The process and characteristics of shell casting
Cover the metal template heated to 180-280°C with a heat-hardening molding sand (phenolic resin-coated sand) to harden it into a thin shell (the thickness of the thin shell is generally 6-12 mm), and then heat and cure. The thin shell can achieve sufficient strength and rigidity. Therefore, after the upper and lower shells are clamped with a clamp or glued with resin, the mold can be formed without a sand box. The heating temperature of the casting metal template is generally about 300 ℃ , The molding sand used is resin sand, that is, resin sand with phenolic resin as a binder.
The use of resin sand to make thin shell molds or shell cores can significantly reduce the amount of molding sand used, resulting in castings with clear contours, smooth surfaces, and precise dimensions that can be machined without or only in small quantities. Therefore, shell casting is especially suitable for castings of various alloys with large batches, high dimensional accuracy requirements, thin walls and complex shapes. However, the resin used in shell casting is expensive, the template must be precisely processed, the cost is high, and a pungent odor is generated during casting, which limits the wide application of this method to some extent.