Abstract: A temperature difference measurement system was designed for measuring the axial and radial temperature distribution of melt online in the injection molding process. Experiment on four different types of injection molding screws. Study on performance evaluation of injection molding screw by measuring the melt temperature homogeneity. When PS pares was molded,the axial average temperature difference was down to 0.45 ℃，and the radial average temperature difference is down to 2 ℃ , the repeating weight precision of products can reach 0.035 %,the impact strength is up to 10 kJ/m2 and the melt pressure fluctuations is down to 0.7 MPa by using a screw processing PS at the same operating condition. It was consider that such a screw in the melt temperature homogeneity could meet the requirements for precise injection molding of PS products

Key words: injection molding, melt temperature, performance evaluation, screw, homogeneity