Autonomous Robotic Feature-Based Freeform Fabrication Approach

Robotic additive manufacturing (AM) has gained much attention for its continuous material deposition capability with continuously changeable building orientations, reducing support structure volume and post-processing complexity. However, the current robotic additive process heavily relies on manual geometric reasoning that identifies additive features, related building orientations, tool approach direction, trajectory generation, and sequencing all features in a non-collision manner. In addition, multi-directional material accumulation cannot ensure the nozzle always stays above the building geometry. Thus, the collision between these two becomes a significant issue that needs to be solved. Hence, the common use of a robotic additive is hindered by the lack of fully autonomous tools based on the abovementioned issues. We present a systematic approach to the robotic AM process that can automate the abovementioned planning procedures in the aspect of collision-free. Typically, input models to robotic AM have diverse information contents and data formats, hindering the feature recognition, extraction, and relations to the robotic motion. Our proposed method integrates the collision-avoidance condition to the model decomposition step. Therefore, the decomposed volumes can be associated with additional constraints, such as accessibility, connectivity, and trajectory planning. This generates an entire workspace for the robotic additive building platform, rotatability, and additive features to determine the entire sequence and avoid potential collisions. This approach classifies the uniqueness of autonomous manufacturing on the robotic AM system to build large and complex metal components that are non-achievable through traditional one-directional AM in a computationally effective manner. This approach also paves the path in constructing an in situ monitoring and closed-loop control on robotic AM to control and enhance the build quality of the robotic metal AM process.

Additive Manufacturing of Micro-Electro-Mechanical Systems (MEMS)

Recently, additive manufacturing (AM) processes applied to the micrometer range are subjected to intense development motivated by the influence of the consolidated methods for the macroscale and by the attraction for digital design and freeform fabrication. The integration of AM with the other steps of conventional micro-electro-mechanical systems (MEMS) fabrication processes is still in progress and, furthermore, the development of dedicated design methods for this field is under development. The large variety of AM processes and materials is leading to an abundance of documentation about process attempts, setup details, and case studies. However, the fast and multi-technological development of AM methods for microstructures will require organized analysis of the specific and comparative advantages, constraints, and limitations of the processes. The goal of this paper is to provide an up-to-date overall view on the AM processes at the microscale and also to organize and disambiguate the related performances, capabilities, and resolutions.

Influence of the beam oscillation parameters on the porosity of electron beam freeform fabricated titanium alloy SPT-2

The effect of electron beam oscillation on the formation of metal during electron beam freeform fabrication has received practically no attention. Nevertheless, it is a variable technological tool that allows to significantly influence the formation of metal during EBFFF process, including the probability of defects formation. The effect of the focus current, the form, and the frequency of the beam oscillation on the formation of pores in single beads by method of electron beam freeform fabrication of the titanium alloy SPT-2 on the substrate of the alloy VT6 was investigated. The porosity of the obtained beads was studied using x-ray images. It was found that too deep an arrangement of the focal plane relative to the substrate surface leads to excessive pore formation. Reducing the oscillation frequency from 1000 Hz to 100 Hz made it possible to completely get rid of the pores in the metal. The use of a spiral-shaped oscillation made it possible to reduce the probability of pore formation in comparison with an oscillation in the form of concentric circles.

Utilizing direct-initiation of thiols for photoinitiator-free stereolithographic 3D printing of mechanically stable scaffolds

The automated production of artificial biological structures for biomedical applications continues to gather interest. Different fields of science are combined to find solutions for the arising multidimensional problems. Additive manufacturing in combination with material science provides one solution for the biological issues around 3D cell culture and construction of living tissues. Here, we present the photoinitiator-free stereolithographic fabrication of thiol-ene polymers with microarchitectures in the range of tens of microns for scaffolds up to the millimeter scale. Scaffolds composed of cubic unit cells were designed using computer-aided design (CAD) and subsequently 3D printed with a custom-made laser stereolithography setup. The process parameters were determined step by step with increasing complexity and number of parameters. Gained insights were applied to the fabrication of 3D printed test specimens. The quality of the 3D printed parts was evaluated by measuring the porosity and optical microscopy images. Furthermore, the mechanical properties of the scaffold structures were characterized using compression testing and compared with the bulk material revealing a lower capacity to bear load but higher flexibility. In this study, we demonstrate the advantages of combining the high-precision, freeform fabrication of stereolithography with a biocompatible material for the fabrication of complex microarchitectures for biomedical applications

Feasibility Study on Topological Optimisation And Additive Manufacturing of An Electric Vehicle Battery Housing

Electric vehicles (EVs) are in the incipient stage today and have the capacity to lead the automobile sector in the future. Battery packs of an electric vehicle are held by a large battery housing located at the bottom of the car body. The battery pack contributes significantly to the vehicle’s overall weight. Reduction of the overall weight of the future cars is a designer’s priority today. The aim to reduce weight can be achieved using topological optimisation. The optimised design is complex and therefore requires freeform fabrication. Additive manufacturing (AM) or 3D printing allows the fabrication of complex structures, hence, enables the fabrication of topological optimised parts without compromising on the part performance. In this paper, the topological optimisation of an electric vehicle battery housing is carried out to reduce the weight of the housing. Certain parts of the battery housing are removed and modified to get the final design. The physical, geometric, and performance aspects of the re-designed and original battery housing are compared. Additionally, the feasibility of the fabrication of the re-designed battery housing is discussed through support structures generation and feasibility index. Different AM methods such as powder bed fusion (PBF) and directed energy deposition (DED) are analysed on the basis of advantages and limitations. Finally, a suitable AM technique, selective laser melting (SLM), is chosen to fabricate the topological optimised battery housing.