(i) Before the mold is fired, vitrified grinding wheel must have a certain wet and dry strength to facilitate the unloading, removal, transportation of the blanks and kiln loading operations. Therefore, the formula data should be determined according to the characteristics of the factory's equipment, the degree of mechanization of the production process, and even the flatness of the workshop road surface.
(ii) For molds that need to be processed as semi-finished products before the kiln, the dry strength should be considered higher.
(iii) It should be conducive to mixing and screening operations. For this reason, the amount, density or concentration of wetting agent and temporary binder for fine-grained molds, harder molds and silicon carbide molds with a large amount of binder added in the formula is generally different from that of coarse and medium-grained vitrified grinding wheel.
(iv) From the perspective of formula, it is necessary to try to avoid possible waste (such as cracks caused by excessive shrinkage; foaming; deformation, etc.). Special attention should be paid to the particle size and hardness that are prone to waste (such as fine-grained; high-hardness molds).
(v) From the perspective of formula, it should be ensured that the vitrified grinding wheel has sufficient strength. Especially for abrasive tools that are easy to break (such as coarse-grained soft vitrified grinding wheels, etc.).
The principles are as follows:
1. The new product should have the same hardness as the old product;
2. The particle size of the abrasive should be the same;
3. The bulk density of the abrasive should be the same or lower;
4. The strength of the abrasive should be the same or the new abrasive has a higher strength;
5. The new formula should have the same or higher tensile strength;
6. The new formula has the same or lower density;
7. The new formula has the same or lower elastic modulus.
The above principles can be roughly summarized as: use abrasives with higher strength; use a binder with high strength and low elastic modulus to reduce the amount of binder and increase the porosity; use abrasives with low bulk density or lower tool density to make the vitrified grinding wheel structure looser.
