An aspect ratio condition for the buckling and folding of polymeric jets in injection mould filling

Authors

  • Nawaz Mahomed Peninsula Technikon
    South Africa
  • Michał Kleiber Institute of Fundamental Technological Research Pohsh Academy of Sciences
    Poland

Keywords:

Injection moulding, free surface flows, ullsteady Non-Newtonian flow

Abstract

The behaviour of planar Newtonian and Non-Newtonian polymeric jets is investigated in the context of injection mould filling. The incompressible Stokes flow mouel consistent with the application of injection mould filling is described together with the shear rate dependent fluid viscosity for a typical polymeric melt. The numerical procedure for the solution of the nonlinear system is briefly discussed as well as the mesh generation and the melt front tracking algorithms employed. In the analysis, the buckling behaviour of Newtonian and Non-Newtonian jets are firstly compared. Thereafter the behaviour of Newtonian jets are analysed for various values of the aspect ratio in an attempt to study the validity of the Cruikshank buckling conditions for planar Newtonian jets, It is argued that the Reynolds number of highly viscous polymeric JlfciLs is relatively low and the aspect ratio condition is the critical condition dictating the buckling behaviour. Finally, an aspect ratio design criteria is established for buckling-free and folding-free flow of polymeric jets.

References

[1] P.L. Bachmann, S.L. Wittchen, M.S. Shepard, K.R. Grice and M.A. Yerry. Robust geometrically based automatic two-dimensional mesh generation, Int. J. Num. Meth. Eng., 24: 1043-1078, 1987.
[2] J.C. Cavendish, D.A. Ficld and W.H. Frey. An approach to automatic three dimensional finite element mesh generation, Inl. J. Num. Meth. Eng., 21: 329- :3,17, 1985.
[3] H.H. Chiang, C.A. Hieber and 1 K Wang. A ullified simulation of the filling and postfilling stages in injection molding. Part I: Formulation, Polym. Eng. Sci., V 31(2): 116-124, 1991.
[4] H.H. Chiang, C.A. Hieber and K.K Wang. A unified simulation of the filling and postfilling stages in injection molding. Part II: Experimental Verification, Polym. Eng. Sci., V 31(2): 125-139, 1991.
[5] J.O. Cruikshank. Low-Reynolds-number instabilities in stagnating jet flows, J. Fluid Mech, 193: 111-127, 1988.

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Published

2023-05-31

Issue

Vol. 5 No. 3 (1998)
pp. 227-243

Section

Articles

License

Copyright © The Author(s).

This work is licensed under the Creative Commons Attribution 4.0 International CC BY 4.0.

How to Cite

Mahomed, N., & Kleiber, M. (2023). An aspect ratio condition for the buckling and folding of polymeric jets in injection mould filling. Computer Assisted Methods in Engineering and Science, 5(3), 227-243. https://cames3.ippt.pan.pl/index.php/cames/article/view/1341

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