Flow surging is defined as the oscillatory change in the output rate of an extruder while maintaining constant set point conditions. Flow surging can originate from many different sources including improper solids conveying, melting instabilities, and improper control algorithms. Surging in most cases results in lower production rates, higher scrap rates, material degradation, and higher labor costs. In this presentation numerous case studies along with diagnostic methods are presented for processes that flow surged.