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Modeling the packing stage in injection molding of thermoplastics
Author(s) -
Huilier D.,
Lenfant C.,
Terrisse J.,
Deterre R.
Publication year - 1988
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.760282410
Subject(s) - materials science , thermoforming , molding (decorative) , compressibility , shrinkage , polystyrene , crystallization , composite material , amorphous solid , mechanics , mold , equation of state , thermal , newtonian fluid , thermodynamics , polymer , physics , organic chemistry , chemistry
A model, for the packing stage In injection molding of thermoplastics is proposed. It allows one to calculate the time evolution of pressure and temperature fields and mass variations in simple geometries. The model holds for amorphous as well as for crystalline polymers if the kinetics of crystallization are known for temperatures far from the melting point, It applies after filling stage; initial temperature and pressure conditions are available from filling‐simulating software. The principles rest on finite difference schemes computing simultaneously temperature and velocity of compressible non‐Newtonian fluid in a filled cavity. The pressure field is determined from an equation of state at any time, owing to a mass balance in each gridmesh. The meaningful results of the simulation are local shrinkage and a good approximation of final weights of finished products. The algorithm is essentially checked for the influence of physical, thermal, and processing parameters on the cavity pressure for the injection of a polystyrene (Gedex 1541) into a rectangular mold cavity.