The position of the casting in the mold during pouring affects the quality, dimensional accuracy, and difficulty of the molding process of the precision casting.
Selection principle of pouring position:
1. The important processing surface or main processing surface of the precision casting is facing down or on the side: when pouring, the gas, molten slag in the molten metal and the sand particles in the mold will float up, which may cause air holes, slag inclusions, etc. The defects such as trachoma, and the possibility of defects in the lower part of the casting, the structure is denser.
a. The pouring position of the machine bed should face down the guide rail to ensure the quality of this important working surface. The quality of the circumferential surface is relatively high. The vertical pouring scheme can be used to keep the circumferential surface on the side to ensure uniform quality.
2. The large plane of the precision casting is poured downward or obliquely: due to the strong heat radiation from the hot molten metal to the upper part of the mold during pouring, the top sand mold expands and even cracks, causing the large plane to contain sand, sand holes, etc. defect. Large planes face down or adopt oblique pouring method to avoid the production casting defects of large planes.
3. The thin walls of precision castings are facing down, sideways or inclined: In order to prevent the cold walls of the castings from being cold-separated and unable to cast defects, the thin walls with a larger area should be placed in the lower part of the castings or placed on the side walls or Tilted position.
4. Most 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 the riser in the thick place for retraction.