Extrusion Processing Guides-2

The feed zone temperature controls the compound sticking to the barrel wall, otherwise known as the bite. Too much bite will lead to overheating of the compound and too little bite will lead to poor output.

The die temperature will also influence output and will have an effect on the dimensions of the extrudate. A cold die will restrict flow where as a too-hot die will affect dimensions.

When optimum temperatures are reached, it is known as the temperature profile; temperature profiles vary greatly and include:

• Straight Profile – a temperature profile with all the same temperatures.

• Ascending Profile - temperatures that rise from the rear to the die.

• Inverted Profile - temperatures that decrease from the rear to the die.

• Hump Profile - a temperature profile with the hottest temperatures in the middle.

All of these temperature profiles may work but finding the right combination for output and aesthetics may take time.

Another controllable setting is the screw RPM. This should be set as high as possible as long as you are producing a consistent quality product.