Investment Casting vs. Sand Casting

What Is Investment Casting?

Also known as the lost wax method, investment casting involves six basic steps: 

1. Wax is poured into an aluminum mold of the part to be cast.
2. The wax shape is removed from the mold and attached to a "tree."
3. The wax tree is repeatedly dipped into a ceramic slurry, which hardens into a shell and serves as an investment casting mold.
4. The wax is melted out of the ceramic shell.
5. Molten metal is poured into the shell.
6. Once the metal has cooled, the shell is removed.

Investment castings can weigh as little as a fraction of an ounce or as much as several hundred pounds.

What Is Sand Casting?

As with the investment casting process, the origins of sand casting date back several thousand years. To create sand castings, a manufacturer:

1. Places a pattern of the part to be cast into sand.
2. Splits the sand mold in two and removes the pattern.
3. Secures the two halves of the sand mold.
4. Pours molten metal into the sand mold.
5. Removes the sand after the metal has cooled.

The sizes of sand castings range from a couple of ounces to several tons.

The Ins and Outs of Investment Castings

Investment casting is a precision casting process that's well suited to aerospace and defense applications. It can produce highly intricate parts, pieces with very thin walls and components with complex internal configurations.

Other advantages of investment castings include:

• Design flexibility
• Minimal material waste
• Extremely close tolerances
• Less weight

The investment casting process produces superior surface finishes, so parts require less post-production machining. Investment castings have fewer joints and require less secondary assembly. Because of the precision of this metal casting method, an investment casting manufacturer can deliver a high level of repeatability and consistency.

The Ins and Outs of Sand Castings