Laszeray Technology, LLC is a leading provider of casting services. Our investment casting tooling systems include but are not limited to wax injection tooling. Investment casting is an economical means of mold and tool-building. Wax has proven to be a highly effective material for rapid prototyping (including CAD and 3-D printing methods) of models used to represent a final part’s shape and geometry.
With wax injection tooling, the wax’s shape is used to form a ceramic mold. A cavity is formed when the wax is removed; this can be filled with metal or other materials later to form parts. There are several steps involved in preparing the wax.
Conditioning the Wax
Before the liquid wax is injected into a cavity, wax pellets are melted in a holding tank. Agitation helps provide consistency to the mixture. The mold cavity it will be injected into is larger than the final product’s dimensions, to account for shrinkage of the wax material and casting metal. This document from the Institute of Electrical and Electronics Engineers helps calculate linear shrinkage using several variables and provides more insights into creating a wax injection tool.
A vacuum casting machine can be used to pattern the wax. However, during the injection molding process, liquid wax is often moved hydraulically from the tank to an injection cylinder. The tool is then closed. Next, the wax is pushed through a heated hose into the injection tool. It fills the cavity and solidifies, forming an investment casting pattern that’s removed once the injection die is opened, and it is then placed on a tray. It is important to monitor the temperature and pressure of the system during this process.
The wax must be carefully removed from the cavity. It then needs to cool in order to maintain its shape. Initially, a wax pattern is very soft and must be evenly supported. A cooling jig that has the same detail as the aluminum injection tool may be used. Sometimes, engineers may use spacers to prevent the wax from distorting as it cools, yielding higher-quality investment casting tools.
Each wax pattern is assembled onto a wax runner, which is later used to feed metal into ceramic casts. The runners are then injected with wax. A metal part at the end of the runner aids in extrusion, while a ceramic cup placed on the wax assembly locks the ceramic mold and funnels the metal as it’s poured in. The tool plate and frame assembly are modular, so the material can be reused to produce additional tools.
Custom Wax Injection Tooling
Wax injection is an efficient process. One study found that design, assembly, and injection took 10 days, saving a great deal of time over other processes, which can take two months or more.1 This makes the process highly suited for mass production.
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