1. Source material for the pattern
This part is very important for lost foam casting casting. We should choose the different material according to the casting material. When we produce the aluminum die castings, we will choose the expandable polystyrene which contain pentane as blowing agent. But for the production of cast iron and steel parts a copolymer made of EPS and EPMMA is used.
Due to the incorporation of pentane which act as a blowing agent, polystyrene is expandable. The following is a bead pr-expanded with a fluidity bed dryer.
For the actual pattern section production, the pr-expansion EPS beads are blown through a fill gun into a metallic permanent mold by using compressed air. In the mold the beads are bonded after heating and the desired pattern geometry is formed. Please check the molding making process below.
4. Pattern section assemble and mounting of the patterns on a gating system
Due to the segmentation of the complex pattern pattern geometries into simple, these sections have to be assembled to one complete pattern after the foaming and drying processes. After that, the several patterns are mounted on one gating system to be the cluster.
5. Coating of the clusters
By dipping, the mounted clusters are coated with a water-based refractory coating. The coating is about 2mm thick.
6. Mold filling
The coated cluster is then posited in a flask, the quartz sand is filled by sand raining feeder and compacted by the vibration table. At the end of compaction the cluster is completely embed in the quartz sand and only the sprue remains uncovered.
A down sprue is placed over the EPS sprue. The molten metal is poured into this downsprue and then flows to the gating system of the foam pattern. The molten metal docomposes the EPS cluster and fills into the mold cavity in all its details. Please check the decomposition process below.
After the solidification of the molten metal , the castings is formed. we will convey the castings to the next shot step for further cleaning.
9. Sand processing department
After demolding, we need to convey the used sand to processing system to return sand for recycling.