An extrusion process can create an object having a complex cross-section. In a conventional process, batch material is inserted into a chamber of an extruder barrel. Once inside the chamber, the material is pressurized by a pressure mechanism such as a pump, a piston, screws, or other conventional means. The pressure inside the chamber must be sufficiently high to overcome the material's resistance to flow, which is produced by a die disposed in the chamber. Once the resistance to flow is overcome, the pressure forces the material through the chamber from the inlet of the extruder barrel towards the die. The material can pass through openings or channels defined in plates disposed throughout the chamber between the inlet and die. As the material reaches the die, it is extruded through one or more feedholes and discharge slots defined in the die to form an extrudate having a desired geometry (e.g., a honeycomb body).
The conventional die is designed to produce a desired shape of the extrudate (e.g., the contour and cell pattern of the honeycomb body), but to do so, the die must also withstand the extreme pressure created within the extrusion chamber. Thin discharge slots required to form, e.g., thin wall honeycomb bodies, require high pressures within the extrusion chamber. If designed incorrectly, the die can deform or rupture due to plate bending from the pressure. Thus, the thickness of the die is often increased to withstand the high pressure built within the chamber. This is the same with other elements having restrictive openings that may be disposed in the chamber. As with any plate bending problem, as the diameter of the plate is increased the thickness of the plate must also be increased to stay within the yield limits of the material. As a consequence, the impedance and resistance to flow through openings in the die undesirably increase as the die thickness increases.
Thus, a need exists for an improved die that reduces the impedance and resistance to flow through the die. It is also desirable to increase throughput of the extrusion process while reducing the stress exerted on the die.