Important parameters of the homogenizing section screw

The depth of the screw groove H3 is determined by the empirical formula H3 =(0.02~0.06)Ds
The length L3 is determined by the following formula: L3 =(20% ~ 25%)L
d. According to the melt conveying theory, the flow of the melt in the screw homogenization section has four forms, and the flow of the molten material in the screw groove is a combination of these four flows:
Positive flow-the flow of the plastic melt between the barrel and the screw along the direction of the screw groove towards the head.
Countercurrent-the flow direction is opposite to the positive flow, caused by the pressure gradient caused by the resistance of the head, perforated plate, filter plate, etc.
Cross flow-the flow of the melt along the direction perpendicular to the threaded wall, affecting the mixing and heat exchange of the melt during extrusion.
Leakage-the backflow formed at the gap between the screw and the barrel due to the pressure gradient, along the axial direction of the screw.