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The purpose of this paper is to develop a build strategy for inclined thin-walled parts by exploiting the inherent overhanging capability of the cold metal transfer (CMT) process, which release wire-arc additive manufacturing from tedious programming work and restriction of producible size of parts.

Inclined thin-walled parts were fabricated with vertically placed welding torch free from any auxiliary equipment. The inclined features were defined and analyzed based on the geometrical model of inclined parts. A statistical prediction model was developed to describe the dependence of inclined geometrical features on process variables. Based on these models, a build strategy was proposed to plan tool path and output process parameters. After that, the flow work was illustrated by fabricating a vase part.

The formation mechanism and regulation of inclined geometrical features were revealed by conducting experimental trials. The inclined angle can be significantly increased along with the travel speed and offset distance, whereas the wall width is mainly dependent on the ratio of wire feed speed to travel speed. In contrast to other welding process, CMT has a stronger overhanging capability, which provides the possibility to fabricate parts with large overhanging features directly with high forming accuracy.

This paper describes a novel build strategy for inclined thin-walled parts free from any auxiliary equipment. With the proposed strategy, a complex structural component can be deposited directly in the rectangular coordinates additive manufacturing system, indicating infinite possibilities on the producible size of the parts. Moreover, equipment requirements and tedious program work can also be significantly reduced.

An accurate prediction of process-induced residual stress is necessary to prevent large distortion and cracks in gas metal arc (GMA)-based additive manufactured parts, especially thin-walled parts. The purpose of this study is to present an investigation into predicting the residual stress distributions of a thin-walled component with geometrical features.

A coupled thermo-mechanical finite element model considering a general Goldak double ellipsoidal heat source is built for a thin-walled component with geometrical features. To confirm the accuracy of the model, corresponding experiments are performed using a positional deposition method in which the torch is tilted from the normal direction of the substrate. During the experiment, the thermal cycle curves of locations on the substrate are obtained by thermocouples. The residual stresses on the substrate and part are measured using X-ray diffraction. The validated model is used to investigate the thermal stress evolution and residual stress distributions of the substrate and part.

Decent agreements are achieved after comparing the experimental and simulated results. It is shown that the geometrical feature of the part gives rise to an asymmetrical transversal residual stress distribution on the substrate surface, while it has a minimal influence on the longitudinal residual stress distribution. The residual stress distributions of the part are spatially uneven. The longitudinal tensile residual stress is the prominent residual stress in the central area of the component. Large wall-growth tensile residual stresses, which may cause delamination, appear at both ends of the component and the substrate–component interfaces.

The predicted residual stress distributions of the thin-walled part with geometrical features are helpful to understand the influence of geometry on the thermo-mechanical behavior in GMA-based additive manufacturing.

This paper aims to fabricate inclined thin-walled components using positional wire and arc additive manufacturing (WAAM) and investigate the heat transfer characteristics of inclined thin-walled parts via finite element analysis method.

An inclined thin-walled part is fabricated in gas metal arc (GMA)-based additive manufacturing using a positional deposition approach in which the torch is set to be inclined with respect to the substrate surface. A three-dimensional finite element model is established to simulate the thermal process of the inclined component based on a general Goldak double ellipsoidal heat source and a combined heat dissipation model. Verification tests are performed based on thermal cycles of locations on the substrate and the molten pool size.

The simulated results are in agreement with experimental tests. It is shown that the dwell time between two adjacent layers greatly influences the number of the re-melting layers. The temperature distribution on both sides of the substrate is asymmetric, and the temperature peaks and temperature gradients of points in the same distance from the first deposition layer are different. Along the deposition path, the temperature distribution of the previous layer has a significant influence on the heat dissipation condition of the next layer.

The established finite element model is helpful to simulate and understand the heat transfer process of geometrical thin-walled components in WAAM.

This paper aims to verify that additive manufacturing technology could be used for the redesign and rapid manufacturing of tools and determine whether the mechanical performance of such tools can satisfy the practical operating requirements.

A special key was selected as the research object in this paper. The special key was innovatively redesigned and manufactured directly using selective laser melting (SLM). The function and critical geometries of the special key were first analysed, which was followed by discussions on the geometrical constraints in the manufacturing of typical geometrical features using SLM technology. Next, the special key was redesigned based on the SLM geometrical constraints and the functional requirements. Finally, the key was manufactured using SLM, and the mechanical performance characteristics of the key were determined.

The minimal geometrical feature was 0.2 mm when manufacturing thin walls using SLM. The reliable building angle of an overhanging surface was 40°. The top surface quality of the part could be greatly improved through laser surface re-melting. The volume of the redesigned special key based on the SLM process was only one-third to one-fourth of the original key. The mechanical properties, such as tensile strength and micro-hardness, of the samples manufactured using SLM were able to reach the practical operating requirements.

