INFLUENCE OF EXTREME-PRESSURE ADDITIVES ON THE PERFORMANCE OF GRINDING FLUIDS IN CREEP FEED GRINDING

This study investigates the performance of grinding fluids containing extreme pressure additives under the conditions of creep feed operatio n. A set of grinding tests demonstrates that a chlorinated paraffin is considerably effective in reducing grinding resistance compared with organo-sulphur and organophosphorus compounds. Further examination is carried out using grinding fluids involving polysulphide combined with calcium sulphonate. Although this combination has recently been appre ciated to present better effectiveness than chlorine in some cases of ordinary metal cutting operations, it is still inferior to chlorinated paraffin when the operation is creep feed grinding. Detailed observat ion of workpiece faces after grinding suggests that poor surface finis h is probably connected with some damage of the wheel face. This situa tion is particularly intensified when polysulphide is combined with ca lcium sulphonate, and is also supported by the experimental event that high reactivity of this combination degrades mainly the wheel bond an d thus promotes the detachment of abrasive grains.