In this paper, the effects of cutting tool coating material and cutting speed on cutting forces and surface roughness were investigated on Taguchi experimantal design. Main cutting force, FZ is considered to be cutting force as a criterion. The effects of machining parameters were investigated using Taguchi L18 ortogonal array. Optimal cutting conditions were determined using the signal-to-noise (S/N) ratio which is calculated for average surface roughness and cutting force according to the "smaller is better'' approach. Using results of analysis of variance (ANOVA) and signal-to-noise (S/N) ratio, effects of parameters on both average surface roughness and cutting forces were statistically investigated. It has seen that while cutting tool and feed rate has higher effect on average surface roughness.