Why The Excavator Bucket Tooth Casting Has Stomata

The stomata in bucket teeth casting is formed in the process of squeeze casting. In the process of liquid metal filling, the gas which has not been discharged will be entrapped into the liquid metal, and subsequently float. The floating rate of the gas is mainly related to the liquid metal viscosity. With the decrease of temperature, the liquid metal viscosity increases. When the liquid metal viscosity increases to a certain extent, the bubble buoyancy velocity tends to zero, then the bubble stops floating up but stay in the liquid metal. Then the stomata are informed.

The main reason for this situation is the unsmooth exhaust of casting mold. Gas in the cavity can not be discharged smoothly. In the filling process, the gas will be stored between the mold cavity and the liquid metal. Since the liquid metal can not completely dissolve the gas, and the part of the metal liquid which firstly contacts air will form a thin solidification shell in advance, the gas is which has not been discharged will gather in a certain internal region and finally the stomata appear. At the same time, as the squeeze casting is under high pressure to do the filling and solidification of liquid metal, the gas above will be compressed rapidly, thus creating conditions for the formation of bucket tooth stomata.