Wax injection is a process used for producing multiple castings via the lost wax casting process.
To produce the wax model for each individual casting, a rubber mold is used. This mold can be produced from an original metal piece.
The mold is formed by pouring melted rubber into a form around the piece. A sprue is attached to allow wax to enter the mold from one end, and a vent is left to allow air to leave. The mold is in two or more pieces, to allow easy removal of the wax model without damage.
Once the injection mold is formed, it can be used to produce the wax model for investment casting. Casting wax is melted in the injection machine, and the mold is placed in a special clamp that prevents it from distorting under pressure. The injection machine forces the molten wax into the mold, where it is allowed to cool and harden. The end result is a wax model of the original piece, with a sprue attached, ready for investing.
Wax injection is often used in conjunction with treeing to easily produce a large number of similar pieces.
Wax injection is very similar to the injection molding process used for production of plastics.