Near infrared spectroscopy for in-line monitoring during injection moulding

• Published in: Polymer testing 2005-05, Vol.24 (3), p.367-375
• Main Authors: Dumitrescu, Oana R., Baker, Dave C., Foster, Gary M., Evans, Ken E.
• Format: Article
• Language: English
• Subjects: Applied sciences; Exact sciences and technology; In-line process monitoring; Injection moulding; Machinery and processing; Moulding; Near infrared spectroscopy; Plastics; Polymer industry, paints, wood; Technology of polymers
• ISSN: 0142-9418; 1873-2348
• DOI: 10.1016/j.polymertesting.2004.10.003

In recent years, near infrared spectroscopy has become a rapid-response analytical tool and has gained acceptance in different production processes and many industrial sectors; for example in the petrochemical, pharmaceutical, environmental, biomedical and automotive sectors. This paper reports on the development and applications of an infrared transmission sensor for plastic injection moulding using near infrared spectroscopy. The nozzle of a 150 tonne injection moulding machine was modified to accommodate two optical fibre probes for in-line monitoring of the injected polymer. The two optical fibre probes are connected to an FTIR portable spectrometer. This machine is able to withstand harsh environments whilst still providing good quality spectra. The primary aims of the current study are: (i) to provide a detailed description of the novel technique, (ii) to present examples of data, which show how this technology is useful to injection-moulders. The application of near infrared spectroscopy to injection moulding is seen as a promising technique with several potential benefits: (i) productivity improvements, (ii) reduction of costs, (iii) real-time monitoring, (iv) improvements in quality control, (v) health and safety. Future developments of this technology would allow the closed loop control of injection moulding machines and the possibility of ‘lights out manufacture’.