Gasified pattern casting is a new casting method in the late 1950s. Some aluminum castings for automobile lightweight, such as cylinder head and intake pipe, are made of sand core, but it is very troublesome to make and clean them in mass production. However, gasified die casting is used, which not only does not need sand core, but also simplifies cleaning, so this method is widely used in automobile casting production.
Gasification die. Its main process is to use foam polystyrene to make moulds, which are usually called foam plastic moulds. After molding and coating, they are put into sand and then poured. The sample mold is gasified under the action of the heat of the aluminum melt, the space occupied is filled by the aluminum melt, and the castings with the same shape and size as the sample mold are obtained after cooling.
The gasification mould is made of polystyrene by adding 3% – 8% foaming agent and pre foaming at 80 ℃ – 100 ℃. The gasified pattern casting process is quite different from the traditional, metal mold low pressure casting and pressure casting process in concept. Its main characteristics are as follows:
(1) No parting, no lifting, no core, easy cleaning of castings;
(2) It can be used as molding sand without binder, which is easy to recover and easy to handle;
(3) There are few sand inclusions and nonmetallic inclusions in the casting, and the internal quality is high;
(4) The production process is simple, universal, highly mechanized and automatic, easy to achieve mass production, low equipment investment, and conducive to reducing production costs;
(5) It can produce complex parts with less machining and 10% – 30% reduction of casting quality;
(6) It is easy to operate, does not need senior technical workers, has less environmental pollution and friendly production environment.