Mold filling and solidification in lost foam casting

Many advantages of lost foam casting technology come from the fact that it does not need to take the mold, but it also brings many problems to lost foam casting technology. During the filling process of lost foam casting, the foam pattern vaporized “disappeared” under the action of high temperature liquid metal, and the lost foam casting metal liquid replaced the original space and formed the same casting with the same shape. In this process, there are complex physical and chemical reactions and heat and mass transfer phenomena in the flow front of liquid metal.

1) There is heat transfer in the front air gap of liquid metal filling in lost foam casting. There is heat transfer between high temperature molten metal and coating, dry sand and foam pattern, such as conduction, convection and radiation.

2) There is mass transfer in the front air gap of liquid metal filling in lost foam casting. There are complex physical and chemical reactions between the liquid and gaseous pyrolysis products of foam patterns and coatings, high temperature molten metal and dry sand molds, and mass transfer is also accompanied.

3) Momentum transfer exists in the front air gap of liquid metal filling in lost foam casting. During the pyrolysis process, the pressure in the front air gap gradually increases, and the endothermic reaction decreases the temperature of the metal liquid at the front of the flow. This process will transfer momentum to the flow of the molten metal in lost foam casting.

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