Excessive Screw Discoloration and Wear
What was the problem?
Discolored and scratched screw!
During the routine maintenance, a barrier type, extrusion screw, operating in an extruder barrel with a “grooved” feed section was found to have discolored and the chrome coating on the primary/solids channel had been partially removed.
The above image shows the discoloration and the damaged region on the screw.
How it was solved?
An improved screw channel profile design!
Using the VEL™, Extruder module a new, optimized, screw was designed. This new screw had improved melting capability that was balanced with a new feed section that provided a more optimized feed rate so that the pressure and stress values were not as high as in the original screw.
Simulation of the design, prior to manufacturing the extrusion screw, could have shown the problems with the feeding/melting. The screw design could then be optimized for the required polymer and processing conditions. Improving the screw design could improve product quality, reduce screw (and barrel) wear and increase the production time before the screw needs to be re-built or replaced.