Shape Optimization of Plunger Tip Based on Linear Cumulative Damage Law

Die casting is suitable for mass production and has the advantage of being able to yield complicated shapes accurately. One disadvantage of die casting for high-speed injection molding is the occurrence of blow holes. To avoid the occurrence of blow holes, the shape of a plunger tip with the curved surface is very effective in actual manufacturing facilities. However, this shape is very weak to wearout. Therefore, this plunger tip is highly breakable. In this paper, an optimum shape of the plunger tip is calculated by utilizing the real - coded genetic algorithm incorporating a FEA and a CFD simulator with stress analysis and a linear cumulative damage law. Then, the fatigue strength of the plunger tip is evaluated, and it is clarified that the optimum shape is superior in strength for reducing the amount of entrained air and preventing the occurrence of blow holes in die-cast products.