Lost Foam Casting

Main Process Flow:

Model Making: Expandable polystyrene (EPS) and other materials are pre-expanded and molded to create foam plastic models.

Model Assembly: The models are bonded to the gating system to form a complete model cluster.

Coating and Drying: A special refractory coating is applied to the model surface and dried to form a high-temperature resistant, breathable coating.

Shaping and Sand Filling: The model cluster is placed in a sand box and filled with binder-free dry sand, while simultaneously undergoing three-dimensional vibration to compact it.

Pouring: Molten metal is poured in under negative pressure. The model rapidly vaporizes and decomposes upon contact with the high-temperature metal, and the molten metal replaces it.

Cooling and Sand Removal: After the casting solidifies and cools, the vacuum is released, the sand box is removed, and the loose dry sand automatically falls off, allowing the casting to be removed.

Main Advantages:

High Precision and Small Tolerances: The castings are dimensionally accurate, have a smooth surface, and can achieve near-net-shape forming.

High Design Freedom: Capable of producing castings with complex structures and internal cavities, simplifying the limitations of traditional processes such as parting and mold removal. Simplified Process and Low Cost: Eliminates the steps of parting, core making, and box assembly required in traditional casting, reducing mold costs and saving manpower and space.

Clean and Environmentally Friendly: Uses dry sand molding, without binders; used sand can be recycled and reused, resulting in low dust emissions.

Main Disadvantages: Single-Use Models: Each casting requires a separate foam model, suitable for mass production, but model costs are high for single pieces or small batches.

Susceptible to Defects: Improper process control may lead to carbon defects, porosity, wrinkles, and other problems.

Limited Model Size: Oversized models are prone to deformation during manufacturing, handling, and pouring.

Application Areas: Widely used in the production of steel, aluminum alloy, and copper alloy castings for automobiles (engine blocks, cylinder heads, etc.), machine tools, construction machinery, mining parts, valves, pipe fittings, etc.

In summary, lost foam casting is a modern casting technology suitable for medium- to large-volume production of complex structural parts that emphasize precision and surface quality. It has significant advantages in improving the technological level and clean production of the casting industry.