Low-pressure casting characteristics:
Compressed gas is put into the enclosed electric stove, applying pressure to the surface of liquid metal, which, smoothly and slowly, flow into mold cavity through the rise-liquid- tube. The gas inside the cavity is expelled from bottom to up through parting surface. Castings crystallize under controllable pressure, thus obtaining compact and high quality castings without porosity.
Smooth filling velocity of liquid metal can be controlled in accordance with different structure and materials of castings, thus avoiding liquid metal boiling, impacting and splashing when filling mold. Besides, layered filling reduces reoxidation, which enhances the quality of castings.
Metal-type gravity casting characteristics:
Liquid metal is poured into metal-type mold cavity under the force of gravity, and then crystallizes, solidifies and cools to form castings.
High cooling velocity and compact crystal structure make it possible to process regular pressure resistance castings.
Dimensional accuracy of metal-type cavity as well as surface roughness ensure castings of high size precision and superior surface quality.
Squeeze casting characteristics:
Liquid or semi-liquid metal is poured into mold cavity, and then crystallizes, solidifies and cools under high pressure to form castings.
Squeeze casting is also called liquid forging casting, which concentrates the merits from casting and forging and saves energy. Besides, it has the virtue of high metal utilization and production efficiency.
Solidification under high pressure and plastic deformation avoid shrinkage cavity or porosity,which leads to compact structure of castings and high mechanical performance.
High-pressure casting characteristics:
Pour the metal liquid into the melter and fill it under high pressure into the metal mold cavity with high speed. It then solidifies rapidly to form castings.
High-pressure casting applies to production of thin-walled cover sheets.
Advantages of high-pressure casting: high efficiency; high dimensional accuracy; high surface finish; good economical benefit.
Drawbacks of high-pressure casting: more equipment investment; longer production circle; higher cost; likelihood to mix gas into the metal liquid and enter the mold cavity; impaired quality of castings due to unexcelled gas in the mold cavity; can抰 be heat treated.