Steps in Making Sand Castings

The six basic steps in making sand castings are:

1. Pattern Making

2. Core Making

3. Molding

4. Melting and Pouring

5. Cleaning

Pattern Making

-Pattern: A replica of the part to be cast, used to prepare the mold cavity. It is a physical model of the casting used to make the mold. Made of wood or metal.

The mold is made by wrapping some easily moldable aggregate material, such as molding sand, around the pattern. When the pattern is removed, its impression provides the mold cavity. This cavity is filled with metal and becomes the casting.

-If the casting is hollow, additional patterns called "cores" are used to form these cavities.

Core Making

The casting core is placed in the mold cavity to form the inner surface of the casting. As a result, the void space is filled with molten metal and eventually becomes the casting.

Molding

Casting is simply the activity of preparing the mold to receive the molten metal.

Molding generally involves: preparing a consolidated sand mold around a pattern held within a supporting metal frame, removing the pattern to leave the mold cavity with the core.

The mold cavity is the primary cavity.

The mold cavity contains liquid metal which acts as the negative electrode for the desired product.

The mold also contains auxiliary cavities which are used to pour and direct the liquid material into the main cavity and act as a reservoir when required

Melting and Pouring

The process of preparing molten metal for casting is simply called melting. The molten metal is transferred to the pouring area where the mold is filled.

Cleaning

Cleaning involves the removal of sand, scale and excess metal from the casting. Burnt sand and scale are removed to improve the surface appearance of the casting. Excess metal, in the form of fins, wires, parting line fins and gates, is removed. The casting is inspected for defects and general quality.