High Pressure Die Casting: Shot Cylinder Optimization
In high pressure die casting, a shot cylinder is used to rapidly push liquid metal into a die. Typically the cylinder is oriented horizontally and metal is poured into it through a fill hole on the top surface. A piston pushes the metal down the cylinder to an outlet at the opposite end. The goal of a properly designed shot cylinder is to push the metal into the die as fast as possible to avoid early solidification that could cause incomplete filling or internal defects. However, if the piston moves too fast, the liquid metal will fold over, trapping air that may appear as internal defects in the final cast part.
Shot Cylinder Pushing Metal into a Die
This simulation illustrates the flow in a shot cylinder approximately 30 inches long and having an internal diameter of 3 inches. Initially, the cylinder was 40% filled with metal and the piston speed was changed with time to reduce the amount of air entrapment. Color in the plots indicates the formation and distribution of surface oxide. Near the end of the piston stroke, one sees that surface-oxide material has been mixed into the metal over a relatively small volume.
More information on FLOW-3D Cast’s air entrainment, defect tracking and other advanced models for casting simulations is available in the FLOW-3D Cast Defect Prediction section.