New System Tracks Contours During Laser Materials Processing

Fraunhofer Institute for Laser Technology has developed a process monitoring system that can precisely measure the position and speed of a laser beam processing point on a surface. The tracking system minimizes deviations from desired contour and speed and helps stabilize energy input.

A novel system developed in Germany allows precise measurement of the position and speed of a laser beam processing point on a work surface. In this image, the measured feed rate and trajectory in a welding process are shown. (Images: Fraunhofer Institute for Laser Technology ILT)

In recent years, the use of modern solid-state lasers has brought about a distinct increase in operational speed in laser materials processing. Whether with scanners or fixed optics, high speeds have almost become the norm. But although the movement of the optic is precisely calculated, the position of the processing point can deviate from the planned contour. This new system enables acceleration-related deviations from the set contour and speed to be measured exactly, and the numerical control system to be adjusted accordingly.

Researchers at the institute developed a camera-based system that analyzes the movements of the workpiece through the optical axis of the laser beam before or during processing. It does not matter whether a fixed or scanning optic is used — in both cases, the system measures the movement of the processing point on the workpiece and documents deviations from the set contour during machine setup or operation.

Shown are the workpiece surface and corresponding velocity vectors.

The system uses image sequence frequencies of up to 10 kHz. In various applications, contours have been measured with a processing speed of up to 10 m/min (fixed optic) and up to 15 m/s (scanner optic). The deviation from a reference system was less than 3 cm/min. Currently, the measured data are evaluated separately. Although the same technology permits real-time measurement, its accuracy class has not yet been specified completely.

For more information, visit: www.ilt.fraunhofer.de