| 摘要 |
PURPOSE:To prevent wash defects, sand sand inclusion defects, thorn-like fin defects, etc. by dissolving boric acid in alcohol, and coating the resultant soln. on molds prepd. by using an org. binder. CONSTITUTION:Boric acid is beforehand dissolved in alcohol such as ethyl alcohol, methyl alcohol or the like, and the soln. is coated on the parts vulnerable to cause wash of molds molded by using an org. binder, so that the boric acid is penetrated in to the inside of the molds. The molds are allowed to stand or dried by firing to remove the alcohol. In this way, it is possible to prevent not only wash defects and sand inclusion defects but also defects of thorn-like fins etc. There is no degradation in the strength of molds and no problems are caused in molding work. |
