Commonly referred to as “grit”, this number designation is determined by the amount of abrasive mineral that can pass through a mesh screen with specific size openings. Therefore, a 40 grit abrasive particle will pass through a mesh screen that has 40 openings in one linear inch.
Consequently, the higher the “grit” number results in a finer abrasive and will produce a smoother surface finish. The lower the “grit” number results in a coarser abrasive that will remove material much faster.
Raw materials containing aluminium oxide are electrothermally melted at a reaction temperature of more than 2,000 °C to produce the various fused aluminas. Different starting materials are used depending on the desired type of fused alumina. For instance,