This study investigates the impact of surface texturing on the durability of slippery liquid-infused porous surface (SLIPS) coatings applied to sheet metal substrates by the double-sided incremental forming (DSIF) process. Toolmarks generated during the DSIF process were leveraged as an efficient method for texturing, enabling both the formation and texturing of surfaces using a single set of universal tools. The effects of texture patterns, spacing, and tool movement on the SLIPS performance were evaluated by comparing samples generated in the presence and absence of tool spinning/rotation. The results indicate that textures with dimple patterns significantly improve coating durability by acting as lubricant reservoirs, reducing oil depletion, and supporting self-healing. In contrast, continuous grooves were less effective due to limited capillary action and increased edge effects. Tool spinning further enhanced the surface topography, producing an undulating texture that minimized contact line pinning and improved the surface hydrophobicity. Low-speed spinning (approximately 10 rpm) facilitated a transition to mixed sliding-rolling friction, resulting in smoother textures and extended coating durability. Combining dimple patterns and controlled spinning provides a synergistic approach for optimizing SLIPS coatings, offering a practical solution for enhancing durability without requiring additional equipment. This study underscores the potential of controlled texturing and tool movement to improve the SLIPS efficacy and broaden its applications in industrial, clinical, and consumer environments.

Advanced materials, better control methods, and unique toolpath planning strategies have recently been enabled through development of novel, in situ monitoring techniques in laser powder-blown directed energy deposition (DED-LB). Specifically, closed-loop control schemes have benefitted from development of in situ monitoring techniques focused on melt pool measurements and control. Implemented closed-loop control algorithms have heavily focused on modulating laser power to influence melt pool size or temperature. While demonstration of controller performance is readily available, there are limited studies addressing the effect of local closed-loop melt pool control on bulk component temperature history, re-heating of previous layers, and resulting material structures. In this study, coaxial photodiodes were implemented as a functioning two-color pyrometer. The photodiodes were used in closed-loop control to maintain a melt pool temperature of 1500 degrees C in a multi-layered thin wall deposited with Nickel alloy 718 (IN718). A thermal history analysis using concurrent infrared (IR) imaging showed that local melt pool control mitigated heat accumulation and improved the uniformity of spatial thermal gradients. In situ heat treatment times relevant to IN718 were quantified, and it was demonstrated that local melt pool control minimized time spent in solidification. Subsequent microstructure analysis demonstrated that the dominant mechanism for smaller grain formation with laser power modulation was the inhibition of epitaxial growth coupled with a change in local thermal gradient rather than a change in local cooling rate for IN718. Grain morphology and size were more uniform and three times as many small grains were present when local melt pool control was used, but primary dendrite size and Laves particle characteristics largely remained the same. It is ultimately shown that future designs of controllers in DED-LB must consider microstructure evolution of the working material system to fully realize improved mechanical properties and higher quality materials in DED-LB.

This study explores Incremental Sheet Forming (ISF) to fabricate mold liners as part of a newly proposed molding system for small-scale applications. A modified toolpath strategy, leveraging the tooltip geometry and feature skeleton, enabled the creation of high-quality features. The rotating forming tool introduced wavy surface textures, enhancing the functionality of the molded products. Polydimethylsiloxane (PDMS) molded with ISF-formed liners demonstrated good dimensional accuracy and smooth surface finishes. Compared to stereolithography (SLA)-printed liners, ISF-formed liners offered easier demolding and broader material compatibility. Future work will address high-pressure applications and more complex mold designs to expand industrial applicability. (c) 2025 CIRP. Published by Elsevier Ltd. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

This paper explores and identifies commonalities among recent Digital Twin (DT) technology definitions. additionally, it introduces a framework for a digital twin of Human-Robot Collaboration (HRC) focusing on English wheel manufacturing as its foundational context. To achieve this, two 3D simulators, namely Grasshopper and Rhino, were employed to faithfully replicate the English wheel process digitally. Subsequently, optimizing these simulators' performance paved the way for a comprehensive visualization of the English wheel using the Microsoft HoloLens. This visualization integrates digital and physical interactions, resulting in a mixed reality environment. The ultimate goal of this research is to enable a bi-directional collaboration within the digital representation of the English wheel, bridging the gap between the virtual and physical realms. (c) 2024 The Authors. Published by ELSEVIER Ltd. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0)

