Initially, before the casting process begins, an injection die is constructed to produce precise wax patterns.
A specially formulated wax is injected into a die to produce the pattern for the part.
The individual wax patterns are assembled onto a wax sprue to form a mold or tree.
A ceramic mold is created by dipping or "investing" the assembled patterns in liquid ceramic slurry, draining, and then coating with a dry "stucco" sand. After drying, this process is repeated several times until a specified shell thickness results.
5.Dewaxing and Firing
The wax is melted out with steam heat in an autoclave and is recycled. Firing at 1800 degrees Fahrenheit fuses the ceramic particles so the mold can withstand the pressure and temperature of the molten metal. It also removes all traces of organic materials.
Molten metal is poured into the pre-heated molds. Typical pouring temperatures are approximately 3000 degrees Fahrenheit for steel. The investment casting process is unique in the broad range of alloys that can be cast.
The ceramic shell is removed from the metal mold by vibration.
8. Casting Removal
Metal castings are removed from the runner using abrasive wheel cutoff saws.
The material protrusion left from the gate, called the gate witness, is ground to print specification using a fixture for repeatability and efficiency.
10. Finished Castings
The final cleaning operation is performed using a blast with abrasive grit or steel short. This blasting produces a surface finish of 90-125 microinch Ra
Typically, investment casting can provide a cast shape that requires no secondary operations. If premium tolerances, surface finish, or coatings are required, Lianmei can supply part-to-print processing.