Cam eccentric wheel

The main reasons for the formation of pores in stainless steel casting processing are:

01: The permeability of the coating is poor or the negative pressure is insufficient, and the permeability of the filling sand is poor. The gas and residue in the mold cavity cannot be discharged in a timely manner, forming pores under the filling pressure.

02: The pouring speed is too slow, unable to fill the pouring cup, exposing the sprue, entraining air, inhaling slag, and forming air pockets and slag holes.

03: A large amount of gas and residues generated from the gasification and decomposition of the foam model cannot be discharged from the mold in time. The drying of foam and dry sand filled with paint layer is poor. Surrounded by the high temperature of liquid alloy, a large amount of hydrogen and oxygen generated from cracking invades the casting, which is the main reason for the formation of air holes.

04: Due to the unreasonable design of the gating system, the filling speed of the molten metal is greater than the foam gasification retreat and gas discharge speed, which causes the gasification residue to be trapped in the metal liquid at the filling front and then gasified again to form a decomposition pore with black smoke on the inner wall.

05: The connection between the sprue cup, the sprue, and the pouring system is not well sealed, especially the connection between the sprue and the sprue cup is not well sealed. Under negative pressure, it is easy to form sand inclusions and pores, which can be calculated and explained using the Bernoulli equation.

06: The particle size of the molding sand is too fine, the dust content is high, and the permeability is poor. The internal blockage of the negative pressure pipeline causes distortion of the negative pressure, causing the negative pressure value around the mold cavity to be much lower than the indicated negative pressure. The vaporized material cannot be discharged from the coating in a timely manner, resulting in the formation of pores or wrinkles.

07: The pouring temperature is low, the molten metal at the filling front cannot fully gasify the foam, and the undissolved residual materials cannot float to the riser and solidify in the casting to form pores.

08: Poor deoxygenation of molten steel, unclean slag removal in the furnace, furnace, and ladle, short settling time, poor slag blocking during the pouring process, and unreasonable pouring process resulting in slag holes.

09: The setting position of the ingate is unreasonable, forming a dead zone during mold filling. Due to the gas pressure in the mold cavity, the gasification residues accumulate in the dead zone to form pores. The sectional area of the ingate is too large, making the mold filling speed greater than the foam gasification retreat speed. Swallowing the foam, the alloy is partially degassed, and the gas cannot be discharged to form pores.

10: The capacity of the pouring cup is too small, causing the metal liquid to form vortices and invade the air to generate pores.