1. Crystallization under pressure
Put the shell in the pressure tank for pouring, after the end of the closure of the pressure tank immediately, to the tank through the high pressure air or inert gas, so that the casting under pressure to solidify to increase the density of the casting.
2. vacuum suction pouring
The shell is placed in a vacuum pouring box and the gas in the cavity is sucked through the tiny pores in the shell so that the liquid metal can fill the cavity better, replicate the shape of the cavity, improve the precision of the casting, prevent the stomata, Lack of defects. This method is more common in foreign countries.
3. Oriented crystal
Some of the investment casting materials such as turbine blades, magnets, etc., if their crystalline structure is arranged in a certain direction of the columnar crystal, their work performance can be improved a lot, so the investment casting oriented crystallization technology is rapidly developed.
4. Hot-type gravity casting
This is the most widely used form of pouring, that is, the shell is removed from the roaster and then subjected to pouring at high temperatures. At this time the metal in the shell cooling slower, can be filled in the case of high liquidity, so casting can be a good copy of the shape of the cavity to improve the accuracy of the casting. However, the slow cooling of the cast in the hot form causes the grain to be coarse, which reduces the mechanical properties of the casting. In the casting of carbon steel castings, the slow cooling of the casting surface is also easy to oxidation and decarburization, thereby reducing the casting surface hardness, finish and dimensional accuracy.
Casting casting is a strict step, different casting methods have different characteristics, so in the investment casting process to choose the appropriate casting method, casting a good melting.