The advantages of low pressure casting are as follows:
1) The pouring pressure and speed are easy to adjust, and can adapt to different mold types; the filling type is stable, the flushing force to the mold is small, and the gas is easy to be excluded.
2) It is convenient to realize sequential solidification, prevent shrinkage and shrinkage, and especially overcome the pinhole defects of aluminum alloy.
3) The surface quality of the casting is higher than that of the metal type, and a thin-walled casting having a wall thickness of 1.5 to 2 mm can be produced.
4) Without the riser, the utilization rate of metal can be increased to 90% to 98%. Equipment costs are much lower than die casting.
Advantages of investment casting:
1) The mold is precise and has no parting surface. The surface of the cavity is extremely smooth, and the precision and surface quality of the casting are excellent. At the same time, complex thin-walled castings can be produced because of the pre-heating and pouring.
2) The shell is made of high-grade refractory material, which can be applied to the casting of various alloys, especially high-melting alloys and difficult-to-cut alloys (such as high-manganese steel, magnetic steel, heat-resistant alloys, etc.).
3) The production batch is not limited. In addition to mass production, it can also be produced in one piece.
The disadvantages are:
The materials are expensive, the process is complicated, the production cycle is long, and the cost of castings is several times higher than that of sand casting. In addition, it is difficult to achieve full-scale mechanization and automated production, and the castings cannot be too large or too long, generally ranging from a few grams to a few kilograms.