Full mold casting
The foam casting is a casting method for the production of complex parts made of metallic materials such. B. aluminum . It belongs to the lost form casting process. The name full mold casting is derived from the process feature. The mold is "full" when it is poured, so it does not have a cavity that corresponds to the workpiece to be manufactured. A similar process is casting with lost foam . Both methods belong to casting with evaporating models .
The procedure
Main process
The special feature of full mold casting is that the melt ( 1 ) is poured into a sand mold that contains a model made of PS-E ( 2 ) that corresponds to the desired workpiece. In the respective vicinity of the melt, the PS-E gasifies completely; the released gas ( 3 ) is sucked out of the mold ( 5 ) by the molding sand ( 4 ) . After the melt has solidified, the workpiece can be removed from the mold, similar to conventional sand casting.
preparation
In preparation for the actual casting, a 1: 1 model of the workpiece is made from expanded polystyrene (PS-E), better known under the trade name Styrofoam. The PSE model can be composed of several parts. This allows complex workpieces (e.g. intake manifold) to be built from elements that are simple in terms of shape and free of undercuts. The PS-E model is covered with a protective layer, the so-called size, so that direct contact of the melt with the sand is avoided when pouring. The prepared PS-E model is placed in a container with molding sand, thus completing the preparatory work.
Special features
- The PS-E model means that there is no need for binding agents in the molding sand, so that the sand can be reused without restriction. The environmental pollution caused by the gaseous PS-E is much smaller than that caused by binding agents, which are required in alternative processes.
- Since complex shapes can be broken down into simpler, undercut-free elements, this process is particularly suitable for complicated parts. Even cavities that are otherwise laboriously mapped with cores are easy to implement.
- Since PS-E can be processed easily and cheaply, even in large numbers, the process can be automated well and is cost-effective.