Machining Depth Research Articles

Research on microscopic fracture mechanism of glass-ceramics grinding surface based on progressive scratch test

Progressive scratch test was carried out on the glass-ceramics to study the continuous micro-fracture mechanism of its surface, which provided an important basis for the research on the grinding mechanism of glass-ceramics. By microimaging of scratch, the continuous material removal process of glass-ceramics from ductility to ductile brittleness to brittleness was observed in micro-view, confirming that there was a ductile brittleness between ductility and brittleness on the surface of glass-ceramics. The critical point for breaking from ductility to ductile brittleness and the critical point for breaking from ductile brittleness to brittleness were measured. The machined critical depth hc1 of the composite domain of ductility and ductile brittleness and the machined critical depth hc2 of the composite domain of ductile brittleness and brittleness for glass-ceramics were further obtained by computational analysis. This study provides valuable insights into the surface machining forming and surface microstructure generating of glass-ceramics material. The research results can also provide reference on determining the critical grinding parameters of glass-ceramics material.

Maximizing efficiency in C45 steel machining: an integrated AI-based approach to coated insert optimization

AbstractMachining involves the subtraction of the material from the sample workpiece to achieve the desired shape or surface. This versatile method is capable of producing a wide range of parts, varying from simple to intricate profiles. Coating materials are increasingly being utilized in tool inserts in the production industry owing to their superior thermal properties and wear resistance. The shielding of hard coatings, with thicknesses of only a few microns, enhances performance and durability. In this study, machining of C45 steel using distinct coated inserts was explored. The experimental trials employed PVD and CVD methods for coated tungsten carbide (WC) tools/inserts and PVD-coated cermet tools/inserts with different machining parameters. Performance metrics, such as the surface finish and reliability of the tool, were considered for the evaluation. The average tool life variation between the PVD-coated cermet and PVD-coated WC was 178.86%, and 30.11% between the PVD-coated cermet and CVD-coated WC at 1 mm DOC. ANOVA was performed using Response Surface Methodology to explore the influence of input parameters on output. The results indicate that the depth of machining and spindle speed significantly influence Ra, whereas spindle speed and type of tool insert have a considerable impact on the life span of the tool. The developed mathematical model for the prediction of tool life and Ra indicates its potential for performance forecasting during C45 steel machining. Grey relation analysis was employed to optimize the process parameters. Optimal results were achieved with a spindle speed of 400 m/min, 0.5 mm depth of cut, and cermet tool inserts. PVD-coated WC inserts performed better. ANFIS was applied for the prediction and optimization of the machining parameters.

Active compliance control of grinding process for stripping enameled copper wire

The hairpin motor is among the motors used in eco-friendly automobiles. Unlike the random-winding method, this method features a square cross-sectional enamel coil formed into several hundred hairpins inserted into the stator. This offers an increased space factor, which leads to enhanced motor power. With the growing use of hairpin motors, there is an increasing demand for automated equipment in their production. With an aim to improve the manufacturing quality of hairpin motors, many countries are conducting research and development. The process of enamel removal is one of the key steps in hairpin-forming equipment and can significantly affect the performance of the motor. A precise machining process technology is required to improve the enamel removal process, achieve higher enamel removal rates, and reduce wire loss rates. Grinding is a technique used for enamel removal. In this study, an adaptive control algorithm was applied to the grinding process to enhance the enamel removal machining performance. During the machining process, the vertical position of the spindle was controlled to maintain a consistent machining depth for tracking the target grinding force. An experimental setup, which included a system for measuring the spindle torque to calculate the grinding force in real time, was created. To validate the performance of the adaptive control technology, experiments were conducted using this setup. Furthermore, experiments were conducted to observe the changes in the grinding force ratio based on the conditions of the grinding wheel. The correlation between the grinding force ratio and tool condition was analyzed, and based on this, the feasibility of assessing tool condition and determining the timing for tool replacement through real-time monitoring of the grinding force ratio was confirmed.

