TEDD is an acronym for Thermal Equalization and Distribution Device. It is designed to reduce the wide temperature variation across the diameter of the melt stream as it exits the extruder. The temperature can have a variety of profiles depending on machine speed and screw design. Peak to peak variations as much as 30o F are common and this translates into large viscosity variations. Cut and try modifications must be made to the die to produce the product profile required. This means the die will produce the right profile over a rather limited production rate range.