Tool Material Research Articles

Study of 3D Metal Printed and Metal Filled Epoxy Materials for Rapid Tooling in Injection Molding

Common rapid tooling techniques can be classified as indirect and direct methods. As indirect methods, casting a mixture of epoxy and metallic powder over a pattern to obtain the mold shape is currently a fast and reliable method. As direct methods, Additive Manufacturing (AM) technologies such as Selective Laser Melting (SLM) can directly manufacture a mold ready for operation. Recently, progress in Fused Deposition Modeling (FDM) materials have brought into play a large variety of 3D printed polymers with high percentage of fiber metals that can be more easily printed using the FDM technology instead of SLM or other more advance techniques. In this paper, a study is conducted to analyze the main characteristics of different FDM materials with metal fibers and different epoxy metal filled materials for rapid tooling in injection molding. The study analyzes the properties of these materials such as yield strength, tensile strength, thermal conductivity and wear resistance, and compares them with those from common traditional machined materials for molding such as tool steels and aluminum. Furthermore, the paper shows a comparison of costs and advantages and drawbacks of using these materials for a standard molding insert in industry.

Optimization of friction stir welding process parameters for weld strength of Inconel 625 parts using genetic algorithm

This research work presents a systematic optimization of friction stir welding (FSW) parameters for the solid-state welding of Inconel 625 alloy using Tungsten carbide tool material. Employing an L9 orthogonal array with three factors and three levels, the study explored nine distinct input parameter combinations and its effect on weld strength. Taguchi analysis unveiled the optimal parameters, emphasizing a tool rotational speed of 300 rpm, welding speed of 115 mm/min, and axial force of 18 kN, in adherence to the 'larger the better' criterion. Notably, the rotational speed exerted a significant influence on joint weld strength, with 300 rpm emerging as the optimal choice. The Genetic Algorithm-based refinement further validated these parameters, resulting in a remarkable maximum weld strength of 403.7 N/mm2. Experimental validation of the model accentuated the efficacy of employing a rotational speed of 300 rpm, welding speed of 115 mm/min, and axial force of 18 kN, culminating in a maximum weld strength of 407 N/mm2. These findings establish a robust parameter combination for achieving superior weld strength in Inconel 625 through the utilization of Tungsten carbide as the tool material in the Friction Stir Welding method.

Microstructure evolution, phase formation, mechanical and tribological response of deep cryogenically treated hard WC-6%Co cutting bits

Improving the productiveness of rock cutting bit is an essential requirement for sustainable mining. Different heat treatment techniques are employed in the past to improve the proficiencies of cutting bits. Out of them, cryogenic treatment (CT) is accepted as a viable method for expanding the service life of a variety of cutting tool materials. The intention of the present study is to evaluate the effect of cryogenic treatment under varying soaking duration (12, 24 and 36 h) on hardness and wear resistance of WC-6%Co rock cutting bits. It also addresses the underlying mechanisms that CT carries in the modifications of microstructure and phase transformation. The β-Co phase fraction has been significantly reduced due to cryogenic treatment. The wear resistance of both cryo-treated and untreated bits was examined by scratch test and sliding wear test. From the results, an increase in hardness (CT 24–13.09 %) was observed as compared to UT, which is associated with a transformation from face-centered cubic α-cobalt (FCC α-Co) to hexagonal close-packed ε-cobalt (HCP ε-Co) phase due to cryogenic treatment. The coefficient of friction and wear resistance for the cryo-treated bits correspondingly increases in comparison to the untreated bit. CT 24 bit exhibits the maximum hardness of 2212 HV, an elevated COF (16.64 %) and the highest wear resistance (87.15 %) compared to UT and other CT bits. From the results, cryogenic treatment of cutting bits can be recommended for rock cutting application in mining industries.

