Abstract: There are often some uneven mixing cells with uneven sizes in supercritical fluid (SCF) microcellular foam injection molding products. This fault was named as “gas surge” phenomenon, and it influenced the quality of foam products, significantly. In this paper, the procedure of gas injection was deduced through the observation and analysis of the experimental phenomena. It was found that the occurrence of gas surge in SCF micro-foam injection molding was due to the clearance for hardware devices. Influencing factors of gas surge were confirmed by the experiment designed in this work and then studied quantitatively. A measurement method of initial gas surge was also proposed as a reference for precise injection of microcellular foam injection.

Key words: microcellular foam, injection molding, supercritical fluid, gas surge, gas measurement