Investigation of generating mechanism of laminations and improvement of gating system

Abstract

Mould filling simulation has been used in foundries for predicting casting defects. However, the characteristic flow pattern of laminations has not been investigated by simulation since the trigger of laminations is a microphenomenon. In this study, the investigation of the generating mechanism of laminations of zinc alloy (ZDC1) die casting products with a streamline shape has been carried out by computer simulation and physical analysis. The trigger of laminations occurs in a very short time, is a microphenomenon and depends on the flow pattern of the molten metal inside the cavities. To simulate such a characteristic flow pattern that causes laminations, the authors adopted an analysis model with a fine mesh near the die surface because a highly accurate calculation is required to capture the characteristic features of the flow pattern of molten metal into cavities. Analysing the blister that occurred after the plating processing on the surface of a zinc alloy die casting product with a streamline shape using SEM images, the authors confirmed that the stripped metallic layer was generated on the bottom of the plated layer. From the flow simulation results and the metallographic microstructural investigation using the SEM images, it was confirmed that the shape feature of the casting products and the rapid solidification caused the laminations.

Keywords:

• Laminations
• Mould filling simulation
• Die casting
• Zinc die casting products
• Blow hole
• Blister

Notes

This paper is part of a special issue of papers selected from MCSP8, the 8th Pacific Rim Conference on Modeling of Casting and Solidification Processes