Research on the performance of the active vibration cutting system for the rotary cylinder of a tunneling machine

High-efficiency rock breaking technology is an important problem to be solved urgently in deep mining. The existing auxiliary rock breaking technology for coal mine excavation has problems such as polluting coal, high requirements for tool materials, and difficulty in subsequent washing. In this paper, an active excitation cutting system for rotary cylinder of cantilever roadheader based on alternating valve is proposed. According to the classical calculation formula of cutting load of roadheader, considering the stiffness-damping characteristics of cutting part and cutting cylinder, the simulation algorithm of cutting load is compiled based on MATLAB simulation analysis software. The excitation cutting experiments of different cutting depths are carried out on the cutting test bench, and compared with the simulation algorithm of cutting load. Taking the cutting load as the discriminant index, the influence of oil supply pressure and excitation frequency of rotary cylinder on the cutting load is analyzed based on the simulation algorithm of cutting load. The results show that the error between the simulation results and the experimental results of the active excitation state is less than 12%, and the two are in good agreement. Under the condition of 30 HZ, when the excitation amplitude is 8 Mpa, 10 Mpa, 12 Mpa, 14 Mpa, when the rotary cylinder excitation amplitude is 10 Mpa, the minimum is 131.42 KN. Compared with the rotary cylinder excitation amplitude under the condition of 10 Mpa, when the excitation frequency is 30 HZ, 35 HZ, 40 HZ, 45 HZ, when the excitation frequency is 40 HZ, the minimum is 83.08 KN, indicating that changing the excitation amplitude or oil supply pressure of the rotary cylinder is helpful to adjust the cutting performance.

Cutting performance and wear behavior of diamond, coated cemented carbide and PCBN tools during milling of Cf/SiC composites

As an advanced material, Cf/SiC composites are wildly used in many aerospace industries due to their excellent properties. However, machining the material often encounters many problems, such as poor machining quality, severe tool wear, and low processing efficiency. Tool materials have a significant influence on the cutting performance of tools and the surface quality of the workpiece being machined. In this study, milling experiments have been performed on Cf/SiC composites with different tools. The tool wear pattern, progression, mechanisms, and milling temperature were investigated. The machined surface quality and removal mechanisms of Cf/SiC composites were studied. The results indicated that polycrystalline diamond (PCD) tools have better cutting performance in milling Cf/SiC composites than other tools. Surface defects, milling temperature, and machined surface roughness (Sa = 2.9 μm) obtained by machining Cf/SiC composites using the PCD tool would be lower. The material removal mode is brittle fracture, and the surface damage (including fiber debonding, fiber pullout, and pits, etc.) is related to the direction of the fibers. Fibers in the X and Y directions can lead to more machined surface defects. Since hard particles formed in the machining process and protruding fibers constantly scratched the flank face, diamond grains were spalled off from PCD tools, resulting in abrasive wear.

Design of metal-cutting tool coatings at the atomic level

The research aims to lower tooling costs by reducing the time allotted to designing coatings on domestic cemented carbide metal-cutting tools by using the atomic force approach. The object of the study is coatings on cemented carbides of the tungsten carbide group such as titanium carbide (TiC), titanium nitride (TiN), and titanium (Ti) coatings or a nitride-based titanium, chromium and aluminum (Ti,Cr,Al)N composite coating. To select the most rational coatings, the article employed the method of calculating the functionals of interatomic systems using the density functional description of single atoms. The simplest measure to reduce the cost of designing metal-cutting instruments for manufacturing parts made of difficult-to-machine materials is to develop coatings for this tool type. The article considers various atomic arrangements in the coating material in relation to the WCo8 cemented carbide (VK8, tungsten carbide-cobalt alloy containing 8% cobalt). The calculated values of the interaction energy of the coating material atoms with one another and with the cemented carbide material ranged from 3.04 to 3.5 J/m2. Moreover, the research has established a correlation between the calculation results and the performance parameter of metal-cutting tools considering fracture toughness K1c (MPa ∙ √m). The main result of the study is that the employed computational method made it possible to determine the adhesion value for the atoms of the above-mentioned coating materials with tungsten carbide and cobalt atoms packed in different scale configurations. This enables the classification of coatings from the perspective of ensuring maximum performance properties of the tooling material. The present article assumes that the higher the adhesion value, the better the performance properties. The hypothesis has been confirmed experimentally as well as by the values of fracture toughness K1c. Thus, the most rational coating options have been selected for specified operating conditions of a metal-cutting tool, which permits reduction of tool design costs and makes it possible to predict the performance properties of tools at the design stage.

