Research article

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Experiments of a new core-back foam injection molding process are described in this paper wherein the blowing agent content [%], mold temperature [°C], shot size [mm], injection speed [mm/s], holding pressure [MPa], holding time [s] and core-back rate [mm/s] were taken as single variables, respectively. The effects and mechanisms of the above parameters on the molding process were studied. The relationships of the parameters with the mechanical properties and the weight reduction effect of the specimens were analyzed. The results show that the effect of blowing agent content, mold temperature, shot size, injection speed and core-back rate in the new method is similar to that of conventional core-back foam injection molding. However, the first stage holding pressure and holding time of the holding process in the secondary filling stage which the new method peculiarly possesses play the same role as shot size and injection speed in conventional foam injection molding, and the second stage holding pressure and holding time play the role of pressure holding in conventional foam injection molding. Compared with the conventional foam injection molding method, the specimens obtained by using the new method have higher weight loss rate, better mechanical properties, and higher specific strength.