1: size or technical parameters (matrix etc.) are different from the requirement of customers’ order
—Replace

2: thread could not fit core barrel
—Repair or replace

3: break down a piece from matrix, and the volume of the piece exceed 2mm*2mm*2mm, and such break is not caused by drilling
—Replace

4: matrix falling not caused by drilling
—Replace or return

5: groove on matrix caused by manufacturer
—Replace or return

6: drilling speed is obvious slower than congener products cause by manufacturer
—Replace, and each item quantity does not exceed 3 pieces

7: bit life is obvious short cause by manufacturer
—Replace, and each item quantity does not exceed 3 pieces

8: breaking down of matrix, falling matrix, groove and short bit life caused by operating reasons- drill rod sticking, premature failure of the bit crown and hole bottom not to be cleaned
—Be excluded from quality guarantee

9: short bit life or no penetration caused by drilling machine, drilling techniques or parameters
—Be excluded from quality guarantee

10: properly worn and the matrix is finished
—Be excluded from quality guarantee

11: thread damaged or distorted due to improper operation
—Be excluded from quality guarantee

12: Steel body cracked in drill
—Be excluded from quality guarantee