A theoretical framework, united by a “system effect” is formulated to model the cutting/haptic force evolution at the cutting edge of a surgical cutting instrument during its penetration into soft biological tissue in minimally invasive surgery. Other cutting process responses, including tissue fracture force, friction force, and damping, are predicted by the model as well. The model is based on a velocity-controlled formulation of the corresponding equations of motion, derived for a surgical cutting instrument and tissue based on Kirchhoff's fundamental energy conservation law. It provides nearly zero residues (absolute errors) in the equations of motion balances. In addition, concurrent closing relationships for the fracture force, friction coefficient, friction force, process damping, strain rate function (a constitutive tissue model), and their implementation within the proposed theoretical framework are established. The advantage of the method is its ability to make precise real-time predictions of the aperiodic fluctuating evolutions of the cutting forces and the other process responses. It allows for the robust modeling of the interactions between a medical instrument and a nonlinear viscoelastic tissue under any physically feasible working conditions. The cutting process model was partially qualitatively verified through numerical simulations and by comparing the computed cutting forces with experimentally measured values during robotic uniaxial biopsy needle constant velocity insertion into artificial gel tissue, obtained from previous experimental research. The comparison has shown a qualitatively similar adequate trend in the evolution of the experimentally measured and numerically predicted cutting forces during insertion of the needle.

Laser polishing (LP) provides a fast and efficient way of remelting part surfaces manufactured by additive manufacturing to alter both their geometric as well as physical properties. Depending on the laser parameters, remelted surfaces with different properties are achieved, with a majority exhibiting lower surface roughness compared to the original surface. In this study, a high-power continuous fiber laser is used to polish Inconel 718 (IN718) surfaces produced by depositing a single layer of clads on a steel substrate by the powder-blown directed energy deposition (DED) process. Polishing was performed under different sets of parameters, namely, laser power, beam diameter, feed rate or feed, hatch spacing, and the number of polishing passes. Their effects on the surface roughness profiles and the microstructural properties of the sample cross section were analyzed after one and two polishing passes. Optical microscopic images of the sample's cross sections show the presence of supersaturated gamma phase particles, gamma '+gamma '' precipitates, Laves phases, and delta phase needles. The combined effect of high-temperature gradients and lower solidification rates in certain regions within the cross section results in undercooled regions and pseudo-heat treatment of unmelted regions close to the undercooled regions. These results are corroborated by indenting the various regions of the IN718 sample cross section with a pyramidal diamond indenter in the form of a grid, resulting in different micro-hardness values due to different densities of precipitate and phase transformed delta particles.

The English wheel is a highly flexible traditional metalworking tool that allows skilled craftsmen to form compound curves on sheet metal panels. Historically, geometric accuracy and repeatability of formed panels using the English wheel have been tied to the operator leading to limited industrial adoption. This paper presents a novel framework for an integrated English wheeling system that leverages robot forming with a newly developed adaptable gripper/end-effector, metrology for deformed geometry tracking and tolerance measurements, integrated sensors for real-time forming force measurements and control, computational modeling for tracking pattern/toolpath generation, and virtual reality (VR) for seamless integration. Sample panels are formed using the integrated system revealing new insights on the forming forces during the process – highlighting why an integrated system is desirable. Concepts from the proposed framework can be applied to other robotic forming processes and its merit is discussed under current digital manufacturing and industry 4.0 literature.

Electrohydrodynamic (EHD) printing is a versatile process that can be used to pattern high-resolution droplets and fibers through the deposition of an electrified jet. This highly complex process utilizes a coupled hydrodynamic and electrostatic mechanism to drive the fluid flow. While it has many biomedical, electronic, and filtration applications, its widescale usage is hampered by a lack of detailed understanding of the jetting physics that enables this process. In this paper, a numerical model is developed and validated to explore the design space of the EHD jetting process, from Taylor cone formation to jet impingement onto the substrate, and analyze the key geometrical and process parameters that yield high-resolution structures. This numerical model applies to various process parameters, material properties, and environmental factors and can accurately capture jet evolution, radius, and flight time. It can be used to better inform design decisions when using EHD processes with distinct resolution requirements.

The concept of molds with gradient cooling characteristics is introduced to actively control the microstructure and, thereby, the physical properties of micro-castings. Such molds are composed of materials with different thermal properties arranged in different geometric configurations imposing varying cooling rates at each point of the casting. To ascertain the feasibility of this concept, molds made of materials with different thermal conductivities were used and their cooling properties were measured. The changes in the microstructure of the castings depending on their location in relation to the mold's body were evaluated. The results confirm the plausibility of microstructure control with such molds.