Research on jet electrochemical machining with coaxial megasonic assistance

In order to address the problem of poor localization in electrochemical machining (ECM), a coaxial megasonic assisted jet ECM method was proposed. Based on theoretical analysis, experiments were conducted to compare the effects of various electrolyte flow rates, electrolytic voltage and megasonic power levels on pit ECM. The results indicate that, in the range of experimental parameters, the increase of electrolyte flow rate and megasonic power can increase the machining depth, so as to improve the depth-diameter ratio of ECM pits. The use of coaxial megasonic-assisted jet ECM can enhance the depth-diameter ratio of etched pits compared to the without megasonic one. When applying a megasonic power of 22 W, the dimensions of the ECM pit were measured as 0.81 mm in depth and 5.73 mm in diameter, resulting in an depth-diameter ratio of 0.140. Under the same conditions, without megasonic assistance, the pit diameter is reduced to 0.65 mm while the pit depth increases to 6.36 mm, resulting in a depth-diameter ratio of 0.102. Additionally, The results also demonstrate that, the increase of electrolytic voltage makes the depth to diameter ratio of pit further increase on the original basis. With an electrolyte flow rate of 0.9 L/min and a megasonic power of 22 W, the use of electrolysis voltage of 50 V increased the depth-diameter ratio of etched pits to 0.173. Using the above preferred parameters, electrolytic milling of the wide groove is carried out. The depth-diameter ratio of the wide groove is increased from 0.039 to 0.059 by appending coaxial megasonic. This further verified the effectiveness of the coaxial megasonic-assisted jet ECM method.

Study on Effect of Surface Micro-Texture of Cemented Carbide on Tribological Properties of Bovine Cortical Bone.

In bone-milling surgical procedures, the intense friction between the tool and bone material often results in high cutting temperatures, leading to the thermal necrosis of bone cells. This paper aims to investigate the effect of micro-texture on the tribological properties of YG8 cemented carbide in contact with bone. The main objective is to guide the design of tool surface microstructures to reduce frictional heat generation. To minimize experimental consumables and save time, numerical simulations are first conducted to determine the optimal machining depth for the texture. Subsequently, micro-textures with different shapes and pitches are prepared on the surface of YG8 cemented carbide. These textured samples are paired with bovine cortical bone pins featuring various bone unit arrangements, and friction and wear tests are conducted under physiological saline lubrication. The experimental results indicate that the appropriate shape and pitch of the micro-texture can minimize the coefficient of friction. The parallel arrangement of bone units exhibits a lower coefficient of friction compared to the vertical arrangement. This study holds significant implications for the design and fabrication of future micro-texture milling cutters.

Advancing Dental Implant Design: A Comprehensive Study of Machining Parameters, Corrosion Behavior, and Microstructural Evaluation.

In this research, we investigate the impact of varying machining parameters [depth of cutting (mm) and spindle rotation speed (rpm)] on the microstructure and electrochemical behavior of Ti6Al4V-ELI dental implants. This comprehensive study employs an approach, leveraging potentiodynamic methods and electrochemical impedance spectroscopy, to analyze corrosion behavior in a phosphate-buffered saline solution. To further deepen our understanding of corrosion kinetics, we used an alternating current circuit model, based on a simple Randles equivalent circuit. This model elucidates the corrosion interface interactions of the Ti6Al4-V-ELI alloy implant within the PBS solution. In addition, our research delves into the microstructural implications of different machining parameters, utilizing scanning electron microscopy and X-ray diffraction (XRD) techniques to reveal significant phase changes. The changes in texture were examined qualitatively by comparing the intensities of the peaks of the XRD pattern. A detailed correlation analysis further links the machining parameters with the corrosion properties of dental implants, offering a comprehensive perspective rarely explored in the existing literature. The results obtained for the three samples showed that the corrosion resistance would be higher by increasing the machining depth and the spindle rotation and that the corrosion current would be lower. As a result, a lower corrosion rate was obtained. Finally, experimental results from electrochemical analyses are compared and discussed.

