对熔模铸造现行制壳工艺的改进和讨论

Improvement and Discussion on Current Shell Moulding Technology of Investment Casting

中温模料硅溶胶制壳工艺是目前国内外用于精密铸件生产的主流工艺。然而此工艺的制壳生产周期长,而且存在因面层型壳缺陷导致铸件缺陷的问题。采用了面层浆料加入防裂剂、面层大风力干燥、面层采用大粒径硅溶胶、取消涂二层前预湿、取消涂面层前沾硅溶胶的工艺举措。结果表明,面层型壳的强度得到了提高,面层型壳的缺陷减少,涂层干燥时间缩短,铸件一次性合格率增大。

Silicon sol shell moulding technology with medium-temperature pattern material is the main technology in production of investment castings at home and abroad. However, production cycle of this technology is too long, and casting defects often occur due to the surface defects of shell mold. Some measures were adopted, such as adding anti-cracking agent to the surface slurry, drying the surface layer by strong wind, using big size colloidal particle in surface slurry, cancelling the prewetting before coating second layer, cancelling coating of the silicon sol before the surface coating. The results show that the surface strength of shell mold is increased, defects on the surface of shell mold are decreased, drying time of coating is shortened, and the qualified rate of the castings is increased.