When mentioning lost wax casting, most people associate it to the investment casting process. In fact, the two terms are sometimes used interchangeably. However, when people start talking about lost foam casting, these metal casting processes start to sound confusing. The confusion may lie with the fact that lost foam casting is remarkably similar to investment casting. When evaluating all these processes, we can determine both similarities as well as differences between them. Here is a straightforward guide to understand each one.

What is Lost Wax Casting?

Lost wax casting is a metal mold casting process that has been in use for thousands of years. This process involves creating a wax pattern of the intended part. This wax pattern becomes coated in a ceramic slurry and allowed to harden. The wax is later removed, and molten metal is poured into the ceramic shell to create the part.

What is Investment Casting?

Investment casting is another term for the lost wax casting method. It uses the wax patterns that are later melted or burned out of the hardened ceramic mold. The process allows for near net-shape of parts with exceptional surface finishes. Often, the metal part does not need additional machining and surface finishing details. A major advantage to investment casting is that the customers can select a wide variety of metals to use with this process. Also, investment casting tighter dimensional tolerances creates simple and complex parts in a range of sizes.

What is Lost Foam Casting?

Lost foam casting processes involve making a pattern made from expanded polystyrene. The polystyrene pattern becomes coated in the refractory slurry as the shell hardens. Then the shell has sand compacted around it to provide extra stability and support. Molten metal is poured into the shell as the polystyrene becomes vaporized inside. Customers may select lost foam casting methods when looking for a process that accepts a wide variety of ferrous and non-ferrous metals while gaining simple and complex parts that may require additional machining after casting.

Similarities and Differences

Both investment casting and lost foam casting processes are similar where they use patterns to make ceramic shells that will hold the molten metal to produce parts. The produced parts seldom require additional machining and both processes can be used for simple and complex parts manufacturing. Both processes can cast parts made from non-ferrous and ferrous metals.

The biggest differences of these processes:

• different materials to make the patterns
• investment casting has more processes, such as removing the wax from the shell
• surface finishes for lost foam castings are lower quality
• Tooling costs are higher for the lost foam casting method

Searching for the right manufacturing method allows you to obtain parts that are high quality, dimensionally accurate, and meet project deadlines. For more information about these processes, contact Impro.