| 摘要 |
PROBLEM TO BE SOLVED: To provide cleanliness of aluminum molten metal M from a filtered flow passed through a filter 6 with high reliability. SOLUTION: Gas pressure F with high initial pressure is applied to the aluminum molten metal M stored in a molten metal container 1, to make steady the flow of the aluminum molten metal M which pass through the filter 6 provided at the bottom of the molten metal container 1. After that, the gas pressure is lowered to a constant pressure, and the cleanliness of the aluminum molten metal is obtained from the filtered flow of the aluminum molten metal M which is applied with the constant pressure passed through the filter 6. Preferably, the initial pressure and the steady pressure during the measurement on the filtered flow are preferably set to the range of 0.75 to 1.00 kgf/cm2 and the range of 0.05 to 0.75 kgf/cm2, respectively. The aluminum molten metal during the measurement on the filtered flow is preferably kept in the range of 680 to 750 deg.C.
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