Optimization of Thermal Drilling Parameters of 6082 Al-Alloy Based on Response Surface Methodology

Thermal drilling is a non-traditional, chip-less, and green hole-forming process affected by the drilling tool rotational speed (RS), feed rate (FR), and drilling tool cone angle (β). The present investigation studies the effect of variations in friction drilling parameters (RS and FR, as well as the cone angle β) on the surface roughness values and the dimensions (height and thickness) of the thermally induced bushing made of 6082 aluminum alloy. The drilling parameters were optimized by response surface methodology. The optimum drilling process parameters, which affect the surface roughness values and bushing dimensions, were predicted separately by applying the main effects plot and analysis of variance. There is a good agreement between the experimental results and the presented models. It was found that the optimal parameters for the lowest surface roughness value involve RS of 1250 rpm, FR of 200 mm/min, and β of 45°, while the greatest bush height was obtained at RS of 1250 rpm, FR of 200 mm/min, and β of 50°. Moreover, the microstructure of the regions surrounding the friction-drilled hole showed the existence of fine grains near the drilled edge.