Welding Arc Laboratory
Main topics of the application-driven research in the laboratory concern process safety, stability and efficiency of arc welding technology. The focus is put on the temporally and spatially resolved analysis of the welding arcs, the arc attachment at the electrodes, the material transfer and the weld pool properties. The plasma diagnostics allows for the measurements of temperature and species densities as well as, finally, the determination of the plasma properties of the welding arc. High-speed imaging techniques is used to study the arc structure, its dynamics and the material transfer. In addition, surface temperatures of the weld pool and of the metal droplets can be analysed.
The laboratory allows for the study of welding arc processes under realistic conditions in practical applications and is equipped with modern measuring techniques, in particular
- Setups with fixed mounting of the welding and flexible movement of test substrates under the burner for the optical study of the process from different sights of view, e.g. from top, parallel or perpendicular to the substrate surface including gas feed, exhaust unit and radiation protection
- Current sources of different manufacturers (e.g. Fronius CMT advanced 4000R, EWM Phoenix 521 progress pulse coldarc) as well as a freely programmable source (TopCon Quadro)
- Electrical and optical sensors (photodiodes) for recording of time sequences of current, voltage and emission signals in specific spectral ranges as well as corresponding methods for their analysis
- 0.5 and 0.75 m spectrographs with intensified CCD cameras (single images with exposure times from few ns to ms) for optical emission spectroscopy, in particular for measurements with high spatial and spectral resolution in the in spectral range from 300 nm to 900 nm with resolution of up to 0.05 nm
- High speed imaging cameras for up to 70000 frames/s for process control including spectral selective filters (narrow band MIF, edge filters, polarizer filters) with double frame optics for simultaneous recording with two different filters and one camera
- Framing camera (4 independent images within e.g. 5 ns with exposure time of 3 ns) and Streak camera (temporal resolution <1 ns, 1 spatial dimension) for the observation of arc ignition processes in the ns-range
- Thermography / pyrometry for contactless measurement of surface temperatures of e.g. electrodes
- X-ray computer tomography for non-destructive diagnostics of electrodes and material probes
Most of the measurement setups (spectroscopy, high speed imaging, thermography) are mobile and can be used for external measurement campaigns.
