Advances in Manufacturing最新文献

Minimum quantity lubrication (MQL), which considers the cost, sustainability, flexibility, and quality, has been actively explored by scholars. Nanoadditive phases have been widely investigated as atomizing media for MQL, aimed at enhancing the heat transfer and friction reduction performance of vegetable-oil-based biolubricants. However, the industrial application of nano-enhanced biolubricants (NEBL) in grinding wheels and workpiece interfaces as a cooling and lubricating medium still faces serious challenges, which are attributed to the knowledge gap in the current mapping between the properties and grindability of NEBL. This paper presents a comprehensive literature review of research developments in NEBL grinding, highlighting the key challenges, and clarifies the application of blind spots. Firstly, the physicochemical properties of the NEBL are elaborated from the perspective of the base fluid and nanoadditive phase. Secondly, the excellent grinding performance of the NEBL is clarified by its distinctive film formation, heat transfer, and multiple-field mobilization capacity. Nanoparticles with high thermal conductivity and excellent extreme-pressure film-forming properties significantly improved the high-temperature and extreme-friction conditions in the grinding zone. Furthermore, the sustainability of applying small amounts of NEBL to grinding is systematically evaluated, providing valuable insights for the industry. Finally, perspectives are proposed to address the engineering and scientific bottlenecks of NEBL. This review aims to contribute to the understanding of the effective mechanisms of NEBL and the development of green grinding technologies.

Metallization, which is coating metals on the surface of objects, has opened up new possibilities for lightweight structures while integrating polymer and metal features. Electroless plating is a potential method for metalizing plastic 3D-printed parts; however, conventional approaches rely on pre-surface activation and catalyzation with expensive metal catalysts and hazardous acids. To address these issues, the current study represents a novel eco-friendly and low-cost approach for direct metallization of non-conductive 3D-printed parts, without using hazardous, toxic, and expensive conventional pre-treatments. Using the developed methodology, we electrolessly copper plated polymer-copper infused 3D-printed part as well as plastic components for the first time, directly. We initiated and implemented the idea of exposing the copper particles embedded in the polymer to the surface of copper-polymer parts by applying a sustainable mechanical or chemical method to make the surface conductive and ready for direct plating. A formaldehyde-free (green) electroless copper solution was developed in-house in addition to skipping conventional etching pre-treatment using harmful chemicals, making this a real step forward in the sustainable metallization of 3D-printed parts. In this study, the mechanical properties of copper-polylactic acid (PLA) 3D-printed parts revealed a 65% reduction in tensile strength and 63% increase in tensile modulus, compared to virgin PLA. Furthermore, the morphological characterization of the copper coated 3D-printed parts showed a homogeneous copper coating on the surface after direct electroless plating, with a plating rate of 7.5 μm/h. Allowing complex and functional devices printed in this manner to be quickly metalized without modification using toxic and costly solutions is a significant advancement in lowering the cost and manufacturing complexity of 3D-printed parts, increasing efficiencies, and lowering weight, and thus is a game changer in the technology’s adoption.

During the last two decades, industrial applications of augmented reality (AR) have been incorporated in sectors such as automotive or aeronautics in tasks including manufacturing, maintenance, and assembly. However, AR’s potential has yet to be demonstrated in the railway sector due to its complexity and difficulties in automating tasks. This work aims to present an AR system based on HoloLens 2 to assist the assembly process of insulation panels in the railway sector significantly decreasing the time required to perform the assembly. Along with the technical description of the system, an exhaustive validation process is provided where the assembly using the developed system is compared to the traditional assembly method as used by a company that has facilitated a case study. The results obtained show that the system presented outperforms the traditional solution by 78% in the time spent in the localization subtask, which means a 47% decrease in the global assembly time. Additionally, it decreases the number of errors in 88% of the cases, obtaining a more precise and almost error-free assembly process. Finally, it is also proven that using AR removes the dependence on users’ prior knowledge of the system to facilitate assembly.

High quality micro mould tools are critical for ensuring defect-free production of micro injection moulded products. The demoulding stage of the micro injection moulding can adversely affect the surface integrity due to friction, adhesion and thermal stresses between the metallic mould and polymeric replicated part. In the present work, we propose the use of precision electropolishing (EP) as a shaping and polishing process to control the draft angle and fillet radius of micro features in order to ease demoulding. Typical defects that occur in replicated polymer parts include cracks, burrs and distorted features. A nickel mould having multiple linear ridges and star shape patterns was designed for the present investigation to have characteristic dimensions ranging from 10 μm to 150 μm and with various aspect ratios to study the effect of electropolishing on modifying the shape of micro features and surface morphology. A transient 2D computational analysis has been conducted to anticipate the effect of shaping on the Ni mould after electrochemical polishing with non-uniform material removal rates, based on the distribution of current density. The experimental results indicate that after shaping using EP, the draft angle of star-patterns and linear patterns can be effectively increased by approximately (3.6^circ), while the fillet radius increases by up to 5.0 μm. By controlling the electropolishing process, the surface roughness can be maintained under 50 nm. This work uses a green and environmental friendly nickel sulfamate electrolyte which can be effective for shaping of nickel micro features without causing any surface deposition.

