Peter Scholz

Large-scale additive manufacturing (LSAM) using fused granulate fabrication (FGF) offers a potential route for the high-value utilization of recycled thermoplastic composites. This study investigated recycled PA6 containing nominally 30 wt.% glass fibers as a candidate feedstock for large-format FGF. An unmodified reference and formulations containing SF315/PTFE, SF315/U15, and MIX-OH were examined. The granulates were characterized using melt mass flow rate measurements, thermogravimetric analysis, and differential scanning calorimetry, while mechanical properties were compared after injection molding and FGF processing. The best FGF performance was obtained for SF315/PTFE (polytetrafluoroethylene) and SF315/U15. Their tensile strengths reached 117.3 and 118.7 MPa, respectively, compared with 56.8 MPa for the FGF-processed reference. Flexural strengths reached 158.8 and 152.4 MPa, respectively, versus 88.0 MPa for the reference. The tensile and flexural improvements produced by MIX-OH after injection molding were not retained after FGF processing, confirming strong processing-route dependence. Preliminary pull-off screening demonstrated that TPU-bonded polymer–steel joints could be produced. Under the investigated conditions, SF315/PTFE and SF315/U15 were identified as promising recycled PA6/GF30 formulations for large-format FGF and further tooling-oriented development.

Dimensional errors, uneven sheet thinning, high forming forces, and inadequate surface quality continue to limit the wider industrial use of incremental forming, particularly when geometrically complex parts must be produced reliably. A review of studies on incremental sheet forming shows that fewer than 21% address optimisation of the analysed parameters. These optimisations are spread across different forming strategies, materials, sheet thicknesses, objectives, and part geometries. However, multi-objective optimisation of technological parameters, and the influence of material and thickness, is even scarcer. This paper provides an overview of currently available optimisation approaches, their target applications, and the evaluation of improvements for commonly used incremental forming strategies. Robot-based incremental forming is also considered, as industrial robots offer high tool path flexibility and allow more adaptable process layouts. The multi-objective optimisation of incremental forming, combining part accuracy, thickness distribution, forming force, and surface quality, is therefore identified as a major research need. Several advanced approaches and their practical implementation aspects are presented comparatively. They enable systematic selection of optimisation strategies for research and industrial applications.

This paper provides an overview of the development of a 3D formed and metal-based facade element that combines a custom design and solar thermal functionality. To achieve this, a novel simplified solar thermal collector structure was developed using formed sheet metal half-shells with an integrated channel structure on the inside and a special absorber coating on the outside. The sheet metal half-shells were manufactured by highly innovative incremental sheet forming (ISF), which allows seamless integration into existing facades. As a part of this paper, the initial test results on thermal efficiency and the energy accumulation of the new collector type are presented.

Fibre metal laminates (FMLs) consisting of layers made of PA6 polyamide prepregs reinforced with glass and carbon fibres and an aluminium alloy core are the new variant of the other types used by aerospace FML materials such as GLARE or CARALL. By using a thermoplastic matrix, they can be shaped by stamping processes, which allows for a more efficient production process than classical laminating methods such as vacuum bagging. In addition to the improved impact energy absorption efficiency, the metallic core can be utilised to effectively bond the composite part to adjacent metallic structures. This article presents the influence of the material configuration of fibre-metal laminates consisting of continuous fibre-reinforced thermoplastic outer layers integrated with a layer of metallic aluminium alloy inserts—a number of layers, type and direction of reinforcing fibres—on the static and fatigue flexural properties. In this study, eight laminate configurations were prepared using a one-step variothermal consolidation process. The results showed that in the three-point flexural fatigue test, the samples exceeded 10 ⁶ cycles at stresses <30% of the static bending strength. Laminates with predominantly longitudinally reinforced layers showed the highest fatigue strength among the FML samples analysed. The type of reinforcing fibres and the number of layers were less affected on the analysed mechanical properties.

This paper will give an overview about the development of a material system, which consists of a novel formable magnesium alloy that is provided with an effective corrosion protection coating. The corrosion protection is to be realized in the form of a forming stable powder coating, which can be applied in the coil coating process. To improve the tribological properties, additional additives are added to the powder coating. Within this paper, first results concerning tribological and forming behavior of the new lightweight material system are given. For the benchmark, the results are compared with commercially available AZ31 Mg alloy.

The paper presents research on increasing the efficiency of industrial centrifugal fans, which are the third highest energy-consuming group of devices. This problem is related to the frequent incompatibility of the fan characteristics with the flow conditions of the installation in which they are operated, which lowers efficiency and increases energy consumption. By ensuring high efficiency of these devices, it is possible to significantly reduce the operating costs of such industrial equipment. For this purpose, a unique concept of regulating the flow parameters of centrifugal fans was developed. The scientific basis of this idea is that a relatively small change in the impeller diameter of the fan significantly affects the flow rate and the pressure rise of the fan. Therefore, the idea uses variable length of the impeller blades by dividing them into a fixed and a movable part. It enables adjustment of the length of the blades, which allows extension of the range of effective and efficient operating parameters. On this basis, several technical solutions of the regulation system were developed, which were then tested using simulation and analytical methods. Two material options for the moving part of the blade have also been developed, one made of metallic materials (high-strength steel and aluminum) and the other made of composite materials. The research showed a significant influence of the mass of the movable part of the blade on the load of the control system. Therefore, ultra-light material variants were used for the impeller blades. The flow simulation tests of the new method of adjusting the fan flow parameters confirmed the effectiveness of this solution. As a result, a wider range of highly efficient centrifugal fans equipped with such a control system was obtained.