Ways to reduce the porosity of Die castings

For Die castings, pores of 0.5 mm or larger can be improved. It is difficult to eliminate pinholes of 0.1~0.3mm, which requires a mold with a higher temperature (200 ~ 280 degrees), pure aluminum water. Low temperature, low speed, vacuum, and even partial extrusion Die casting can achieve a porosity of 1% to 5%.
For die-cast parts that allow pores below 0.5 mm, the method for improving the pores is: 1 The structure and flow direction of the mold casting system should be reasonable, the inner gate should be thick, and the exhaust should be unblocked;
2 If aluminum water is used to return the charge, degassing and slag must be carried out;
3 spray paint should not contain too much oil. The spray effect should be good. Don't spray too much. After spraying, use enough time to blow the mold surface with compressed air ("blowing" is very important);
4 The temperature of the mold should be properly controlled. After spraying the surface of the mold, 170 ~ 220 degrees is good, so that the coating water is completely evaporated, so that the mold can quickly cool the casting;
5 The spray casting chamber and the spray oil of the punching machine are as much as possible in the oil water, so that the excess oil can be volatilized after heating of the punching oil, leaving an effective lubricant to adhere to the surface of the injection chamber; the punching oil and the spraying have the same The atomization effect allows the punching oil to be evenly sprayed on the surface of the injection chamber, and the perforated oil is not allowed to accumulate, preventing the pouring of the aluminum water chamber to generate a large amount of fireworks and fire gas. It is also necessary to prevent the press from leaking, prevent the spray water from the spray mold from being sprayed into the injection chamber, and prevent the aluminum water from wrapping too much gas in the injection chamber.
6 Die casting speed is low, 0.12~0.2m/s is better, preventing aluminum water from rolling packaging gas in the injection chamber;
7 The high-speed water injection stroke should be short, the high-speed speed should be fast, and the atomization effect of aluminum injection into the cavity should be good;
Of course, the pressure of the boost should be large enough. Efforts 80~120MPa, the lifting time should be small, 15~36ms.

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