Mechanical Machining Research Articles

In-situ characterization of thermo-mechanical deformation fields based on DIC during orthogonal cutting of Ti6Al4V

Cutting phenomena containing abundant kinematic and thermo-mechanical information during the cutting process provide direct evidence for investigating machining mechanisms. In-situ digital image correlation (DIC) measurements are important methods for obtaining dynamic data such as strain and strain rate during the material deformation process. However, the secondary development of those deformation data is limited. The deformation information obtained by DIC is also limited to understanding complex thermo-mechanical deformation. In this study, an in-situ imaging system was developed to simultaneously acquire gray and infrared radiation (IR) images within the same deformation area during orthogonal cutting of Ti6Al4V. The deformation evolution and thermal history can be obtained simultaneously. In addition, a postprocessing methodology based on the DIC was proposed to derive thermo-mechanical information. Based on the postprocessing methodology, the stress fields were determined by the constitutive equation combined with the strain, strain rate, and temperature data. The stress propagation path during the formation of the chip segment was determined. Finally, the strain energy fields were derived to assess the potential energy of plastic deformation with the generation of the adiabatic shear band. The dependency between the machining phenomena and the cutting parameters was investigated. This work provides a novel understanding of the thermo-mechanical coupling behavior during the generation progress of serrated chips. The nature of the formation mechanisms and the deformation process involved for serrated chips are closely revealed.

Design of a New Drip Irrigation Belt Recovery Machine with Anti Breakage Function

Drip irrigation technology is widely used in agricultural production in the Xinjiang region. However, there are still a series of problems in the mechanized recovery of field drip irrigation belts, such as easy breakage of drip irrigation belts, low recovery efficiency, and excessive doping of recycled drip irrigation belts. This study focused on the problems of mechanized recovery of drip irrigation belts in Xinjiang and designed a new type of drip irrigation belt recovery machine. The key mechanisms of the new drip irrigation belt recovery machine were designed and theoretically analyzed, and their basic parameters were determined. Then, the superiority of the new drip irrigation belt recovery machine’s operational performance was verified through experiments. The experimental results showed that the new drip irrigation belt recovery machine is superior to existing machines in terms of the drip irrigation belt recovery rate and operational efficiency. In addition, the drip irrigation belts recovered by the newly designed machine have low impurity content. During the recovery process, the new machine requires less labor input than that of the existing machine.

Digital Slot Machines: Social Media Platforms as Attentional Scaffolds

In this paper we introduce the concept of attentional scaffolds and show the resemblance between social media platforms and slot machines, both functioning as hostile attentional scaffolds. The first section establishes the groundwork for the concept of attentional scaffolds and draws parallels to the mechanics of slot machines, to argue that social media platforms aim to capture users’ attention to maximize engagement through a system of intermittent rewards. The second section shifts focus to the interplay between emotions and attention, revealing how online attentional capture through emotionally triggering stimuli leads to distraction. The final section elucidates the collective implications of scaffolding attention through social media platforms. The examination of phenomena such as emotional contagion and the emergence of group emotions underscores the transition from individual experiences to shared collective outcomes. Employing online moral outrage as a case study, we illustrate how negative emotions serve as scaffolds for individuals’ attention, propagate within social groups, and give rise to collective attitudes.

Analysis and Comparison of Even-Order Back EMF Harmonics of Fractional-Slot Concentrated-Winding Consequent Pole Permanent Magnet Vernier Machines

Fractional-slot concentrated-winding (FSCW) consequent pole (CP) permanent magnet vernier (PMV) machines have received increasing attention due to their less magnet consumption but larger torque capability. However, the PM magnetomotive force (MMF) distribution is asymmetric in the CP structure. Thus, even-order air-gap flux density and back-electromotive force (back-EMF) harmonics are generated, which increases torque ripples. In this paper, to eliminate the even-order back-EMF harmonics and the resulting torque ripples, a comprehensive investigation on even-order flux density and back-EMF harmonics of five-phase FSCW CP PMV machines was presented, and then the general design rules without even-order back-EMF harmonics were summarized. Firstly, considering single- and double-layer windings, the effects of slot/pole number combination and flux modulator distribution on even-order flux density and back-EMF harmonics were analyzed. Secondly, the optimal slot/pole number combinations were selected, and then the rules for eliminating even-order back-EMF harmonics of CP PMV machines were summarized. As an extension, it was revealed that the harmonic elimination mechanism of CP PMV machines is applicable to CP-Halbach PMV machines. According to the summarized general design rules, the five-phase CP and CP-Halbach PMV machines with <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S</i> =20/ <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">P_r</i> =21/ <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">z_f</i> =10 were proposed. Their detailed performance has been comparatively analyzed and then the optimal one was selected for prototyping. Both finite element analysis (FEA) and experiments were carried out to validate theoretical analyses.

