Filter having multilayered structure for filtering impurity particles from molten metal

A filter having a multi-layered structure for removing impurity particles from a molten metal, the filter comprising:

• a plurality of filter layers sequentially disposed along the flow direction of the molten metal in a downward direction and comprising a plurality of pore channels,
• wherein the filter layers disposed upstream comprise larger pore channels than those of the filter layers disposed downstream, and
• wherein the plurality of the filter layers comprise a first, second, third, fourth, fifth, and sixth filter layers, sequentially in a downstream direction, and
• wherein the density of the pore channels of the first filter layer is 5 ppi (pores per square inch), and
• the density of the pore channels of the second filter layer is 10 ppi, and
• the density of the pore channels of the third filter layer is 15 ppi, and
• the density of the pore channels of the fourth filter layer is 20 ppi, and
• the density of the pore channels of the fifth filter layer is 25 ppi, and
• the density of the pore channels of the sixth filter layer is 30 ppi.