Te Tian Qian Industries Holdings Co. Ltd is located
on the bank of Taihu Lake where the maximum humidity reaches 90-98%; however, molds and cores still have good curability and strength. Good breakdown property—Bangni resin sand
has good shakeout characteristics, and large pieces of molding sand can be seen falling off the casting during the shakeout process, which is welcomed by fettling operators. The delegates who attended The National Conference on Steel Casting Sand visited Wuxi foundry and were interested in the surface quality of steel castings after shot blasting. They were even more focused on the large pieces of mold- ing sand seen falling off the castings (Fig. 3). Toughness of Bangni resin sand—Because Bangni
resin contains high molecular alkene genus carbon chains, after mold-making, the mold surface is tough and smooth; Bangni resin sand molds have good strip- ping characteristics and molds are not easily damaged during stripping. Also, when coating with a brush, the sand surface is not easily brushed off. Bangni resin sand and surface quality of steel cast-
ings—From a practical application, Bangni resin sand has two positive effects on the surface quality of castings. Te first is similar to other resin-bonded sands.
Because resin undergoes a pyrolytic reaction after pouring, a reducing atmosphere forms at the interface between mold and metal. Tis protects the metal sur- face from oxidation. After shakeout, the casting surface has no sign of oxidation. Secondly, Bangni resin sand has appropriate
strength and the mold surface has good stability, thus the surface finish of the molds is improved and steel castings made with Bangni resin sand have a good surface quality. Te castings for ships and large slag ladles produced by Wuxi Foundry for Japanese customers all received good comments.
一定的硬化速度与初始强度，克服了过去水玻璃砂的 吸湿、硬化速度缓慢产生的问题。
地处于太湖边沿的天乾铸钢厂，湿度最大达到90% ～98%，但铸型和芯子仍有较好硬透性与强度。
（3）落砂性能好
邦尼树脂砂型浇注后脱箱时有良好的落砂性能，并 在脱箱时可看见铸型表面的大片型砂脱落，受到清理 工人的好评。2010年在无锡召开的全国铸钢型砂会议 期间，代表们在参观无锡铸造厂时，不仅对铸钢件抛 丸后的表面质量感到兴趣，对脱箱后铸件表面的型砂 大片脱落更为关注。图3为脱箱后铸钢件表面型砂大片 脱落的情况。
（4）邦尼树脂砂的柔韧性
由于邦尼树脂中含有高分子的烯属碳链，树脂砂 造型后砂型表面柔韧、光滑，工人普遍反映起模性能 好，起模时铸型不易损坏，上涂料时不易起砂，很受 操作者的欢迎。
5、邦尼树脂粘结砂与铸钢件的表面质量
从用邦尼树脂粘结砂生产铸钢件的实践中体会到： 邦尼树脂对铸件的表面质量有两种有利的作用。 一种作用与其他树脂相同，由于树脂在高温下热 解，在铸型与金属的界面处形成还原性气氛，从而避 免了金属表面的氧化。铸钢件脱箱后，即可明显地看 出铸件表面无氧化的现象。
Figure 4. These steel castings were produced for Sandvik using Bangni resin sand.
图4 用邦尼树脂粘 结砂为山特维克公司 生产的铸钢件
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FOUNDRY-PLANET.COM | MODERN CASTING | CHINA FOUNDRY ASSOCIATION February 2013
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