It is completely feasible to redesign and manufacture precision tools based on the innovative approach of SLM. The advantages of the redesigned tools includes the lack of design restrictions that hinder traditional manufacturing methods, material savings, ability to produce tools that cannot be easily copied and rapid production speed for a small number of tools.

Among the different methodologies used for performance control in precision manufacturing, the measurement of metrological test artefacts becomes very important for the characterization, optimization and performance evaluation of additive manufacturing (AM) systems. The purpose of this study is to design and manufacture several benchmark artefacts to evaluate the accuracy of the selective laser melting (SLM) manufacturing process.

Artefacts consist of different primitive features (planes, cylinders and hemispheres) on sloped planes (0°, 15°, 30°, 45°) and stair-shaped and sloped planes (from 0° to 90°, at 5° intervals), manufactured in 17-4PH stainless steel. The artefacts were measured optically by a structured light scanner to verify the geometric dimensioning and tolerancing of SLM manufacturing.

The results provide design recommendations for precision SLM manufacturing of 17-4PH parts. Regarding geometrical accuracy, it is recommended to avoid surfaces with 45° negative slopes or higher. On the other hand, the material shrinkage effect can be compensated by resizing features according to X and Y direction.

No previous work has been found that evaluates accuracy when printing inwards (pockets) and outwards (pads) geometries at different manufacturing angles using SLM. The proposed artefacts can be used to determine the manufacturing accuracy of different AM systems by resizing to fit the build envelope of the system to evaluate. Analysis of manufactured benchmark artefacts allows to determine rules for the most suitable design of the desired parts.

In additive manufacturing processes such as stereolithography and fused deposition modeling, optimal part orientation is pivotal in improving the quality of the part. This paper aims to propose an automatic and optimal part orientation system to improve part quality/accuracy in additive manufacturing, which minimizes the production time and hence reduces the cost of product.

The developed system reads STEP AP 203 E2 file from CATIA V5 and generates data extraction output file by extracting the relevant geometrical and topological data using an object-oriented approach. Afterwards, the algorithms and rules are developed to extract and recognize feature faces along with their geometric properties such as face type, face area, parallelism and perpendicularity. The feature data obtained that are used to develop feasible part orientations depend on the maximization of G&DT for all part faces. The automatic slicing is then achieved by creating slicing file using CATVBA editor inside CATIA V5.

After slicing, output data are exported in Excel data sheet to calculate the total additive volume of the part. The building time of the part is then calculated on the basis of machine parameters, part geometry, part height, layer thickness and amount of support volume needed to build the part. The optimal orientation of the part is achieved by maximization of G&DT value and minimization of production time. The proposed methodology is tested using an illustrative example.

Although lot of approaches have been discussed in the literature, automation of setup planning/orientation of the part in additive manufacturing is not fully attained. Therefore, the article focuses on the automation of setup planning by adding automatic feature extraction and recognition module along with the automatic slicing during setup planning. Moreover, the significance of adding feature extraction and recognition module is to achieve best accuracy for form feature faces and hence reduction in post processing machining/finishing operations.

Additive manufacturing has paved a way for geometrical freedom and mass customization of new and innovative products. However, it has a few limitations in printing complex geometries and sizes. The purpose of this paper is three-dimensional printing of metal parts using selective laser melting (SLM) has several intricacies.

To test the capabilities of SLM, the complex geometries of varying sizes, orientations, shapes such as square and cylindrical features, thin wall structures and holes were checked for dimensional accuracy and surface roughness.

The outcome of the study represents the capabilities of SLM and provide insight for solving the technological issues and processing constraint in the manufacture of metal parts from aluminum alloy. The analysis has proven that there is significant accuracy in dimension for large features in comparison with smaller one. The dimensional reproducibility was determined with the aid of an optical measuring system and the range of errors were calculated. These results show that the dimensional accuracy of the features in the printed part was within acceptable tolerance limits. This paper also investigated the significant contributing factors influencing printing of two and three-dimensional surface roughness based on the result of surface profilometer and it was observed that the surface was smoothened with the presence of overhangs and supports.

The ability of SLM to fabricate conformer cooling channels to support mould fabrication was tested. From the experimental result, it was observed that the quality of printing of conformal cooling channels depended on the diameter of channels with larger distortions in the channel having smaller diameter. The innovative aspect of the work was the study of build orientation combined with the investigated material.

The assembly of surface mounted component parts into 3‐dimensional moulded circuit boards enables the integration of electronic and mechanical functions. However, this requires the assembly processes to be adapted to the MID’s 3‐dimensional geometry. This paper describes research on the development of assembly systems for MIDs at the FAPS Institute. Limits on the application of solder paste on inclined process planes are discussed, as well as possibilities of assembling with conventional assembly systems. A possibility for adapting existing assembly systems to new requirements is demonstrated and a concept for an optimised MID assembly system will be given.

