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A simplified method for analyzing mold filling dynamics Part I: Theory
Author(s) -
Stevenson James F.
Publication year - 1978
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.760180706
Subject(s) - dimensionless quantity , materials science , isothermal process , mold , mechanics , viscosity , amorphous solid , thermodynamics , power law , composite material , constant (computer programming) , molding (decorative) , physics , chemistry , mathematics , statistics , organic chemistry , computer science , programming language
A graphical method based on dimensional analysis is presented for estimating the injection pressure and clamp force required for injection molding amorphous polymers to form disk‐shaped parts with a constant wall thickness. A procedure is suggested for estimating clamp force when the projected area of the mold cavity is smaller than the surface area of one side of the molded part. The results reported here are based on a numerical simulation of a power‐law fluid filling a cold mold at a constant injection rate. The dimensionless bulk temperature and the ratios of the nonisothermal injection pressure (clamp force) to the isothermal injection pressure (clamp force) are given as functions of the dimensionless cooling time τ, the Brinkman number Br which characterizes viscous heating, the power‐law exponent n , and a dimensionless temperature β which includes the inlet melt and mold wall temperatures and the temperature coefficient for viscosity.