Constant use of the abrasive wheel leads to wear of the surface and abrasive grains, making it less sharp. The same result can be obtained if the surface becomes “kneaded”, that is, it is filled with shavings. It is therefore necessary to revive the grinding wheel using dressing stones, i.e. remove this worn layer, remove the worn abrasive grains, regenerating it and thus bringing the new, much sharper abrasive grains back to the surface.