Influência dos sistemas de lubri-refrigeração MQL e MQL-criogênico no processo de roscamento do aço inoxidável AISI 304L

Abstract

Companies in the metal-mechanic sector are looking for new technological solutions to optimize machining processes to remain competitive and promote green manufacturing. Due to this, solutions to increase productivity and efficiency in machining processes must be continuously developed. The threading process becomes one of the most difficult to perform when dealing with austenitic stainless steels, due to the chip formation and chip flow in the cutting zone. This work analyzes the influence of MQL and CO2 cryogenic cooling systems on external turning threading by applying radial, modified flank, and incremental infeed methods on 304L stainless steel, and using PVD coated M-class carbide inserts (TiC, Al2O3 TiN) GC 1020. For this purpose, the morphology of the chips obtained was verified, the resulting chip ratio was compared, tool wear was analyzed through the scanning electron microscope (SEM), and the microhardness of the flanks of the threads was obtained for each method and system used. With the progression of the tests, it was observed that the radial method was the one that presented the lowest chip ratio and the highest tool wear for both cooling systems. The use of modified flank and incremental methods resulted in better chip formation with similar morphologies, regardless of the applied cooling system. For all the machining conditions tested, there was wear of the tooltip and flank, in addition to adhesion of the workpiece material on the flank and face of the tool. The best results were obtained with the incremental infeed method using the MQL-cryogenic system, which provided a higher chip ratio, longer tool life, and better quality of the machined parts, in addition to reduction of the resulting microhardness on the flanks of the threads when compared to other methods and systems analyzed.