The dimensional stability of a microcellular injection molded gear shaft

There are several benefits of using the supercritical fluid microcellular injection molding process. One of the benefits of microcellular injection molding is that the dimensional stability can be improved. In this study, the mechanical properties of the material Polyamide(PA) 66 (glass fiber (G. F.) 33% wt.) and the dimensional stability of a microcellular injection molded gear shaft were investigated. L9 experimental tests based on Taguchi's method were performed and a Tokyo TF 40 gear experiment machine was used to measure gear profile and to determine the optimal process conditions. The gear diameter of the gear shaft molded by conventional and microcellular injection molding were compared. The results showed that dimensional stability was improved by microcellular injection molding. The microstructure of cells at the weld-line and flow end is clearly observed from the micrographs.