Lost Foam Casting (LFC) is a new casting technology of precise forming. In 1958, American H.F.Shroyer first used foam board to form foam shape, and made use of molding sand with binder to make metal blank and patent. Until the patent failed in 1980s, lost foam technology was applied in large scale, especially in complex cylinder block and cylinder head production.
Lost Foam Casting (EPC) is a new casting method that combines the foam model with the size and shape of the casting into a model cluster, which is coated with fire-resistant coating and dried, then embedded in dry sand in vibration modeling, pouring under normal pressure or negative pressure, making the model gasified, liquid metal occupy the model position, and solidified and cooled to form a casting.
(1) The casting has the characteristics of precise size and shape, high surface finish and precision casting.
(2) Because there is no need for core making, box closing and mold taking, the molding process is greatly simplified and sufficient freedom is provided for the structural design of castings.
(3) The reasonable shape of the riser can be set in the ideal position, which is not restricted by the traditional factors such as parting and mold taking, and reduces the internal defects of the casting.
(4) negative pressure pouring is beneficial to remove gas generated by foam combustion during casting, improve working environment, and also facilitate liquid metal filling and feeding, and increase the density of castings.
(5) Old sand can be recycled with less environmental pollution, which is known as “green casting project”.
But the unique disadvantage of lost foam casting is that the flow front of molten metal is the pyrolysis product (gas and liquid) of the foam pattern, which will make the filling metal produce carbon defects on the surface. Therefore, the cast steel joint and impeller of desulfurizing pump which are studied in this paper can not be directly produced by lost foam casting.