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Flow and heat transfer in the nozzle of an injection molding machine
Author(s) -
Nunn R. E.,
Fenner R. T.
Publication year - 1977
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.760171110
Subject(s) - nozzle , materials science , mechanics , heat transfer , flow (mathematics) , thermodynamics , convective heat transfer , mechanical engineering , engineering , physics
Abstract When a polymer melt is forced through the nozzle of an injection molding machine, the material temperature increases significantly. This increase, which is very difficult to measure, is not uniform and local temperature peaks may cause thermal degradation. A method is described for the analysis of timedependent heat transfer and flow in such nozzles. Melts are treated as being inelastic but with viscosities which are nonNewtonian and dependent on both temperature and pressure. Distributions of velocity, temperature and pressure are obtained with the aid of a finite difference method for solving the differential conservation equations' of continuum mechanics. Typical results show that the times required to reach steady flow conditions are small compared with total injection times. Heat transfer is predominantly convective, and flows leaving injection nozzles and entering molds are very far from being thermally fully‐developed.