Using Soluble Cores in Investment Casting

Do your metal components require complex inner cavities?

Investment casting is ideal for parts that require tight tolerances, repeatability, and complex design characteristics. For parts that require particularly complex inner cavity configurations, our design engineers can incorporate a soluble core into the investment casting process. The use of soluble cores allows for more intricate cavity patterns to be included in the casting, reducing or eliminating the need for additional machining.

Designing for soluble core

Incorporating a soluble core into the investment casting process is achieved through strategic design and a few additional steps to our advanced investment casting process.

During the standard investment casting process, the pattern wax is injected into the mold cavity, cooled, ejected, and then attached to the sprue before continuing on for the remainder of the casting process. If the part does not require a particularly intricate core, this process is automated with our state-of-the-art technology. If the part does require an inner channel, the soluble core process is best-achieved by one of our specialized operators.

First, a soluble wax is injected into a mold to form the geometry of the core. The core is then ejected from the mold and cooled.

An operator will mount the soluble core in a precise position within the cavity of the mold for the entire component. The position of the soluble core within the mold is held by points of support that are incorporated into the mold during the design process. The added support ensures that the core stays in place when the pattern wax is injected and helps to facilitate the removal of the wax from the mold. The mold is then closed and the pattern wax is injected into the cavity around the soluble core. In the mold, the soluble core creates the inner baffles, channels, and ports that will be included in the final casting.

Once the pattern wax is cooled, the whole part is ejected from the mold. The part is then inserted into a bath of mild muriatic acid, and the soluble core is dissolved out, leaving behind a geometrically complex core that could not be otherwise achieved with standard investment casting.

The remaining pattern wax is then attached to the sprue and continues through the remainder of the investment casting process as normal. The end product is a repeatable, intricate part that delivers high performance without demanding costly secondary operations.

So why soluble cores?

Utilizing soluble cores provides many benefits, but the biggest benefit is the ability to design components with more complexity in the core of the part without costly secondary operations.

Without the need for additional machining, engineers enjoy greater design freedom. Additionally, the elimination of secondary operations mean that you’ll save time in the manufacturing process, and therefore, save on manufacturing costs.