| 摘要 |
PURPOSE:To obtain air permeable casting molds easily and safely by forming a plaster base molding material by mixing water and a water absorbent into the material and removing the water being in the absorbent by drying. CONSTITUTION:Water and a water absorbent such as starch which absorbs a lot of water are mixed into a molding material consisting of plaster, cement, and aggregates. That slurry is formed, dried to remove the absorbed water, and removed from a mold. The above treatment forms a lot of continuous blow holes and provides the mold with a sufficient air permeability. Casting of zinc alloys and others having a dimensional accuracy are produced by increased fluidity and reduced blow holes when the air permeable mold is used.
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