Patent ID: 6926858

Claim:
A method for use with an extrusion die in which material exits the die at an annular orifice in a direction generally parallel to a central axis of the die, the method comprising: receiving a flow of material and dividing it into a first flow and a second flow within a die layer; providing the first flow to a first annular region; providing a second flow to a second annular region spaced from the first annular region axially along the central axis, the flow to the first and second annular regions each having alternating higher flow regions and lower flow regions, the higher flow regions of the first annular region being axially aligned with the lower flow regions of the second annular region, and the higher flow regions of the second annular region being axially aligned with the lower flow regions of the first annular region; and recombining the flow from the first and second annular regions so that higher flow regions and lower flow regions combine.