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The injection molding of thermoplastics part II: Experimental test of the model
Author(s) -
Kamal M. R.,
Kenig S.
Publication year - 1972
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.760120409
Subject(s) - materials science , molding (decorative) , reciprocating motion , viscoelasticity , injection molding machine , experimental data , flow (mathematics) , compression molding , mechanics , composite material , composite number , stage (stratigraphy) , mold , mechanical engineering , mathematics , engineering , paleontology , statistics , physics , gas compressor , biology
Experimental studies have been conducted with a 2 1/3 oz reciprocating‐screw injection molding machine to check the validity of a proposed theoretical model for injection molding. A semi‐circular cavity has been employed in the study to achieve spreading radial flow during the filling stage. Both high speed photography and pressure transducer measurements have been employed to obtain data on polyethylene. The photographic studies confirm the existence of spreading radial flow throughout the filling stage, and are in very good agreement with data obtained with the transducer on the progression of the melt front in the cavity. The results show that the proposed theoretical model yields predictions which are in good agreement with experimental data for all stages of the injection molding cycle with polyethylene. The model also predicts a composite pressure‐time curve for the overall cycle which is similar to those reported in the literature and which satisfactorily represents the data obtained in this study. It is also possible to predict a short shot under selected molding conditions in agreement with observation. The main problems in the application of the model arise during the filling stage near the cavity entrance where viscoelastic and end effects are important and where some of the assumptions inherent in the model may not be valid.