The process parameters of Directed Energy Deposition (DED) have been widely studied including laser power, powder flow rate, and scanning speed. These parameters affect clad dimension and melt pool temperature, which are directly related to part quality. However, laser/powder profiles and their alignment have obtained less attention due to the cumbersome characterization process, although they can be directly associated with local energy density for melt pool formation. This study examines the impact of the alignment between the laser beam and powder flow distributions in DED on clad dimension and melt pool temperature. The laser beam and powder profiles are characterized by measuring their respective 2D Gaussian profiles for a given standoff distance. Aligned and misaligned laser-powder profiles are then used to build single-clad square geometries. It was found that a 500-mu m offset between the centers of the laser and powder profiles causes up to a 20% change in both the width and the height of a single clad as well as an average temperature increase of 100 K. To understand the interaction between powder flow, energy flux, and local temperature, the local specific energy density distribution was plotted in 2D. These results suggest that laser-powder misalignment may significantly alter the thermal history and shape of deposited clads, possibly preventing DED-manufactured parts from meeting design properties and causing build failures.

An English wheel is an exceedingly adaptable instrument in traditional metalworking. It is a manual manufacturing technique, enabling skilled craftsmen and blacksmiths to shape complex compound curves in sheet metal panels. Accurate measurements and precise adjustments are essential when operating an English wheel to ensure that the metal is shaped with the desired curvature. An automated method to form English wheeled panels through robot forming has recently been proposed. For such a method to be successful, accurate tracking of sheet information including positions, orientations, and deformation is important for error compensation and the design of the subsequent tool paths. In this study, a Vicon motion capture system is employed to monitor the position and shape of the sheet metal during the English wheeling process. The initial experimental results demonstrate the potential of such an in-process metrology system, along with possible avenues for future work.

The primary cause of tool failure in rough cutting is the severe tool-chip friction brought on by chip adhesion and abrasive wear. To address the problem, the influence of combinations of micro-textures and AlCrN coating, and the sequence of their combinations on tool surface characteristics and cutting performance in dry cutting AISI 304 were investigated. The results of wettability and indentation tests indicate the micro-textures reduce the contact angle of the tool surface (by 13.26%) and increase the contact area between micro-textures and the coating, resulting in a better adhesive strength (grade HF3) for the first micro-textured and then AlCrN-coated tool (TCT). The results of cutting experiments demonstrate that the TCT’s cutting performance is improved as the cutting speed increases between 50 and 141 m/min, with the highest reductions in main cutting force and radial cutting force reaching 27% and 38% at 141 m/min. The TCT’s micro-textures reduce tool-chip contact area, while the intact AlCrN coating film decreases chip adhesion and improves the wear resistance of cutting tools. This study is expected to be applied to further improve the tool performance under dry and rough cutting conditions.

In situ monitoring is critical for developing new control methods, advanced materials and toolpath planning strategies in laser beam directed energy deposition (DED-LB). Coaxial melt pool monitoring has typically been performed with cameras [e.g., infrared, two-color pyrometer, charge-coupled device, or complementary metal-oxide semiconductor], which have focused on melt pool morphology and temperature distribution. While these techniques capture critical deposition information, they do not capture other important phenomena such as the unique coupling between the laser and melt pool, which limits the design and generality of open-loop and closed-loop process control. We establish in situ, parallel signals by monitoring multiple process phenomena at the same time through different wavelength bands and thermal correlation. Increased laser coupling was observed using in situ, parallel monitoring, where lower reflectivity/higher absorption of the laser light within a vapor depression led to an increase in thermal emission in the visible region. Ultimately, a relationship between each change in process parameter and the relative absorption of the laser was established. In situ monitoring of the laser coupling phenomena not only provides insight into material processing conditions but will also enable more complex control in DED-LB processes.

Atomic and close-to-atomic scale manufacturing (ACSM) aims to realize cost-effective, deterministic, and scalable manufacturing of next-generation products with atomic-level precision by addressing quantum uncertainty in atomic-level material manipulation (removal, migration, and addition). It is the fundamental technology for opening a new manufacturing paradigm—“Manufacturing III”. This essay introduces a research framework, including scientific issues and research content of ACSM, followed by the current status, scientific and technological challenges, and future research perspectives. Fundamental knowledge and theory, industrially viable processing technologies and equipment for atom manipulation, multiple chemical bonds/atoms interactions, and associated measurement and characterization approaches and systems are concluded as future key research focuses of ACSM.

As an established tool-based micro-machining technique, micro electrical discharge machining (μEDM) has received widespread attention from academia and industry for its capability of producing intricate micro-scale structures and features on various difficult-to-cut materials. However, assurance of the as-built surface quality and consistency has been a challenge due to the complex interactions among machining parameters and the unpredictable variability of material properties and the discharge process. In this paper, an efficient closed-loop control methodology based on an innovative application of on-machine metrology (OMM) and in-process roughness prediction (IPRP) is proposed for automatically ensuring the μEDM surface quality. The work takes into consideration process fundamentals related to size and distribution of craters by means of single crater experiments and pulse discrimination studies in order to analyze the influence of actual energy parameter on the evolving surface roughness. The OMM enables accurate in situ surface characterization while the IPRP, which is built on an online Bayesian regression model, allows for the prediction of surface quality according to the monitored process features. This IPRP model presents an increased predictive performance and confidence when more OMM data become available. Depending on the acquired quality outputs, a two-step quality control strategy involving energy adaptation and discharge stability regulation is implemented. This novel control strategy has proven to achieve a consistent areal surface roughness with variations smaller than 0.1 μm for a specific material and dielectric combination in μEDM milling.

