At present, there are four main shell making processes used in the domestic precision casting industry: silica sol low-temperature wax shell, composite shell, water glass shell, and silica sol medium temperature wax shell. Among them, the first three shell making processes all use low-temperature wax molds, while the fourth one uses medium temperature wax molds.

1. Water glass shell

The water glass shell process requires low cost, short production cycle, excellent shelling performance, and high breathability, which are also advantages that other processes cannot match. In recent years, due to the improvement of refractory materials and the widespread application of new hardening agents, the strength, standard accuracy, casting surface quality, and yield of the shell produced by this process have been greatly improved

2 Composite shell

Due to the aforementioned drawbacks of the water glass shell process, many manufacturers now choose the composite shell process, which means that the second layer uses zircon/mullite silica sol shell, while the back layer still uses water glass shell. This method combines the advantages of silicone shell and water glass shell, improves the surface quality of castings, reduces surface roughness, and reduces the repair rate.

3 silica sol (low-temperature wax) shell

The silica sol (low-temperature wax) shell process has its common advantages and adaptability in manufacturing large parts. The low-temperature wax shell process is relatively simple compared to the medium temperature wax equipment, and the molding is simple. The final surface roughness obtained is not significantly different, which can meet the lower requirements of standards, accuracy, and other aspects for medium and large castings. Compared with composite shells, it has high standard accuracy, good high-temperature performance, and strong creep resistance. This process can produce both thin-walled and small parts, as well as oversized parts, and can achieve a high yield.

4 silica sol (medium temperature wax) shell

This process is a popular precision casting production process internationally today, which produces high-quality castings with low repair rates, making it particularly suitable for the production of small and medium-sized parts.