Study of injection molding: (4th report. Analysis of pressure build-up during the packing and the cooling stage in the injection molding)

The fluid motion within the mold cavity during the packing and the cooling stages is studied. To evaluate the pressure history in the postfilling process of injection molding, an analytical approach is chosen. The fluid is considered as Newtonian, and its compressiblity is explained by the Spencer-Gilmore equation. Also, the cooling effect during the whole process is considered. The results of the analysis are compared with the experimental pressure profile in the model die. The analytical pressure profile is in fairly good agreement with the experiment for different mold thickness parameters. The pressure drop by the cooling effect is also explained quantitatively.