INVESTMENT CASTING

Difference Between Sand Casting And Investment Casting

Here are some key differences between the two processes:

(1)Materials: Sand casting is typically used for casting larger, more basic shapes made of iron, bronze, brass, and aluminum, while investment casting is used for smaller, more intricate shapes made of metals like steel, stainless steel, and titanium.

(2)Process: Sand casting involves making a mold out of the sand, which is packed around a pattern made of wood or metal. Molten metal is then poured into the mold, and after it cools and solidifies, the sand is removed to reveal the casting. Investment casting involves creating a wax pattern, which is coated with a ceramic shell. The wax is then melted out, leaving a hollow shell that is filled with molten metal. Once the metal has solidified, the shell is broken away to reveal the casting.

(3)Surface finish: Sand casting typically produces a rougher surface finish, while investment casting produces a smoother and more precise finish, with very fine details.

(4)Tolerances: Investment casting is capable of producing parts with much tighter tolerances than sand casting, making it ideal for parts that require high precision and accuracy.

(5)Tooling: Sand casting typically requires less tooling than investment casting, as sand molds can be easily created and reused. Investment casting, on the other hand, requires the creation of a new wax pattern for each casting, which can increase tooling costs.

How Is The Surface Finish Of The Final Part Achieved In Investment Castings?

The surface finish of the final part in investment casting is achieved through a series of processes that are designed to remove any surface imperfections, such as flash or roughness, and to create a smooth, even finish. Here are some of the options:

(1)Grinding and sanding: Grinding and sanding can be used to remove any rough spots or imperfections from the surface of the part. This is typically done using a belt sander or other abrasive tool.

(2)Polishing: Polishing can be used to create a smooth, mirror-like finish on the surface of the part. This is typically done using a polishing wheel or other polishing tool, along with a polishing compound.

(3)Shot blasting: Shot blasting involves using high-pressure air or water to blast small metal or ceramic particles at the surface of the part, removing any surface imperfections and creating a uniform finish.

(4)Chemical treatments: Chemical treatments, such as acid etching or electroplating, can be used to create a specific surface finish, such as a matte or shiny finish. These treatments can also be used to add a layer of corrosion protection to the part.

(5)Tumbling: Tumbling involves placing the part in a rotating barrel along with abrasive media, such as ceramic or plastic beads, to remove any burrs or rough spots on the surface of the part.