What are the prevention methods for casting defects in cast iron parts? In the production process of cast iron parts, various casting defects often occur in cast iron parts. How to prevent these defects from occurring has always been a concern for castings manufacturers.
The pores in the casting refer to the lubricating pores of different sizes that exist inside the casting, on the surface or near the surface. The wall of the hole is often also oxidized with color, because of the origin of the gas and the reasons for its formation are different, the expression of the pore is also different, there are invasive stomata, the separation of stomata, subcutaneous stomata and so on.
1, Distinguishing pores
These pores are often scattered, and most of the castings that are generally cast on the outside of the casting are often found in the same batch. This kind of air hole is mainly because in the smelting process, the gas absorbed by the molten metal is not fully separated before the condensation, and many small loose pores are formed in the casting.
(1) Use clean and dry charge material to restrict the use of charge materials with more gas content.
(2) Guarantee “Three Drys”: Ironing troughs, tapholes, and bridges must be completely dried.
(3) The ladle should be dried. Before the application, it is best to use iron liquid to burn it. There is iron liquid in the package. It is necessary to put the masking agent on the surface of molten iron.
(4) Various additives (balling agents, inoculants, masking agents) should be kept dry for a period of time, and when the humidity is high, it must be dried before use.
2, Invasive stomata
This type of stomata is less in number and larger in scale. It occurs in some parts of the outer surface of the casting, and it is pear-shaped or spherical. The primary reason is that the gas generated by the mold or core intruded into the molten metal did not escape.
(1) Improve the air permeability of sand, select the appropriate compactness of air space, and arrange the position of the air eye in a reasonable manner to facilitate the exhaust and ensure the ventilation channel of the sand core.
(2) Properly increase the pouring temperature, open the exhaust hole, and vent the riser, etc., in order to facilitate the intrusion of the gas that has intruded into the molten metal.