The
investment casting process starts by making a pattern that has the same shape as the finished cast part. A sacrificial pattern is the name used for the pattern because you make the pattern from wax,and it will melt away in the process. Specifically,you make the pattern by injecting wax into a metal wax injection die. You then dip the wax pattern in a ceramic slurry covered with sand stucco,repeating the process several times until you achieve the desired thickness. The thickness will depend on the specifications of the finished product and what raw materials you will use to make the final product.
The Mold
Once the ceramic slurry has dried,the mold is placed in an oven. This will melt the wax,leaving a one-piece mold that you can fill with your desired material. These molds are typically made using stereo lithography or other computer-aided technology; this makes the mold highly accurate. Examples of products made using
investment casting include aircraft parts such as turbine blades,armament parts,hand tools and jewelry.
Waxes
You can use a variety of industrial waxes to make
investment casting molds. Your specific needs for the final product will determine the type of wax that you should use. Filled pattern wax,emulsified pattern wax,straight pattern wax,low expansion wax and automatic injection machine wax are some of the waxes commonly used for this process. The viscosity,melting point and types of injections used are the primary considerations that will determine the type of wax you want to use.
Materials
Virtually any type of metal can be cast using
investment casting,including alloy steel,carbon steel,stainless steel,aluminum,copper,nickel,cast iron,lead,magnesium,tin,titanium and zinc. You can also use many precious metals. You will generally not need to use any machining for the pieces because of the accuracy of the
investment casting process.
References
WTEC; Metal Casting Applications; Clinton L. Atwood; March 1997
investment casting Wax: Categories of
investment casting Wax
Cypress Industries: The
investment casting Process