The experiments prove that after being modified treatment, the addition of cold-hardening resin is cut down, so that the cost of cold-hardening resin sand can be decreased.
实践证明：采用适当工艺附加少量硅酸乙酯，可减少树脂加入量、降低冷硬树脂砂成本。
2
The paper introduces the present situation, Charac-teristice, principle and typical process flow of SO_2 gassing hardeningcold box process in our country.
文章介绍了我国目前SO_2吹气硬化冷芯盒制芯的现状、特点、原理及典型的工艺流程；
3
The high frequency induction hardening can't raise the surface microhardness of the cold precision forging spur gear.