coarse grained

fine grained

medium grained

Brinell hardness number

Rockwell hardness number

Vickers pyramid number

letter of alphabet

hardness of the material being ground

speed of the wheel and work

condition of grinding machine

all of these

coarse grained

medium grained

fine grained

the soft grade grinding wheels are used for grinding soft materials

the soft grade grinding wheels are used for grinding hard materials

the hard grade grinding wheels are used for grinding hard materials

the hard grade grinding wheels are used for grinding soft materials