The present invention provides a composite bond wheel that has both excellent wear resistance and self-edging properties. The composite bond wheel of the invention includes: a grain layer including abrasive grains and a bonding phase; wherein the bonding phase includes a metal bonding phase and a resin bonding phase, wherein said metal bonding phase includes a metal having the abrasive grains and outside-opening pores dispersed therein, and wherein at least a portion of the outside-opening pores are filled with a resin of the resin bonding phase.

The invention relates to grinding tools, particularly to grinding wheels having an annular band of abrasive material at their periphery and provides an improved method of manufacture. A mixture of abrasive material, temporary binder and ceramic bond is heated to paste-like consistency and then coated on to the desired part of a support member, e.g. on to hub (5) of wheel (4) in the form of an annular band (11). The coated support member is then fired to drive off the temporary binder whereby the coating is firmly bonded to the support member.

A tool insert comprises a composite abrasive compact bonded to a polymer-based support. The composite abrasive compact consists of a compact layer bonded to a substrate and is bonded to the support through bonding surfaces. The composite abrasive compact provides a cutting edge for the tool insert.

In accordance with the present invention, a composition of matter is provided for forming a vitrified abrasive wheel having an inner core and outer rim of differing compositions wherein said outer rim contains cubic boron nitride. The composition for the preferred rim material is a mixture comprising between about 10 to 70% by weight cubic boron nitride, between about 5 to 60% alumina, and about 15 to 35% bonding medium; and the preferred core composition comprises between about 10 to 65% silicon carbide, 10 to 60% alumina, and 5 to 30% bonding medium. In another aspect, a bonding medium is provided which is compatible with cubic boron nitride and in one embodiment has an oxide composition comprising about 71% silicon dioxide, 14% by weight boron oxide, about 5% by weight aluminum oxide, and about 10% by weight sodium oxide.

Improved rigid grinding wheels are described which have a rigid organic matrix binding particulate diamond or cubin boron nitride abrasive uniformly dispersed therein between a plurality of spaced-apart apertures extending inwardly from the operative grinding surface of the matrix. The cross-sectional open area of the apertures in the matrix reduces the operative solid grinding surface and provides swarf relief while also increasing the effective concentration of a given amount of abrasive in the griding surface, this increasing the efficiency of the grinding wheel while reducing the cost of the wheel and power consumption in use.