However, vacuum systems also have many disadvantages, such as prolonged cycle time, stronger clamping force and more maintenance of vacuum valves in many systems. The thin parts used in the welding system can have good dust removal effect after vacuum treatment. ThyssenKrupp Fahrzeugguss uses their own vacuum system, which is called "platinum mold casting". The system can work under the pressure of 30 to 80 MPa, without vacuum tube, and a standard batching furnace can be installed.
If the standard Al-Sn alloy is to be used for die casting with corresponding characteristics, it needs to have a low iron content so as not to cause cracking in the matrix, and it also needs to use a metal containing more magnesium to ensure the stability of Mg-Sn during heat treatment. This requires good management of product waste treatment and recycling in smelting workshop to prevent confusion between alloys.
However, parts cast by standard Al-Sn alloy, such as Al-Sn-Mg, need to be treated at high temperature to achieve certain flexibility. This is not the same as mold casters. Because air will be mixed in the casting process due to pressure, these air will form bubbles after heat treatment. The optimized heat treatment process will reduce the heating temperature, thus avoiding this phenomenon.
The more mature method is not to use heat treatment process. Al-Mg alloy is difficult to melt and cast. However, if proper processing is used, heat treatment is unnecessary. Due to the high content of magnesium in the alloy, many nonmetallic substances will be formed during the melting process. Therefore, it is necessary to clean these substances with argon extraction device, and the frequency of cleaning the batching furnace should be twice that of cleaning alloy substances.
Adding beryllium and vanadium to the casting can effectively prevent the mold from oxidation due to long-term exposure. The shrinkage of aluminum-magnesium alloy is also different from other alloys, which may be more obvious in those thick-walled die castings. These problems can be overcome by changing the proofing angle, mold temperature control or better design, and good parts can be made. 38+0 in 438 of figure 65 is an example of a component made of magnesium 59.