Innovative Product Development by Additive Manufacturing 2021

Wire-and-arc-additive-manufacturing (WAAM) can be employed with Gas-Metal-Arc-Welding, Gas-Tungsten-Arc-Welding or Plasma-Welding to manufacture steel parts with higher deposition rates than other additive manufacturing processes. WAAM can be used to produce graded components. A graded component can be described as a component with varying material properties, such as varying hardness. The work focuses on manufacturing a component out of G3Si1 with a pre-defined hardness profile. The targeted hardness profile was a constantly increasing hardness along the build direction. Since the hardness of steel is strongly dependent on the cooling rate, faster cooling rates in upper layers are desired. A calculation of the components thermal behavior was used to detect the necessary trends of the process parameters. Finally, a component with the planned process parameters was manufactured and the resulting hardness profile was evaluated.

In the field of metal additive manufacturing, the metal binder jetting process is mainly characterized by its cost advantage and a higher level of detail compared to the established laser powder bed fusion process. This allows the design freedom of additive manufacturing to be applied to an even wider range of industrial fields. However, to avoid costly iteration loops and to fully exploit the potential of metal binder jetting, design guidelines are needed that systematically identify the restrictions and possibilities of this process. Therefore, in this paper, a procedure for determining a comprehensive design compendium is presented.

Laser wire Direct Energy Deposition (L-DED) is a manufacturing process capable of producing additively generated structures as well as repairing and coating of surfaces. The use of a coaxial system technology enables a direction-independent application of the weld deposit. For coaxial Laser Double-wire DED (LD-DED), a processing head with a centric wire feed for two wires has been developed. Using three single beams with a maximum output power of 220 W each and a wavelength of 970 nm, a combined focus point of 1.6 mm in diameter is realised. The single beams are guided using an optical fibre for each laser beam source. The advantages of the system are the small footprint, the individual control of the single laser beams and the ease of conversion to other applications. This paper describes the development of the coaxial laser-processing head for the Additive Manufacturing that is capable to produce functionally graded structures.

The size of components manufactured by laser powder bed fusion is limited by the available powder bed volume. To create larger structures, additively manufactured components can be combined with intermediate products to increase cost efficiency and amend the requirements. Joints of fiber-reinforced plastic profiles adhesively bonded with laser powder bed fusion manufactured aluminum couplers were investigated as examples. The geometric freedom of design in AM-processes enables optimization of the joint properties:To reveal the adhesive distribution during injection, tests with transparent acrylic models where carried out. The AM components’ topology was optimized using finite element analysis to homogenize the stress distribution within the adhesive. The static strength and fatigue properties were validated experimentally. Results on adhesive distribution and fatigue behavior will be presented.

Evaluation tables, which are often used for identification of potentially profitable additively manufactured (AM) parts, are widely based on AM-expert knowledge. In many applications these approaches suffer from deficient data quality in ERP and PLM systems. Furthermore, they exploit potential AM benefits such as function integration and resource efficiency through part consolidation only to a small extent. This paper proposes the use of product architecture (PA) as a baseline for functionality analysis in products. The introduced scenario based method uses a heuristic approach to restructure the conventional manufacturing-PA towards an AM-supporting PA by analysing the functional structure of the product. The current approach aims to prompt the integration of AM in product development by both expert and non-expert users. The feasibility of the proposed transformation methodology is demonstrated on a complex part assembly for high temperature applications.

Soft robotics is an emerging field in science and technology that extends the area of classical robotics to new types of applications. Soft robots uniformly conform to their objects in contact without damaging them, but also without being damaged themselves by these objects. In the field of pneumatic soft robots, the classical production method is silicone injection molding. This method, however, is only economical for relatively large batch sizes. In this context, additive manufacturing (and especially silicone 3D printing) offers a promising alternative for small and medium batch sizes. In this paper, we describe the technology of silicone 3D printing, discuss the way to develop a comprehensive design compendium, and present the application of first design guidelines using an illustrative example.

Additive manufacturing is a strong enabler for the individualization trend in product development and is also increasingly finding its way into medical technology. This is made possible by the immense design freedom as well as new modeling methods, which can transform the design phase in product development. This paper presents a process chain for automating the design synthesis of a parameterized hip endoprosthesis based on patient-specific computed tomographic image data. Expert systems are used to simplify and automate critical design steps of the endoprosthesis, which are specified at a high level of abstraction by the user's input of design goals. This process chain, in contrast to the conventional design synthesis, can also be extended with multi- objective optimization strategies, like a maximize bone-ingrowth through a surface layer with lattice structures, so that the efficiency of the automated design synthesis of the short stem endoprosthesis can be maximized.

