Barrel zone override
Vol. 17 #4, Mar. 1991
The barrel/screw combination on an extruder is a very complex heat transfer system. To understand something that seems as simple as a zone override can require a complete analysis of the system.
Just a few of the factors that can cause a zone override are screw design, barrel mass, thermocouple placement, cooling jacket fit, barrel/screw wear, head pressure, overall temperature profile, defective temperature controllers and inadequate cooling.
Before assuming that zone override is strictly a screw design problem, you should analyze the system as a complete heat transfer mechanism. Although the screw is responsible for most of the heat input, it cannot control the heat distribution.
See also
Barrel thermocouple maintenance
Extruders
Heat exchanger
Heat transfer
Screw design
Thermocouple connections 1
Troubleshooting with barrel zones