and concentration, ρ, of the polisher suspension. Then Preston equation has to be modified i.e. h = h(ffr(v), ρ).