made from Ap-17, it is calcined at 1000oC-1300oC, the grit inside crack will be well repaired after heating, the toughness also will be improved after heating. Then the grits will be well washed and carefully sieving again to kicked off the needle and flake shape . It is used for making high quality coated abrasives products like abrasive waterproof paper, sanding cloth, sanding belt, flap wheel and so on.