Flaws of Liquid Model Dies and Prevention
The die casting process is an important process for large-scale production of metal components with complex shapes in modern industry. The liquid model die mold (die) is used more and more due to its accurate and complex shape and good surface finish. However, in the die casting process using liquid die, because of its higher filling pressure, the die is prone to crack and breakage. In order to produce high quality liquid die castings, it is necessary to control and prevent flaws.
Firstly, liquid die should be able to prevent cracking of the die during use. As liquid die is usually composed of complex shape, surface and precision parts, under the pressure of die filling, the die is prone to crack. The stress concentration of the liquid die is higher due to the crystallization of the ligaments in the material, which may easily lead to the variation of the internal and external forces on the die surface, therefore resulting in its cracking. In order to prevent die cracking, it is necessary to properly design the structure and shape of the die, reasonable selection of die materials and reasonable heat treatment process.
Secondly, liquid die should be able to protect itself from the erosion of molten metal to the greatest extent. Due to the high temperature of molten metal and its strong carrying ability, the molten metal will corrode or even melt the surface of the die. In order to reduce the corrosion of molten metal and good lubrication performance, it is necessary to select the die material with better corrosion resistance and lubricity and properly design the structure of the liquid die and the geometry and size of the die casting cavity; in addition, reasonable and effective cooling system should also be considered to protect the die surface from damage due to the erosion of the molten metal.
Thirdly, liquid die should have appropriate pouring system to ensure the die filling during casting, and the pouring system should be designed so as to reduce the turbulence of molten metal and the fluctuation of molten metal temperature which defers metal shape, eliminates air bubbles and reduces shrinkage defects of the casting. Meanwhile, it is necessary to select the enough breaking distance and choose adequately cold iron or alloy to make the die casting easier.
Finally, liquid die should be able to ensure the precision and accuracy of cast parts. Liquid die components, especially complex components of high precision and surface finish, should be polished in time to ensure the smooth surface of liquid die and reduce die wear. In addition, pay attention to the periodic maintenance and replacement of liquid die to control the precision and accuracy of parts.
In summary, liquid die is of many important factors that require special attention or caution. It is necessary to pay attention to the aspects of structure defect, surface erosion and precision, so as to design the die with appropriate materials and requirements, choose the suitable pouring system, carry out regular maintenance of liquid die, in order to reduce the defect of liquid die casting parts and ensure the quality of castings. 。