The Effect of Different Cooling Methods to Hole Quality and Tool Life in the Drilling of AA7075 and AA2024 Aluminum Alloys

Controlling the amount of the cutting fluid used in machining processes is important in terms of its effects on the environment, human health, and also on the total cost of production. In this study, the AA7075 and AA2024 aluminum alloys were subjected to drilling process using four different cooling conditions (internal MQL, external MQL, conventional cooling and compressed air cooling), four different cutting speeds (100, 125, 150, 175 m/min) and four different feed rates (0.10, 0.15, 0.20, 0.25 mm/rev). At the end of experiments which have been performed with respect to Taguchi experimental design method, in addition to the hole quality such as surface roughness of hole, diametrical deviation, ovality and axial deviation, wear/build-up edge on cutting tools were investigated. The obtained data were evaluated by performing ANOVA and Signal/Noise (S/N) tests. At the end of experiments, it was determined that cooling method has the most effect on output parameters. It was observed that while the lowest values were found at conventional cooling application, the results from the application of internal MQL were very similar to conventional cooling method. While increased feed rate generally caused increase in all the output parameters, the cutting speed has unclear effect on the test results. The results of the hole quality obtained from the AA7075 alloy were found to be better than the results obtained from the AA2024 alloy, especially in poor cooling conditions such as compressed air cooling and external MQL application.