Investment Casting

Castings vs Forging Comparison Chart

castings vs forging comparison chart

Investment Casting is known as the lost wax program. This process is one of the oldest manufacturing processes. The Egyptians used it in the time of the Pharoahs to make gold jewelry (hence the name investment) some 5,000 years ago. Intricate shapes can be made with high accuracy. In addition, metals that are hard to machine or fabricate are good candidates for this process. It can be used to make parts that cannot be produced by normal manufacturing techniques, such as items with complex shapes, or parts that have to withstand high temperatures.

The mold is made by making a pattern using wax or some other material that can be melted away. This wax pattern is dipped in refractory slurry, which coats the wax pattern and forms a skin. This is dried and the process of dipping in the slurry and drying is repeated until a robust thickness is achieved. After this, the entire pattern is placed in an oven and the wax is melted away. This leads to a mold that can be filled with the molten metal. Because the mold is formed around a one piece pattern, (which does not have to be pulled out from the mold as in a traditional sand casting process), very intricate parts and undercuts can be made.

The types of materials that can be cast are aluminum alloys, bronzes, tool steels, stainless steels, Stellite, Hastelloys, and precious metals. Parts made with investment castings often do not require any further machining, because of the close tolerances that can be achieved.