Experimental study of grinding fluids for abrasive-belt grinding of stainless steel

A number of ferritic stainless steels with high corrosion resistance have recently been developed, but these steels are known to be difficult to grind in coated abrasive-belt grinding operations. In order to formulate or select an optimum oil-based grinding fluid with which such stainless steels can be successfully ground, an optimum base oil was first experimentally selected, and then additives were evaluated for their effect in improving abrasive-belt grinding performance. A paraffinic mineral oil having a certain viscosity was found to be suitable for the base oil. Chemical grinding oil additives were found markedly effective in improving the abrasive-belt grinding performance for both 19Cr-2Mo ferritic stainless steel and SUS 304 austenitic steel, with those containing sulphur or chlorine being superior to those containing phosphorus, fatty acid or alcohol. Among all the additives tested, chemically active oils, such as sulphurized mineral oil, exhibited the best performance. Effects of chlorinated paraffins on the grinding performance could be perceived but were not so great as those of sulphur-series additives. The addition of TCP (tricresyl phosphate) to the grinding oil containing sulphur reduced metal removal in the case of 18Cr-2Mo ferritic stainless steel (SUS 444). In the case of SUS 430 ferritic stainless steel, however, TCP increased metal removal for a comparatively low sulphur concentration, but, above an optimum concentration of 0.4 wt% S, metal removal was reduced by TCP addition. A comparison of sulphur-series additives added to a sulphurized paraffinic mineral oil showed that nonyl polysulphide was superior to any other additives for improving the grinding performance in 19Cr-2Mo steel (SUS 444) and SUS 430. Excess addition of sulphurized fatty oil to a grinding fluid lowered the cutting ability of abrasive grains.