Plasma characteristics and material erosion mechanism in multi-channel wire electrical discharge machining

Multi-channel wire electrical discharge machining (MC-WEDM) is an advanced and high-efficiency machining technology, but its material erosion mechanism remains unclear. In this study, dual-channel wire electrical discharge machining was utilized as a case study to investigate the impact of the plunging current on both the plasma characteristics and material erosion under complex discharge conditions. Force analysis was conducted on the charged particles in the plasma, revealing that the plunging current can influence the trajectory of the plasma by modifying the self-magnetic field. The particle tracking method was employed to simulate the motion of electrons, revealing that in MC-WEDM, electrons exhibited a larger and more uniform distribution. The evolution of the plasma within a single-pulse discharge was observed using high-speed photography technology, and the discharge signals collected from different channels were analyzed. It was observed that the plasma in MC-WEDM experienced more intense back-and-forth sweeping on the workpiece surface, facilitating the ejection of molten metal from the molten pool. The oscillating plasma exhibits a larger processing area and a more uniform distribution of energy, resulting in the formation of larger and shallower discharge craters. Furthermore, the influence of the amplitude and time point of the plunging current on the volume and area of the discharge craters was summarized. Finally, MC-WEDM significantly reduced the occurrence of holes and micro-cracks and exhibited a thinner recast layer in the continuous discharge experiment.

ПЕРСПЕКТИВЫ ПРОЕКТИРОВАНИЯ И ПРИМЕНЕНИЯ МЕХАТРОННОГО СТАНОЧНОГО ОБОРУДОВАНИЯ В ГИБРИДНОМ ПРОИЗВОДСТВЕ

World trends and prospects of development of technological equipment complexes are considered. The applied stages and phases of machining equipment design are analyzed by means of constructing design schemes traditional for machine mechanics. It is proposed to create technological machine tool complexes by layout synthesis with the help of element base, which should contain functional technological and service modules, and the service purpose of the machine tool should include the nomenclature of manufactured surface modules. It is shown that the prospects of application of energy flows for intensification of machining processes should be analyzed at the early stages of design, using thermal and electrophysical criteria to study the emerging relations in the system. It is suggested to start designing mechatronic systems of machine tool complexes from the analysis of structural relations of information technologies in hybrid production including traditional and additive technologies.

Data-driven initial peak crushing force prediction of hybrid tubes

Accurately predicting the initial peak crushing force (IPCF) of the CFRP/metal hybrid structure is of great significance for the high-efficiency energy absorption of energy-absorbing elements and ordered deformation of combined energy-absorbing devices. Due to the significant differences in material properties between CFRP and metal and the high complexity of cross-sectional shape, a combined method of machine learning and mechanism analysis is proposed for predicting the IPCF of CFRP/Al hybrid energy-absorbing tube. First, a high-precision finite element model validated by the axial and oblique experiments is conducted to generate the dataset for predictive analysis. Second, a sample space through the design of experiment (DOE) is established for data fitting between structural parameters and IPCF based on traditional response surface model (RSM). It is found that traditional RSM method can successfully predict the IPCF of the single-cell hybrid tube, but cannot effectively predict the IPCF of the multi-cell tube due to the strong coupling effect between inner and outer plates. To address the issue of the lack of accurate correspondence between structural parameters and IPCFs in multi-cell hybrid tube, the indicator of relative density is proposed to characterize complex cross-sectional features. Surprisingly, there is a strong correlation between relative density and IPCF where multi-cell tubes with the same relative density have almost the same IPCF. Third, different artificial neural networks (ANN) are trained by a pre-simulated IPCF database of CFRP/Al hybrid energy-absorbing tube depending on the parameter characterization scheme based on mechanism analysis. In order to enhance the network's performance, the optimal configuration parameters of the neural network, including the number of layers and nodes, are ascertained through a combination of K-fold cross-validation and the Grid Search method. As a result, compared with the traditional RSM and Kriging model, the IPCF of CFRP/Al hybrid energy-absorbing tube can be predicted in small samples with high accuracy using the optimal ANN model. Finally, Through the comparative analysis of the IPCF of hybrid tubes with reported multi-cell configurations, it is found that the prediction model proposed in this paper has good generalization ability, which can be used to predict more complex types of multi-cell tube configurations. The present study offers important suggestions for the overall control of multi-materials hybrid energy-absorbing tube and the ordered deformation of combined energy-absorbing devices.