Experimental investigation on the machining performance of honeycomb seal structures by using electrochemical discharge machining

Aerospace metal honeycomb seal structures are an essential component of aircraft engines, and their manufacturing has been at the forefront of industrial focus. Due to the low structural stiffness and high-strength materials, it has become one of the complex components that are difficult to machine. To achieve precision manufacturing of honeycomb seal structures, this study proposes the use of electrochemical discharge machining (ECDM) for machining honeycomb seal structures, which has the high efficiency of electric discharge machining (EDM) and superior surface quality of electrochemical machining (ECM). The experiment results explored the influence of different experimental variables on surface quality, energy distribution relation and material removal rate (MRR). Moreover, in order to predict the machined depth, the mathematical relation between different variables and machined depth was established, which can be expressed as h = 1.407c0.1135u0.3102v-0.391, and a better machining outcome was achieved at 1 wt%, 15 V, and 22 mm/min with an optimal η2 of 0.36. Finally, this study elucidates the material removal mechanism of honeycomb seal structures in ECDM, which demonstrates that ECDM has a high application value in the manufacturing of honeycomb seal structures.

Numerical analysis of machinability and surface alterations in cryogenic machining of additively manufactured Ti6Al4V alloy

Metal additive manufacturing (AM) technology has been utilized in many industries including automotive, aerospace, and medical. AM Ti6Al4V (Ti64) alloy is highly noticed for production of medical instruments such as dental implants and the machining process is mostly needed during the production or post-processing of these components. Numerical model, as a powerful tool, can be efficiently used for analyzing the machining process. A customized model was employed using a user-written subroutine in this work to evaluate machinability and microstructural changes in cryogenic machining of AM Ti64 alloy. For this purpose, the microstructural changes were simulated as the new numerical outputs. The numerical results of cutting forces, temperature, nano-hardness, and alpha lamellae thickness (grain size) were successfully verified by corresponding experiments from literature. Then, the impact of tool geometry (including rake and clearance angles, cutting edge radius, and nose radius) on the machinability performance was examined. It was found that, the variation of clearance and rake angles were more effective on depth of the hardened layer compared to the other parameters. Thickness of alpha lamellae phase near the machined surface and depth of the affected layer by nano-hardness changes were changed from 0.9 to 1.58 µm, and from 18 to 40 µm, respectively. Overall, it was concluded that the variation of insert positioning made by tool holder (change in rake and clearance angles) was an effective parameter on the process outputs when machining AM Ti64 alloy.

Assessment of Surface Quality during EDM of AISI 4147 with Copper Tool

This experimental assessment is performed to estimate the impact of EDM parameters on surface quality while machining AISI 4147 with a copper tool. The need of the present-day is to achieve good surface quality. Here, an investigation was performed to depict surface quality characteristics with respect to machine variables. The machined specimens were examined under white light interferometry (WLI) for the crests and troughs developed post-machining. The range of average surface finish was found to be between 5.32 to 7.67 µm. The test of model highlighted that the relation linking the EDM variables and surface roughness could be modelled using quadratic equations. As per the SMSS and lack of fit tests, a quadratic model is suggested for the roughness trend obtained. The analysis apprised that duration (p-value = 0.0006) major influence on the surface quality produced while the depth of machining (p-value = 0.9251). At all levels of on time, the surface roughness initially increases and then tends to decrease on increasing peak current. At all current levels, the surface roughness is almost constant with the machining depth; as suggested by ANOVA, it is the least influencing factor. At all levels of duration, the surface roughness is almost constant with depth of machining, and as suggested by ANOVA, it is the least influential factor. Model surface plots are curved representing the presence of quadratic terms in the model. Model validation for surface finish showed that the residual error was lower than 1.48%, proving the adequacy of the model.

Development of Electrochemical Microtextured Cell for Fabrication of Complex Micropattern

Introduction: This paper highlights the representative patents related to the application of maskless electrochemical micromachining (EMM) using microtextured tools and developed cells under electrolysis conditions for the generation of high-quality complex patterns, i.e., cascade micropattern on stainless steel. background: Electrochemical Microtextured Cell Method: To acquire high accuracy level, the workpiece and tools are fixtured properly in the developed microtextured cell, and a developed vertical cross-flow system is utilized for the generation of a precise cascade micropattern. An electrochemical microtextured cell is designed and developed inexpensively for the fabrication of high-quality complex micropatterns. The eco-friendly combined electrolyte of NaNO3 and NaCl is employed for precise micro texturing. Result: The consequence of predominant input factors, i.e., IEG, voltage, and flow rate, are explored on machining rate, precision, depth, and surface finish during complex micro-texturing using developed microtextured cells. The complex microtextured tool is fixtured in tool holding device in a developed microtextured cell and fabricates nineteen precise complex micropatterns. Conclusion: An effort has been made to find suitable input factors for the generation of precise complex micropatterns.

