Arc Sensor

Arc Sensor

Correction signals from the arc

The CLOOS arc sensor uses the arc to simultaneously weld and measure the joint position of the workpiece. The welding torch oscillates along the joint scanning the edges of the weld seam preparation. If the measured values, which are obtained electronically from the welding current and voltage, are not the same on both sides, the weld seam position deviates from the programmed path. The computer-based robot controller adjusts the welding head position so that the seam is placed exactly in the centre of the joint. In addition, this procedure corrects the distance of the welding torch to the workpiece.

Welding and measuring

As the arc sensor enables measurement and welding to be carried out simultaneously, the loss in time is minimal. At the same time workpiece distortions – for example due to heat expansion – are directly compensated for. In this way the CLOOS arc sensor combines productivity with optimum quality. No additional intrusive parts are necessary.

Saving the measured values

After the robot has welded the root seam, the correction data determined is saved and used for welding the cover runs ensuring the built-up of thee runs is continuously optimized. The final result is further improved when combined with the CLOOS gas nozzle sensor which determines the start of the weld seam.

Advantages … for more productivity


  • Nearly constant cycle times
  • No interference from attached parts
  • Direct connection to the robot controller
  • Adaptation of the correcting sensitivity
  • Memory function – data storage for welding of cover runs