How to improve the quality of zinc alloy die casting?
Release time:2024-04-15
These methods improve the technological level of zinc alloy metal die-casting
Ustar introduces the following 4 methods of zinc alloy metal die casting to improve the technological level.
1. Single liquid quenching method of zinc alloy metal die-casting mold opening
The die or part is heated to austenitizing and then quenched into water and oil medium. After a certain period of time, the die steel is cooled to a region lower than the pearlitic type transition temperature or the martensitic transition temperature region. Because the mold cooling process is completed in a single cooling medium, it is called single-liquid quenching method.
2. Double liquid quenching method of zinc alloy metal die-casting mold opening
As the name suggests, the quenching and cooling process of the mold is completed in two cooling media (commonly water and oil). The cooling process is more ideal, both in the pearlite transition region fast cooling, in the martensitic transition region slow cooling.
The specific practice is that the die steel or parts heated to the austenitizing temperature are first quenched into a medium (usually water or saline solution) that is quickly cooled in the high temperature region to inhibit the pearlite transformation of the supercooled austenite, and when the temperature is lowered to about 100 ° C, the two media (usually oil) are quickly removed into the low temperature region. Because the martensitic transformation is carried out under moderate cooling conditions, deformation and cracking can be prevented, commonly known as water quenching oil cooling. This method requires high operating skills, and can sometimes be understood as three media, that is, first water, oil, and then air.
3. Spray quenching method of zinc alloy metal die-casting mold opening
For large and complex zinc alloy die castings and dies with large thickness difference, in order to reduce the temperature evenly, avoid excessive quenching stress, and control the cooling rate at different stages and different parts of the cooling process. The method has spray liquid (water or aqueous solution), spray (compressed air and water atomized to different parts), gas quenching and other ways, its advantages are: can control different media or different flow, pressure to control and adjust the cooling rate of each temperature region; Or change the number and position of different nozzles; Can make the temperature drop evenly. At present, vacuum high pressure gas quenching is more popular in the heat treatment of die casting mold.
4. Fractional quenching method of die casting mold opening
The workpiece heated to the austenitizing temperature is quenched in the cooling medium (commonly used as a salt bath) near the martensitic transition temperature, and stays for a period of time, so that the surface and temperature of the workpiece gradually converge to take out the air cooling, and the martensitic transition is completed at a lower cooling rate. This method can significantly reduce the deformation and improve the toughness of the die steel, and is one of the commonly used quenching methods for die casting parts.
There are two kinds of temperature choices for grading quenching of zinc alloy metal die casting die steel. One is to take the Markov transition starting temperature (Ms point) of the workpiece steel to be treated above 10~30C; The other is to choose 80~100 ° C below the Ms point. The residence time of classification should also be mastered. If it is too short, the temperature is not uniform enough and the purpose of classification quenching can not be achieved. If it is too long, non-martensitic transformation may occur and reduce the hardness.
