Experimental and Computational Analysis of the Heating Step during Thermoforming of Thermoplastics

Abstract:

The present study addresses the difficulties in heating thermoplastic sheets for ther-moforming applications. In industrial environments, the sheets are heated in a contact free method by means of convective hot air ovens and infrared radiation. In this study the temperature evolution at the outer surface as well as the core of thermoplastic sheets as a function of time is measured by means of thermocouples. These measurements reveal significant through thickness temperature dif-ferences which need to be resolved before high quality products can be made. The temperature dif-ferences can be decreased by decreasing the radiative power. This is however not acceptable in in-dustry since it lowers the number of produced parts per unit of time.In order to gain insight in the time-temperature relationship during the heating phase, a finite differ-ence model is developed. The model clearly shows the constantly changing through thickness tem-perature distribution and can be used as a tool by the thermoforming industry to optimize the pro-duction process.

• Periodical: Key Engineering Materials (Volumes 651-653)
• Pages: 1003-1008
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.651-653.1003
• Online since: July 2015
• Authors: Bart Buffel*, Marijke Amerijckx, Martijn Hamblok, Bart van Mieghem, Frederik Desplentere, Albert Van Bael
• Keywords: Finite Difference, Radiant Heating, Thermoforming

References

[1] J.L. Throne, Technology of thermoforming, Hanser Gardner Publications, Munich, (1996).

[2] J.P. Holman, Heat Transfer, eight ed. McGraw-Hill New York, (1997).

[3] Moore, B., In-cycle Control of the thermoforming reheat Process, McGill Univ., Canada (2002).

[4] A. Youesefi, A. Bendada, R. Diraddo, Improved modeling for the reheat phase in thermoforming through an uncertainty treatment of the key parameters, Pol. Eng. And Sci. 42 (2002) 1115-1129.

DOI: 10.1002/pen.11016

[5] R. Courant, K. Friedrichs, H. Lewyt, On the partial Difference Equations of Mathematical Physics, IBM Journal (1967) 215-234.

[6] G. Gauthier, M. Ajersch, B. Boulet, A. Haurani, P. Girard, R. Diraddo, A new absorption based model for sheet reheat in thermoforming, Proceedings of the ANTEC conference 2005, 353-357.