ABSTRACT
Foundries are still using trial and error methods to solve casting problems. There are benefits to using a more disciplined approach to define, identify and determine the root cause of a defect. Use of international standard defect codes for classifying the defects is illustrated. Powerful techniques such as defect mapping, questioning to narrow down the root causes and design of experiments to identify and control the variables are explored. An actual case history in solving shrinkage porosity is described to illustrate these techniques in practical use.
INTRODUCTION
A tremendous amount of productivity is lost through defective castings. By employing a disciplined approach
to understand the nature of defects and the mechanism of defect formation and controlling the key process
variables we can significantly reduce the scrap both in- house and at the customer. Misidentification of
defects leads to costly scrap, lost time and customer dissatisfaction. It is not uncommon to have different names for the same defect, making it difficult to compare the successes and failures of other foundries in solving the same problems. The AFS has published a book standardizing the names of almost all the defects seen in the industry, but the foundries have not yet adopted the standardized codes and names. Even if in-house names unique to the foundry are used they can be cross-referenced with the published codes to help disseminate the knowledge for solving casting defect problems.
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