Method and apparatus for forming an outer skin or honeycomb structures

Novel method and apparatus is disclosed for forming an integral skin on an extruded honeycomb structure, wherein the skin material is collected in a peripheral area of a die body, is passed through an adjustable flow control gap, and then through a predetermined gap thickness of a skin forming slot so as to then knit with the honeycomb structure extruded by the die prior to being extruded from the die. A plurality of flow control plates having different internal peripheral diameters are provided so as to provide different flow control gaps, as desired. In addition, a plurality of shims having different thicknesses are provided so as to position the mask a given distance away from the die, and thereby control the skin thickness gap. The die may be formed by merely relieving a peripheral portion of a typically automotive catalytic converter extrusion die and providing a trim ring about the relieved portion so as to inhibit the flow of batch material from partially open feed holes.