Thermoelectric cooler with embedded teardrop-shaped milli-channel heat sink for electronics cooling

Thermoelectric coolers (TECs) offer a site-specific, on-demand, and solid-state thermal management solution for on-chip electronics cooling. To maximize their cooling performance, it is essential to integrate an effective heat exchanger, such as microchannels, on the TEC’s hot side. However, traditional microchannel heat sinks pose challenges, including the necessity for high-cost equipment and the manifestation of deleterious parasitic contact thermal resistance with the TEC. Recent studies have demonstrated the superior performance of teardrop-shaped microchannels compared to their conventional counterparts, yet their effectiveness at the milli-scale remains unexplored. In this work, through systematic numerical simulations across nine milli-channels with distinct variable cross-sections, we propose a teardrop-shaped milli-channel heat sink designed for fabrication through cost-effective mechanical machining. The optimized teardrop-shaped milli-channel exhibits a superior overall thermo-hydraulic performance evaluation factor (PEC) of approximately 1.8 with respect to its rectangular cross-sectional counterpart. Furthermore, we seamlessly embed the designed milli-channel heat sink into the substrate of the TEC to mitigate the parasitic contact thermal resistance. Measurements on the TEC embedded with the teardrop-shaped milli-channel heat sink show that the cold end temperature reaches a minimum value of −18.6 °C at an optimal input electrical current of 3.5 A and an inlet coolant flow velocity of 0.2 m/s. This temperature represents an improvement of approximately 3.5 °C and 4.4 °C compared to the TEC with an attached teardrop-shaped milli-channel and a conventional water block heat sink, respectively, under identical operating conditions. Additionally, a prototype TEC cooling system with the embedded teardrop-shaped milli-channel for high-power field-effect transistor (FET) cooling is demonstrated. Operating at an input electrical current of 3.5 A and an inlet flow velocity of 0.6 m/s, our proposed TEC cooling system achieves a steady-state working temperature of 51.3 °C for the FET at a high heat flux of 75 kW/m2, outperforming the TEC with an attached teardrop-shaped milli-channel and a conventional water block heat sink by approximately 1.4 °C and 2 °C, respectively.

Biodegradable cutting fluids for sustainable manufacturing: a review of machining mechanisms and performance

Biodegradable cutting fluids for sustainable manufacturing: a review of machining mechanisms and performance

Atomic-level insight into process and mechanism of ion beam machining on aluminum optical surface

Polycrystalline Al workpieces go through a complex surface atom sputtering and surface/subsurface atom diffusion throughout the ion beam machining process that plays a critical role in determining machining quality of optical mirror surfaces. Here, we leverage molecular dynamics method for the first time to reveal the machining mechanism and the polycrystalline effect of aluminum during ion beam sputtering, in term of cascade collision, atom trajectory, sputtering yield, and surface characteristic. Polycrystalline Al presents a significant low potential energy state, leading to milder cascade collision and weaker sputtering effects than monocrystalline Al during ion beam machining. The atom trajectory demonstrates irregular variation as the atom diffusion is blocked by grain boundary (GB) in polycrystalline Al, leading to the relief microstructure and poor surface quality. With incident ions increasing, the GBs are broken and atom diffusion enhancing, as well as lower subsurface defects and better finishing surface quality. The microscopic morphology evolves into gravel microstructure. Simulation results also reveal that atom diffusion will benefit from high ion concentration and low ion energy. Sputtering yield variation is more sensitive to ion energy. To acquiring better finishing surface quality of Al without influencing machining efficiency, ion concentration must be increased while the ion energy needs to be decreased appropriately but a large number of cascading collisions need to be ensured.

Machining characteristics in ultrasonic vibration-assisted powder-mixed electrical discharge machining of TiN ceramics

This study aims to investigate the application and machining characteristics of brittle conductive ceramics using ultrasonic vibration-assisted powder-mixed electrical discharge machining (UV-PMEDM) technology. Titanium nitride (TiN) ceramics are widely used in aerospace, biomedicine, and electronics due to their excellent properties. However, the conventional mechanical machining methods of these materials result in severe tool wear, high costs, and low efficiency. Although electrical discharge machining (EDM) can overcome some limitations, it typically exhibits a low material removal rate and poor surface quality. This study utilizes the UV-PMEDM technology to process TiN ceramics. Single-factor experiments are conducted to analyze the effects of processing parameters, including ultrasonic amplitude, powder concentration, pulse-on time, and pulse-off time, on the material removal rate, surface roughness, and relative electrode wear rate, which indicate the EDM processing performance. With the assistance of ultrasonic vibration and mixed powders, the material removal rate of TiN ceramics using UV-PMEDM reaches 0.50 mm3/min, while maintaining a relative electrode wear rate below 1 % and surface roughness lower than 4.2 μm. The synergistic combination of ultrasonic vibration and mixed powders significantly enhances the processing efficiency and reduces surface roughness of TiN ceramics. These findings contribute to a better understanding of machining strategies for brittle conductive ceramics.

