Lost wax casting or precision casting or investment casting is a popular and well-known metal casting process. For centuries, this method has been used to make jewelry and various fine metal products. It is a popular choice because of its accuracy, integrity, and repeatability.
Lost Wax Casting’s History
Precision casting has existed for hundreds of years. The oldest recorded example of this method dates back to the early 3700 BC. They were unearthed in a cave in Southern Israel. Even in the Mesopotamian Civilization, lost wax casting was used for large-scale and small-scale casting.
Objects cast through the precision casting technique have been discovered in different parts of the world like Africa, Greece, Pakistan, Europe, etc. So, the technique came into existence thousands of years ago, but it still plays a major role in today’s casting industry.
What kind of wax is ideal for lost wax casting?
The best kind of wax used for investment casting is microcrystalline wax. It is pliable and sticky in nature. This type of wax has a crystal structure and is soft, making it the perfect wax for delicate metals.
Difference between sand casting and investment casting
People often get confused between lost wax casting and sand casting, but these two are processes are different. In sand casting, the metal is melted and poured into a specific mold made of compact sand and this technique is perfect for large metal parts. Moreover, investment casting is a complex process and is costlier than sand casting. Lastly, investment casting processes complex parts than sand casting cannot process.
Phases of Investment Casting
1. Cutting the aluminium tool to proceed with aluminium casting
2. Creating a positive model in wax
3. Assembling the wax on a runner system
4. Construction of a ceramic shell surrounding the assembly via investment (a dipping process followed by drying)
5. De-waxing of the shell with the help of high-pressure steam and firing in an oven for providing mechanical strength
6. Pouring of the molten metal into the shell which is pre-heated
7. Breaking the ceramic after the metal is cooled
8. Cutting of the parts from the runner system
9. If necessary, setting, machining, and finishing
Advantages of Precision Casting
1. This method is ideal for complex and small parts. With investment casting, dealing with small parts becomes easy.
2. One of the major benefits of precision casting is that the products do not need finishing jobs or secondary processing. The surface is almost ready and there is no need for additional polishing.
3. Getting precision casting designs is also cost-effective. Compared to other metal casting processes, lost wax casting is undoubtedly cheaper.
4. For metals with a high melting points, investment casting is the best solution. Machining those metals by other methods can be hectic.
Wrapping Up
Lost wax casting has various applications, casting jewelry being the most common use. In the medical industry, hip and knee implants are remarkable instances of precision casting. The automotive, mining, aerospace, and rail industry too require metal components shaped by precision casting.
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