Finding the Source of Defects
When scrap rates rose after the installation of a new molding line, Landers Foundry turned to its sand testing laboratory to remedy the problem.
MAURICIO AYCARDI, LANDERS FOUNDRY, MEDELLIN, COLOMBIA; MARY BETH KRYSIAK, SAND TECHNOLOGY CO. LLC, NEW HUDSON, MICHIGAN, U.S.; DEAN MARTIN, HUNTER AUTOMATED MACHINERY CORP., SCHAUMBURG, ILLINOIS, U.S.; CESARE FRIGO, SPACE SRL, LONATE, ITALY
寻找缺陷来源
Landers 铸造厂引入新的造型线后废品率居高不下， 决定在型砂检测实验室寻找解决问题的方法。
MAURICIO AYCARDI, LANDERS 铸造厂, MEDELLIN, 哥伦比亚; MARY BETH KRYSIAK, SAND TECHNOLOGY CO. LLC, NEW HUDSON, 密歇根;
DEAN MARTIN, HUNTER AUTOMATED MACHINERY CORP., SCHAUMBURG, 伊利诺伊; CESARE FRIGO, SPACE SRL, LONATE, 意大利
expected to increase its capacity and improve efficiency with the modernized equipment; it was not, however, expect- ing the burn-in, rough casting surface, friable mold edges, and fins and flash that also resulted. After three months of production, the facility’s scrap rate rose to 22%. Te sand system for the new molding line, which began
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operation in July 2007, was using molding sand taken from the older part of the metalcasting facility that still operated manual squeezers. While the sand performed adequately on the squeezers with facing sand, it was causing defects on castings produced on the automatic molding machine, which did not use facing sand. Trough various sand control tests at the metalcasting facility,
Landers Foundry was able to diagnose its sand problems and monitor quality as changes were made to fix the problems. Once the improvements were made, the scrap rate dropped to 9% and continues to shrink further.
Testing Works Te majority of casting defects in sand casting facilities
are sand-related, but many metalcasters fail to recognize that molding sand quality is as important as metal quality. In or- der to consistently produce world-class castings, metalcasters must control their molding sand. An adequate sand control program requires a complete sand laboratory with trained and knowledgeable technicians and equipment capable of running at least the basic tests. Te minimum tests (and equipment) required for a com-
plete green sand control program include: • moisture (sand dryer and balance or digital moisture analyzer);
• compactability (sand rammer with base, tube filler acces- sory and compactability accessory);
anders Foundry, Medellin, Colombia, began overhauling its casting facility in August 2006 by replacing 16 manual squeezers with an automatic matchplate molding machine. Te metalcaster
位 测试工作
砂型铸造设备中，大部分缺陷都和型砂有关，因此 质量和铸件质量同等重要，但是遗憾的是很多铸造工 作者意识不到这一点。要想持续生产世界级的铸件， 对型砂的控制势在必行。一套合理的型砂控制系统要 有一个完整的型砂实验室，配备一套基本的型砂测试 设备以及经过相应培训的技术员。
一个完整的湿型砂控制系统至少需要以下试验及相 应设备：
• 含水量（烘干机和天平或者数字的水分分析仪） • 紧实率（带底座的锤击制样机、样筒及相应的填充 设备以及其它测试紧实率的设备）
• 密度和样重（锤击制样机） • 透气性（鼓式或标尺式透气性测试仪）
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FOUNDRY-PLANET.COM | MODERN CASTING | CHINA FOUNDRY ASSOCIATION Summer 2011
于哥伦比亚Medellin的Landers 铸造厂 从2006年8月开始升级铸造设备，将16个 手动造型机更换成自动分型造型机。他们
希望这些设备能够增加产
量并提高效率，但是粘砂、表面粗糙、型边易碎，毛 刺和飞边等缺陷也不期而至。三个月的生产之后，废 品率已升至22%。
新的造型线是于2007年投入使用的，当时使用的还 是过去手工造型所用的型砂。这种型砂在过去用做面 砂时表现正常，而自动造型机中不使用面砂，这时型 砂就引发了各种铸件缺陷。 通过一系列型砂控制试验，Landers 铸造厂确定了 型砂问题所在，并且采取了相应措施。这些改进措施 实施后，废品率降为9%，并且还在继续降低。
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