Abstract: A ceramic honeycomb filter has (a) cross section areas of intake flow paths being larger than those of discharge flow paths; (b) the intake and discharge flow paths having octagonal cross section shapes with four-fold rotation symmetry each obtained by cutting off four corners from a square; (c) the intake and discharge flow paths being alternately arranged in a first direction and a second direction perpendicular to the first direction, such that their opposing sides are parallel; (d) the opening ratio of the intake flow paths being 45-60%; (e) the number of the flow paths per cm2 being 30-60; (f) the thickness t1 of a cell wall between an intake flow path and a discharge flow path adjacent to that intake flow path being 0.150-0.260 mm; and (g) the thickness t2 of a cell wall between adjacent intake flow paths meeting 1.175<t2/t1<1.6.

Abstract: A ceramic honeycomb filter has (a) cross section areas of intake flow paths being larger than those of discharge flow paths; (b) the intake and discharge flow paths having octagonal cross section shapes with four-fold rotation symmetry each obtained by cutting off four corners from a square; (c) the intake and discharge flow paths being alternately arranged in a first direction and a second direction perpendicular to the first direction, such that their opposing sides are parallel; (d) the opening ratio of the intake flow paths being 45-60%; (e) the number of the flow paths per cm2 being 30-60; (f) the thickness t1 of a cell wall between an intake flow path and a discharge flow path adjacent to that intake flow path being 0.150-0.260 mm; and (g) the thickness t2 of a cell wall between adjacent intake flow paths meeting 1.175<t2/t1<1.6.

Abstract: A die having large numbers of grooves for molding a material to a honeycomb structure, wherein a surface having the grooves has an outer periphery in a polygonal shape having 6 or more corners, and wherein the grooves are crossing the outer periphery at an angle of 30° or more.

Abstract: A die comprising molding grooves arranged in a lattice pattern and moldable-material-supplying holes communicating with the molding grooves for molding a ceramic honeycomb structure, the molding grooves having width of 0.05-0.5 mm, the moldable-material-supplying holes being arranged in every intersecting portions of the molding grooves, or in every other intersecting portions of the molding grooves in a checkerboard pattern, and an average distance between the centers of the intersecting portions of the molding grooves, at which the moldable-material-supplying holes are arranged, and the center axes of the moldable-material-supplying holes being 10-100 ?m.

Abstract: A method for producing a die for molding a ceramic honeycomb structure, which has molding grooves arranged in a lattice pattern and apertures communicating with the molding grooves for supplying a moldable material, wherein the formation of the lattice-patterned grooves by machining is conducted by a first machining operation for forming pluralities of first parallel grooves, and a second machining operation for forming second grooves crossing the first grooves; wherein the first and second machining operations are conducted by at least 2 passes of grinding or cutting using a rotating tool; and wherein the second machining operation is conducted by up-cutting in the second pass or later, and a method for producing a ceramic honeycomb structure using such a die.

Abstract: A die comprising molding grooves arranged in a lattice pattern and moldable-material-supplying holes communicating with the molding grooves for molding a ceramic honeycomb structure, the molding grooves having width of 0.05-0.5 mm, the moldable-material-supplying holes being arranged in every intersecting portions of the molding grooves, or in every other intersecting portions of the molding grooves in a checkerboard pattern, and an average distance between the centers of the intersecting portions of the molding grooves, at which the moldable-material-supplying holes are arranged, and the center axes of the moldable-material-supplying holes being 10-100 ?m.

Abstract: A method for producing a die for molding a ceramic honeycomb structure, which has molding grooves arranged in a lattice pattern and apertures communicating with the molding grooves for supplying a moldable material, wherein the formation of the lattice-patterned grooves by machining is conducted by a first machining operation for forming pluralities of first parallel grooves, and a second machining operation for forming second grooves crossing the first grooves; wherein the first and second machining operations are conducted by at least 2 passes of grinding or cutting using a rotating tool; and wherein the second machining operation is conducted by up-cutting in the second pass or later, and a method for producing a ceramic honeycomb structure using such a die.

Abstract: A die having large numbers of grooves for molding a material to a honeycomb structure, wherein a surface having the grooves has an outer periphery in a polygonal shape having 6 or more corners, and wherein the grooves are crossing the outer periphery at an angle of 30° or more.