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What is Water Glass Investment Casting

Update On Sep 30.2022

What is Water Glass Casting

Water glass casting is one of the most common investments casting processes in China, but it is rare in other countries. (Originally cast in Russia, Water glass casting is also known as sodium silicate casting). Among Chinese investment foundries, about 85% of the foundries focus on water glass casting, and the rest are silica sol foundries.

Would you like to learn more about water glass investment casting? Read on as we walk you through all the essentials of water glass casting services.


What is Water Glass Investment Casting? Definition

Water glass casting is also called sodium silicate casting. Its casting process is very similar to investment casting (that is the lost wax investment casting method). It is a technology that uses water glass as the binder for the shell to cast. The process provides a far superior surface finish and dimensional precision to that achieved through sand casting. And more complex shapes can be achieved.


What is Water Glass Casting Process? How Does This Work

1. Wax Injection

For each casting to be made, melted wax is injected into a mold to produce a wax pattern of the casting. The wax molds are constructed of Aluminum and sized to account for shrinkage in the wax and metal that are being used. Wax tooling ranges from simple two-piece dies to multi-cavity automated dies and complex dies featuring water-soluble or ceramic cores.

2. Wax Assembly

Once the wax patterns have cooled and settled to a stable size and shape, they are mounted onto a sprue or tree. The sprue, also made of wax, contains all of the necessary gates, runners, and supports to adequately feed the part during the casting process.

3. Shell Building

The wax sprue is now “invested” in ceramics to create the mold for the metal to be poured into. The ceramic consists of two parts, a liquid slurry covered with dry sand. Each sprue is covered in multiple layers of slurry and sand until the ceramic shell is thick enough to hold up during the casting process. The shell building process usually takes 24 hours, with anywhere from 2 days to almost 2 weeks for the shells to fully dry.

4. Dewax

Once the shell has fully dried, the wax is melted out using an autoclave to counteract the expansion of the wax. The shells are then fired to remove any remaining wax residue and cure the ceramic shell. Once the shells have been fired, they are now ready for the casting process.

5. Casting

The processed shells are placed back in the oven to be pre-heated prior to casting. Once the shells are at the proper temperature and the molten metal has been prepared and qualified, the shells are removed from the oven and the metal is poured into the shells.

6. Finishing

The shell is hammered, media blasted, vibrated, waterjet, or chemically dissolved (sometimes with liquid nitrogen) to release the casting. The sprue is cut off and recycled. The casting may then be cleaned up to remove signs of the casting process, usually by grinding.


The Benefits of Water Glass Casting

It is advisable to try out water glass and here are the benefits that you are likely to gain from it:

Superior surface finish than sand casting

When it comes to metal casting, the quality of the surface finish matters. You would always want your metal to have a smooth finish. The good news is water glass investment casting has proven to be a viable solution to this problem.

High tolerance levels of water glass investment castings are more exact than other casting forms—particularly when contrasted with the sand cast, fashioned, or welded creations.

Such tight resiliences are useful for less or no machining and give predominant surface finishing.

Minimum casting defects

Water glass investment casting can supply high-quality products. The results of this process exhibit minimum casting defects

With the right control measures put in place, the rejection rates in water glass investment casting are fewer than in other methods such as sand casting.

Unrivaled casting tolerances

The issue of tight tolerance will always come up when analyzing different methods of metal casting and processing.

Contrasted with comparative metal machining processes, this method can meet great tolerance level CT5-CT6, which can keep away from further machining.

Regardless of whether more tight tolerances are required, when casting, we simply leave a small machining allowance, and less machining processing will be done after that.

Cost effective

There are many ways in which water glass investment casting has proven to be cost-effective. One way is by minimizing the loss of the material.

The close to the net state of water glass casting requires next to no machining, which limits material waste.

Water glass casting involves minimum scratching and scrubbing of the material. This means that you won’t waste material in the processing of metals.

Minimum wastage means that you will gain more economic returns.

Water glass casting requires more affordable hardware and is naturally less dangerous. It takes into consideration expenses to remain low.

The maximum utilization of the material and the form cost is low.

There is little water glass investment required for product development through investment casting.

So Manufacturing is basically cost-effective.

Larger size parts can be cast

Water glass casting is not limited by the size of the material to be processed. With it you can cast large products.

The method is also less affected by the weight of the material. You can weigh as little as 0.4kg and throw up to 200kg.


Main Applications of Water Glass Casting

Water glass casting components are mainly used for complex shaped parts. Applications of this technique are widely presented in the production of trailers, agricultural machinery and offshore industry. The water glass lost wax casting process provides a far superior surface finish and dimensional precision comparing to sand casting.  


The Difference Between Water Glass Casting and Sand Casting

While looking for water glass casting services, you might have come across sand casting.

Although the two are used for metal processing, there are some differences between them.

Sand casting is a process of producing casting from the sand molds

The table below summarizes the difference between water glass casting and sand casting:

Sand casting Water glass casting
Advantages Disadvantages Advantages Disadvantages
Low cost Rough surface finish Smooth surface finish High tooling cost
Easy to change design Somehow complex Cab process complex designs Longer lead time
Takes a short time Requires secondary machining Ideal for thinner walls Require longer production cycles


Besser Casting: Water Glass Casting Company

Are you looking for a reliable water glass casting company? Then we are the people you should talk to.

As a leading investment casting company in China, we provide overseas customers with high-quality water glass casting technology and casting services at reasonable prices.

We can meet dimensional tolerance CT7-CT8. Our value-added services (machining, surface treatment, heat treatment, etc.) ensure that we ultimately deliver finished castings to our customers. To be more competitive, we have introduced automated production lines.

With such an automated production line, we can keep the quality of water glass castings stable. And help save labor costs and shorten production time. This line is ideal for castings with high volume requirements.

Just contact us and we will be happy to meet your investment casting needs.

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