In this study, The effect of aging heat treatment on machinability of AA7075 aluminum alloy is investigated. Turning experiments were performed on the aluminium test pieces obtained commercially as T6 heat treated and the aged test materials to investigate the effects of cutting tool tip radius and cutting parameters on surface roughness. Machining conditions are designed in the L18 array according to the Taguchi method. The machining tests were carried out at without coolant on CNC turning. Variance analysis (ANOVA) was used to determine the effect of cutting parameters on the surface roughness. According to the variance analysis results, it has been determined that the most efficient cutting parameter on surface roughness (Ra) is the feed rate with 68.28% for the main material and 55.21% for the aged material.