Abstract: Turning is one of the most important machining operation in industries. Turning is affected by many factors such as cutting speed, feed rate, depth of cut, geometry of cutting tool etc. Input parameters in this project work is cutting speed, feed rate and depth of cut. Output parameters are surface roughness and tool life. The objective of this paper is to evaluate the optimal setting of cutting parameters to have a maximum cutting tool life under wet machining environment. In this investigation HSS cutting tool with carbide insert is used. Mild steel and aluminium are workpiece material. The experiment are conducted under three different spindle speeds ( 600, 800, 1000 ), feed rates are ( 0.1, 0.15, 0.2 ) and depth of cut are ( 0.5, 1.0, 1.5 ). The relationship between cutting parameters and tool life obtained. This paper reviews the machining parameters affecting the performance of turning such as spindle speed, feed rate and depth of cut. Keywords: CNC turning, tool life, surface roughness, carbide insert, cutting Parameters