In this work, effects of friction on the machining process during orthogonal cutting are theoretically investigated. Mathematical models were developed to predict the effects of friction and cutting force on the machining process. The results showed that the coefficient of friction increased with increased cutting forces, cutting stress and temperature. The frictional stress decreased as the exponent (P) increased. However, the frictional stress increased as the coefficient of friction increased. Also, study revealed that as the temperature increased, the flow stress decreased. Furthermore, it is shown that as the feed speed increased, there is an increase in the flow stress of the material used. The cutting force increased with increasing the feed rate, depths of cut but decreased with increasing cutting speed. This work will enhance the influence of friction on the cutting process and also assist in the development of good products with good surface finish.