Plastic extruders are machine for forming plastic polymers into specific shapes according to the die used - a process similar to pressing a toothpaste tube, where the polymer would be the paste and the die the tube outlet.
In this analogy with the toothpaste tube, the squeezing is done by a screw usually driven by a gearmotor, since the screw speed for plastic forming is very low.
In order to adapt to different polymers, dies and production paces, the screw speed is variable, and in the older extruders such variation was obtained by means of direct current motors.
This alternative was used before the evolution of power electronics and consequent popularization of frequency inverters. In the past, it was the only alternative for a drive with variable speed.
WEG energy-efficient solution for extruders replaces the DC motors by an alternate current motor with a permanent-magnet rotor. Thus, the gains with energy savings are optimized, because it is a motor that presents higher efficiency than a direct current motor, in addition to being a motor with smaller dimensions, which greatly simplifies its installation in place of a direct current motor.
Indirectly, maintenance costs are greatly reduced (cleaning of brush holders, brush replacement, expensive preventive maintenance, etc.). The production of plastic pipes especially benefits from the solution, since the permanent magnet motor presents a very precise speed control, thus minimizing thickness variations in the pipes and improving the product quality.
The final energy savings may reach 30%, because it is a system which originally already features speed variation; therefore, the gain will be obtained by means of a better energy performance of the permanent magnet motor in comparison to the direct current motor, besides the elimination of the forced ventilation, unnecessary for permanent magnet motors.