Water glass composite shell VS Silica Sol shell investment casting for heat treament fixtures

Are you confused what’s water glass composite shell investment casting? You may know there are two main processes for investment castings: water glass shell and silica sol shell. Today let’s discuss water glass composite shell investment casting.

If you are not familiar with investment castings, you can refer my previous article: https://www.linkedin.com/pulse/investment-casting-production-process-eva-kong/ 

Water glass shell temperature resistance is low, it’s suitable for carton steel castings, as the temperature of molten carbon steel is about 1450°C. Molten heat resistance steel is more than 1600°C，the water glass shell will be broken if use it to pour heat resistance steel shell castings, and the material of water glass shell will react with the alloy in heat resistant steel.  So water glass shell can’t be used to produce heat resistant steel castings. But water glass shell is much cheaper than silica sol shell, after years of production experience, we successfully developed a cost-effective process for heat resistance steel fixtures: Water glass composite shell. 

Following is the main difference for Water glass composite shell and Silica Sol shell investment castings: 

1, Outer surface: Silica Sol shell casting surface is better

For Water glass composite shell castings, when making shell, silica sol shell is used on the first layer (face layer) and second layer (transition layer), water glass shell is used from the third layer, until the desired shell thickness achieved. As the first and second layer are very thin, so the casting surface is not as better as Silica Sol shell castings. 

2, Dimension accuracy: Silica Sol shell castings dimensions are more accurate

The shrinkage rate of water glass shell is higher than silica sol shell, wax used in water glass composite shell casting is low temperature wax, it’s medium temperature wax used in silica sol shell casting. The shrinkage rate of low temperature wax is higher than medium temperature wax, as a result, the casting dimensions of silica sol shell casting are more accurate. 

3, Price: Water glass composite shell castings are cheaper as water glass shell material is cheaper. 

4, Inner quality and life time of castings: Both casting process are the same.  

Conclusions: Water glass shell investment casting is cost-effective for heat treatment fixtures, Silica sol shell casting is suitable for customers who pursuit the good appearance of castings. 

Contact Shinning Metals to check if your heat treatment fixtures are suitable for Water glass composite shell castings.