Effect of temperature fields on wear of nonmetallic materials at abrasive machining

Wear characteristics of silicate glass and sapphire at abrasive machining have been studied. The data obtained and the analysis of images of worn surfaces have allowed the authors to conclude that two modes of material damage run simultaneously; these are the local melting of the glass followed by its squeezing towards the contact exit and periodical fatigue fracture (growth of microcracks). Under a short-term effect of high thermal stresses the glass was found to undergo thermal cracking even outside the contact site. The crystalline material (sapphire) demonstrated anisotropy of fatigue strength under abrasive wear, when its wear rate in two perpendicular directions differed almost by an order of magnitude. The possibility of sapphire damage outside the contact site is explained by the position of the maximal surface temperature region being some distance ahead of the zone of the abrasive tool-blank contact.