Clogged holes are a defect caused by molten zinc metal not draining adequately and partially or completely filling holes with excess zinc. Molten zinc will not drain easily from holes less than 3/10 (8mm) in diameter due to the viscosity of zinc metal. A good example is the screen shown to the right. Clogged holes can be minimized by making all holes as large as possible; regardless, clogged holes less than 1/2 in diameter are not a cause for rejection, unless it prevents the part from being used for its intended purpose.
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