1,720,989 research outputs found
Comparative study on the properties of 17-4 PH stainless steel parts made by metal fused filament fabrication process and atomic diffusion additive manufacturing
No full textPurpose: This paper aims to provide a comparison between the mechanical performance and microstructural aspects of stainless steel 17-4 PH processed using, respectively, two technologies: atomic diffusion additive manufacturing (ADAM) and metal fused filament fabrication (MFFF). Design/methodology/approach: Different tensile specimens have been printed using an industrial system and a consumer three-dimensional (3D) printer, varying two main 3D printing parameters. Mechanical and microstructural tests are executed to make a comparison between these two technologies and two different feedstock material, to identify the main differences. Findings: These 3D printing processes make parts with different surface quality, mechanical and microstructural properties. The parts, printed by the industrial system (ADAM), showed lower values of roughness, respect those produced using the 3D consumer printer (MFFF). The different sintering process parameters and the two debinding methods (catalytic or solvent based) affect the parts properties such as porosity, microstructure, grain size and amount of δ-ferrite. These proprieties are responsible for dissimilar tensile strength and hardness values. With the aim to compare the performances among traditional metal additive technology, MFFF and ADAM, a basic analysis of times and costs has been done. Originality/value: The application of two metal extrusion techniques could be an alternative to other metal additive manufacturing technologies based on laser or electron beam. The low cost and printing simplicity are the main drivers of the replacements of these technologies in not extreme application fields
Preliminary study for a full colour low cost open source 3D printer, based on the combination of fused deposition modelling (FDM) or fused filament fabrication (FFF) and inkjet printing
No full textAdditive manufacturing techniques (AM) have enhanced product quality and exponentially increase their application both from the industrial point of view and from the consumer point of view. A decisive development in the consumer sector has been observed over the last 5 years thanks to open source projects (Fab@home, RepRap), which enabled the production of low cost machines with the use of cheap electronic and mechanical components and open source software. Among the possible future developments of low cost AM technologies, there is an improvement of finished product capabilities and appearance to obtain coloured components, made directly during printing phase. This paper tries to respond to this need by assessing the feasibility of realizing a low-cost AM system that integrates automatic colouring in a consumer 3D printer. The proposed system is a hybrid between a fused filament fabrication 3D printer, derived from an open-source project, and a 2D commercial inkjet printer; the two systems share the mechanics, but keep the movement control and the three-dimensional and two-dimensional printing process separate. The study continues with the theorization, modeling and creation of the interfaces required for conversion of control signals and a first experimentation of the same control. The two systems, using a different mechanics, use different motor control systems
A powerful scanning methodology for 3D measurements of small parts with complex surfaces and sub millimeter-sized features, based on close range photogrammetry
No full textA powerful and cost effective photogrammetric scanning methodology, suitable for reconstructing a full 3D digital model of parts with complex surfaces and sub millimeter-sized features, is described. The scanner employed for this purpose is composed of a computerized system that drives and control the movements of a rotary table, and a digital SLR camera for the images acquisition. The object is positioned on the rotary table that rotates at fixed angles, while the digital camera, mounted on the stator through a rigid frame, captures the images. The scanning process has been optimized with the aim to minimize the number of shots and thus, the time needed to obtain a complete 3D digital model, which is not dependent from the dimensions of the object. With the aim to demonstrate the effectiveness of the proposed scanning methodology, four benchmarks have been realized to provide complex examples. The 3D digital models were compared with those obtained with an OptimetTM Conoscan 4000 which uses a conoscopic holographic sensor
3D Digitization of Curves on Human Bodies by Means of Digital Close Range Photogrammetry
No full textThe realization of custom made clothes implies continuous tests, long times of delivery and often prohibitive costs. In this field, one of the most interesting challenges is to automate some parts of the process to obtain a competitive product.The first step to be completed to automate the realization of customized garment apparels is the 3D Digitization of customers. In the present research the authors present a properly designed low cost offline 3D body digitizer, based on Digital Close Range Photogrammetry. The results are satisfactory for tailoring applications that do not require high accuracy. Furthermore, essays on Dense Surface Models are described
Validation study of an analytical model of FDM accuracy
No full textThe diffusion of Additive Manufacturing technologies is leading to new needs in industrial research and development sectors. In particular, mating additive manufactured parts is not a simple task, due to the poor accuracy of several additive technologies, such as Fused Deposition Modeling (FDM). Several papers are focused on studies of how FDM accuracy is affected by process parameters. In this paper the authors report a study of the influence of working parameters on FDM dimensional accuracy, paying particular attention to variables that can affect axial symmetric mating between parts, and how these parameters can be set to improve the mating proces
A simple photogrammetric system for automatic capture and measurement of facial soft tissues during movement
No full textA proper diagnostic classification of developmental disharmonies, congenital or acquired
malformations is essential for assessing spontaneous or induced rehabilitation of facial soft tissue and skullfacial structures, and for monitoring the changes induced by surgical, esthetic and functional treatment
methodologies. In this work the authors describe a digital close-range photogrammetric system developed to acquire the spatial coordinates of facial landmark points and track their movements. The obtained results allow biometric measurements and tests to be made to evaluate the clinical and functional characteristics of a subject. The system produces a 3D animated model (wireframe, tasseled and textured surfaces), which accurately reproduces the subject's facial movements during opening and closure of the mouth. Recognition and tracking of facial landmarks were achieved by automated procedures that required minor human intervention
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Effect of layer and raster orientation on bending properties of 17-4 PH printed via material extrusion additive manufacturing technology
No full textMaterial Extrusion (MEX) is one of the most popular Additive Manufacturing technologies. Over the years, the material portfolio has expanded and nowadays, it covers metals such as stainless steels, copper and titanium alloys. The mechanical behaviour of metal parts realized by MEX is of great interest to understand both the potentialities and the limits of the technology. In the present work, a commercial filament of 17-4 PH stainless steel was used as feedstock material to realize four groups of bending specimens obtained by varying the printing direction and the infill line strategy. The main goal of the paper was to evaluate the effect of the above-mentioned factors on the flexural properties. With this purpose, a three-points bending test was performed and results were analysed using the one-way ANOVA approach. The density of the parts was also evaluated
Analysis of Microstructure and Mechanical Properties of CoCrMo Alloys Processed by Metal Binder Jetting Multi-Step Technique
No full textMetal Binder Jetting (BJT/M) has emerged as a promising additive manufacturing (AM) technology for the realization of complex parts using a wide range of metal alloys. This technology offers several advantages, such as design flexibility, reduced lead times, a high building rate, and the ability to fabricate intricate geometries that are difficult or impossible to achieve with conventional manufacturing methods. Cobalt Chromium Molybdenum (CoCrMo) alloys are particularly suitable for demanding applications in the aerospace, biomedical, and industrial sectors that require high strength and hardness, corrosion resistance, and biocompatibility. In this work, ten cubic and ten tensile samples were printed with a layer height of 50 μm using the shell printing method, debound and sintered at 1325 °C for 4 h, with the aim of investigating the properties of CoCrMo parts made using BJT technology. A density of 7.88 g/cc was obtained from the Archimede’s test. According to the printing and sintering parameters, an average hardness of 18.5 ± 1.8 HRC and an ultimate tensile strength of 520.5 ± 44.6 MPa were obtained. Finally, through a microstructure analysis, an average grain size of 182 ± 14.7 μm was measured and the presence of an intergranular Cr-rich phase and Mo-rich carbides was detected
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