Each casting system has different advantages and disadvantages:
Design 1 with two ingates and a relatively short flow path results in low temperature losses during filling and good feeding capabilities. The strong deflection of the melt at the runner and the associated high flow velocities may lead to die erosion. When the filling fronts from the two gates meet, there is also an increased risk of air entrapment. Due to its positioning, the gating area does not allow additional machining, which requires a very precise trimming.
Design 2 has only one ingate, which is located laterally in the throttle axle. This layout allows a runner with a smooth transition, preventing turbulences and thus air entrapment, oxides and other filling related defects in the casting. The ingate lies within the machining allowance, reducing the amount of trimming work. However, the relatively long flow path increases the risk of cold shuts and thus has also an unfavorable effect on the feeding.
Design 3 also has a single ingate located at the throttle axle, but with a different orientation of the component. This setup shows the shortest flow length. This leads to minimum temperature loss during filling, lower effort for trimming and a maximum feeding efficiency and yield. However, due to the short flow length, this layout has the disadvantage of being sensitive to dosing variations. This means that the position of the melt in the casting system may change so unfavorably at the time of piston acceleration that it leads to a significantly worse filling behavior.
Therefore, the engineers extended the virtual DoE (Design of Experiments) accordingly and analyzed the robustness with regard to the dosing variations. In order to display the dosing variations in MAGMASOFT®, the switchover point ('Switch Over Point') was varied in a range between 340 mm and 350 mm. Due to the specifications, the objectives of the DoE were a low-turbulence filling ('Smooth Filling') and minimal air entrapment ('Entrapped Air Mass') in the component.