A method and system for monitoring and controlling the feedstock during the processing of thermoplastics. The hardware of the present invention includes at least a sensor which outputs a signal proportional to the current drawn by main drive motor of the cuber, a programmable logic controller (PLC) which has a high calculation speed, and a variable speed drive (VSD) which is configured to stop, start, accelerate or decelerate the feedstock flow to the cuber based on instructions received from the PLC. The configuration of the present invention is such that the information provided to the PLC approximates real-time load information. The software used to monitor the feed rate into the cuber uses a modified proportional integral derivative (PID) algorithm in which the prime feedback input is a real-time electrical consumption signal derived from the motor driving the cuber. Because the torque required to process non-uniform feedstock varies widely, the system uses a two-stage feedback modulated loop. Initially, the feed rate is increased to a relatively high value at which point the first stage of the feedback modulated loop is engaged. At such time as a critical current threshold is reached and maintained for a certain period of runtime, the second stage of the algorithm is engaged in which the feeder is operating in a high pressure, low current configuration and is set to shut the system down if the current load exceeds a preset value.