In this type of feed system, the plastic melt reaches the injection molded part through a rod-shaped sprue, either directly or via a simple runner system. It typically forms as a cylindrical or tapered solidified residue in the sprue channel and is separated from the molded part after ejection. The sprue bar is mainly relevant in conventional cold-runner molds because it is ejected together with the part and must then be recycled or discarded. Its geometry affects pressure loss, filling behavior, solidification time, and material consumption in the injection molding process. Proper design supports stable mold filling and helps reduce scrap and post-processing.
Injection Molding Process: Filling a cavity via a sprue bar
Related topics:
Sprue
Gate
This glossary of plastic industry is provided by PLEXPERT Canada Inc.
