The cutting and welding of carbon fiber reinforced polymer composite (CFPR) requires a precisely defined energy input from the laser. Precision is vital as the carbon fibres only start to melt above 3,000 °C whereas the polymer matrix making up the composite has already begun to melt and vaporize at temperatures as low as 130 °C. Because of the wide variation in the thermo-physical properties of the fibre and matrix a highly precise and temporally resolved temperature measurement is required. Fast image acquisition is necessary as the operational cycles of the laser processes are often very short. Only by using such fast measurement capability can processes be understood overcoming thermal interference effects from the base material in the quality of cut edges and weld seams produced.

To investigate the emitted thermal radiation from the laser cutting and welding processes Dr. Peter Jäschke and his composite material team use a cooled camera operating in the mid-wave infrared waveband (2 … 5) microns – the ImageIR® 8300 from InfraTec. With two separate filter wheels, each with five positions, spectral anomalies during CFRP processing can be detected at a level of accuracy in temperature measurement of ±1 %.

This high level of accuracy can only be achieved by the implementation of specially developed precision calibration methods to use the full dynamic range of the infrared detector as well as the integration of several calibration curves to guarantee for long-term stability and drift compensation. Using InfraTec's special lenses the smallest detail can be well resolved from a relatively large and therefore safe working distance.

Control of the camera, acquisition, storage and analysis of measurement data is performed with the IRBIS® 3 thermographic software ensuring the efficient conversion of acquired data into usable knowledge.

Infrared camera ImageIR® 8300 Series from InfraTec
Further information about ImageIR® 8300

InfraTec Solution

Laser Zentrum Hannover e.V.
30419 Hannover

www.lzh.de

Infrared camera: ImageIR® 8300

Temperaturverteilung während des Laserstrahlschneidens eines CFK-Bauteils

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