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The current study aims to design optimal support structures for the fabrication of titanium alloy overhangs by electron beam melting such that they are easy to remove and consume less material without affecting the part quality. To achieve this objective, the effect of design and process parameters of the perforated block support structures was evaluated and optimized using response surface methodology and multi-objective genetic algorithm. The results showed that it is possible to reduce the support volume by 19% and support removal time by 45% without any warping deformation using the optimum combinations (tooth height of 2.885 mm, tooth base interval of 1.677 mm, perforation beam of 4.611 mm, beam current of 5.327 mA, and beam scan speed 1347.197 mm/s). In addition the multi-objective optimization results found the optimal perforated supports characterized by 4-mm tooth height, 2-mm tooth base interval, 2-mm perforated beam, 6-mA beam current, and 1600 mm/s beam scan speed. The study also showed that the use of optimum support structures results in substantial reduction of the support volume and post-processing. [ABSTRACT FROM AUTHOR]

Electron-beam melting (EBM) is a rapidly developing metal additive manufacturing (AM) method. It is more effective with complex and customized parts manufactured in low volumes. In contrast to traditional manufacturing, it offers reduced lead time and efficient material management. However, this technology has difficulties with regard to the construction of overhang structures. Production of overhangs using EBM without support structures results in distorted objects, and the addition of a support structure increases the material consumption and necessitates post-processing. The objective of this study was to design support structures for metal AM that are easy to remove and consume lower support material without affecting the quality of the part. The design of experiment methodology was incorporated to evaluate the support parameters. The multi-objective optimization minimizing support volume and support removal time along with constrained deformation was performed using multi-objective genetic algorithm (MOGA-II). The optimal solution was characterized by a large tooth height (4 mm), large tooth base interval (4 mm), large fragmented separation width (2.5 mm), high beam current (6 mm), and low beam scan speed (1200 mm/s). [ABSTRACT FROM AUTHOR]

The restoration of mandibular defects, especially large deformities is regarded as the most challenging surgical procedure owing to complicated anatomy and the requirement of customized design. Presently, the commercially available reconstruction plates with standard shapes and sizes are frequently utilized. However, these typical plates exhibit several disadvantages, including high cost, poor performance, etc. They are ineffective and do not exactly match the bone contours. Besides, trial and miss approach and several revisions associated with these plates involve significant effort and time. To overcome these issues, a framework based on the integration of design, analysis, evaluation, and fabrication phases have been developed and implemented. The objective was the attainment of a cost-effective, reliable, and sturdy design for the mandibular implant. A customized plate merged with a mesh structure matching the patient bone contours as well as guide and support the growth of neighboring bones was the crux of this mandible implant. The proposed methodology was made of three primary pillars: technology unification, multi-disciplinary notion, and a quality emphasis. A lattice structure, instead of a solid framework was utilized to reconstruct the large mandibular defect. Indeed, the various porous structures were analyzed to finally derive the appropriate lattice structure. The scans from computer tomography were utilized to model the customized plate and scaffold framework, while electron beam melting was used to fabricate the implant. Moreover, the proposed implant design was analyzed using finite element analysis as well as the fabricated specimen was validated for mechanical and structural behavior. The biomechanical analysis outcome revealed lower stresses (214.77 MPa) as well as well-connected structures involving proper porosity and robust mechanical properties. The cost analysis also established that the employment of the proposed design would result in a lesser burden on the patient as compared to the existing practices. [ABSTRACT FROM AUTHOR]

The aim of this study is to identify the limitations of self-supporting structures and evaluate the deformations associated with overhang structures fabricated without support structures. To achieve these objectives, a series of experiments involving different overhang geometries were designed, fabricated, and evaluated. The formation of defects during the fabrication of overhanging structures is detailed, and the self-supporting limits for different overhangs are established. A segmentation strategy for the support structure addition is proposed and evaluated in different configurations for ledge overhangs to reduce the amount of support structures without affecting the overhang accuracy. Based on the inferences of this study, design rules are proposed for producing overhang structures through electron beam melting. The results identified the self-supporting limits for different overhang geometries. In addition, the proposed segmentation strategy for support generation in ledge overhangs resulted in reduction of support structure materials and post-processing time without any effect on the quality of the fabricated overhang. [ABSTRACT FROM AUTHOR]