Laser cleaning is an environmentally friendly method based on laser extraction processes to remove impurities or contaminants from a surface layer of a material. The configuration of a laser station in the case of flat surfaces is not complicated because laser irradiates from a fixed position. In contrast, controlled laser processing of 3D surfaces is not yet completely solved because the laser beam must be scanned along a three dimensional (3D) path.
A 3D laser processing strategy was developed to achieve an accurate and successful cleaning of freeform surfaces. Laser processing trajectories can be programmed directly on the 3D surface model instead of the 2D projection, which ensures both constant fluence and constant scanning speed all over the 3D surface during the laser processing. The strategy was applied to the removal of spray paint from a granite carved skirting board in order to validate the 3D cleaning system. The results, evaluated by means of hyperspectral imaging, stereomicroscopy and scanning electron microscopy, were compared with those of the surfaces treated with the same parameters but deactivating the 3D processing system. These analyses confirmed the improvement of the cleaning process when the 3D processing system is applied.
Time reduction and quick geometrical changes of complex components and tools are currently the most important demands in product development. The manufacturing process presented in this paper is based on multiple additive and subtractive technologies such as laser cutting, laser welding, direct laser metal deposition and CNC milling. The process chain is similar to layer‐based Rapid Prototyping Techniques. In the first step, the 3D CAD geometry is sliced into layers by a specially developed software. These slices are cut by high speed laser cutting and then joined together. In this way laminated tools or parts are built. To improve surface quality and to increase wear resistance a CNC machining center is used. The system consists of a CNC milling machine, in which a 3 kW Nd:YAG laser, a coaxial powder nozzle and a digitizing system are integrated.