The use of the Lost Foam Process has been growing in the foundry industry, because its unique properties offer advantages in the production of castings in various metals and applications. It is best described as the metal displacement of the foam pattern assembly using an unbonded media that replicates the original foam pattern. Although simply described, a number of factors must be controlled to obtain the desired results. A component to the success of the process is the selection and control of the refractory coating. The key tests that are normally associated with control of the coating to insure consistent casting results are viscosity, percent solids, density, and permeability. Tests used in production of castings are percent solids, wet weight and dry weight of the coated cluster assembly, and pouring times and temperature. Finally, the coating must be monitored for biological activity. The presence of biological activity will negatively affect many of the refractory coating properties. The tests that have been outlined set the control parameters for the refractory coating to produce acceptable castings. For successful operation of the lost foam process, controls for the other facets of the process namely, white side foam pattern production and assembly, molding media, compaction, and metal pouring must also be established.
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