Abstract
Sticking sand is a common defect of die casting and is mainly caused by the poor liquidity of molten metal. This paper summarizes the reasons, characteristics and prevention measures of sticking sand. The methods used to reduce sticking sand defect include modifying the composition of the alloy, reasonably selecting additives and controlling the cooling rate of the casting mold.
1 Introduction
Die casting is a metal forming technology that melts and injects molten metal into the cavity of a reusable metal die at high pressure. With the development and accumulation of die casting technology, die casting has become one of the most important manufacturing processes in the automotive and electronics industries, and industrial products and civil goods have become diversified. Die casting defects are an important issue that must be properly managed and operated during the die casting process, otherwise it will cause serious caused loss due to scrap, slow down the working speed and reduce the quality of the product. One of the most common defects of die casting is sticking sand.
2 Understanding Sticking Sand Defects
Sticking sand is a common defect of die casting. This defect is mainly caused by poor liquidity of molten metal. When molten metal with high pressure is injected into the mold cavity, water-solid lubricant can’t flow linearly along the mold cavity. Instead, it precipitates on the surface of the model forming a layer of adhesive sand. Under the effect of high temperature and high pressure, the adhesive sand layer is tightly adhered to the surface of the die casting and is difficult to remove after the product is demoulded. As a result, fine sand ridges appear on the surface of the die casting, which affects the texture and dimensional accuracy of the casting. Studies have shown that sticking sand defects are mainly caused by muddy raw material, weak fluidity of molten metal and improper casting structure design.
3 Characteristics of Sticking Sand Defects
Sticking sand defects are characterized by rough surfaces and irregular shapes. In addition, sticking sand defects have no obvious bonding interface with other particles. When viewed under a microscope, the surface of the sticking sand defect is filled with micro pits, indicating poor surface quality.
4 Prevention of Sticking Sand Defects
Sticking sand defects can be reduced by taking the following steps:
(1)Modifying the composition of the alloy. By adding elements such as silicon, calcium, aluminum and titanium to the alloy, the viscosity of the molten metal can be reduced, making it more liquid and reducing sticking sand defects.
(2)Reasonably selecting additives. The appropriate amount of lubricant and flux should be added properly to improve the liquidity of the molten metal and reduce sticking sand defects.
(3)Controlling the cooling rate of the casting mold. It is necessary to control the cooling rate of the mold properly. If the cooling rate of the mold is too slow, the molten metal will cool too quickly, resulting in sticking sand defect.
5Conclusion
Sticking sand is a common condition in die casting and can result in surface quality defects and impaired dimensional accuracy. To reduce the occurrence of sticking sand defects, it is necessary to modify the alloy composition, select appropriate additives, and properly control the cooling rate of the mold.
References:
[1] Guo, H., & Xie, P. (2013). Analysis of die casting sticking sand defect and its prevention. Mould and Die Technology of China, (1), 105-107.
[2] Li, E., Li, N., Li, G., & Jiang, D. (2006). Cause analysis and prevention measures of sticking sand defects. Foundry Technology, (2), 46-48.
