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In the context of the fourth industrial revolution, condition monitoring and predictive maintenance of machines are becoming increasingly important, as unplanned machine failures can lead to high costs for the operator. Many of these machine failures can be traced back to bearing damage, which must be prevented. In order to be able to make reliable statements about the remaining service life of the bearings, a condition monitoring system is required. For the development of these systems, bearings with a defined level of damage are needed. Since there are not enough reproducible methods for bearing damage so far, the defined generation of reproducible, local bearing damage is researched by using laser technology. The damage caused is checked and evaluated by means of vibration analysis and white light interferometry. The results confirm a reproducibility and scalability of the bearing damages by means of laser technology. The damaged bearings can be used for research-based development as well as in industrial implementations of condition monitoring systems.

Laser Powder Bed Fusion (LPBF) is an Additive Manufacturing technique, which allows production of highly complex solid metal parts with good mechanical properties, compared to conventionally manufactured parts. Nevertheless, the layer-by-layer fabrication process also offers several disadvantages, including a relatively high surface roughness depending on the shape of the component, its position and orientation during the fabrication process. This paper deals with investigations on the surface roughness reduction capability, and residual surface structures by laser polishing of LPBF AlSi10Mg parts under varying initial surface roughness in order to investigate the influence of the surface behavior and initial surface roughness to the achievable surface quality by laser polishing. Hereto test specimens with varying fabrication orientations regarding to the built platform are printed and further polished. Thereby the initial arithmetic roughness varies between 19.2 μm and 8.0 μm. It could be shown that the achievable surface roughness by laser polishing with continuous and pulsed laser radiation is increasing with rising initial roughness, but the relative roughness reduction is almost constant in the range of 95% - 97.5%. The analyzation of the residual roughness structures shows, that the main roughness differences is found in the middle and long structure wavelength regime, which are directly depending on the initial surface structures of 3D printing.

In this study, the influence of laser polishing on the microstructural and mechanical properties of additively manufactured aluminium AlSi10Mg Laser Powder Bed Fusion (L-PBF) parts is analysed. The investigation is carried out on a 5-axis laser cell equipped with 1D Scanner optics driven by a solid-state disc laser at a wavelength of 1030 nm. Laser polishing is performed with pulsed or continuous laser radiation on samples in the initial L-PBF state or after stress relief treatment in a furnace. The metallurgical investigation of the remelting zone with a depth of 101–237 µm revealed an unchanged and homogeneous chemical composition, with a coarsened α-phase and a changed grain structure. The hardness within the remelting zone is reduced to 102–104 HV 0.1 compared to 146 HV 0.1 at the L-PBF initial state. Below the remelting zone, within the heat affected zone, a reduced microhardness, which can reach a thickness up to 1.5 mm, occurs. Laser polishing results in a reduction in residual stresses and resulting distortions compared to the L-PBF initial state. Nevertheless, the re-solidification shrinkage of the polished surface layer introduces additional tensions, resulting in sample distortions well above ones remaining after a stress relieve heat treatment of the initial state. The mechanical properties, analysed on laser polished flat tensile specimens, revealed an increase in the ultimate elongation from 4.5% to 5.4–10.7% and a reduction in the tensile strength from 346 N/mm2 to 247–271 N/mm2 through laser polishing. Hence, the strength resulting from this is comparable to the initial L-PBF specimens after stress relieve heat treatment.

In this study a new approach to laser polishing with periodic modulated laser power in the kilohertz regime is introduced. By varying the modulation frequency and modulation time, different periodic laser power curves with varying minimum, peak and average laser power can be created. The feasibility of the method is shown by polishing of vertical built AlSi10Mg L-PBF parts with an initial roughness of Ra = 12.22 µm. One polishing pass revealed a decreasing surface roughness with increasing energy density on the surface up to Ra = 0.145 µm. An increasing energy density results in a rising remelting depth between 50 and 255 µm and a rising relative porosity of 0.3% to 4.6%. Furthermore, the thermal process stability, analysed by the melt pool length in scanning direction, reveals a steadily increasing melt pool dimension due to component heating. Multiple laser polishing passes offers a further reduced surface roughness, especially at higher modulation frequencies and provides an improved orientation independent roughness homogeneity. The process stability regarding varying initial surface roughness revealed an almost constant relative roughness reduction rate with an achievable roughness variation after two polishing passes between Ra = 0.13–0.26 µm from an initial state of Ra = 8.0–19.2 µm.