Analysis of material removal mechanism in nanoscale machining of copper

In the current study, molecular dynamics modeling and simulation are carried out to analyse mechanisms in tool-workpiece interaction in nanoscale cutting. Various combinations of a/ r ratios for constant r ( r = tool edge radius and a = uncut chip thickness) are considered and different crystal orientations of the workpiece specimen are employed in the nanoscale cutting model. From the simulation, material anisotropy behavior is observed during the nanoscale cutting of copper material. Analysis at the molecular scale reveals that the crystal orientations family {1 1 0}&lt;1 0 0&gt; is hard to machine and the family of crystal planes {1 1 1}&lt;1 1 0&gt; is easiest to cut. While comparing in different crystal planes and directions, it was noticed that the material deformation in nanoscale machining takes place only in slip directions, that is, &lt;1 1 0&gt; family of directions. It is also found that as the uncut chip thickness is decreased, the cutting mechanism changes from shear plane cutting to plowing to sliding in Cu.

Mechanically processed, vacuum- and etch-free fabrication of metal-wire-embedded microtrenches interconnected by semiconductor nanowires for flexible bending-sensitive optoelectronic sensors

Abstract We demonstrate the facile fabrication of metal-wire-embedded microtrenches interconnected with semiconducting ZnO nanowires (ZNWs) through the continuous mechanical machining of micrograting trenches, the mechanical embedding of solution-processable metal wires therein, and the metal-mediated hydrothermal growth of ZNWs selectively thereto. The entire process can be performed at room or a very low temperature without resorting to vacuum, lithography, and etching steps, thereby enabling the use of flexible polymer substrates of scalable sizes. We optimize the fabrication procedure and resulting structural characteristics of this nanowire-interconnected flexible trench-embedded electrode (NIFTEE) architecture. Specifically, we carefully sequence the coating, baking, and doctor-blading of an ionic metal solution for the embedding of clean metal wires, and control the temperature and time of the hydrothermal ZNW growth process for faithful interconnections of such trench-embedded metal wires via high-density ZNWs. The NIFTEE structure can function as a bending-sensitive optoelectronic sensor, as the number of ZNWs interconnecting the neighboring metal wires changes upon mechanical bending. It may benefit further potential applications in diverse fields such as wearable technology, structural health monitoring, and soft robotics, where bending-sensitive devices are in high demand.

TEM and zeta potential titration as suitable techniques for investigating the joining of modified ceramic surfaces

Transmission Electron Microscopy (TEM-EDS) and Zeta potential titration of ceramic surfaces allowed researchers to go inside their adhesion mechanism when joined with an adhesive. The case study concerned the plasma Corona treatment to improve the joint strength between SiC surfaces joined with an epoxy adhesive. The formidable mechanical and chemical properties inherent to silicon carbide pose challenges in applying conventional methods like mechanical machining and wet etching for surface texturing. Exploring alternative strategies, plasma Corona treatment which is an Atmospheric Pressure Plasmas (APPs) process emerges as a potential solution. The mechanism of chemical interaction and mechanical interlocking between plasma-treated surfaces and the epoxy adhesive used for the joining was never explored in detail and proven. The presence of layers with different crystallographic natures and chemical compositions was assessed by TEM-EDS: an amorphous silica layer was produced by the corona activation treatment and it created a mechanical anchoring system when penetrated by the adhesive. The zeta potential titration as a function of pH evidenced that untreated SiC had a surface with amphoteric functional groups, while the Corona treatment induced the formation of surface functional groups (OH) with a strong acidic behavior on SiC. The investigated epoxy adhesive exposed a prevalence of basic amino groups. Zeta potential titration curves highlighted the chemical interaction between the treated SiC surfaces and the epoxy adhesive: the large electrostatic attraction between the OH groups of the treated SiC and the amino groups of the epoxy adhesive had a role in the mechanical strength of the joining. TEM and Zeta potential titration can be proposed as suitable techniques to evaluate the effectiveness of the plasma corona discharge system in modifying the surface of SiC and to solidify its standing in comparison to other established surface modification techniques to improve SiC-based joints.

