Casting is a method of plastic processing. Early casting is under normal pressure to liquid monomer or prepolymer (see polymer) into the mold, the polymerization and curing molding, into the same shape with the mold cavity products. At the beginning of the 20th century, phenolic resin was first formed by casting.
In the mid-1930s, the prepolymer of methyl methacrylate was cast into plexiglass (see polymethylmethacrylate). During the Second World War, the development of unsaturated polyester casting products, followed by epoxy resin casting products, 60 years appeared in the nylon monomer casting casting (see polyamide). With the development of molding technology, the traditional concept of casting has changed, polymer solutions, dispersions (PVC) and melt can also be used for casting molding. Extrusion of molten flat film with an extruder, casting on a cooling drum to produce a polypropylene film, known as extrusion-casting.