Additve Manufacturing (AM) offers the possibility to design and optimise Heat Exchangers (HX) in a completely new way, beyond the conventional types, which are limited by semi-finished products like pipes and plates. This paper starts with a short summary of the limitations of conventional Heat Exchangers along with possible solutions and potentials offered by AM of Heat Exchangers. A special focus is on the use of lattice structures to enhance heat transfer. A thermo-hydraulically optimised Heat Exchanger for AM by Laser Powder Bed Fusion (LPBF) is presented. Before designing the Heat Exchangers, considerations made are shown. This gas cooler was flow-optimised using CFD simulations and it has an internal lattice structure on the gas side. For a reference element of the structure used, the simulations show an enhancement in heat transfer between 187 and 266% compared to a plain tube. Finally, LPBF printed demonstrator Heat Exchangers and geometries are shown.

Based on layer-by-layer component generation, AM offers immense freedom in terms of design and material capabilities that cannot be achieved by conventional manufacturing. AM also provides potential for guiding and influencing the electromagnetic flux. The manufacturing process allows to realize a three-dimensional iron circuit design. Air gaps or powder cavities can be specifically placed in components to minimize the circulation paths of the induced voltage and thus the resulting eddy currents. In this investigation, additively manufactured toroidal cores are tested on a self-developed testing rig with regard to the resulting magnetization losses. For the toroidal cores, an iron-silicon alloy (FeSi3%) is used under the Laser Beam Melting process (LBM). The results provide a comparison of the specific power losses between solid and thin-walled structures of the iron cross-section.

Powder bed fusion (PBF) enables the manufacturing of complex structures. While part consolidation is a widespread method of utilizing the design potentials of additive manufacturing, new approaches in research suggest a systematic separation of parts. Conclusively, separated parts must be joined after the manufacturing process. In this paper, electroplating is proposed as a joining process for PBF fabricated components. The joining by electroplating process is described and successfully used to join PBF manufactured tension rods. The influence of the joining geometry on the buildup of the joint is investigated. Furthermore, tensile strength and failure causes of the joined specimens are determined. Tensile strength for nickel joined specimens is 127.4 MPa and for copper joined specimens 83.2 MPa. Causes of failure are delamination in the zinc layer and fracture of the base body. The tool-free character of the process holds potential for joining complex geometries in PBF.

Heat dissipation inside diode-pumped Nd:YVO₄ laser crystals requires an efficient cooling concept to reduce heat-induced stress and thus to avoid the mechanical destruction of the laser medium. Due to a high degree of design freedom, additive manufacturing of heat sinks offers great potentials to integrate cooling channels and sensors within a single component. These advantages are associated with a reduced choice of materials. The thermal and mechanical properties of the printing material have a significant impact on the emerging stress. For a suitable choice of printing material, temperatures and stress occurring in the application of the product are calculated using a multi-physical simulation model. By coupling optical, thermal and mechanical effects within a single simulation model, the mechanical stress in the laser crystal is investigated as a function of thermal material properties. Based on this information, thermal requirements are defined to ensure a non-destructive operation of a present laser application.

The quality of the powder layer is a decisive factor for the stability of powder bed fusion processes. Stereo-vision in-situ monitoring based on two high-speed cameras in combination with fringe projection is used to investigate the 3D topography of the powder bed in the L-PBF process. This paper proposes a method to determine the powder layer quality, by developing a powder bed quality factor from the so obtained data of the layers’ depth map. The proposed method is evaluated in the course of an empirical investigation, which consists of thirty-six experiments. In a quantitative evaluation, separated aspects of the analysed height data are combined to a powder bed quality factor in order to be able to compare the powder bed quality for different parameter sets. The focus of this analysis is on levelness and reproducibility, compared between layers within one experiment as well as the layers between experiment iterations.

The sustainability assessment of a product and the related process chain is the result of balancing influencing factors. Using different methods, such as life cycle assessment according ISO14040/44, it is possible to determine the ecological impact based on an evaluation of various influencing factors. For being able to identify and validate the potential of laser powder bed fusion process compared to conventional processes, a standardised approach is required. Following the “technical–economic evaluation” as defined in VDI2225 and the basics of the utility value analysis, objectives and evaluation criteria must be established and combined in a methodical approach. In this paper, a possibility to standardise the various influencing factors of additive and conventional manufacturing processes by a developed normalization matrix is presented. The effects of this norming are validated and discussed regarding their applicability based on the process chain of a demonstrator.

