For resin bonded grinding tools grit break-out is the main wear mechanism and, therefore, the grit holding forces within the bond are essential for tool wear [TOML76]. Abrasive particles worn more than 50 % of their diameter are not likely to retain in the bond any more. Moreover, there are details in the literature that not even 35 % of blocky grits can be used in the machining process before break-out [TOML76].
However, abrasives to be used in resin bonds should have high surface roughness and irregular shapes to have high bond adherence. Often metallic coatings optimise the retention of superabrasives by providing even rougher surfaces and possible chemical reactions to the bond additional the mechanical clamping.
Btittner found that diamond grits in resin bonding showed more grit break-outs than grits in bronze bonding, which were held more strongly and showed attritious wear [BUTT68, p. 72].
Several chemical reactions can happen at the wheel bonding [BRIN04]. There Brinksmeier and Walter found chemical reactions of the fillers in a resin bonded corundum wheel with the cooling lubricant additive [BRIN00].
In many cases, grit wear leads indirectly to mechanical bond wear. Worn and flattened cutting edges expose an enlarged friction surface, which leads to an increase in cutting forces on the individual grit. Consequently, the bond can be mechanically overloaded and entire grits or grit sections can break out of the bond [KLOC05a].