In order to avoid porosity in copper castings during precision casting, the mold should be fully preheated, and the particle size of the coating should not be too fine, with good gas permeability. Secondly, castings should be cast at an angle. In addition, raw materials should be stored in a well ventilated and dry place.

Shrinkage holes are another rough surface on the outer or inner surface of copper castings. Fine shrinkage pores are multiple dispersed small shrinkage pores, which refer to the shrinkage, contraction, or contraction of grains. Usually in copper castings, the runner is located near the root of the riser, the thicker part, the thicker transition part of the wall, and the thicker part with a large flat surface.

To avoid shrinkage of copper castings, on the one hand, it is necessary to increase the temperature of the mold; On the other hand, in order to avoid shrinkage of the mold, it is necessary to increase the temperature of the mold, adjust the thickness of the coating, and spray the coating evenly; On the other hand, the mold should be heated or insulated.