ABS 엔지니어링 플라스틱의 하향밀링 시 절삭조건이 표면거칠기에 미치는 영향

In this study, we investigate surface roughness, which can serve as the basis for optimal cutting conditions for ABS engineering plastic processing, and propose optimal cutting conditions for down-cutting using machining center equipment. Accordingly, we aim to provide basic data for setting cutting conditions in the field.
 The cutting conditions are compared with the values of surface roughness by substituting the values for cutting speed and feed as given in a textbook. Optimal cutting condition values are suggested by comparing different levels of surface roughness based on machining depth.

Ultrasonic elliptical vibration micro-cutting mechanism of CoCrFeNiAlX short fiber reinforced aluminum-based composite

This study explores the precision micro-machining of CoCrFeNiAlX short fiber-reinforced 7A09 aluminum matrix composites, focusing on the interplay between machining parameters and composite properties. The investigation scrutinizes the influence of vibrational amplitude, oscillation frequency, penetration depth, fiber orientation, and aluminum concentration on machining dynamics. Findings reveal that enhancing the X-axis vibrational amplitude to 80 μm is associated with a decrease in machining force, which then rises after reaching a threshold. In contrast, maintaining the Y-axis amplitude below 90 μm significantly increases the machining force. Higher amplitudes and frequencies were observed to reduce machining forces by up to 57% at an ultrasonic frequency of 15 kHz. Employing ultrasonically assisted vibration cutting (UEVC) culminated in a substantial 72% decrease in machining forces when fibers were optimally oriented at 45°. The study also identifies a direct correlation between the cutting temperature and both the vibrational amplitude and penetration depth, with the Y-axis amplitude having a more significant impact, causing a 55% variation in temperature. An increase in frequency initially lowers the cutting temperature, with the lowest temperature of 92 °C achieved at 5 kHz, while the peak temperature occurs at a machining depth of 60 μm. Temperature profiles indicate an initial rise with increased fiber orientation, followed by a decline. A slight increase in aluminum concentration marginally raises the cutting temperature. Furthermore, UEVC is found to produce a parabolic residual stress distribution, where amplitude and penetration depth determine the peak stress levels, and higher frequencies contribute to stress reduction. Fiber orientation also affects residual stress, with proper alignment reducing compressive stress and misalignment increasing it. The lowest point of residual compressive stress is detected in the Al0.6 fiber composite, while the peak is observed in the Al1 composites.

Electrical discharge drilling of blind holes with injection flushing dielectric and stepped electrodes

Electrical discharge drilling of blind holes has been a challenging task due to the inherent difficulties in removing debris from the discharging gap. This paper investigates the working mechanism and effects of new stepped electrodes which are used in conjunction with injection flushing in drilling deep blind holes. A series of theoretical simulations and comparative experiments were conducted using cylindrical electrodes and two types of stepped electrodes. Pulse waveforms were captured to analyse the discharge status. Surface topography and machining quality were analysed using scanning electron microscope (SEM) images. The machining performance was evaluated by studying the material removal rate (MRR) and tool wear ratio (TWR). Experiment results show that internal flushing caused the debris to circulate in the machining zone and led to abnormal discharges, disrupting the formation of the plasma channel. The MRR was increased by 75% and 82% when using cylindrical electrodes with pressures of 120 psi and 40 psi, respectively. In contrast, the MRR with injection flushing was about 80% of that without injection flushing when using stepped electrodes. Regardless of the type of electrode, the application of injection flushing resulted in the increase in the maximum effective machining depth.

