Effect of shrinkage and process parameters on the monitoring of bulk and surface stream temperatures in injection molding via the infrared waveguide method

• Published in: Polymer engineering and science Vol. 44; no. 5; pp. 955 - 964
• Main Authors: Bendada, A., Simard, Y., Lamontagne, M.
• Format: Journal Article
• Language: English
• Published: New York Society of Plastics Engineers, Inc 01.05.2004; Wiley Subscription Services; Blackwell Publishing Ltd
• Subjects: Applied sciences; Exact sciences and technology; Injection molding; Materials science; Physicochemistry of polymers; Polymer industry, paints, wood; Polymers; Technology of polymers; Injection press; Injection molding; Polymer; Kinetics; Shrinkage; Monitoring; Optical fiber
• ISSN: 0032-3888; 1548-2634
• DOI: 10.1002/pen.20087

This paper analyzes for the first time the application of the infrared hollow waveguide method for the remote sensing of the temperature decay of polymer streams during injection molding. The key feature of the infrared procedure employed is its low transmission loss of the thermal energy in the mid and far infrared spectral regions. This particular advantage allows the hollow waveguide device to measure not only the bulk temperature within the polymer, as commercially available full‐core optical fiber instruments do, but also the temperature at the polymer surface. Moreover, the hollow waveguide device is able to measure quite low temperatures, which conventional thermometers cannot do either. Experimental trials have been run on a Husky injection molding press in order to investigate the effect of some process parameters and shrinkage on the bulk and surface temperature decay signals. The results showed a drastic deviation between the kinetic behaviors of the surface and bulk temperature traces throughout the injection cycle. Particularly, it was noticed that the cooling rate of the surface temperature was more affected by part shrinkage than the cooling rate of the bulk temperature. The experimental results showed also that temperatures below 60°C could be reliably measured with reasonable signal‐over‐noise ratio. Polym. Eng. Sci. 44:955–964, 2004.