The resistance exerted by the bond against

Hardness of abrasive grains

Hardness of bond

Its ability to penetrate

Dressing operation

Turning operation

Facing operation

Cutting operation

High Speed Steel

Cast Iron

Wrought iron

Pig iron

Speed at which wheel is to be used

Diameter of wheel

Thickness of wheel

Spindle size of grinder

High grade is used

Softer grade used

Medium grade is used

Any grade can be used