Ultra-fast lasers have already been used to machine rotational symmetric metallic cylinders for printing and embossing applications for several years. To achieve a fully seamless structuring around a circumference often a helical gravure approach is used by constantly slowly moving the machining head in direction of the axes of the rotating cylinder. An approach for machining tools is the tangential machining where the small movement giving the local for of the tool is realized with a galvo – scanner whereas the tool itself is moved with an x, y, z, B and C axes.

The realization that will be presented here uses a high-end galvanometric scanner to move the laser beam at speeds of several ten meters per second across a constantly rotating part. The most important part is the synchronization of the laser, the scanner and the axes. The galvanometric scanner is controlled by means of a specialized hardware based on a Zynq-SoM and a RTC5 controller card in a way that it can be synchronized to the ultrafast pulse laser (EP000003045257A3). In addition, the position and speed of a linear or a rotary axis can be controlled and synchronized to the ultrafast pulse laser as well. In contrast to currently used “Marking-on-the-fly” feature, in which the scanner adapts its speed according to the encoder signs of the linear or rotary axis, the presented setup controls the speed of the linear or rotary axis actively.

To achieve a straight movement parallel to the rotation axes of the scanned laser beam in bi-directional mode (forth and back movement) its trajectory has to be calculated according to the speed of the rotation axes and the speed this axis is actively controlled according to the pulse to pulse distance in circumference direction. With this control an accuracy in the range of a few µm can be guaranteed over several 100 turns of the rotation axis offering the possibility to machine rotation symmetric parts totally seamless with highest precision. This principle will be extended to small high precision embossing cylinders with about 10 cm diameter.