Just like sand casting, vacuum molding and shell molding processes, metal casting is also done with expanded foam molding process. It has a very basic application logic, and this logic gives to expanded foam molding process some advantages and disadvantages over other processes. In here, we will explain the process parameters of expanded molding process and advantages/disadvantages of this casting process.
In most basics, polystyrene foam is used in the pattern making for expanded molding process. This polystyrene foam pattern is placed into a mold box, and sand is packed the space between pattern and mold box walls. The used sand can be a gree moisturized sand or dry sand. So, molding cavity is obtained with this pattern.
Before the placement of pattern inside mold box, it is coated with refractory coating to obtain better surface characteristics from produced part. When the poylstyrene pattern and sand is placed into the mold box, the liquid metal is poured on this polystyrene pattern. Polystyrene pattern turns into gas phase immediately by the application of intense heat from liquid metal. These produced gasses because of the melting of polystyrene foam pattern, go out from the mold cavity. And mold cavity is filled with liquid metal.
The most important advantage of expanded foam molding process, risers, gatings and cores can be obtained with the polystyrene foam, which saves from separate workforce for different things.
There is no need for parting line to extracy the pattern from the mold cavity of expanded foam molding system. This also give very good saving of time.
The biggest drawback of expanded foam molding process is the need of separate polystyrene foam patterns for each products, which creates an additional cost. But in general, foams can be very cheap compared with the job done with foam molding process.
These are the general characteristics of expanded foam molding process. Do not forget to leave your comments and questions about expanded foam molding process below.
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