Oxygenated Die Casting Process
Oxygenated die casting
, also known as pore-free die casting, mainly applied to aluminum alloy die cast process. It is a method that replaces oxygen with the gas in the cavity before die casting
, and then press the metal liquid into the cavity. The oxygen in the cavity reacts with the aluminum alloy and form small particles (0.1% to 0.2% of the total mass). These particles are dispersed in aluminum alloy, but they don't affect the processing.
1.The characteristics of oxygenated die casting
To eliminate or greatly reduce the internal gas hole of die casts to achieve dense microstructure, so that the strength of die casting can be increased by 10%. We can have a heat treatment for the oxygenated die cast part to enhance its mechanical properties. The die cast part is suitable for an environment of 200 ° C to 300 °C and can be welded. Compared with vacuum die casting, oxygenated die casting has the advantage of simple device structure, easy to operate, less investment. And its elongation can be increased by 0.5% to 1%.
2. Oxygenated die-casting equipment and process parameters
Oxygenated die-casting requires the air in the cavity and pressure chamber to be replaced by oxygen at the shortest time and completely.
A.Oxygenated die-casting equipment. There are plenty of ways of adding oxygen, generally we can add oxygen in the pressure chamber and die casting die. We often oxygenate at the refeeding punch of vertical cold chamber die casting machine. Because it has simple structure, reliable sealing, good quality, which is good for the central gate die cast. And we often adopt the method of oxygenating through oxygen hole in the die casting die of horizontal cold chamber die casting machine. After the pressure chamber is filled with oxygen, aluminum alloy liquid contacts oxygen, which will cause oxidation easily. B. Oxygenated die-casting process parameters. We should started to oxygenate when the gap of mold closing is 2～3mm, and the mold closing is supposed to stop for 1～2 second, then continue or slow down the process, so as to assure that there is no air left in the cavity. We need to keep oxygenating for a period of time after closing the mold. The best time for oxygenating is based on the size of the die cast, the degree of complexity and the position of oxygen hole, and the time is generally 3 ~ 6 second.