The Manufacturing Process of Investment Castings

Casting is an age-old process that continues to be of utmost importance for civilizational development. This is particularly so because science has not been able to devise a better technique for molding and structuring mineral resources into desired shapes and sizes. However, the casting process has been developed to fulfill the different kinds of demands that are encountered by industrial manufacturers in their day to day activities.

Investment casting is one type of casting process that involves the production of units using ceramic and hard shell molds. Investment casting manufacturers are often contacted when a client intends to produce multiple batches of a singular product that has a complex pattern. The intricate process of investment casting can be crystallized to the following essential steps:

Chalking and MaterializingMold Pattern

The mold pattern is the framework due to which a cast product attains its refined shape and specific dimensions. Drawing out a pattern as per the client’s specifications is the primary step for it directly affects the quality of production. Besides the minor thermal contraction changes that may occur at later stages, casting pattern is expected to be a flawless replica of desired cast design. Investment casting manufacturers use metal injections for carving patterns on wax.

Locking Down Wax Pattern

Once a sample pattern has been approved by the client, multiple patterns of the same size and shape are created. Each part of its parts is joined with the other to make a complete passageway for the liquid metal to flow. Once assembled, the pattern is referred to as a tree and each tree is firmly placed to a pedestal for further processing. The number of trees needed for production is calculated on the basis of the number of batches demanded by the client.

Creation of Mold Shells from Trees

Every tree is picked up carefully by cranes and dipped in a ceramic slurry. Consequently, it is submerged into a sand stucco container to prevent running off of ceramic liquid. Each dipping cycle forms a layer on the tree surface that later becomes the mold shell thickness. Soinvestment casting manufacturers continue the dipping process until the desired shell thickness is not achieved.

Removal of Wax from Shell

Mold shell cannot perform casting processes until its hollow cavity is occupied with wax. Hence, the steam autoclave is used to melt away the unwanted wax filled in the crevices of the shell, while heating by an open fire is used to extract out the little amounts of wax filled in cavities. The heating process is also necessary because it stabilizes the mold shells and makes them harder. When it is ensured that no amount of wax is left in the shell, it is sent further for casting.

Performing Casting Operations

Once the mold shells are ready, the only significant step left to do is pouring in of liquid metal into them for casting units. For better results, manufacturers often conduct this process in an isolated space where atmospheric conditions are measured up to optimum levels. As an exception, reactive metals are cast in a vacuum setup to ensure the safety of workers and high-quality output.

Machining until Perfection

For improving the surface finish of investment cast goods, they are sandblasted and machined using specialized instruments.

Investment casting manufacturers find their regular clients in electrical and piping industries because the precision required in the latter’s products can only be achieved by their production process. Thus, even though their services are slightly higher priced than other casting manufacturers, they are preferred almost invariably. However, before choosing investment casting, one must be thoroughly aware of its limitations as well.