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In-situ infrared thermography measurements to master transmission laser welding process parameters of PEKK

Villar, Miguel and Garnier, Christian and Chabert, France and Nassiet, Valérie and Samélor, Diane and Diez, Juan Carlos and Sotelo, Andres and Madre, Maria A. In-situ infrared thermography measurements to master transmission laser welding process parameters of PEKK. (2018) Optics and Lasers in Engineering, 106. 94-104. ISSN 0143-8166

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Official URL: https://dx.doi.org/10.1016/j.optlaseng.2018.02.016

Abstract

The temperature field along the thickness of the specimens has been measured during transmission laser welding. Polyetherketoneketone (PEKK) is a very high performance thermoplastic with tunable properties. We have shown that this grade of PEKK can be turned to quasi-amorphous or semi-crystalline material, due to its slow kinetics of crystallization. Its glass transition temperature is 150 °C. The effect of its crystalline rate directly impacts its optical properties: the transmittance of quasi-amorphous PEKK is about 60% in the NIR region (wavelength range from 0.4 to 1.2 μm) whereas it is less than 3% for the semi-crystalline material. The welding tests have been carried out with an 808 nm laser diode apparatus. The heat field is recorded during the welding experiment by infrared thermography with the camera sensor perpendicular to the lasersheet and to the sample’s length to focus on the welded interface. The study is divided in two steps: firstly, a single specimen is irradiated with an energy density of 22 J.mm − 2 : the whole sample thickness is heated up, the maximum temperature reaches 222 ± 7 °C. This temperature corresponds to about T g + 70 °C, but the polymer does not reach its melting temperature. After that, welding tests were performed: a transparent (quasi-amorphous) sample as the upper part and an opaque (semi-crystalline) one as the lower part were assembled in static conditions. The maximum temperature reached at the welded interface is about 295 °C when the upper specimen is irradiated for 16 s with an energy density of 28 J.mm − 2 . The temperature at the welded interface stays above T g during 55 s and reached the melting temperature during 5 s before rapid cooling. These parameters are suitable to assemble both polymeric parts in a strong weld. This work shows that infrared thermography is an appropriate technique to improve the reliability of laser welding process of high performance thermoplastics.

Item Type:Article
Additional Information:Thanks to Elsevier editor. The original PDF of the article can be found at Optics and Lasers in Engineering website : https://www.sciencedirect.com/science/article/pii/S0143816617308977
HAL Id:hal-01726061
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution:French research institutions > Centre National de la Recherche Scientifique - CNRS (FRANCE)
Université de Toulouse > Institut National Polytechnique de Toulouse - INPT (FRANCE)
Université de Toulouse > Université Toulouse III - Paul Sabatier - UPS (FRANCE)
Other partners > Universidad Zaragoza (SPAIN)
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Deposited By: Diane SAMELOR
Deposited On:07 Mar 2018 17:42

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