1,721,040 research outputs found
Design optimization of supports for overhanging structures in aluminum and titanium alloys by selective laser melting
No full textInvestigation of the accuracy and roughness in the laser powder bed fusion process
No full textLaser powder bed fusion (L-PBF) process has had a rapid growth in the industrial fields because of
the capability to manufacture metallic complex shapes. The purpose of this study is to investigate
the accuracy and surface roughness of parts manufactured by L-PBF in the AlSi10Mg alloy. The
results showed that the choice of parameters of conversion from the CAD model to STL file and
the setting of process parameters can affect the accuracy. In the L-PBF process, the staircase
effect, inherent in additive manufacturing technologies due to the layered nature of the process,
is not visible due to the melting of thin layers of metal powder. The surface roughness is mainly
caused by the process parameters, orientation and position of the part with respect to the
recoating blade and by the presence of partially fused particles that adhere to the molten part
Influence of the aspect ratio of an additive manufacturing component on the surface roughness during cutting with wire EDM
Full text linkAluminum alloy AlSi10Mg is among the most used alloys in powder bed additive technologies with laser source (PBF-LB/M) to make light components in sectors such as aerospace and automotive. These components can have complex shapes and are made in some extrusions directly on the construction platform in order to remove them by wire electrical discharge machining (WEDM) and obtain a surface roughness already suitable to be able to assemble the parts with other components. This study investigated two aspects: the robustness of different instruments for profile and areal roughness measurements on AlSi10Mg parts produced by the PBF-LB/M process; and the effect of the aspect ratio of the components on the surface roughness obtained from WEDM. A better correspondence between the P- and S-parameters was found than that reported in the literature between the S- and R-parameters. Analyzing the relationship between weight and height of the AlSi10Mg components, the results showed that the heaviest and tallest component presents the least roughness (Ra = 5.05 ± 0.63 μm and Rz = 33.11 ± 4.29 μm). However, it emerged that the various areas of the piece have different roughness values (from Ra = 7.65 ± 2.85 μm and Rz = 43.07 ± 13.12 μm to Ra = 15.21 ± 7.37 μm and Rz = 68.39 ± 25.75 μm) of and this requires constant adjustment of the cutting parameters to have uniform surface roughness
A customer oriented methodology for reverse engineering software selection in the computer aided inspection scenario
No full textIndustrial metrology of mechanical components has been facing a gradual revolution recently through the application of contactless 3D scanners in Computer Aided Inspection. Following the industrial trend and request, new modules for quality control activities on scan data have been integrated in Reverse Engineering software packages. The aim of this work is to propose a structured methodology for the screening and comparison of Reverse Engineering programs that are suitable for inspection activities. Specific features that distinguish this kind of software are described and detailed. Six different commercial software are tested using invariant scan data from a reference part that was specifically designed for inspection purposes. The selected packages are then compared by means of a multicriteria fuzzy AHP analysis that considers quantitative and qualitative criteria. The criteria were grouped into three categories related with the user, the vendor and the technical requirements. Two different scenarios are considered for the choice of the software that best suits to computer aided inspection activitie
Comparing geometric tolerance capabilities of additive manufacturing systems for polymers
No full textIn all manufacturing processes, there are several factors for which the final product exhibits dimensional and shape deviations from its ideal nominal geometry. In additive manufacturing (AM) and 3D printing, a part is built layerwise in a single manufacturing step and is often net-shaped. In most cases, no finishing operation is applied to change the dimensions of the product, apart from a reduction of the superficial roughness through sandblasting or polishing. Therefore, knowing the dimensional tolerance of AM processes in advance is of fundamental importance, but little information is currently available in the literature. A benchmarking analysis of three different AM systems for polymers is presented in this paper. The compared machines are based on different AM techniques which are fused filament fabrication (FFF), selective laser sintering (SLS) and Arburg plastic freeforming (APF). The dimensional accuracy of the machines has been defined using the ISO IT grades of a reference artifact. In the analysis of the benchmarking results, a specific focus is made on the importance of the thermal household in SLS and a parameter named SLS modulus is proposed to identify critical heat concentrations in the powder bed that may influence the dimensional accuracy of the manufactured part
Comparison of dimensional tolerance grades of AM systems
No full textEvery manufacturing process allows fabricating a product with some dimensional and shape errors from the ideal nominal geometry. For this reason, on the product blueprint engineers indicate the admissible tolerance interval for critical dimensions. Unlike traditional manufacturing processes, no tools, molds or dies are needed in additive manufacturing (AM), so a single machine can produce an infinite number of different shapes. In a single operation, an AM part is built layerwise and often net shape, that is no finishing operation is carried out to change its dimensions apart from some sandblasting or polishing required to reduce superficial roughness. It is therefore fundamental to know in advance the dimensional tolerance for AM processes but currently little information is available in the literature. In this paper, a benchmarking analysis is carried out among three different AM systems for polymers and their dimensional accuracy is defined using the ISO IT grades of a reference artifact
Influence of Process Parameters on the Porosity, Accuracy, Roughness, and Support Structures of Hastelloy X Produced by Laser Powder Bed Fusion
No full textThe manufacture of highly complex components from nickel-based superalloys with laser powder bed fusion (L-PBF) technology can reduce the production costs parts with comparable microstructural and mechanical properties when compared to casting. The purpose of this study was to investigate the characteristics of samples produced in commercial Hastelloy X (with w% composition of 21Cr-18Fe-9Mo-0.7W-1.5Co-0.1C-1Si-1Mn-0.5Al-0.15Ti-bal.Ni) with an L-PBF process in terms of build density, accuracy, surface roughness, and interface area between the part and the support structures. Samples were obtained with a high density (99.88%), without cracks and with low surface roughness. From the analysis of the support structures, it emerged that the choice of the parameters between support structures, the lower face of the part (down-skin) and the internal area of the part (in-skin) is fundamental to the correct realization of these structures in order to avoid deformation of the components that is induced by thermal stresses during part building
Combined reverse engineering and CAD approach for mould modelling in casting simulation
No full textCasting process simulation is nowadays established as a strategic tool in process optimisation to improve product quality. However, sometimes the required three-dimensional mathematical model of the casting is not available, because the original drawings are not-up-to date and parts are subjected to design changes. In these cases, reverse engineering (RE) is the most suitable method to reconstruct the geometrical model of the casting. In this paper, a RE-based procedure is proposed to obtain the three-dimensional CAD model of a casting from its physical equipment. The proposed procedure involves four phases: pre-digitising, digitising of equipment parts, surface reconstruction, and three-dimensional CAD modelling. An aeronautical part fabricated by sand casting is selected as case study to verify the feasibility of this approach. Outcomes prove that the RE methodology is adequate to virtually reconstruct the geometry of each single part of the equipment as well as the whole geometry of the assembled moul
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