Lost foam offers tremendous design flexibility by allowing multiple features to be oriented as required for the form, fit, and functionality compared to the conventional sand-casting process, which is restricted by considerations for the parting line and drafting. 

Pressurized lost-foam is a near-net-shaped casting process to make complex castings with thin walls that also have excellent dimensional tolerance and surface finish.

For this casting, design flexibility allowed the water jacket to twist inside the casting like a vortex, meeting requirements of the water and exhaust passages to provide a constant and even flow of water to the manifold and engine heads. The result was a compact, one-piece, lighter-weight shape with improved overall performance and efficiency. 

The environmentally friendly (binderless) lost-foam production process was also an economical solution.

The lost foam casting process replicates fine detailed features with zero draft and desired orientation, which would not otherwise be possible by conventional sand casting. A good example of this are the casting’s intertwined water and exhaust channels.

Flexibility with the placement of features—inside passages, for example.

• The lost foam casting process replicates fine detailed features with zero draft and desired orientation, which would not otherwise be possible by conventional sand casting. A good example of this are the casting’s intertwined water and exhaust channels.
• The lost foam pattern is an exact replica of the finished casting shape and typically the pattern is made out of multiple foam sub-components glued together. Binderless dry silica sand is used as the molding substrate and has much better flowability––it also allows fine details to be captured. Being borderless eliminates any potential interaction of binder with liquid metal as seen with conventional sand castings. 

Increased complexity by feature consolidation.

• Since the pattern is an exact replica assembled together by gluing individual foam pieces together, it is possible to consolidate multiple features with random orientations. This capability offers design engineers flexibility with part consolidation and enhanced product performance. In this example, the foundry was able to incorporate mounting brackets and cored holes right into the housing.

Reduced draft and generous fillet, radii, and transitions

• Zero draft features are possible with lost foam; however, smooth transitions are achieved by incorporating fillets and radii for sounder castings.
• The overall result of lost foam’s near- net capabilities are reduced weight and lower cost because the need for machining in most areas is eliminated. There is also opportunity to reduce the machining stocks.