Elimination of casting defects requires proper collection and analysis of data. Attempting a corrective action without knowing exactly what the problem is may prove very expensive. In certain instances application of experimental designs have been applied in aluminum foundries for scrap reduction programs. However, for a Design Of Experiment (DOE) technique to succeed, it is imperative that the defect be properly diagnosed. Unfortunately, it is not uncommon practice that a foundry tries to eliminate a casting defect based on an improper diagnosis. Consequently, this article presents a case study in which a DOE was conducted before the defects were properly identified. The purpose is to reflect on the methodology and cultural thinking of a jobbing foundry to eliminate metallurgical defects in a particular automotive green sand casting. This article also demonstrates how improper diagnosis of defects lead the experiment the wrong path yielding ambiguous results. In addition, it clearly shows the benefits of scanning electron microscopy (SEM) analysis for evaluation of the metallurgical defects. Furthermore, it provides practical knowledge regarding identification of casting defects with scanning electron photomicrographs. Finally, it will emphasize the importance of proper defect analysis before a corrective action be considered.
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