| 摘要 |
PURPOSE:To obtain molding sand which has sufficient wet strength and does not generate surface roughening and pinholes in a casting by adding and mixing rye beta-starch of only the seed as an auxiliary binder to the molding sand having an ordinary compounding compsn. CONSTITUTION:The rye beta-starch of only the seed is added and mixed as the auxiliary binder in a 0.5-3.5% range by weight to and with the molding sand consisting of molding sand and bentonite at an ordinary compounding ratio. The molding sand which has the sufficient wet strength and does not generate the surface roughening and pinholes in the casting is thereby obtd.
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