Design and Fabrication of a Sensors-integrated Silicon Electrode for Gap Status Monitoring in Micro Electrochemical Machining

Abstract The monitoring of micro machining gap and the control of machining status within the gap have become bottlenecks in the research and development of micro electrochemical machining (ECM). General electrical signals are difficult to reflect the status of micro machining gap. Electrolytic products in micro machining gap are prone to precipitation and retention, leading to unstable material removal process. Micro ECM urgently requires gap status monitoring and feedback control. To realize gap status monitoring, a sensors-integrated silicon electrode, with a micro temperature sensor and a micro conductivity sensor on the silicon electrode near-front sidewall, is proposed innovatively in this study. Based on bulk silicon process and electroplating process, sensors-integrated silicon electrodes are designed and fabricated. Based on the signal processing system built for the temperature and conductivity sensor, the temperature and conductivity detection functions are verified and the sensors are calibrated. Micro ECM experiments with sensors-integrated silicon electrodes are carried out and micro holes with 200 μm depth are machined. For the conductivity sensor on the sensors-integrated silicon electrode, due to the affection of electrolytic environment, the function surface is contaminated and damaged, and the structural design needs to be further improved. For the temperature sensor, it is not affected by the electrolytic environment due to insulation-film’s protection, and reliable temperature monitoring is achieved in micro ECM. The detection results indicate that the temperature inside the machining gap has increased by 20 ℃ due to the electrochemical thermal effect and resistance thermal effect in micro ECM, and the temperature shows an increasing trend while machining depth increasing. The feasibility of process monitoring with sensors-integrated silicon electrode in micro ECM is preliminarily verified.

Alternate activation-annihilation of dislocations realizes the plasticity of sapphire during indentation

A “renaissance” of sapphire is regarded as one of the most significant tendencies of modern materials science. But sapphire has almost no plasticity at room temperature, making its surface finishing a formidable challenge. Realizing the plasticity of sapphire and revealing its plastic deformation mechanism are crucial for the micro-nano and ultra-precision machining of sapphire. In this work, the deformation behavior of sapphire during indentation is revisited using molecular dynamics simulation. It finds that sapphire possesses a diverse plastic deformation behavior during the nanoindentation. Systematical investigation into the evolution of dislocation confirms that sapphire realizes plasticity during indentation through alternate activation-annihilation of dislocation. In light of these results, it is reasonable to believe that an improved machining quality can be obtained by precisely controlling the machining depth to keep sapphire in the dislocation activation stage. Furthermore, our simulations provide a possible physical essence of the ductile–brittle transition during material removal observed in experiments.

Enhancing the borosilicate glass micromachining by using mixed alkaline electrolytes in the ECDM process

ABSTRACT This article investigates the effects of mixing different alkaline electrolytes on the geometrical features created by the ECDM. Sodium hydroxide (NaOH) and potassium hydroxide (KOH) were mixed in varying volumetric proportions. Effect of critical process parameters on the depth and width of the microchannels and the associated tool wear was investigated. Pure NaOH electrolyte has resulted in the highest depth compared to the pure KOH electrolyte. Process mechanism behind the role of mixed electrolytes on the opening sizes and depths of microchannels is explained. Higher material removal by the NaOH electrolyte was due to the larger number of sodium (Na+) ions in the electrolyte, resulting in more aggressive electrochemical discharge; however, it also resulted in severe tool wear. Mixed electrolytes with a KOH yielded lower width and low tool wear. Increasing the volumetric proportion of KOH in the mixed electrolyte gradually decreased the machining depth, width, and tool wear.

Segmented electrochemical milling of large and difficult-to-machine curved surfaces

In aerospace and other industrial manufacturing domains, the use of parts with large and difficult-to-machine thin-walled curved surfaces is widespread. Achieving good surface morphology when processing these curved structural parts is a critical research focus due to their insufficient stiffness, variability and susceptibility to noticeable tool marks. This study conducted experimental research based on the principle of electrochemical milling (EC milling) of surfaces, considering different machining sequences. The processing sequence of "first middle and then two sides" obtained a superior surface morphology. Secondly, to address the issue of tool marks, tools with different outlet surface lengths were designed. The results demonstrate that increasing the outlet surface length to 20 mm minimized machining depth deviation, roundness error, and tool marks on the machined surface. Ultimately, the experiment confirmed the feasibility of enhancing tool marks by adjusting the length of the outlet surface, thereby achieving excellent surface morphology in the processed workpieces.

