Correct option is A
In the abrasive wheel specification:
·
51: Manufacturing symbol.
·
A: Abrasive type (e.g., Aluminium oxide).
·
60: Grit size.
·
K: Grade or hardness of the wheel.
·
5: Structure of the wheel.
·
V: Bond material (e.g., vitrified bond).
Grade (K) refers to the
hardness, which determines how firmly the abrasive grains are held.