This article presents the design potential of a novel additive manufacturing process for three-dimensional (3D) multilayer devices with vertical interconnect accesses (VIA). The technical approach is based on multilayer printing of alternating metal-containing and insulating ink layers on 3D component surfaces. Additional laser ablation of the insulating coating creates VIA cavities, and the laser structuring of the metal ink sinters the conductive traces. Digital processing with a laser enables high variability in the generation of multilayer circuits. In particular, this enables the specific design of fully additively manufactured components with highly integrated electric circuits, including micro-VIA and fine-pitch contacts for area-array chip packages. An illustrative layout of a fully additive manufactured 3D multidirectional illumination device for customized and controllable lightning of test specimens shows the new freedoms in design that the process provides.

This study presents an automated approach that identifies suitable geometric structures in CAD-data for functional integration. Assemblies are processed and analysed in conjunction with a product's ERP data through filtering processes and classification algorithms. The main focus is on classifying parts regarding their degree of freedom to identify those that allow or restrict relative movement. With this information, the developed approach can recognize static associations of parts without relative movements via modularity optimization. The automated recognition of these static part groups creates starting points for the development of functionally integrated parts for Additive Manufacturing. Finally, it is shown that Additive Manufacturing can be beneficial for the economic production of these parts.

Recent growth of the microfluidics technology field and its applications demands more modular, flexible, reliable, easy to use and complete solutions. One key component in a microfluidic system is the section in charge of propelling and controlling flow through the microfluidic chip, this consists mainly of an impulsion (actuator) part, a sensor to read a signal and feed it to the actuator which modifies flow, and a closed control loop to set the desired operating point. Present solutions are not completely integrated as a final product to the user, but merely as a group of components which need to be coupled. The approach presented here provides one single plug and play device for liquids. Users only have to connect it to the hydraulic circuit of their microfluidic system and define a flow rate set point to start their experiments, thus avoiding setup difficulties. This microfluidic flow rate control device consists mainly of an electronics control board and a fluidic section composed of sensors and actuators. For the latter component, DLP 3D printing process of additive manufacturing was used as a rapid prototyping tool, going from conceptual design to a final product in a few months. Feedback between real performance and numerical modelling allowed operation improvements in the equipment thanks to fast prototyping and testing capacity. Finally, a fully integrated plug and play system which controls flows in a range of 10–1000 µL/min with a ± 1 µL/min resolution and easily coupled to microfluidic lines is obtained. In summary, additive manufacturing contributes not only as a tool to build new ideas, but also to optimize an already designed device, thanks to reduced costs and simplified fabrication processes for complex three-dimensional structures.

Additive manufacturing is an established technique in much of industry for manufacturing complex structures from polymer and metal materials. The additive manufacturing of glass materials is a very young process, which is based on through various approaches. For example, such processes are based on a glass powder bed or the layer-by-layer deposition of viscous glass from a crucible. In the Laser Glass Deposition process (LGD), a fused silica glass fiber (0.43 mm) is additively deposited onto a fused silica substrate by CO₂ laser irradiation. In order to form structural components from complex contours, or solids, experimental investigations on the printing of homogeneous layers were carried out in this paper. The main focus of the investigations is the influence of the laser power, the printing speed and the line spacing of single tracks and single layers on the deposition morphology. The results were used to realize multilayer complex structures with more than 300 layers.

Additive manufacturing is a versatile fabrication technology for many different applications. The flexibility of additive manufacturing opens a wide range of design opportunities. Contrary, due to the single material approach in additive manufacturing, the functional application of these objects is limited by the material's parameter. An approach to overcome this limitation are multi-functional objects, which combine different materials. The combination of different materials with specific parameters enables the generation of parts with tailor-made functionality. The paper aims to investigate the approach of multi-functional objects to be used with semi-finished parts (e.g. tubs, rods, formed sheet structures). The additional functional elements are deposited on the semi-finished parts by a wire-based additive manufacturing process. Materials like wood and thermoplastics have been selected for characterizing the adhesional properties and the requirements in designing the interfaces. Mechanical properties of the joints will be presented in dependency on material combination and surface preparation.

Advances in process and material technology of Additive Manufacturing (AM) and the design freedom resulting from the layer-by-layer build-up principle provide new possibilities in product design. In order to utilize the resulting AM potentials in product development in a focused and effective manner and thus to increase the overall product performance, the research field “Design for Additive Manufacturing” (DfAM) supports the identification of difficulties and provides suitable solutions, such as databases for the transfer of AM-specific knowledge, or design methodologies for the product development context. In this paper, a customer benefit oriented approach based on product property trade-offs for the application of AM potentials considering existing DfAM methods is presented and evaluated by academic and industrial workshops. For this purpose, the workshop concept and the required tools for the identification of possible conflicts of objectives and other DfAM tools are explained and exemplary results of the conducted workshops are presented.