Matteo Perini, Paolo Bosetti and Nicolae Balc
This paper aims to decrease the cost of repairing operations, of the damaged mechanical components, by enabling the strong automation of the process and the reduction of manual…
Abstract
Purpose
This paper aims to decrease the cost of repairing operations, of the damaged mechanical components, by enabling the strong automation of the process and the reduction of manual labor. The main purpose of the hybrid repair process is to restore the original shape of the mechanical parts, by adding and removing material according to the mismatch between the damaged object and the virtual model, to restore its geometrical properties.
Design/methodology/approach
The DUOADD software tool translates the information collected from a 3D scanner into a digital computer aided design solid model, which can be manipulated through Siemens NX computer aided manufacturing (CAM), to obtain the tool paths, for the Direct Laser Deposition (DLD) technology. DUOADD uses octrees to effectively analyze the damaged region of the mechanical part and then to discretize the volume to be added to export CAM-compatible information as a 3D model, for additive operations.
Findings
DUOADD is the missing link between two valuable existing technologies, 3D scan and CAM for additive manufacturing, which can now be connected together, to perform automatic repairing.
Research limitations/implications
A trade-off between resolution and computational effort needs to be achieved.
Practical implications
DUOADD output is a STEP file, transferred to the CAM software to create the additive and the milling tool paths. The maximum deviation was 40 micrometers, as compared with the original solid model.
Originality/value
The paper presents a new procedure and new software tools (DUOADD), for the automation of damaged objects restoration process. DUOADD software provides suitable data for using a 5-axis computer numerical control (CNC) milling machine equipped with a DLD tool.
Details
Keywords
Dan Leordean, Cristian Dudescu, Teodora Marcu, Petru Berce and Nicolae Balc
The purpose of this paper was to present how customized implants could be made with specific properties, by setting different values of the laser power, within the selective laser…
Abstract
Purpose
The purpose of this paper was to present how customized implants could be made with specific properties, by setting different values of the laser power, within the selective laser melting (SLM) process. A detailed case study was undertaken and a new multi-structured femoral prosthesis was designed and analyzed, to simulate its behavior for a specific case study.
Design/methodology/approach
The materials and manufacturing methods are presented, with details regarding the SLM process, using the Realizer 250 machine. The laser power was varied between 50 and 200 W, thus obtaining samples with different physical and mechanical characteristics. All those sample parts were characterized and their properties were measured.
Findings
A practical methodology was found to produce multi-structured implants by SLM. Significant changes of the porosity and properties were found, when modifying the laser power at the SLM machine. The studies have indicated an open porosity varying between 24.810.83 per cent. Tensile tests of the samples showed Young’s modulus values varying between 13.5 and 104.5 GPa and an ultimate stress between 20.2 and 497.5 MPa.
Research limitations/implications
There is no Additive Manufacturing (AM) machine available, to work with different laser power values, in different regions of the same section of the implant. Hence, a multi-structured implant cannot be obtained directly.
Practical implications
The prosthesis should be specifically designed to contain separate models/regions to be made with appropriate laser power values.
Originality/value
This paper presents a new method to design and manufacture a multi-structured implant, using the existing AM equipment. A detailed case study is presented, showing the design procedure, the way to simulate its behavior and the methods to produce the implants by SLM.
Details
Keywords
Luis Lisandro Lopez Taborda, Heriberto Maury and Jovanny Pacheco
There are many investigations in design methodologies, but there are also divergences and convergences as there are so many points of view. This study aims to evaluate to…
Abstract
Purpose
There are many investigations in design methodologies, but there are also divergences and convergences as there are so many points of view. This study aims to evaluate to corroborate and deepen other researchers’ findings, dissipate divergences and provide directing to future work on the subject from a methodological and convergent perspective.
Design/methodology/approach
This study analyzes the previous reviews (about 15 reviews) and based on the consensus and the classifications provided by these authors, a significant sample of research is analyzed in the design for additive manufacturing (DFAM) theme (approximately 80 articles until June of 2017 and approximately 280–300 articles until February of 2019) through descriptive statistics, to corroborate and deepen the findings of other researchers.
Findings
Throughout this work, this paper found statistics indicating that the main areas studied are: multiple objective optimizations, execution of the design, general DFAM and DFAM for functional performance. Among the main conclusions: there is a lack of innovation in the products developed with the methodologies, there is a lack of exhaustivity in the methodologies, there are few efforts to include environmental aspects in the methodologies, many of the methods include economic and cost evaluation, but are not very explicit and broad (sustainability evaluation), it is necessary to consider a greater variety of functions, among other conclusions
Originality/value
The novelty in this study is the methodology. It is very objective, comprehensive and quantitative. The starting point is not the case studies nor the qualitative criteria, but the figures and quantities of methodologies. The main contribution of this review article is to guide future work on the subject from a methodological and convergent perspective and this article provides a broad database with articles containing information on many issues to make decisions: design methodology; optimization; processes, selection of parts and materials; cost and product management; mechanical, electrical and thermal properties; health and environmental impact, etc.
Details
Keywords
Chiara Bregoli, Jacopo Fiocchi, Carlo Alberto Biffi and Ausonio Tuissi
The present study investigates the mechanical properties of three types of Ti6Al4V ELI bone screws realized using the laser powder bed fusion (LPBF) process: a fully threaded…
Abstract
Purpose
The present study investigates the mechanical properties of three types of Ti6Al4V ELI bone screws realized using the laser powder bed fusion (LPBF) process: a fully threaded screw and two groups containing differently arranged sectors made of lattice-based Voronoi (LBV) structure in a longitudinal and transversal position, respectively. This study aims to explore the potentialities related to the introduction of LBV structure and assess its impact on the implant’s primary stability and mechanical performance.
Design/methodology/approach
The optimized bone screw designs were realized using the LPBF process. The quality and integrity of the specimens were assessed by scanning electron microscopy and micro-computed tomography. Primary stability was experimentally verified by the insertion and removal of the screws in standard polyurethane foam blocks. Finally, torsional tests were carried out to compare and assess the mechanical strength of the different designs.
Findings
The introduction of the LBV structure decreases the elastic modulus of the implant. Longitudinal LBV type screws demonstrated the lowest insertion torque (associated with lower bone damage) while still displaying promising torsional strength and removal force compared with full-thread screws. The use of LBV structure can promote improved functional performances with respect to the reference thread, enabling the use of lattice structures in the biomedical sector.
Originality/value
The paper fulfils an identified interest in designing customized implants with improved primary stability and promising features for secondary stability.
Details
Keywords
Ratnadurai Dhakshyani, Yusoff Nukman and Abu Osman Noor Azuan
The purpose of this paper is to examine the use of fused deposition modelling (FDM) models and finite element analysis (FEA) related to dysplastic hip orthopaedic surgery.
Abstract
Purpose
The purpose of this paper is to examine the use of fused deposition modelling (FDM) models and finite element analysis (FEA) related to dysplastic hip orthopaedic surgery.
Design/methodology/approach
The study involved the use of Mimics and Abaqus softwares. Mimics was used to process the CT scan patient data to STL format before producing FDM models which were for before and after surgery. FEA was done to study the two different type of implant biomaterials used in dysplastic hip surgery.
Findings
The use of FDM pre models for preplanning of dysplastic hip surgery by orthopaedic surgeons and viewing of the surgery outcome via FDM post models. Different implant biomaterials used gave different results in reduction of stresses that were achieved.
Originality/value
This is original work involving patients in hospital, which got ethical approval and was funded by a university grant. The paper describes a new kind of research in the university.