What are the reasons for the angry holes in stainless steel casting?

Let me share with you the main reasons for the angry holes in stainless steel casting as follows:

1. The air permeability of the coating is poor or the negative pressure is insufficient, and the air permeability of the filling sand is poor, and the gas and residue in the cavity cannot be discharged in time, forming pores under the filling pressure.

2. The pouring speed is too slow, failing to fill the sprue cup, exposing the sprue, entraining air, sucking in slag, and forming enveloping air holes and slag holes.

3. The gasification and decomposition of the foam model produces a large amount of gas and residues that cannot be discharged in time. The foam and coating layer are filled with dry sand. The drying is not good. Under the high temperature of the liquid alloy, a large amount of hydrogen and oxygen are cracked to invade the casting. The main cause of stoma.

4. The connection between the sprue cup and the sprue and the pouring system is not well sealed, especially the connection between the sprue and the sprue cup is not well sealed. This phenomenon can be calculated and explained by Bernoulli equation.

5. Due to the unreasonable design of the pouring system, the filling speed of the molten metal is greater than the speed of foam vaporization and gas discharge, and it vaporizes again in the molten metal to form smoke-black decomposition pores on the inner wall.

The air holes in stainless steel casting are mainly due to the above reasons. We need to avoid the above problems and achieve perfect stainless steel casting.