The fusion of corundum began at the Niagara Falls using cheap hydro-electric power. Today China has huge capacities for producing fused corundum, and Eastern Europe, India, South Korea, and South America are growing manufacturers in the world production of fused corundum [JACK11, p. 27]. Low cost energy has become an important factor for the competitiveness of corundum producers, as well as furnace capacity, and low costs of raw material sourcing [JACK11, p. 27]. Similar challenges apply for manufacturers of all abrasive grit types.
Today, tool producers can choose between several grit toughnesses amongst one grit type [MARI04, p. 347]. A high toughness does not necessarily lead to the longest grit life. On the one hand, grits which are too tough for a special application will become dull and increase friction. This leads to unnecessary thermal influence and process vibrations. On the other hand, too friable grits wear away quickly resulting in short tool life and possible form errors.
The tool user can choose between conventional and superabrasive grits, which both generate highly efficient grinding wheels. The decision has to consider the grit properties in the abrasive layer on the one hand. For example, superabrasives have higher raw price costs than conventional abrasives, but also a better wear resistance leading to higher efficiency of superabrasives. On the other hand, the production environment has to be taken into account. For example, the usage of CBN can be very cost-effective in serial and mass production with appropriate machine tools. In contrast, in small and middle-size companies, flexible production with conventional tools follows the trend towards product diversification and stock reduction.
The price of grinding tools is strongly influenced by the price of the grit material, accounting for up to 50 % of CBN tools. The grit price increases with the pressure during the production process, the length of the process, and the overall energy consumed (Fig. 2.26 left). Although diamond synthesis needs very high pressures, the process happens only in several minutes. In contrast, corundum synthesis takes hours or even days and needs therefore power longer. Grit costs and hardness, which indicates wear resistance against abrasive wear, shows some correlation (Fig. 2.26 right).