Drilling of cryogenically treatment applied Al7075-T651alloy material with coated and uncoated cutting tools

In the machining of Al 7075 aluminum alloy using chip removal methods, maximizing machining efficiency is of great importance. However, undesirable consequences such as high cutting forces, increased surface roughness, and tool wear occur during the machining of aluminum materials. This study investigated the cutting forces, surface roughness values, cutting tool wear, chip morphology, microstructure, and hardness measurements resulting from drilling aluminum (Al7075-T651) alloy in cryogenically treated and untreated workpieces using coated (Zirconium) and uncoated cutting tools under both dry and Minimum Quantity Lubrication (MQL) conditions. It was observed that the hardness value of the Al 7075 workpiece decreased by 11% after cryogenic treatment. It was observed that feed forces and surface roughness values increased with increasing cutting speed and feed rate in dry and MQL machining conditions. The results of drilling tests performed under MQL machining conditions were better than those under dry machining conditions. Experimental results obtained with Zr coated cutting tools gave better results than uncoated cutting tools. While the feed forces obtained during the machining of the cryogenically treated workpiece were lower than the untreated workpieces, the opposite was true in terms of surface roughness values. It was determined that the most common wear type in tool wear is BUE. SEM images of the cryogenically treated and untreated Al 7075 workpiece revealed that the resulting chips had a sawtooth (serrated) shape and a lamellar structure. EDS analyses of the cutting tools revealed that the alloying element had an impact on the adhesion of the cutting tool to the rake surface.