Sharp SH-920 Instruction Manual page 40

2.3 Grade: It indicates the strength of the bond which hold abrasive.
Soft: A-H
Medium: I-P
Hard: Q-Z
Grade
Grinding
Condition
Workpiece hardness
Surface contacted
Movement of workpiece
Wheel speed
2.4 Structure: The structure number of a wheel refers to the relative spacing of
abrasive grains, the larger the number, the wider the grain spacing.
Close: 0, 1, 2, 3, 4, 5
Medium: 6, 7, 8, 9
Wide: 10, 11, 12
Structure
Grinding
Condition
Surface roughness
Surface contacted
Workpiece hardness
Soft
hard
wide
slow
high
Wide
rough
wide
soft
P.40 OF 70
Hard
soft
narrow
quick
slow
Close
fine
narrow
hard