In the present investigation, holes were produced in AA7075 aluminum alloy sheets using friction
stir drilling. The friction stir drilling process was performed using computer numerical control (CNC) vertical
machining center. The influence of the spindle rotational speed and the tool's conical angle on the hole
characteristics, typically, hole diameter, bushing height and thickness, were investigated. The analysis of
variance (ANOVA) calculations were performed to estimate the significance of the studied process parameters.
Regression analysis was carried out to find correlations between the investigated friction stir drilling process
parameters and the fabricated hole characteristics. The results revealed that the conical angle is the most
influential factor that affect the hole characteristics. Increasing the tool rotational speed reduces the hole
diameter and the bushing thickness. However, increasing the conical angle increases the bushing height. The
developed regression equations showed high accuracy. The equations for the hole diameter, bushing height and
bushing thickness have mean absolute error (MAE) values of 0.6%, 3.04% and 6.10%, respectively.