Optimizing micro-EDM with carbon-coated electrodes: A multi-criteria approach

The pursuit of precision machining in engineering materials has ignited an imperative to advance electrical discharge machining (EDM) techniques. This study is a deep dive into the domain of micro-electrical discharge machining ([Formula: see text]EDM) with a specific focus on the utilization of carbon-coated tool electrodes. The primary objective is to elucidate the influence of carbon-coated electrodes on vital machining parameters, including machining depth (Z coordinate), tool wear rate (TWR) and overcut (OC) in [Formula: see text]EDM operations. Moreover, the investigation extends to scrutinizing surface characteristics generated by [Formula: see text]EDM with carbon-coated tool electrodes. To enhance performance, carbon-coated tungsten carbide tool electrodes are employed for machining titanium alloy (Ti–6Al–4V) workpieces. The optimization process seeks to identify the optimal combination of process parameters using a Taguchi-DEAR-based multi-response approach. Experimental findings reveal that integrating carbon-coated electrodes significantly improves the [Formula: see text]EDM process, leading to enhanced surface performance metrics. Notably, this study identifies specific parameter settings that effectively optimize machining quality indicators. By achieving a voltage of 160[Formula: see text]V, a capacitance of 10,000[Formula: see text]pF and a tool rotation of 600[Formula: see text]RPM, the research contributes valuable insights into the intricate realm of [Formula: see text]EDM, highlighting the potential for enhanced surface performance through strategic parameter manipulation.

Shock Wave Detection for In-Process Depth Measurement in Laser Ablation Using a Photonic Nanojet

Three-dimensional micro- and submicrometer-scale structures exhibit unique functions that cannot be obtained with bulk materials. To create such three-dimensional microstructures with high precision and efficiency, we proposed laser ablation using a photonic nanojet. A photonic nanojet is an optical beam with both a small beam diameter and a large depth of focus, which is obtained by irradiating a dielectric microsphere using a laser beam. In this study, we proposed an in-process depth measurement method to improve the machining accuracy of laser ablation using a photonic nanojet. We focused on the propagation characteristics of the shock waves generated during laser ablation. Shock waves were generated at the deepest point of the machining area and reached the microspheres as the pressure decayed, showing that different machining depths exerted different pressures on the microspheres. The microspheres were displaced by the pressure of the shock wave, and the amount of displacement depended on the pressure. Therefore, microspheres can be used as probes for shock wave detection, and the machining depth can be determined by measuring the displacement of microspheres during photonic nanojet machining. In this study, the displacement of a microsphere was measured simultaneously during photonic nanojet machining using a confocal optical system. From the obtained microsphere vibration data, the effect of the shock wave pressure was extracted, and the displacement of the microsphere due to the shock wave was obtained. When the hole depth varied from 155 to 1121 nm, the displacement of the microspheres varied from 0.58 to 0.03 µm. The experimental results show that the displacement of the microspheres vibrated by the shock wave decreased as the machining depth increased. This was due to an increase in the shock wave propagation distance and a decrease in the pressure of the shock wave as the machining depth increased. In conclusion, in-process depth measurements are possible in laser ablation using a photonic nanojet with a microsphere as a probe to detect shock waves.

ANALYSIS OF THERMODYNAMIC, STRESS-STRAIN, AND LOADED STATES OF CHROMIUM-NICKEL ALLOY WORKPIECES USING MACHINING PROCESS SIMULATION IN ADVANTAGE SOFTWARE

Machining difficult-to-cut materials, which include most high-alloy chromium-nickel steels and alloys, requires optimization of cutting parameters, correct application of tool materials, cutting blade geometry, etc. The particular relevance of a scientifically based analysis in addressing these issues is due to the large costs incurred in machining products made from such materials. The possibilities of experimental research to provide correct technological recommendations are quite limited. Instead, analytical modeling is imperfect due to the complexity of formalizing dynamic processes accompanied by fast-moving power, thermodynamic, and stress-strain phenomena. An effective research mechanism is simulation modeling of the cutting process of a hard-to-machine material (including in the AdvantEdge software). The article presents an analysis of the results of simulation studies of the influence of the main parameters of machining (depth and cutting speed) on the formation of power, thermodynamic, and stress-strain (including residual) parameters formed during cutting of chromium-nickel alloy Inconel IN 718. This analysis allows us to conclude the feasibility of choosing cutting parameters to ensure the effective performance properties of products made of this material