Study of the Thermal Cooling during the Injection Moulding Cycle on Amorphous Polymers
Isabel Barros, António Brito, António Cunha, José Carlos Teixeira
Universidade do Minho
Portugal

Keywords: Injection moulding, Mould cooling, Finite volumes

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In injection moulding of thermoplastics, the productivity is strongly dependent of efficiency of heat transfer from moulding to the mould, being this process controlled by the thermal contact resistance (TCR) at the mould/polymer interface. Therefore, this phenomenon should be accurately considered in commercial codes.
The mathematical model developed describes the time dependent heat flux during the entire moulding cycle and takes into account the contact interface between the mould and the polymer. An additional model is added to the code in which the physics controlling the contact (or its absence) are described [1]. This procedure enables the determination of a time dependent value for the TCR at any point of the surface. The equations were discretized using a finite volume technique and subsequently solved by the iterative method SIP (Strong Implicit Procedure).
In this work, the effect of including a local time dependent value for the TCR was evaluated against the traditional assumption of a constant value. The results were compared with experimental data for amorphous polymer and a variety of mould and melt temperatures.
The experimental data was obtained on an instrumented test mould under typical operating conditions for both single and multiple production cycles.


[1] BARROS, I.; CUNHA, A. M.; BRITO, A. M.; TEIXEIRA, S. F. C. F.; TEIXEIRA, J. C. F.; Modelo de Contracção para Computação do Tempo de Contacto na Moldação por Injecção. In “Proceedings of the V Congreso de Métodos Numéricos en Ingeniería”. Madrid: E.T.S.I. de Camiños, Canales y Puertos (2002), 10 páginas.