Sodium Silicate Investment Casting (Water Glass Casting): A Comprehensive Overview

Sodium silicate casting is a common processing of precision casting used in the most precision foundries. We’ll make brief introduction about the it’s principle and detailed processings.

Firstly, we need to melt and mold the glass. Generally, after the mold is made, the liquid glass is poured into the mold or the leftover glass is stacked in the pre-made mold, and then the mold is put into the furnace and the pre-made mold with leftover glass is annealed.

Lost wax casting is using the mud to replicate the silicone rubber mould fixed by plaster which the liquid wax is poured into and generate the “wax prototype” which known as the “wax pattern”.

Removing the wax pattern once it cooled, then embedded with fireproof plaster under high temperature to dewax and form the desired shape. After that, the mould with the glass blanks within the shapes is putted inside the furnace to melt the glass blanks until the mould is completely filled and then annealed.

The glass blocks or plates, especially the flat glass which will cover on the deep mould, are cut into a certain shape according to the mold.

This is because that we must leave some allowance to smoothly place the glass blanks on the edge of the grinding tool support in the heating furnace since there will be slight changings arisen by glass softening and bending.

If the desired component is with bigger curve which will require a deeper mould, we can split the heating processing into 2 times in accordance with the actual size and thickness of the part, and then apply the annealing treatment.

Above are some fundemental processing methods for precision casting and there are some other casting processes for the industry. The casting processing will need to be decided by actually desired component.

The main differences between the advantages and disadvantages of sodium silicate sand fine casting and cold hardened resin sand casting are mainly due to the different binder and hardener, which generate different processings.

Sodium silicate is colorless, odorless, non-toxic, and easy to remove by washing after staining on skin and clothes, but must avoid splashing in people’s eyes. There’s no black and acid pollution, like irritating or harmful gas, during the sand mixing, molding, hardening and pouring process.

But with improperly operating, like too much sodium silicate added, it’s collapsibility is then affected. Pollution can also caused during the sand removal process. There are also other disadvantage of the Sodium silicate casting, like difficulty of old sand recycling and alkaline pollution caused by the discharge of waste sand.