INTRODUCTION: This work aims to pre-operatively manufacture custom-made low-cost implants and physical models (‘biomodels’) of fractured skulls. The pre-DOI: operative manufacturing of biomodels and implants allows physicians to study and plan surgery with a greater possibility of achieving the expected result. Customization contributes to both the esthetic and functional outcome of the implant because it considers the anatomy of each patient, while the low cost allows a greater number of people to potentially benefit. METHODS: From CT images of a fractured skull, a CAD model of the skull (biomodel) and a restorative implant were constructed digitally. The biomodel was then physically constructed with 3D Printing, and Incremental Sheet Forming (ISF) was used to manufacture the implant from a sheet of pure grade 2 titanium. Before cutting the implant’s final shape from a pre-formed sheet, heat treatment was performed to avoid deformations caused by residual stresses generated during the ISF process. RESULTS: A comparison of the dimensions of the implant and its respective CAD biomodel revealed geometric discrepancies that can affect both functional and aesthetic efficiency. Nevertheless, the final shape preserved symmetry between the right and left sides of the skull. Electron microscopy analysis did not indicate the presence of elements other than pure titanium. CONCLUSION: Dimensional variability can be decreased with changes in the manufacturing process (i.e., forming and cutting) and the heating ramp. Despite biomedical characteristics, there was no contamination of the implant by harmful chemical elements. 3D Printing was effective in making the biomodel, enabling pre-operative planning and improving physician-patient communication. Current results indicate that ISF is a process that can be used to obtain custom-made implants.
Problem-based learning (PBL) approaches are well-accepted and disseminated and have been intensively employed in several engineering programs. This article aims to present a teaching experience in which PBL was applied in one course of a mechanical engineering graduation program. The PBL approach applied is described step-by-step as well as the goals and constraints related to Computer-Aided Design, Engineering and Manufacturing (CAD/CAE/CAM) technologies employed in this particular case. The evaluation process is described, as well as the quantitative results, and also the results obtained from questionnaires answered by the students at the end of the PBL experience. Additionally, the team’s technical success in solving the proposed CAD/CAE/CAM problems was also taken into account. This PBL approach provided the students with the required autonomy to develop their argumentative skills within the team, defending their ideas, and at the same time, promoting self-criticism and ethical and impartial judgment among the other team members.
6 June 2022 in European Journal of Engineering Education
This study captures student perceptions of the effectiveness of remote learning and assessment in two associated engineering disciplines, mechanical and industrial, during the COVID-19 pandemic in a cross-national study. A structured questionnaire with 24 items on a 5-point Likert scale was used. Parallel and exploratory factor analyses identified three primary subscales. The links between student perceptions and assessment outcomes were also studied. There was a clear preference for face-to-face teaching, with the highest for laboratories. Remote live lectures were preferred over recorded. Although students found the switch to remote learning helpful, group work and communication were highlighted as concern areas. Mean scores on subscales indicate a low preference for remote learning (2.23), modest delivery effectiveness (3.05) and effective digital delivery tools (3.61). Gender effects were found significant on all subscales, along with significant interactions with university and year-group. Preference for remote delivery of design-based modules was significantly higher than others.
Analysis of a formed metal sheet shows the data of the incremental forming process. Variation in sheet deformation results from the process and shows how forming occurred. Another important result is the surface roughness of the sheet, which reports the parameters of the process, machine and tool used. Incremental forming of the titanium CP-Ti grade 2 sheet was performed in the SPIF modality – forming without a point of support, in order to look at the thickness deformations. SPIF incremental forming is characterized as forming that does not use points of support, and therefore simple tooling is used in the process. The following resources were used to perform the practical tests: CAD/CAM software, CNC machining center, incremental die, incremental forming tool and a sheet press device. The results obtained were the finish of the formed surface, measured by the roughness parameter RZ, and the measurement of the true strains ( ) and thickness (s1). Practical tests showed that the limit wall angle ( ), for the CP Ti grade 2 sheet, 0.5 mm thick, is 47º.
This work addresses through bibliographies and experiments the behavior of sheet brass 70/30 for Incremental Sheet Forming process - ISF, based on the parameters: wall angle (), step vertical (ΔZ) strategy and the way the tool. Experiments based on the method called Single Point Incremental Forming - SPIF. For execution of practical tests, we used the resources: software CAD / CAM, CNC machining center with three axles, matrix incremental, incremental forming tool and a device press sheets. Furthermore, measurement was made of the true deformation () and thickness (s1). Practical tests have shown that the spiral machining strategy yielded a greater wall angle, compared to the conventional strategy outline.
4 August 2017 in International Journal of Material Forming