Process to make a ceramic filter for metal casting

A method to manufacture a ceramic foam filter, comprising:

• applying a mixture of at least one ceramic powder and at least one binder using additive manufacturing to shape a filter body;
• extending multiple filter body tortuous path channels through the filter body including at least a first cross section having a first area and a second cross section having a second area less than the first area;
• creating a flow passage for individual ones of the multiple filter body tortuous path channels having an impact wall positioned between opposed first and second path channel walls oriented at an angle to a flow direction of molten metal within the flow passage, wherein the impact wall includes multiple impact wall tortuous path channels configured to permit flow of the molten metal through the impact wall;
• varying an equivalent circle diameter of the multiple filter body tortuous path channels between 0.1 mm and 5.0 mm;
• and
• sintering the filter body to a temperature greater than a molten metal to be filtered through the filter body.

A method for making a ceramic foam filter, comprising:

• selecting a ceramic foam filter body having a cell geometry of the ceramic foam filter body including one of a plurality of multiple filter body tortuous path channels extending through the ceramic foam filter body wherein the multiple filter body tortuous path channels have a repeated and controlled passage geometry;
• creating a flow passage for individual ones of the multiple filter body tortuous path channels by adding an impact wall between opposed first and second path channel walls oriented at an angle to a flow direction of molten metal within the flow passage, wherein the impact wall includes multiple impact wall tortuous paths configured to permit flow of the molten metal through the impact wall;
• combining ceramic powders and at least one binder in a combining operation;
• printing the ceramic foam filter body using the ceramic powders and the binder using an additive manufacturing operation;
• and
• sintering the ceramic foam filter body at a temperature greater than a molten metal to be filtered by the ceramic foam filter body.