Silica Sol Investment Casting

The silica sol also shares the name of water glass in general. It is used in the metal casting process as mold adhesive which is mixed with sand and several other materials. The silica sol is applied to both sand casting and silica sol investment casting technics. Silica sol investment casting is one of the most common investment casting processes. As the molding material, silica sol is able to stand temperature up to 1800℃. Similar to other investment casting processes, the silica sol investment casting process mainly consisted of wax injection, assembly, shell preparation, dewax, pouring, cut-off, finished casting, etc.

What is silica sol casting?

Compared to the resin sand casting, the silica sol investment casting method dewaxes into the high-temperature water, and the ceramic mold is made of water glass quartz sand. The surface quality made by silica sol investment casting is not as good as the resin casting, but it's cheaper and a bigger-sized part could be manufactured than silica sol casting.

Application of Silica Sol Casting

Mainly the silica sol is applied to the precision casting, because of its relatively high production cost but gives out a very fine accurate dimension, nice surface finish, and very good quality result overall. One of the other advantages of silica sol investment casting is that the internal defects such as porosity, holes, and shrinkage are better controlled compared to another way of casting. So when you looking for a method to produce a small part but with high accuracy, surface demand, and high corrosion resistance and you don't want to waste time waiting for the casting quality to slowly improve gradually, silica sol investment casting is surely on your options list.

Basic Property of Silica Sol Casting:

dimension tolerance ±0.1mm, CT4~6；

surface finish Ra6.3;

wall thickness up to 1mm;

unit weight extent 0.1~100kg;

the unit size limitation of 0.01~0.5 meters;

degree of complexity- very complex;

machining required- less or none due to its accurate dimension;

production lead time- long;

production cost- high.

Influence Factor in Silica Sol Investment Casting

The whole process of silica sol investment casting has more than 40 procedures, which is complex. There are many factors that affect the casting quality.

There are many kinds of raw and auxiliary materials, such as silica sol, wax, zircon sand, molybdenum powder, defoamer, wetting agent, steel, rare metal, etc. According to the different mesh, there are more than 10 kinds of sols, including precision casting surface silica sol, precision casting backside silica sol, ordinary silica sol, enhanced silica sol, fast-drying silica sol, and zirconia powder. It is not suitable to control its quality, which affects the silica sol investment casting quality in different degrees.

The production cycle of silica sol investment casting is long and there are many uncontrollable factors. In the whole process, only the shell-making process takes 3-5 days. It takes 6-8 hours to dry the surface shell of silica sol, 4-6 layers to dry the back shell of silica sol, and 8-12 hours to dry the shell without silica sol. There are too many uncontrollable factors and defects will be formed with slight deviations in the silica sol investment casting process.

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