Titanium Investment Casting: Less Common, but Just as Important
Titanium is not your typical investment casting metal. The combination of its very high melting point and its high cost can make titanium less attractive than lighter, more malleable, less expensive metals. Aluminum, stainless steel, copper and nickel are more commonly investment cast than titanium. However, in certain ways, titanium is well-suited to investment casting.
Investment casting is a complex, time-intensive and labor-intensive process. It involves many steps. First, a wax pattern must be designed by engineers. The wax pattern is designed in the shape that the desired cast metal product will take when finished. Then, the wax pattern is submerged in a slurry of ceramic materials, and the ceramic is often coated with sand. This process can be repeated many times, depending on the circumstances. After this step, when the ceramic shell hardens, the wax pattern is melted out of the shell and discarded. Molten metal is then poured (or invested) into the shell, and when it cools and hardens the metal emerges as a newly investment casting. Because the process is labor-intensive and is used to create complex, specialized parts, it can be costly. However, titanium is itself a specialty metal of sorts; because of its unique properties of strength, non-toxicity and corrosion resistance, titanium is an in-demand quantity for specialized applications.
In the medical products industry, for example, titanium can be investment cast in order to form prostheses. Because prosthetics must be specially formed and completely defect-free, the titanium investment castings are particularly well-suited for use as medical devices. The investment cast titanium prostheses require comparatively little finishing and are unlikely to cause reactions in patients or degrade to the extent that they cause injury. So, though titanium is a special metal and can be expensive, it also can be uniquely suited to the investment casting process in some applications.