In final thesis the effect of 4 injection molding parameters on weight and curvature of HDPE parts which undergo non-uniform cooling in the mold has been studied. 6 different combinations of injection molding parameters were used for producing parts. At each combination of parameters all parts (48 cavity mold) from 5 injection molding cycles were measured. Products were weighed and measurements of curvature were performed on each molded part to determine angle of curvature. It was determined that weight of molded part depends on hold time and screw back pressure. Important influence on curvature of molded parts was found in cooling time and hold time, since bigger influence of injection speed and screw back pressure on curvature of parts wasn't detected.