The relationship between the cutting speed of metal and tool life is examined in this paper. Taylor’s equation of tool life expectancy is used to estimate the tool life under various cutting speeds and cutting conditions. Metal cutting data about HSS tool on a special die steel was used The least squares method for correlating data was applied to the experimental data to obtain the relationship between the cutting speed and the tool life. In addition, the relationships between cutting speed and depth of cut and between cutting speed and feed rate for a specified tool life of 60 minutes were obtained using the least squares approach. Such relationships will serve as guides in machining operations. Similar analysis could be applied to other available experimental data about lathe machining.