Introduction
The term Investment Casting was created when an analogy was drawn to the method used for creating art pieces by investing the shape in wax and then encasing it in plaster. Investment Casting is the process of precision casting in which a wax mold of a desired shape is covered with a refractory slurry to form a shell, which is then heated to vaporize the wax as well as cure the refractory shell. Investment casting is commonly used to manufacture high precision and intricate components that could not otherwise be made using traditional casting methods.
Investment casting has been used in a wide range of industries, such as automobile, aerospace and medical, where intricate and complex shapes are required. The most important advantages of this process are high precision and accuracy, low cost and flexibility in design, as well as significant cost savings from reduced machining requirements and lower scrap rates.
History
Investment casting was first developed over 6,000 years ago, when the Egyptians and Chinese used the process for the creation of small sculptures. The modern version of this process was originally developed in the late 18th century in Europe, for the manufacture of porcelain figurines. Over time, the technique was refined and perfected, and is now widely used for a variety of metal manufacturing processes including aerospace and medical components.
Process and Materials Used
The process of investment casting begins with the creation of a wax pattern. This is usually done by injecting molten wax into a die, or by hand carving the desired shape from a block of wax. Once the wax pattern is complete, it is encased in a refractory slurry to form a refractory shell. This shell must be allowed to cool, before the wax can be melted out of the shell and replaced with molten metal. Once the molten metal has been poured into the shell, it is allowed to cool and solidify. Once the metal has cooled and solidified, the refractory shell is then removed and the casting is complete.
Both ferrous and non-ferrous alloys are commonly used for investment casting. Steel alloys, aluminum alloys, copper alloys and titanium alloys are among the most commonly cast metals, but virtually any metal can be used.
Advantages of Investment Casting
One of the main advantages of investment casting is the fact that it can produce complex parts with greater precision and accuracy than many other manufacturing methods. The process also has the benefit of reducing the amount of machining needed to finish a part, which can result in significant cost savings. Additionally, investment casting produces high quality surface finishes, is fast and efficient and allows for a great deal of design flexibility. Finally, scrap rates are often lower than with other manufacturing methods, providing additional cost savings.
Conclusion
Investment casting is a highly efficient and cost-effective process that has been used in a variety of industries to manufacture parts with complex geometries and precise dimensions. By using wax patterns and refractory shells, investment casting can produce parts with excellent surface finishes and tolerances of less than .02 mm. Additionally, the process is adaptable to a variety of different metals, and significantly lower scrap rates as compared to other processes. Investment casting is a reliable, consistent, and cost-effective method for producing precision components that is well-suited for low to medium-volume jobs.
