Fiducial marks or other markings are intended to ensure that printed workpieces are cut precisely according to the specific contours. Even more security is offered by the combination with the optical recognition system POSITIONplus from eurolaser.
Any material shifts on the work surface are automatically compensated for by the software. Quality defects caused by faulty cuts are effectively prevented.
Even with the most careful preparation, it can happen that printed workpieces “veer off course” a little during material feed on the working surface of the laser system. This particularly affects flexible materials such as textiles or soft signage fabrics, where shrinkage, stretching or twisting can occur unpredictably and change the position of the print. If the trim allowance is no longer sufficient, the result is undesirable margins outside the contour. Cut products containing such “glitches” then at best have to be manually reworked with great effort.
Conventional technology requires post-processing
The extent to which conventionally made-up foam has to be reworked depends not only on the method used but also on the composition and above all on the pore structure of the starting material. Open-cell foams are air- and water-permeable, making them ideally suited for storing liquids. During the assembly in the water jet process, however, the material absorbs moisture along the cut edges and must first be dried before final processing can begin. Closed-cell foams, on the other hand, are usually waterproof, but cutting them to size mechanical means then practically always requires further cleaning processes. Contactless material processing by a laser cutter, on the other hand, not only makes post-processing irrelevant but also meets the highest quality requirements for the use of foam products in sensitive areas.
Deviations compensated without interruption
Instead of correcting the material position and possibly having to interrupt the process, POSITIONplus automatically adjusts the path of the laser beam to the deviation during operation. POSITIONplus combines the optical detection of fiducial marks (printed, woven, or embroidered) and other reference points such as edges with the intelligent correction function of the eurolaser software LaserScout. Mounted directly on the processing head of the laser system, a CCD camera continuously records the actual position data of the cutting contours and compares the information with the reference values from the print data. If LaserScout detects an offset of the workpiece, a twist, shrinkage, or other changes in the position of the material, the respective cutting contour is recalculated within fractions of a second, and the alignment of the processing head is adjusted accordingly. The use of POSITIONplus and LaserScout has no significant effect on the eurolaser systems with processing speeds of up to 1,414 mm/s.
Circle best suited as fiducial mark
Although LaserScout can detect a variety of different types and shapes of fiducial marks on a workpiece and use them to adjust the machining process, the detection system developed by eurolaser achieves the best possible results with plain geometric circles. Since the distance from the edge to the center of a circle is the same from all sides, this shape is best recognized by the camera. A high contrast of the marking against the background (black circle on white material) further improves identification. Ideally, a circle as a fiducial mark has a diameter of about 6 mm and thus stands out well within the approximately 30 x 30 mm “field of view” of the camera. Last but not least, the quality of the recognition and correction process with POSITIONplus and LaserScout also depends on the number of fiducial marks that signal the respective position of the motif to be cut out. Depending on the contour shape, at least three marks should be used so that the cutting guide can be precisely adjusted even if several material-related deviations occur simultaneously.
Can be combined with additional tools
POSITIONplus and LaserScout ensure that the processing of printed workpieces with systems from eurolaser can always be carried out with the highest quality and performance. The technology is compatible with all laser machines offered by eurolaser and also works in combination with additional tools. Parallel to the processing head, each of the systems can be equipped or retrofitted with up to two additional tool heads from the ZÜND product portfolio. In addition to classic contour cuts, the eurolaser system is then also capable of milling fittings for automotive applications, for example, or mechanical assembling large-area soft signage products using a knife. In combination with the optical recognition system from eurolaser, a maximum degree of automation of the entire workpiece processing is thus achieved while obtaining the highest product quality.