Screw wear is usually a slow process and may be overlooked before performance is greatly reduced. Slight wear has little effect on overall performance, because machine parameters can be adjusted to maintain productivity.
When the radial gap between the screw thread and the barrel wall increases, leakage is inevitable. Operators usually see a drop in output and an increase in melt temperature, forcing higher speeds and energy consumption to maintain the
required rate.
As the radial clearance increases, the screw cannot generate the necessary pumping pressure to maintain the desired output.
