What is the Investment Casting Process?
The investment casting process, similar to Lost-Wax casting, is thousands of years old. Documented for the first time around 1100 A.D. by a monk named Theophilus Presbyter, the term “investment” refers to the mold being filled or invested with metal. Investment casting was originally used to produce decor, religious statues, and jewelry. This investment casting process eventually made its way to the industrial revolution and became a favorite method of Dentists for creating crowns and inlays. The investment casting process is still used today to produce intricate castings with brilliant, smooth finishes.
Investment Casting Process
Investment casting is the process of casting in which a mold is created:
1. Creating a Pattern
- Patterns are made from wax (though some use plastics) using a metal injection die.
2. Assembling the Wax Patterns With the Tree
- Once the pattern is created, it will be assembled with other components to create a gate and runner metal delivery to create the casting.
- Depending on the finish component size and configuration, multiple wax patterns can be processed on one tree.
3. Mold Shell
- Once the wax pattern is assembled it gets dipped in a ceramic slurry then covered with sand stucco and given time to dry.
- If necessary cycles of wet dipping and stuccoing are repeated until you acquire the desired shell thickness.
- Once the ceramic shell has dried, it has become strong enough to retain molten metal during the casting process.
4. Wax Removal
- The assembly is put inside a steam autoclave to melt away the wax.
- If any wax remains it will be burned out in a furnace. Once all the wax has been removed, the cavity with the shape of a desired cast part.
5. Melt and Cast
- The mold is preheated to a temperature that is specific and then filled with molten metal, creating your desired metal casting.
6. Final Touches
- When the casting has cooled, the mold shell is broken from the casting in a knockout operation.
- If necessary the gates and runners are cut from the casting, and if necessary it will be sandblasted, ground and machining are performed to finish the casting dimensionally.
The Pros of Investment Casting
Investment casting is a technique people have been using for hundreds of years, and for a good reason: it works great! The pros of investment casting include:.
- Ideal for creating intricate patterns as metal castings made with the investment casting process can be made very thin with great accuracy.
- The hard molds within the investment casting process allow for a smoother surface of the final product.
- The size range of the investment casting products can range from very small to greater than 1,000 lbs. While most parts are 20 lbs or below, some investment casting experts have larger production offerings.
- Products created from investment casting are often high-quality and dependable. Investment casting has been used in industries such as defense, medical, chemical, petroleum, and more.
The Cons of Investment Casting
While investment casting is an efficient, reliable process, there are a few cons to consider:
- Although the wax can be used many times, the ceramic shell can only be used once, making the process slightly more complicated and expensive.
- The process is not completely automated and involves manual procedures.
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General Kinematics is a great investment for any casting process or pattern. With over half a century of experience and a track record for reliability, GK’s equipment can improve the performance of your metal casting process. Ask a GK Engineer how we can automate your workflow today, check out our foundry equipment, or read the stories of others in the metal casting industry that have used (and loved!) GK equipment to improve the investment casting process.
Frequently Asked Questions
What is investment casting used for?
Investment casting is a production technique used for creating intricate metal objects. It was originally used for making decor, jewelry, and religious statues but is now commonly used for producing high-quality, intricate casts of objects such as dental crowns, pieces of firearms, parts of turbine engines, medical instruments, and more.
What is the difference between die casting and investment casting?
The die casting process has reusable molds while the investment casting process requires disposable molds.
How do I start investment casting?
To begin investment casting, you will need the correct tools and supplies such as wax, molten metal, plaster, and the tools to handle all of it. If you think investment casting would benefit your production process, ask a GK engineer about how to get started today!