This study aims to numerically examine the influence of various geometric parameters of a novel W-shaped porous cavity undergoing hybrid nanofluid-based magnetohydrodynamic mixed convection. The W-shaped cavity is modified from the classical trapezoidal cavity by constructing a triangular shape at its bottom. This cavity is isothermally active at the bottom, with different numbers and heights of the triangular peak (or undulation). The heated hybrid nanofluid (Cu–Al₂O₃–H₂O) flow is cooled through the translating top wall. Inclined sidewalls are thermally insulated. To compare the impacts of change in geometric parameters, a square cavity under similar boundary conditions is also simulated. This study is carried out systematically addressing the various influences from a range of parameters like side angles (γ), number (m) and height (λ) of the bottom undulation, Reynolds number (Re), Richardson number (Ri), Darcy number (Da), Hartmann number (Ha), hybrid nanoparticles volume fraction (φ) on the overall thermal performance of the cavity.

Applying the finite volume approach, the transport equations involving multiphysical conditions like porous substance, hybrid nanofluid, magnetic field and shearing force are solved numerically by using a written FORTRAN-based code following the SIMPLE algorithm. The algebraic equations are solved over all the control volumes in an iterative process using the alternate direction implicit scheme and the tri-diagonal matrix algorithm. The converged solution of the iterative process is obtained when the relative error levels satisfy the convergence criterion of 10^–8 and 10^–10 for the maximum residuals and the mass defect, respectively.

It is revealed that an increase in the bottom undulation height always improves the thermal energy transfer despite the reduction of fluid volume. Thermal energy transfer significantly depends on the heating and cooling surface lengths, fluid volume in the cavity and the magnitude of the bottom undulation height of the W-shaped cavity. With the increase in bottom undulation height, effective heating length increases by ∼28%, which leads to a ∼15% reduction in the effective volume of the working fluid and a gain in heat transfer by ∼56.48%. In general, the overall thermal energy transport is improved by increasing Re, Ri and Da; whereas it is suppressed by increasing Ha.

There are many opportunities for future research experimentally or numerically, considering different curvature effects, orientations of the geometry, working fluids, boundary conditions, etc. Furthermore, this study could be extended by considering unsteady flow or turbulent flow.

In many modern systems/processes pertaining to materials processing, continuous casting, food processing, chemical reactors, biomedical applications, etc. fine control in the transport process is a major concern. The findings of this analysis can effectively be useful for other applications for getting more control features in terms of achieving the operational objectives. The approach of the system analysis (considering geometrical size parameters to delve into the underlying transport physics) and the obtained simulated results presented in the work can usefully be applicable to similar thermal systems/devices such as materials processing, thermal mixing, chemical reactors, heat exchangers, etc.

From the well-documented and vast pool of literature survey, it is understood that there exists no such investigation on the considered geometry and study. This study contributes a lot to understanding magnetic field moderated thermofluid flow of a hybrid nanofluid in a porous medium filled W-shaped cavity, in consideration of different geometrical shape parameters (undulation peak numbers at bottom wall, peak heights, side angles and heating and cooling length). Findings brought by this study provide great insights into the design and operation under various ranges of multiphysical thermofluid-flow processing phenomena.

Robotic wire and arc additive manufacturing (RWAAM) is becoming more and more popular for its capability of fabricating metallic parts with complicated structure. To unlock the potential of 6-DOF industrial robots and improve the power of additive manufacturing, this paper aims to present a method to fabricate curved overhanging thin-walled parts free from turn table and support structures.

Five groups of straight inclined thin-walled parts with different angles were fabricated with the torch aligned with the inclination angle using RWAAM, and the angle precision was verified by recording the growth of each layer in both horizontal and vertical directions; furthermore, the experimental phenomena was explained with the force model of the molten pool and the forming characteristics was investigated. Based on the results above, an algorithm for fabricating curved overhanging thin-walled part was presented and validated.

The force model and forming characteristics during the RWAAM process were investigated. Based on the result, the influence of the torch orientation on the weld pool flow was used to control the pool flow, then a practical algorithm for fabricating curved overhanging thin-walled part was proposed and validated.

Regarding the fabrication of curved overhanging thin-walled parts, given the influences of the torch angles on the deposited morphology, porosity formation rate and weld pool flow, the flexibility of 6-DOF industrial robot was fully used to realize instant adjustment of the torch angle. In this paper, the deposition point and torch orientation of each layer of a robotic fabrication path was determined by the contour equation of the curve surface. By adjusting the torch angle, the pool flow was controlled and better forming quality was acquired.