Transient melting models for the three stages of reciprocating extrusion

The analysis of mass flow inside the injection screw of injection molding machines is similar to that of an extruder with a reciprocating effect. Although the use of plastic injection molding machines is very extensive in industry, most studies have been on extruders which were simpler to model. This paper studies the transient models for the melting process in the three stages (melting stages, injection stages and stop stages) in the reciprocating extruder. Based on these transient models, factors affecting the melting speed in reciprocating extruders at different stages are explored. These include screw rotating speed, screw rotating time, time of stop stages (time of packing, mold opening, etc.), time of injection, screw axial movement speed, barrel thickness, barrel heat capacity, temperature of heater and polymer, etc. The model derived was used to explain the experimental results obtained by previous researchers. The model is found to give a good description of injector dynamics in reciprocating extrusion.