Usually, there are 3 types of sand that are used by the foundry to produce the metal casting part: green sand, sodium silicate sand, and resin sand.
The green sand, in Chinese foundry it is called clay sand because it is in red color and looks like to be clay. Green sand is the most commonly used sand because the sand can be reused, so making it to be a cheap method to do the casting jobs.
The sodium silicate sand has another name: water glass sand which is more popular among casting engineers. Sodium silicate is actually a liquid substance, it can be transformed into a solid with extremely fast speed when it is combined with carbon dioxide. So the foundry uses it to form the mold which is much more reliable than the green sand mold.
The resin sand. When the resin is heated, it becomes solid and with a very smooth surface. So using the resin sand to form the mold is able to produce a flawless and beautiful metal part. However, the resin sand is quite expensive while it’s used to make the highest quality casting product.
Sand casting actually refers to using sand to create the mold and to do the casting jobs. Sand-made mold is able to withstand the high temperature of melt metals. So if a pre-shaped mold could be created according to the product we need, pour the molten metal into the mold, after the metal cools and remove the mold, the finished product is available.
There is a very wide range of metals, such as iron, steel, brass, zinc, and most alloy can be applied to the sand casting process.
Investment casting employs a shell that is typically formed from the ceramic slurry, when it is dried and heated the inside wax pattern melts out, leaves the hard ceramic shell. Then the melted metal pour into the shell, after cooling and remove the shell, the final casting part is able to available.
The basic flow of the investment casting operation is as follows:
Heated the pattern
Mounting the wax patterns and creating the tree
Creating the mold shell
Melt and cast