Overview
The heat profile of conductive heat generated with heater bands is probably the most important and perhaps least understood factor in successful plastics processing.
An incorrect heat profile is the single most important cause of wear in barrels and screws.
This is due to the natural tendency to cool down the heater bands when a heat override condition occurs. Because most heat overrides are caused by excessive shear heat, the best way to decrease shear is to apply more, not less conductive heat. It will not increase the temperature of the melt, but instead it will change the source of the heat energy used to melt the plastic.
It is the uncontrolled, excessive shear of material that causes most abrasive wear and, through melt blockage and screw deflection, adhesive wear. In addition, too much shear heat may cause extensive damage to the quality of the melt and have a negative impact on the physical properties of the plastic part.