Experimental investigation on the environmentally friendly turning of Al7075 using ultrasonic nozzle-minimum quantity lubrication (UN-MQL) system

In this experimental work, the effects of cutting fluid and different cutting parameters on surface roughness, tool wear, and chip morphology during turning of Al7075-T6 were investigated. Machining experiments have been done in different environments such as dry, wet, minimum quantity lubrication (MQL) as well as a homemade ultrasonic nozzle- minimum quantity lubrication (UN-MQL). Ultrasonic vibrations can be used to effectively atomize the cutting fluid into fine and uniform-sized droplets and smaller spray angles with a larger spray deposition distance. The MQL system and machining parameters were evaluated by the design of experiments (DOE) method which allows us to carry out the optimization analysis by performing a relatively small number of experiments while determining the influence on the machining performance using the analysis of variance technique. In the second step, an optimization of the machining parameters was sought using signal-to-noise ratio analysis. Therefore, the response surface methodology was determined in a regression analysis, which was used to model the influence of the parameters on the performance. The fine droplets produced by the UN-MQL system penetrate effectively into the machining zone. Finally, the chip morphology, tool wear and surfaces of the machined parts were examined using optical microscopy to identify the chip formation mechanism in different machining conditions. Cutting tool wear were also examined using the SEM tests to quantify the tool wear zones under specific process parameters. Experimental results show that applying UN-MQL system reduces the surface roughness and tool wear by up to 30% in comparison to the conventional MQL system.