Manufacturing Shell Of Investment Casting

There are two types of materials used to manufacture the shell. One is used to directly form the shell, such as refractory, binder, etc;

The other is to obtain high-quality shell, simplify operation and improve process materials, such as flux, hardener, surfactant, etc.

1) Refractory

At present, the refractories used in investment casting are mainly quartz and corundum, as well as aluminum silicate refractories, such as refractory clay,Bauxite, pyrogem, etc. Sometimes zircon and magnesia (MgO) are also used.

2) Binder

The most common binder used in investment casting is silicic acid colloidal solution (hereinafter referred to as silicic acid sol), such as ethyl silicate hydrolysate,Water glass and silica sol, etc. They are mainly composed of silicic acid (H2SiO3) and solvents, and sometimes stabilizers, such as silica sol NaOH.

Ethyl silicate hydrolysate is the earliest and most common binder used in mold casting of silicic acid sol obtained by hydrolysis of ethyl silicate;

The water glass shell mold is easy to deform and crack, and the dimensional accuracy and surface finish of the castings poured with it are poor. But in China, when the production accuracy.

Water glass is still widely used in the production of carbon steel castings with lower requirements and non-ferrous alloy castings with lower melting point; The silica sol has good stability and can be stored for a long time. No special hardener is required when making the mold shell, but the wetting of the silica sol to the investment mold is slightly poor. The mold shell hardening process is a drying process and takes a long time.