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FUNCTIONING |
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GREEN SAND MOLDING |
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Among the foundry techniques, the most common is the molding in green sand, that consists in a mold use made of wet sand and, soon after, compacted. The word “green” means that the moist was added in the sand and binders. This technique is broadly used due to its easiness, raw material low cost and availability. The green sand is the combination of the silica sand with binders, usually clay, that are usually cheap components.
Before molding in green sand it is necessary to determine the mechanical strength of the sand, the pattern format, inclusive channel and riser, as well as the metal that is being used and the casting desired quality.
The sand is prepared through the addition of water and of binders, forming the green sand. The molding flask (cope or drag) is placed on the pattern to be molded and, soon after, is filled with sand that is then compacted by means of one of the various existing molding techniques. In case it is necessary the use of cores, they are inserted in this phase. Joining both molding flask halves (cope and drag), it is formed the complete mold with the respective cavities.
After the pouring of the molten metal in the cavity, the metal is cooled, reaching the solidification. Once finished the cooling process, the casting is removed from the mold in the shakeout. The used sand is reconditioned to be used again in the molding process.
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