Materials selection applied to vitrified alumina & CBN grinding wheels

The selection of the most appropriate and cost effective vitrified alumina and cubic boron nitride (CBN) grinding wheel has, in recent years, become increasingly complex owing to the availability of high- and premium-quality abrasive materials. Developments in alumina abrasive materials have been advanced mainly by sol-gel technology and the synthesis of high purity single crystals of alumina, while developments in CBN abrasive materials have focused on producing CBN crystals with a variety of morphologies. The development of vitrified bonding systems for these new abrasives involves a number of compromises in order to balance the requirements between grinding performance, the ability to manufacture the wheels, wheel safety, and product consistency. The selection of raw materials has a major effect on mixing quality, stability, and the ability to handle the grinding wheel in its green state, and its viscosity during vitrification heat treatment, whilst the composition of the vitrified bond tends to affect the strength, safety, and performance of the product. Traditionally the type of abrasive selected has been matched to the workpiece material to be ground without reference to the economics of the grinding process. The present work describes the influence of the metal removal rate on the choice of abrasive in terms of wear and power consumed during grinding which greatly affects the economics of grinding. The final part of this paper describes the process of selecting new abrasive products based on the size and shape of the grinding wheel, and the grinding operation for a particular application. (C) 2000 Elsevier Science B.V. All rights reserved.