Experience in the application of simulation of hot forging in production conditions at the KUMW JSC

Software for computer simulation of metal forging processes is a reliable tool for designing dies and developing technological processes, which allows one to avoid defects and predict product quality. The paper describes the experience of the KUMW JSC in simulating with the Deform and QForm software packages. The distinctive advantages of the QForm domestic software are exemplified by the forging of a roller disk. Proceeding from the described advantages, the KUMW JSC has selected QForm as effective software to solve the problems of die forging. The paper provides examples of applying this software. QForm is used to evaluate die filling in the forging of an odd-shaped part. Significant under-forming of the part was identified, and the technology was optimized in order to eliminate them. Additionally, by using this software, the shape and weight of a blank for forging a landing gear leg were optimized, and this has resulted in a 15% increase in geometric yield. After only one die-forged item code was modeled and the durability of the tooling was evaluated from stress intensity and displacement, the tooling material was replaced, the critical zone radius was locally increased, and the method for manufacturing die tooling was altered. This increased tool durability by 28%. The presence of the Hartfield postprocessor subroutine in QForm has made it possible to predict the zones of the occurrence of forging defects during the processing of the odd-shaped part and to correct the production scheme in good time. Each simulation example is supported by industrial experiment.

Comparison of single nozzle and dual nozzle MQL performance in hardened steel turning: A case study

This study focused on comparing the machining output performance of single and dual jet nozzle assisted MQL (Minimum Quantity Lubrication) in CNC hard turning. Two case studies were conducted using different hardened steels and cutting tools. The cutting parameters including feed rate (0.1 mm/rev), cutting speed (60 m/min) and depth of cut (0.1 mm) were maintained constant. In the first case study, AISI 4340 hardened steel workpiece and CVD-coated carbide cutting tool were used. The results showed that the dual nozzle MQL system achieved lower tool flank wear (30.54 %), cutting power (11.33 %), surface roughness (24.59 %), cutting temperature (22.36 %), and cutting sound (2.35 %) compared to the single nozzle system. The second case study used AISI D2 steel workpiece and PVD-coated carbide tool, and similar findings were observed. Cutting power observed during hard turning operations in a dual nozzle MQL environment was 0.360 kW for AISI 4340 Steel and 0.386 kW for AISI D2 Steel, respectively, which is very low in terms of hard turning concerns. Dual Nozzle Overall, the dual nozzle MQL system consistently demonstrated more efficient machining, regardless of the variations in tool material, workpiece material, and hardness. Therefore, it is suggested for further research in machining applications in the future.

Finite element simulation of frictional surface hardening by a rotary tool during the hardening of the faces of fixation holes for washers

The paper discusses a methodology for simulating friction stir processing in order to determine the process parameters and to provide surface hardening for flanges with a cavity. In accordance with the developed methodology presented by the results of literature analysis, it describes a computational computer model developed in Ansys Mechanical and based on the finite element method. The thermophysical properties of the material under study and the tool material, which are taken into account in the FEM simulation of the processes, are presented as dependent on temperature. By comparison with experimental research, the simulation results are verified in terms of a number of parameters, such as the depth of the hardened layer and the diameter of the surface area of the faces of holes for bolted joints. The results of measuring the microhardness of the hardened layers of the AISI 420 steel are presented, and their dependence on the depth of the hardened layer is determined. Numerical simulation is used to compute the values of the geometrical parameters of the areas subjected to surface hardening by friction stir processing with the variation of the process parameter, namely tool rotation speed, the force acting along the normal to the surface being processed, and the friction coefficient. The numerical simulation gives results on the thermal state of the specimen, particularly, maximum temperatures in the contact zone, as well as temperature and time dependences.

