In the manufacture of precise mechanical components, which requires high mechanical and wear resistance, the grinding process is used to give the desired finishing and to eliminate the distortion occurred during the quenching step in the steel heat treatment process. However, the grinding conditions should be appropriate so that flaws are not incorporated into the piece. New lubrication and cooling concepts for the grinding process are being researched in order to reduce costs and environmental damage caused by cutting fluids. The influences on the surface integrity and surface quality of the ABNT 4340 hardened parts have been analyzed in this research by employing the minimum quantity of lubrication (MQL), optimized and conventional cooling, different flows and velocities in the application of the cutting fluid and a super abrasive grinding wheel in the cylindrical plunge grinding process. The ABNT 4340 steel, with several industrial applications, is considered for aeronautical use due to its high strength without increasing the weight of the components. The quality analysis of the parts was done by roughness verification and electron scanning microscopy (ESM). The tangential cutting force was also verified. Regarding the different forms of the cutting fluid application, the best performance was verified for the optimized for higher speeds showing the efficiency of the nozzle used. The optimized and the MQL processes were able to maintain the surface hardness and integrity of the produced parts. The only exception occurred for the MQL condition with a cutting fluid flow rate at 40ml/h, which led to cracks and superficial burns. Grinding wheels with low CBN concentration, therefore cheaper, produced good results when associated with more efficient techniques of cutting fluid application, showing reduced wear.
Grinding process; CBN grinding wheel; ABNT 4340 Steel; minimum quantity of lubrication (MQL); optimized cooling; conventional cooling
