The market demand for machining and cutting of various plastics parts is in continuous increase. The aim of this study is to extract prediction laws for surface roughness, cutting forces and temperatures evolution during the machining of two polyethylene pipes grades (HDPE-100) and (HDPE-80). It was found that feed rate is the most prevailing factor on roughness criteria and that better surfaces are obtained during the machining of the harder HDPE-80 resin. Also, cutting speed improved surface quality for speeds up to 200 m.min-1 but the rising interface temperature caused surface damage and material rapid softening. Also, feed exponents, in mathematical models, were found to be 3 to 4 times higher than those of cutting speed and depth of cut. An increase in the cutting speed led to a gradual reduction for the 3 cutting forces components (Fr, Fa and Fv) with a dominance of the tangential force (Fv). As expected, the value of the depth of cut had a large influence on the temperature within the cutting zone. This temperature is slightly higher during the machining of HDPE-80 compared to that of HDPE-100 most probably because of hardness differences. The analysis of variance (ANOVA) was performed to check the adequacy of the mathematical models relating cutting parameters with roughness, cutting forces and global cutting zone temperature.