Abstract: Based on the high scrap rate of a certain 3T axle housing of a forklift, this study is conducted. Through analysis, it is found that the main cause of the scrap is shrinkage cavities. The shrinkage cavity defects are verified from several dimensions including carbon equivalent, pouring temperature, primary graphite, magnesium in the spheroidizing line, and rare earth content. Eventually, it is confirmed that excessive primary graphite is the main inducing factor for the occurrence of shrinkage cavity defects. The improvement plan is solidified, and measures for melting and pouring improvement, molding improvement, core improvement, and equipment improvement are formulated. The improvement plan can effectively reduce the scrap rate, save costs, reduce the labor intensity of workers, and enhance the mechanical properties of parts.

Key words: 3T axle housing; shrinkage cavity defect; reduce the defect rate; optimization plan

摘要： 基于某叉车 3T 桥壳出现的废品率较高问题展开研究，通过分析发现主要废品原因为缩 孔，从碳当量、浇注温度、初析石墨、球化线镁、稀土含量几个维度对缩孔缺陷进行验证， 最终确认初析石墨过多为导致出现缩孔缺陷的主要诱导因素，对改进方案进行固化，制定熔 浇改进措施、造型改进措施、泥芯改进措施、设备改进措施等，改进方案可以有效降低废品 率、节约成本、减少工人劳动强度和提升零件力学性能。

关键词: 3T 桥壳；缩孔缺陷；降低不良率；优化方案