The Pouring Method Of Investment Casting

1) There are several hot gravity pouring methods.
This is one of the most widely used forms of pouring, i.e. the shell is removed from the roaster and poured at high temperatures. At this time, the metal cools slowly in the shell, and the mold can be filled with high fluidity, so the casting can copy the shape of the cavity well and improve the accuracy of the casting. However, the slow cooling of the casting in the hot mold will make the grain coarse, which reduces the mechanical properties of the casting. When pouring carbon steel castings, the surface of the casting with slow cooling is also prone to oxidation and decarburization, thereby reducing the surface hardness, finish and dimensional accuracy of the casting.
2) Vacuum suction pouring
The shell is placed in the vacuum pouring box, and the gas in the cavity is sucked away through the tiny pores in the shell, so that the liquid metal can better fill the cavity, copy the shape of the cavity, improve the accuracy of casting, and prevent the defects of porosity and insufficient pouring. The Act has been applied abroad.
3) Crystallization under pressure
The shell is placed in the pressure tank for pouring, and after the end, the pressure tank is immediately closed, and high-pressure air or inert gas is introduced into the tank to solidify the casting under pressure to increase the density of the casting. The maximum pressure abroad has reached 150atm.
4) Directional crystallization (directional solidification)
Some investment castings such as turbine blades, magnets, etc., if their crystalline structure is columnar crystals arranged in a certain direction, their working performance can be improved a lot, so investment casting directional crystallization technology is developing rapidly.