The Investment Casting Process
This detailed explanation of the investment casting process is intended to help our customers learn about investment casting to be able to make better purchasing decisions.
Replicas of the desired investment casting are produced by injection molding or for smaller volumes using rapid prototyping (SLA or SLS). These replicas are referred to
ASSEMBLY OF WAX TREE
Patterns are then attached to a central wax stick, called a sprue, to form a casting. This is called a wax tree.
CERAMIC SHELL BUILDING
The shell is built by immersing the wax tree assembly in liquid ceramic slurry and then into a bed of fluidized fine sands. Up to eight layers may be applied in this manner depending on the shape and weight of the part.
Once the ceramic is dry, the wax is then melted out, creating a negative impression of the assembly within the ceramic and sand shell. This process uses autoclaves to maintain shell integrity.
In the conventional lost wax casting process, the preheated shell (up to 1800 deg F) is filled with molten metal by gravity pouring the metal into the ceramic shell. As the metal cools, the parts, gates, sprue and pouring cup become one solid casting. Shell temperature and melt temperature will vary depending on the alloy.
Once the metal is cooled and solid, the ceramic shell is broken off by vibration or water blasting.
CUT OFF OF PARTS
The parts are then cut away from the central sprue using a high speed saw.
FINISHED METAL INVESTMENT CASTINGS
After minor finishing operations, or possible required machining operations, the metal investment castings--identical to the original wax patterns--are ready for shipment to the customer from our metal investment casting China foundry. We are able to provide finished stainless steel investment casting, steel investment casting, aluminum investment casting, cobalt alloy investment casting, nickel alloy investment casting and precision investment castings.
Please call for tolerance specifications for wall thickness or any tolerances in general. Depending on the metal or alloy, minimum wall thickness can range from 0.04 inches to 0.08 inches.