Grinding burns are actually caused by excessive grinding temperature, resulting in changes in the metallographic structure of the surface layer being ground.
There are generally two situations of grinding burns. One is that the grinding temperature exceeds the phase transition temperature of the material, often causing "secondary quenching" burns; Another type is that although the grinding temperature is high, it does not exceed the material's phase transition temperature, often causing "tempering" burns.
The method to solve the problem of grinding burns is to fully pour grinding fluid during grinding and use slotted grinding wheels for intermittent grinding. During the grinding process, the grinding wheel groove passes through the grinding area without cutting the workpiece, which relatively reduces the sliding and cutting of the grinding wheel. The slotted grinding wheel with intermittent grinding has good self sharpening, which means that the abrasive particles on the surface of the grinding wheel are often in a sharp state. The deformation of the chips during grinding will be reduced, and the friction between the grinding wheel and the workpiece will also be reduced. The cutting performance consumed during the grinding process will also be correspondingly reduced, so the cutting force and cutting temperature can be reduced.
The grinding temperature of intermittent grinding is lower than that of ordinary grinding, and another reason is that it can reduce or interrupt the accumulation of heat. Grinding burns are mainly caused by changes in the metallographic structure of the surface layer of the workpiece due to grinding temperature. During the grinding process, as long as the generation of cutting heat can be reduced or the cutting heat can be transferred out in a timely manner, grinding burns can be alleviated or avoided. In ordinary grinding, the grinding wheel is always in contact with the workpiece. The heat generated by the workpiece before grinding is transferred to the part of the workpiece that is about to be ground later. The heat generated by grinding the part of the workpiece after grinding needs to be accumulated by stacking with the heat transferred in front, causing the temperature in the grinding area to rise. If the grinding amount is not suitable, it is easy to cause "secondary quenching" or "tempering" burns. Using slotted grinding wheels for intermittent grinding can reduce the temperature in the grinding area and alleviate burns, but the surface roughness value of intermittent grinding is higher than that of ordinary grinding, causing slightly larger vibrations, which also has a certain impact on the grinder. The appropriate selection should be made according to the processing situation during grinding.