The position of the castings machining in the mold during casting affects the quality, precision and dimensional accuracy of precision castings.
Selection principle of pouring position:
- The important machined surface or main machined surface of precision casting is facing down or on the side: during pouring, gas, slag in the metal liquid and sand particles in the mold will float, which may cause pores, slag inclusions in the upper part of the casting, Defects such as trachoma, and the possibility of defects in the lower part of the casting, the structure is denser.
a. For the pouring position of the machine bed, the guide rail should face down to ensure the quality of the important working surface. The quality of its circumferential surface is relatively high, and the vertical pouring scheme can be used to make the circumferential surface on the side to ensure uniform and consistent quality.
- The large plane of the machining casting is poured downward or inclined: due to the intense heat radiation from the hot metal liquid to the upper part of the mold during pouring, it causes the top sand mold to expand and even crack, which causes sand inclusions and trachoma on the large plane. defect. The large plane faces down or the oblique pouring method can avoid the production casting defects of the large plane.
- The thin wall of the precision casting is facing downward, sideways or inclined: In order to prevent the thin wall of the casting from being cold-separated and unable to cast defects, the thin wall with a larger area should be placed on the lower part of the casting or placed on the side wall or Tilt position.
- The majority of the thickness of precision castings should be placed on the top or on the side of the parting surface. The main purpose is to facilitate the placement of feeders in the thick places for shrinkage.