The surface integrity of machined parts is critical to their in-service function, longevity and overall performance. The integrity of the surface is dominantly affected by the chip formation process that can be significantly altered and controlled, among other methods, by ultrasonic vibration assistance. This work will explore the integrity of surfaces generated in three-dimensional ultrasonic vibration-assisted turning (3D-UVAT). The integrity of the obtained workpiece surfaces will be systematically explored in terms of surface roughness, the microstructure of the surface obtained by heat-assisted turning, surface hardness and wettability. A comparative assessment with other surface generation methods, i.e., common turning (CT), one-dimensional (UVAT) and two-dimensional elliptical ultrasonic vibration-assisted turning (EUAT) is also given. The results show that 3D-UVAT can reduce the depth of surface damage and enhance the hydrophobicity of the surface while reducing surface roughness.

In 1973, a group of eminent manufacturing engineering researchers, known today as the Founders, organized the first North American Metalworking Research Conference (NAMRC). Seven years later, the name was changed to the North American Manufacturing Research Conference. In 1982, the institution known today as the North American Manufacturing Research Institution (NAMRI), with a formal board, Scientific Committee, and membership formally became part of SME. As we commemorate 50 years of its continuing success, we use this opportunity to recall and summarize our past: the achievements, milestones reached, and evolving themes. It is also a time to reflect on the challenges that we face today and on how we can better contribute and innovate into the future in terms of advanced manufacturing.

Process defects currently limit the use of metal additive manufacturing (AM) components in industries due to shorter fatigue life, potential for catastrophic failure, and lower strength. Conditions under which these defects form, and their mechanisms, are starting to be analyzed to improve reliability and structural integrity of these highly customized parts. We use in situ, high-speed X-ray imaging in conjunction with a high throughput laser, powder-blown directed energy deposition setup to observe powder particle impact behavior within the melt pool. Through fundamental observations of the stochastic, violent powder delivery in powder-blown DED, we uncover a unique pore formation mechanism. We find that a pore can form due to air-cushioning, where vapor from the carrier gas or environment is entrapped between the solid powder particle surface and liquid melt pool surface. A critical time constant is established for the mechanism, and X-ray computed tomography is used to further analyze and categorize the new type of "air-cushioning" pores. It is shown that the air-cushioning mechanism can occur under multiple laser processing conditions, and we show that air-cushioning pores are more likely to be formed when powder particles are larger than 70 μm. By quantifying the effect of powder particle impact, we identify new avenues for development of high-quality laser, powder-blown DED products. Furthermore, we deepen knowledge on defect formation in metal additive manufacturing, which is being increasingly utilized in high performance situations such as aerospace, automotive, and biomedical industries.

Dry cutting acting as a green machining technology is a promising manufacturing process in industrial applications; however, severe friction under dry cutting conditions aggravates tool wear and reduces tool life. Self-lubricating cutting tools exhibit excellent benefits in improving cutting properties and that can be used in sustainable machining. The complex process, low efficiency and thin coating thickness limit the production and use of present self-lubricating cutting tools with traditional methods. To enhance the lubricating effect and motivate the development of fabrication methods for self-lubricating cutting tools, Ni-based powders dispersed with MoS2 and Al2O3 particles were preset on the tool substrate; afterward, the self-lubricating coatings were deposited by laser powder-bed fusion additive manufacturing (AM) with a nanosecond fiber laser for cutting application. The self-lubricating coatings were characterized, and the friction and cutting performances of the AM self-lubricating coated tools (SLCs) were evaluated by sliding friction and dry machining tests. The results show that the developed SLC tools reduced the friction coefficient by 8.8–11.7%, cutting forces by 17.6–29.6%, and cutting power by 17.3–22.0% compared to conventional high-speed steel cutting tools (HSS). Built-up edge formation and tool wear were also significantly reduced. The observed mechanisms were attributed to the release of MoS2 particles from the coatings forming a lubricating film at the tool-chip interface, while the Al2O3 particles enhanced surface hardness. The results revealed the practicability of self-lubricating coated cutting tools fabricated by laser-based AM for friction-reduction, and that provide a cleaner process for dry cutting applications.