Low-pressure casting is a way in which liquid metal fills the cavity under pressure to form a casting. Because the pressure used is low, it is called low pressure casting. The skill process is: in the sealed crucible (or sealed can), a monotonous compressed air is introduced, and the molten metal 2 rises along the riser 4 under the effect of the gas pressure, and smoothly enters the cavity 8 through the gate 5. And insist on the gas pressure on the liquid surface of the crucible until the casting completely condenses and stops. Then, the gas pressure on the liquid surface is exempted, and the uncondensed metal liquid in the liquid opening tube is flowed, and then the cylinder 12 is opened and the casting is pushed out.
The benefits of low pressure casting together are reflected in the following aspects:
1. Liquid metal filling is relatively stable;
2. The casting has good formability, which is beneficial to the construction of a well-integrated, bright-surfaced casting. It is more advantageous for the formation of large-scale thin-walled castings;
3. The castings are arranged finely and have high mechanical properties;
4. Improve the skill collection rate of molten metal. Under normal conditions, no riser is required, so the yield of molten metal is greatly improved, and the yield is generally up to 90%.
In addition, the labor conditions are good; the equipment is simple, easy to complete mechanization and automation, is also an outstanding interest in low-pressure casting.