To accurately discriminate defects of casting products before cutting, in manufacturing products by grinding die casting products.
A workpiece formed by die casting and before cutting is detected in weight by a weight sensor and is discriminated as defective if the detected weight of the workpiece is less than a threshold. As the threshold, a relation is preliminarily determined between a cutting margin of a cutting process, a defective ratio, and a workpiece weight, and then using the relation so determined, the threshold is set near the lowest limit value of a workpiece weight at which a defective ratio is within an allowable range based on the cutting margin of the cutting process. Thus, defects of die casting products can be accurately discriminated before cutting.
IKEDA SHIGEHARU
HIDAKA MINORU
UENO MITSUO
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