Simply put, the investment casting process is made of fusible materials (such as wax or plastic), a fusible model (referred to as fusion mold or model), coated with a number of layers of special refractory coating, after drying and hardening to form a whole shell, and then melt off the model from the shell with steam or hot water, then the shell in the sandbox, filled with dry sand modeling around it, and finally the cast into the roaster after high-temperature
The dimensional accuracy of investment casting is high, generally up to CT4-6 (CT10-13 for sand casting, CT5-7 for die casting), of course, due to the complex process of investment casting, there are more factors affecting the dimensional accuracy of the casting, such as the shrinkage of the mold material, the deformation of the molten mold, the change in the linear volume of the shell in the heating and cooling process, the shrinkage of the alloy and the deformation of the casting in the solidification process, so the general Although the dimensional accuracy of molten die castings is high, its consistency still needs to be improved (the dimensional consistency of castings with medium and high-temperature wax materials should be improved a lot).
When pressing the molten die, the cavity surface finish is used to press the mold with a high surface finish. In addition, the mold shell is made of high temperature resistant special binder and refractory material formulated with refractory coating hanging on the molten mold, and the surface finish inside the cavity in direct contact with the molten metal is high. Therefore, the surface finish of molten die castings is higher than that of general casting parts, generally up to Ra.1.6~3.2μm.
