Principles for selecting casting positions in precision casting

In precision casting, the position of the casting in the mold affects the quality, dimensional accuracy, and difficulty of the molding process.

Follow Hongyang all month to see the selection principles for pouring positions:

1. The important or main machining surface of precision castings is facing downwards or located on the side: During pouring, gases, slag in the molten metal, and sand particles in the mold may float upwards, which may cause defects such as pores, slag inclusions, and sand holes in the upper part of the casting, while the lower part of the casting may have defects, resulting in a denser structure.

The pouring position of the machine tool bed should be with the guide rail facing downwards to ensure the quality of the important working surface. The quality requirements for its circumferential surface are relatively high. By adopting a vertical pouring scheme, the circumferential surface can be placed on the side with uniform and consistent quality.

2. The large plane of precision castings is poured downwards or obliquely: Due to the strong thermal radiation of the hot metal liquid on the upper part of the mold during pouring, it causes the top sand mold to expand, arch or even crack, resulting in defects such as sand inclusion and sand holes on the large plane. The method of pouring with the large plane facing downwards or using an inclined pouring can avoid production casting defects of the large plane.

3. Thin walls of precision castings facing downwards, sideways or inclined: To prevent cold insulation and inability to pour defects in the thin-walled parts of castings, larger thin-walled parts should be placed at the lower part of the casting, or placed on the side wall or inclined position.

4. The majority of the thickness of precision castings should be placed at the top or on the side of the parting surface, mainly to facilitate the placement of risers for shrinkage filling in the thick areas.