Investment casting is one option for creating intricate parts and components. There are several specific steps in the entire process to design and create the desired workpieces. It is named such because the workpieces are created around a shelled casting, which is later removed once the workpieces have been poured into the mold and are set.
Steps 1: Creating the Die/Pattern
The first step in the process is to create the die or pattern of the desired workpiece. The pattern is made from wax. It can be poured into a die using injection molding, carved by hand from a block of wax, or printed using a 3D printer and the appropriate wax material.
Step 2: Mounting the Wax Patterns
Investment casting tooling involves creating multiple wax patterns and attaching these onto a “gate” device. This device is where metal or other materials will be poured to eventually create the desired workpieces.
Step 3: Tree Assembly
The tree assembly finishes the mounting of the wax patterns on the “gate” device. It is called a tree at this step because each individual wax pattern is essentially a “branch” and will be one finished workpiece once the process is finalized. You may have seen tree assemblies in new board games that need to have pieces detached before use.
Step 4: Shell Molding
Once the tree is assembled, the next step is to add the shelled casting around it. First, the tree is dipped into a ceramic slurry. Then it is dipped into a stucco of fine sand. The molding must fully dry before it can be used. These two processes can be completed multiple times until the mold is thick enough to handle casting stresses.
Step 5: Wax Removal
Before the desired material can be poured into the newly shelled mold, the wax patterns have to be removed first. This is often done by heating the wax inside an oven. Steam can also be used to heat the wax. The mold is placed upside down so that the liquid wax can flow out of it and be reused to create new wax patterns.
An alternative process of wax removal is to heat the wax so that it “burns” off and is fully removed from the shelled casting.
Step 6: Mold Casting
After the wax has been removed, there will be open spaces inside the shelled casting in the shape of the formal wax patterns. Molten metal or another liquid material is poured into the casting. The material remains in the casting until it has fully cooled and solidified.
Step 7: Removing the Shelled Casting
A hammer or another tool is used to remove the shelled casting until all that is left is the original tree. In place of the wax patterns, there will now be the finished workpieces attached to the tree. After the casting has been removed, the workpieces are carefully cut off the tree.
Step 8: Finishing Operations
Each workpiece is inspected for imperfections. If any are found, they are discarded, and the material is recycled. The last step in the investment casting process is to use different finishing methods on the workpieces. They may be sanded, coated, smoothed, machined, etc. to achieve the desired results.
Investment cast tooling is well-suited for large quantities or intricate workpieces that require precision details. The exact steps in the process can and do vary based on the complexity of the workpieces being created.
To learn more about investment casting and whether this is the best solution to create the workpieces you require, please feel free to contact Laszeray Technology, LLC at 440-582-8430 today!
We offer a wide range of services, including product design, rapid prototyping, injection molding, investment casting, CNC machining, secondary and finishing operations, and more!
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