Precitec (Germany)

Today’s manufacturing processes, especially 3D printing with powder or wire, presuppose Industry 4.0 solutions, which require supervision of every single production step. Transforming machine elements into intelligent cyber-physical systems involves the integration of smart sensors for condition and process monitoring. As photonic solutions are by nature contact-free processes it would be advantageous if the sensor is based on light as well if the light could be coupled into the beam path of the processing laser and if the sensor can measure surface topography in micrometer resolution. In this case, the production process can be directly connected to the CAD data set, the process could be controlled to eliminate geometrical deviations to the desired geometry and first-time-right is not a pious hope anymore. We talk about controlled individualized lot size 1 production based on OCT sensor technology. This contribution to the SPIE Optics & Photonics 2024 conference will report on industrial solutions where sensor technology is ready to take the lead, which is only is possible, when the measurement provides undoubtedly information about the actual process status. Especially for additive manufacturing processes the implementation of OCT technology will introduce a new level of automation.

It becomes clearer and clearer that there is more than a gradual transition in automotive industry, especially when it comes to the future propulsion systems. Whether we talk about e-mobility or hydrogen drive, laser and photonics industry take the chance to transform manufacturing processes, convince decision makes on the undoubted advantages of photonic tools in the relevant production chains. As most of the applications e.g., in e-mobility start from scratch one can directly use the most profitable manufacturing tools. There is no need to transform an already existing process from the “pre laser age” into modern times. This paper reviews some of the applications in battery production from the perspective of a supplier of sensor technology and processing tools, without claim of completeness. The focus will concentrate on laser welding as here process monitoring and control plays an important role, laser marking, drilling, surface processing will not be part of the deliberations. This contribution to the Photonics West '22 LASE conference describes the intersection between photonics and demands when it comes to efficient production tools for tomorrow’s mobility. Further intersections with respect to Industry 4.0 and artificial intelligence haven’t even been mentioned, but here we easily find more examples which underscore the uniqueness of the laser in the context of e-mobility.

Abstract This paper addresses in-process monitoring of part-to-part gap and weld penetration depth using photodiode-based signals during Remote Laser Welding (RLW) of battery tab connectors. Photodiode-based monitoring has been largely implemented for structural welds due to its relatively low cost and ease of automation. However, the application of photodiode-based monitoring to RLW of thin foils of dissimilar metals for battery tab connectors remains an unexplored area of research and will be addressed in this paper. Motivated by the high variability during the welding process of thin foils of dissimilar metals, this paper aims to evaluate the photodiode-based signals to determine if variations in weld quality can be isolated and diagnosed. The main focus is in diagnosing defective weld conditions caused by part-to-part gap variations and/or excessive weld penetration depth. Photodiode-based signals have been collected during RLW of copper-to-steel thin foils lap joint (Ni-plated copper 300 μm to Ni-plated steel 300 μm). The methodology is based on the evaluation of the energy intensity and scatter level of the signals. The energy intensity gives information about the amount of radiation emitted during the welding process, and the scatter level is associated to the accumulated and un-controlled variations. Findings indicated that part-to-part gap variations can be diagnosed by observing the step-change in the plasma signal, with no significant contribution given by the back-reflection. Results further suggested that over-penetration corresponds to significant increment of the scatter level in the sensor signals. Opportunities for automatic isolation and diagnosis of defective welds based on supervised machine learning will be discussed throughout the paper.

The geometry of the cutting front and the cutting kerf was measured with an online high-speed x-ray diagnostic system. X-ray videos from fusion cutting of 10 mm thick stainless steel samples were recorded with a frame rate of 1000 Hz. A three-dimensional reconstruction of the time-averaged geometry of the cutting front and cutting kerf out of these images made it possible to apply ray-tracing for calculating the overall absorptance and the distribution of the absorbed irradiance at the cutting front. When increasing the feed rate, it was observed that the local inclination of the lower part of the cutting front with respect to the laser beam increased as well as the locally absorbed irradiance on the cutting front. This also leads to an increase in the overall absorptance with increasing feed rates.

Abstract Der Wandel von energiehungrigen Arbeitsmaschinen hin zu leistungsoptimierten Fertigungsverfahren kann in allen industriellen Produktionsprozessen beobachtet werden.Die Innovationsallianz „Green Carbody Technologies”︁ untersucht Möglichkeiten zur Energieeinsparung im Karosseriebau. Im Rahmen des Teilprojektes 4.3.3 werden die Potentiale zur Leistungseinsparung beim Laserschweißen untersucht.

Das Kapitel enthält die folgenden Abschnitte: Der Bearbeitungsprozess - Pre-, In- und Post-Prozess Position Pre-Prozess Sensorik In-Prozess Sensorik Post-Prozess Sensorik Kombination verschiedener Messverfahren Literatur

5.1 Introduction An aspheric surface is considered a special optical surface. It is special because it can do more than a spherical surface with regard to aberration correction. But it is also special because it is much more expensive to manufacture, especially if the surface is produced by means other than diamond turning. A diffractive surface with its grating profile engraved into it to act as a thin lens belongs in this category of special surfaces as well. Both will be discussed in detail. Because windows, filter substrates, and other plane-parallel elements such as beam splitters and Dewar windows are often ignored by the user and not considered to be optical elements, we treat them here as elements with special surfaces. These elements in converging or diverging light contribute to aberrations just as a lens or a curved mirror does. In addition, they shift and displace image locations. Knowing the behaviors of plane-parallel plates allows us to correct for their aberration contributions or take advantage of that knowledge in balancing the system's aberrations. Another element surprisingly often ignored in the layout stage is the concentric dome. It contributes to the aberrations and has focusing power. The details of these characteristics will be addressed. Ball lenses and gradient index lenses are frequently used as coupling elements with optical fibers. Their features and performances are included as well, even though their applications are limited to the visible (VIS) and near-infrared (NIR) spectra. 5.2 The Plane-Parallel Plate By definition, a plane-parallel plate is flat and parallel. If this is not the case, it is a lens with convex or concave spherical or cylindrical surfaces. The surfaces can also be toroidal or general aspheres on either or both sides. The plate can also be flat on both sides, with the surfaces not parallel to each other. In that case the element is a prism. 5.2.1 Displacements If a plane-parallel plate is inserted into an image-forming optical system, with its surfaces perpendicular to the optical axis, the image plane is shifted toward the right, assuming the light is coming from the left (see Fig. 5.1).