In this article, we will look at lost foam casting, one of the metal casting methods used in modern casting.

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What is lost foam casting?

Lost foam casting is a casting method that uses expanded polystyrene (EPS) material, also known as styrofoam, as a patterned material and is planted in silica sand with the compaction of sand molds using a vibration system on the mold frame.

Evaporative casting is another name for lost foam casting. This type of casting is classified as casting without binders.

Do you understand why it’s called lost foam? Yes, because when the molten metal is poured into the mold, the EPS melts and evaporates, allowing the metal liquid to fill the space.

This casting method requires a layer of refractory material on the surface of the pattern to support the weight of the sand before the molten metal freezes. Refractory plating must be resistant to high molten metal temperatures. The coating of expanded polystyrene patterns with refractory materials is an important factor in producing high-quality castings using the lost foam casting method.

Lost foam casting stages

Creating patterns with EPS materials

The pattern material can be formed into the desired shape of the object using blocks. Furthermore, the pattern material can be polystyrene foam granules molded in metal molds and heated with moisture, causing the grains to bind together and form a pattern.

Creating a gating system (casting channel)

The pouring channel is constructed from polystyrene foam material by the design, and the forming process is identical to the pattern-making process. The runner (flow channel), sprue (inlet), and pattern are all included in the gating system. After the gating system is created, the pattern and gating system is assembled to form a cluster (pattern tree).

The process of pattern coating with ceramic material.

Ceramic powder or powder dissolved in colloidal silica or a similar material. The process of coating the pattern by dipping to achieve coating homogeneity on all parts. When pouring liquid into the mold and producing a smooth cast surface, coating serves to hold molded sand into cast objects. Depending on the need, the coating can be done once or multiple times depending on the need, a thick coating will prevent gases from escaping from the mold and may result in cast object defects.

Insert the coated pattern into the molding frame.

The pattern is stockpiled with sand without binders until it is flush with the pattern’s top. A vibratory machine is used in the compaction of the mold using the vibration method.

Pouring Liquid into Molds

After all of the processes are completed, the liquid is poured into the mold. If the pattern does not completely burn, it will be converted into a gas or residue by the metal liquid.

Mold Disassembly

Turning over the printed frame begins the disassembly process. Because cast objects do not contain a binder, they will easily separate from the molded sand.

The Advantages and Disadvantages of Lost Foam Casting

Aluminum alloy castings are frequently made using lost foam casting. Lost foam casting is also one of the most cost-effective and environmentally friendly casting methods.

There are numerous advantages to lost foam casting, including:

• Flexibility in designing casting patterns.
• Can create complex objects and shapes.
• There is no mold partition.
• Not wearing the core.
• It is cutting labor in its foundry.
• Molds made from polystyrene foam patterns are simple to make and inexpensive.
• Environmental pollution caused by binder and sand removal materials can be reduced because binders and sand can be directly reused.
• The use of foam molds increases dimension accuracy and casting quality when compared to conventional molds.

This casting method has some disadvantages, including:

Because of the influence of burnt polystyrene foam, the degree of porosity is greater.

Conclusion

That concludes the discussion of Lost Foam Casting, beginning with the basics and progressing to the advantages and disadvantages. If you have any questions or need more information, please leave them in the comments section or contact our Team directly.

Contact us to discuss your requirements of Complete equipment for lost foam casting. Our experienced sales team can help you identify the options that best suit your needs.

Investment Casting vs Lost Foam

The lost foam process is extremely similar to the investment casting process sometimes leading to confusion between the two. Lost foam is essentially the same process as investment casting except that that patterns are created using expanding polystyrene foam instead of wax. There are also some differences in the shell building process due to this change. Many of the benefits of investment casting can also be attributed to lost foam; however, tooling and processing costs make the process more prohibitive with little to no additional benefit. As such, investment casting is the much more popular choice for production.

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