Recently, low-cost desktop three-dimensional (3D) printers, employing the fused deposition modeling (FDM) technique, have gained widespread popularity. However, most users cannot test the strength of printed parts, and little information is available about the mechanical properties of printed high-impact polystyrene (HIPS) parts using desktop 3D printers. In this study, the user-adjustable parameters of desktop 3D printers, such as crisscross raster orientation, layer thickness, and infill density, were tested. The experimental plans were designed using the Box-Behnken method, and tensile, 3-point bending, and compression tests were carried out to determine the mechanical responses of the printed HIPS. The prediction models of the process parameters were regressed to produce the optimal combination of process parameters. The experimental results showcase that the crisscross raster orientation has significant effects on the flexural and compression strengths, but not on the tensile strength. With an increase in the layer thickness, the tensile, flexural, and compression strengths first decreased and then increased, reaching their minimum values at approximately 0.16 mm layer thickness. In addition, they all increased with an increase of infill density. It was demonstrated that when the raster orientation, layer thickness, and infill density were 13.08°/–76.92°, 0.09 mm, and 80%, respectively, the comprehensive mechanical properties of the printed HIPS were optimal. Our results can help end-users of desktop 3D printers understand the effects of process parameters on the mechanical properties, and offer practical suggestions for setting proper printing parameters for fabricating HIPS parts.

The maximum flyer impact velocity based on a dynamic solidification cracking mechanism is proposed to describe the upper limit of collision welding process windows. Thus, the upper limit of the weld window is governed by the evolution of dynamic stresses and temperatures at the weld interface. Current formulations for the upper limit of the collision weld window assume that both the flyer and target are made of the same material and approximate stress propagation velocities using the acoustic velocity or the shear wave velocity of the weld material. However, collision welding fundamentally depends on the impacts that generate shockwaves in weld members, which can dominate the stress propagation velocities in thin weld sections. Therefore, this study proposes an alternative weld window upper limit that approximates stress propagation using shock velocities calculated from modified 1-D Rankine-Hugoniot relations. The shock upper limit is validated against the experimental and simulation data in the collision welding literature, and offers a design tool to rapidly predict more accurate optimal collision weld process limits for similar and dissimilar weld couples compared to existing models without the cost or complexity of high-fidelity simulations.

Ultrasonic-vibration-assisted milling (UVAM) is an advanced method for the efficient and precise machining of difficult-to-machine materials in modern manufacturing. However, the milling efficiency is limited because the ultrasonic vibration toolholder ER16 collet has a critical cutting speed. Thus, a 2D UVAM platform is built to ensure precision machining efficiency and improve the surface quality without changing the milling toolholder. To evaluate this 2D UVAM platform, ultrasonic-vibration-assisted high-speed dry milling (UVAHSDM) is performed to process a titanium alloy (Ti-6Al-4V) on the platform, and the milling temperature, surface roughness, and residual stresses are selected as the important indicators for performance analysis. The results show that the intermittent cutting mechanism of UVAHSDM combined with the specific spindle speed, feed speed, and vibration amplitude can reduce the milling temperature and improve the texture of the machined surface. Compared with conventional milling, UVAHSDM reduces surface roughness and peak-groove surface profile values and extends the range of residual surface compressive stresses from −413.96 MPa to −600.18 MPa. The excellent processing performance demonstrates the feasibility and validity of applying this 2D UVAM platform for investigating surface quality achieved under UVAHSDM.

Reducing the short-circuit rate and increasing the effective discharge rate are important targets for improving the servo control effect of micro-electrical discharge machining (micro-EDM), as these two indicators are closely related to the machining efficiency and quality. In this study, a feed-pulse collaborative control (FPCC) method is proposed for micro-EDM based on two dimensions (space and time). In the spatial dimension, a feed control strategy with a discharge holding process is adopted. Meanwhile, in the time dimension, a forward-looking pulse control strategy is adopted, in which the pulse interval is adjusted based on a sequence analysis of feed commands and discharge states. Process experiments are carried out to determine the key parameters used in this method, including the discharge holding threshold and pulse interval adjustment value ((T_{{text{off}_{{text{adj}}} }})). The feed smoothness and discharge sufficiency analyses of the experimental results show that compared to the traditional double threshold average voltage method, the FPCC method reduces the number of long-distance retreats by 64% and improves the effective discharge time by 40%.

Profile grinding is the most crucial method for the ultra-precision machining of special-shaped surfaces. However, profile grinding produces a unique machining profile, and many random factors in the machining process lead to complex surface characteristics. In this study, the structural and probabilistic characteristics of the profile grinding of a special-shaped surface were analyzed, and a probabilistic algorithm for the forming and 3D characterization of special-shaped surfaces under profile grinding was developed. The forming process of a GH738 blade tenon tooth surface was considered as an example to demonstrate the algorithm. The comparison results showed that the simulation results had similar surface characteristics to the measurement results, and the relative error range of the 3D roughness parameter was 0.21%–19.76%, indicating an accurate prediction and characterization of the complex special-shaped surface under the action of multiple factors.