Filtering extrusion batch material

Claim 1

IN THE METHOD OF FORMING HONEYCOMB ARTICLES FROM EXTRUDED CERAMIC BATCH MATERIAL WHEREIN CERAMIC BATCH MATERIAL IS EXTRUDED UNDER PRESSURE THROUGH A FINAL EXTRUSION DIE HAVING A GRIDWORK OF NARROW DISCHARGE SLOTS TO FORM THINWALLED HONEYCOMB CERAMIC ARTICLES, THE IMPROVEMENT COMPRISING A METHOD OF REMOVING CONTAMINANTS FROM THE EXTRUDABLE CERAMIC BATCH MATERIAL PRIOR TO SUCH MATERIAL BEING EXTRUDED THROUGH THE FINAL EXTRUSION DIE SO AS TO AVOID THE CLOGGING OF THE DISCHARGE SLOTS THEREOF WITH SUCH CONTAMINANTS WHICH COMPRISES, INITIALLY BLENDING CEAMIC BATCH MATERIAL INGREDIENTS IN A DRY STATE, ADDING WATER TO SAID INGREDIENTS AND FURTHER MIXING THE BATCH MATERIAL, SUBJECTING SAID MIXED BATCH MATERIAL TO A PRESSING FORCE PROVIDING AN EXTRUSION PRESSURE FOR EXTRUDING THE SAME THROUGH A PRE-EXTRUSION DIE, AND WHILE SUBJECTED TO SAID EXTRUSINON PRESSURE AND PRIOR TO PASSING THROUGH SAID PRE-EXTRUSION DIE, SCALPING SAID BATCH MATERIAL OF CONTAMINANT PARTICLES TO THEREBY PRODUCE BATCH MATERIAL OF IMPROVED PURITY AND HOMOGENEITY, IMMEDIATELY PASSING SAID SCALPED BATCH MATERIAL THROUGH A PRE-EXTRUSION DIE IN ORDER TO FURTHER PLASTICIZE AND DE-AIR THE CERAMIC BATCH MATERIAL, REMOVING SAID CERAMIC BATCH MATERIAL FROM SAID PRE-EXTRUSION DIE, AND THEN SUBSEQUENTLY PRESS EXTRUDING SAID SCALPED AND DE-AIRED CERAMIC BATCH MATERIAL THROUGH A SEPARATE FINAL EXTRUSION IE UNCONNECTED TO SAID PRE-EXTRUSION DIE AND HAVING A GRIDWORK OF NARROW DISCHARGE SLOTS TO FORM THIN-WALLED HONEYECOMB CERAMIC ARTICLES.