An Overview of Casino and Gambling

A significant number of individuals engage in the gaming sector due to its association with financial prosperity. The gambling sector has experienced significant growth, leading to a heightened interest among the general public in its wealth and prosperity. Casinos that generate annual revenues in the billions have demonstrated remarkable resilience in the face of economic downturns. This research paper aims to investigate a relatively obscure domain within the gaming industry. It will employ a combination of scholarly theoretical analysis and empirical research to examine various aspects, including game categorization, the mechanics of gaming machines, effective marketing strategies employed by casinos, and the interplay between perceptions of gambling, psychological profiles, and behavioral patterns. The paper additionally investigates the efficacy of doubling and continuous betting techniques and provides recommendations pertaining to the marketing, management, and regulation of the gaming business.

Kinematic analysis of gear-lever combined differential transmission mechanism

The article presents the result of kinematic analyzes of the gearlever combined differential transmission mechanism (GLCDTM) of roller machines with a large change in the center distance of the working shafts. Equations have been obtained for determining the gear ratio and angular velocity of the characteristic points of the GLCDTM.

Theoretical trends in the dynamics simulations of molecular machines across multiple scales.

Over the past few decades, molecular machines have been extensively studied, since they are composed of single molecules for functional materials capable of responding to external stimuli, enabling motion at scales ranging from the microscopic to the macroscopic level within molecular aggregates. This advancement holds the potential to efficiently transform external resources into mechanical movement, achieved through precise control of conformational changes in stimuli-responsive materials. However, the underlying mechanism that links microscopic and macroscopic motions remains unclear, demanding computational development associated with simulating the construction of molecular machines from single molecules. This bottleneck has impeded the design of more efficient functional materials. Advancements in theoretical simulations have successfully been developed in various computational models to unveil the operational mechanisms of stimulus-responsive molecular machines, which could help us reduce the costs in experimental trial-and-error procedures. It opens doors to the computer-aided design of innovative functional materials. In this perspective, we have reviewed theoretical approaches employed in simulating dynamic processes involving conformational changes in molecular machines, spanning different scales and environmental conditions. In addition, we have highlighted current challenges and anticipated future trends in the collective control of aggregates within molecular machines. Our goal is to provide a comprehensive overview of recent theoretical advancements in the field of molecular machines, offering valuable insights for the design of novel smart materials.

Millisecond fibre laser drilling of alumina-alumina CMC

Alumina-Alumina (OX-Ox)CMCs are a technical ceramic composed of alumina fibres in an alumina matrix, with a primary usage case in the aerospace industry. Ox-Ox CMCs offer the traditional benefits of high toughness and bending strength, along with resistance to oxidation and corrosion associated with monolithic alumina, coupled with low brittleness and crack arresting behaviour of fibre in matrix composites. Whilst these properties are highly desirable, CMCs present significant difficulties for conventional mechanical machining, with laser machining offering potential solutions providing the impetus to the work presented in this paper. This work presents a parametric study of the effects of frequency and pulse energy for 10mm deep laser percussion drilled holes and a response surface study for these two variables, using an industrially representative 20kW peak power laser. Results show that for an 800µm diameter hole, a taper angle of <1⁰ and average recast layer thickness of <40µm are achievable, while the response surface study highlights the importance of considering input variables as a complex system, particularly for recast layer thickness.

Effects of material properties on texturing of mold materials using ultrasonic-assisted grinding and the machining mechanism of grinding grooves

Effects of material properties on texturing of mold materials using ultrasonic-assisted grinding and the machining mechanism of grinding grooves

Impact of smoothing interpolations on the non-conventional machining of pockets

Smoothing curves have been used in computer aided design software for years. This is the reason why machinists very early wondered about the possibilities of creating toolpaths directly generated from this type of mathematical curves. In addition, in recent research work, we have shown that the non-uniform rational Bspline interpolation is the most favorable towards high-speed machining of complex shapes. As a result, we are thinking of simulating by this type of interpolation the pocket recess machining strategies proposed by a computer aided manufacturing software, currently developed in linear and circular interpolations only. In this article we propose a study of the influence of the parameters of Bspline curves on the hollowing out of pockets by smoothing initial cutting methods. To do this, we chose the smoothing of the zigzag method by Bspline and NURBS while varying the order and the discretization parameters to know the impact on the dynamics of the high-speed machining mechanism and on the non-conventional machining precision. This work has shown that parametric curves are favored for this type of machining provided that this tool is mastered.