Selective laser melting is gaining importance to manufacture reliable and highly complex parts. However, the surfaces of the selective laser melted parts exhibit for many applications an insufficient high roughness, thus require subsequent post processing steps. A relatively new way to reduce the surface roughness is the laser polishing technique. In the present paper, additively manufactured AlSi10Mg samples were polished with different laser intensities and laser modes. The investigations contain the potential of roughness reduction and enhancement of the surface appearances, which can be achieved by laser polishing of the as-built surfaces. An initial arithmetic mean roughness of 8.43 μm was remarkably reduced up to 98 %. The compositions of the polished surfaces were detected and the surface appearances were examined. Reasons and mechanisms were explained and depicted for the occurred shade formations on the polished surfaces. High laser intensity led to segregation of silicon and magnesium on the surface. A higher laser intensity enabled an increased melt depth within the conture layer of the selective laser melting structure. Through increasing melt depth, a porosity of max. 1.7 % was detected in the remolten area. Hardness investigations of the initial and laser remolten cross section revealed no significant reduction in hardness.

Due to its flexibility, laser can be used for a wide variety of applications. Applications that are suitable for laser material processing include polishing, hardening, cleaning structuring, soldering and 3D printing (SLM). However, treating of complex freeform surfaces is challenging in terms of track planning. As manual track planning is not economically viable, there is a demand for software solutions for track planning with respect to time-based processes. This paper deals with the development of a software solution for automated track planning with respect to time-based processes. In addition, the introduced software includes postprocessors for fully automated G-Code, Rapid and Kuka Robot Language (KRL) generation. To demonstrate the feasibility and advantage of a time-based offline track planning of robot guided laser application, an additively manufactured freeform surface was laser polished. An application example represents the robot guided laser polishing of a complex 3D freeform surface. Investigations revealed a relative roughness reduction ~92 % of X2CrNiMo17-12-2 steel (1.4404).

Laser based additive manufacturing is a key technology for sustainable mobility and power engineering. It has undergone a dynamic development in recent years regarding process stabilization, reliability and standardization. However, in the current state laser based additive manufacturing still requires extensive R and D work in process understanding and investigation of material properties as well as developing new materials and advance the process possibilities. To overcome restrictions of commercially available AM machines with regard to necessary powder quantity and adaptable equipment such as sensors and e.g. heating devices two individual laser process chambers (LPCs), manual and partly automated, have been established. In addition to the low powder quantities needed to produce samples for process and material development the LPCs also offer the possibility to manufacture two materials in alternating layers to combine physical properties. A manual LPC is used to produce small scale samples from lab scale adjusted WC-Co powder types to further develop the material class for AM and to deepen understanding of phase formation. WC-12Co with additives is successfully manufactured to a high density and phase formation is investigated. The manual LPC is also used to proof the concept of layered AM structures from a combination of Fe and FeAl for magnetic applications. A further developed and automated version of the manual LPC is then used to produce larger layered samples for further analysis.

Powder-bed based additive manufacturing techniques, such as selective laser melting (SLM), are gaining in importance due to the opportunity to produce highly complex shapes. This offer new construction possibilities in the design. However, the surface of the produced SLM parts exhibit a high roughness which can affect the integrity and geometric tolerance. To reduce the surface roughness and to improve the mechanical properties of the outmost layer, laser polishing by re-melting the surface can be used. The present paper focus on the laser polishing of additive manufactured parts. This investigation contains measurement results of the initial and laser polished surfaces out of AlSi10Mg. The surfaces have been analyzed by roughness spectroscopy and white light interferometry. By utilizing a disk laser with a maximum power of 4 kW in combination with a 1-D scanner system, the initial surface roughness was reduced up to 92 %.

Conventional polishing of components is a time- and labor-intensive process. Moreover, manual polishing mostly depends on the processor's abilities. In accordance with these and additional difficulties, there is a strong need for automatable and efficient variants. For this purpose, polishing by means of laser beam, which enables a contact free and automatable processing of surfaces, provides a promising alternative. This paper investigates the laser polishing of the aluminum alloy AlSi9MnMg. Aluminum poses a particular challenge for laser polishing, due to high level of reflection, high thermal conductivity, and high coefficient of thermal expansion. For the investigations, a disk laser with a maximum power of 4000 W was used. The processing took place with pulsed wave laser beam at a pulse frequency of 1000 Hz and a minimal pulse duration of 0.3 ms as well as a continuous wave laser beam. The beam guidance was done by 1D-scanner optics in a highly pure inert gas atmosphere. The samples were first genera...