Electrodeposition of Double Chromium Plating to Improve Corrosion Performance of Screw Drilling in Chloride Environment

To adapt to and satisfy rising energy demand, oil and gas exploration and production are gradually spreading to locations with poor underground conditions, and the demand for screw drilling instruments is rising as well. When underground drilling tool materials are subjected to these harsh operating circumstances, they corrode severely and may even cause drill pipe breakage and blowout incidents. Failure due to corrosion is still the most common type of failure, with drilling fluid being the leading cause of downhole drilling tool corrosion and equipment damage, particularly in high-temperature and high-pressure working conditions with higher corrosiveness, which must be avoided and controlled. Double chromium was successfully plated on the surface of the screw rotor using the electrodeposition method to extend the service life of screw drilling instruments. Electrochemical methods such as scanning electron microscopy, open circuit potential, electrochemical impedance spectroscopy, and potentiodynamic polarization curve were used to analyze the plating’s morphology and corrosion resistance. The research results show that at high chloride concentrations (50g/L∼100g/L), when the chloride ion concentration is 60g/L, corrosion resistance is the lowest, and that double chromium plating enhances threaded drilling tool corrosion resistance. The dual chromium plating’s polarization resistance has been enhanced by 18 times. The double chrome plated milky white chrome plating functions as a physical barrier to prevent corrosive substances from diffusing to the substrate interface, corrosive ions from reaching the substrate, and considerably improving the screw rotor’s anti pitting performance.

Study on the rapid synthesis of high-entropy carbonitride powder and its remarkable hardening effects on cemented carbide tool materials

As a novel high-entropy ceramic material with a multi-cation and multi-anion sublattice structure, high-entropy carbonitride ceramics (HECNs) have exhibited outstanding comprehensive properties and attracted increasing attention. In this study, a new WC-based cemented carbide material reinforced by high-entropy carbonitride (Ti0.2W0.2Mo0.2V0.2Nb0.2)(C0.7N0.3) (marked as HECN) was successfully fabricated by vacuum hot-pressed sintering. The mutual constraints between hardness and fracture toughness in extant WC-Co cemented carbide tool materials and their deficient high-temperature mechanical properties were effectively addressed. Moreover, for the low efficiency of the traditional carbothermal reduction nitridation, a novel method for rapidly preparing HECN powder was firstly proposed, namely the microwave-assisted carbothermal reduction nitridation, which could accelerate the heating rate and shorten the holding time. Single-phase HECN powder was successfully synthesized by this method, and the impacts of varying HECN content on the room and high-temperature mechanical properties of WC-based cemented carbide were investigated combined with the microstructure analysis by XRD\\SEM. The results revealed that HECN effectively inhibited the grain growth of WC in cemented carbide, and the refined WC grains provided a high-volume fraction of grain boundaries, which prevented dislocation movement and increased the hardness. With the optimized HECN content of 10 wt%, the Vickers hardness and fracture toughness of WC-HECN-Co composite reached 21.58 ± 0.36 GPa and 12.27 ± 1.17 MPa∙m1/2 respectively. Furthermore, WC-10HECN-10Co composites possessed outstanding high-temperature hardness and maintained a high hardness value of 13.16 ± 0.30 GPa at 800 °C, 37% higher than that of WC-10Co. The findings of this research hold significant practical implications for applying cemented carbide cutting tools in high-speed dry cutting.

Effect of tool wear on machining quality in milling Cf/SiC composites with PCD tool

Carbon fiber reinforced silicon carbide ceramic matrix (Cf/SiC) composites have great application potential in aerospace. But their high hardness and anisotropy cause rapid tool wear during machining, which affects machining quality and efficiency. However, tool wear mechanisms in milling Cf/SiC composites are still unclear. There is a lack of research on the relationship between tool wear and cutting performance. In this paper, milling experiments on 2.5D Cf/SiC composites were conducted using polycrystalline diamond (PCD) cutters. The tool wear mechanisms and effect of tool wear on surface roughness, milling force, burr damage, surface microstructure and chips were explored. The results show that abrasive wear caused by chips continuously scraping tool material and diamond particle fragmentation and falling off caused by sprouting and expansion of cracks inside grain were primary causes of tool failure. The formation mechanism of burr damage was analyzed. It was proved that the peak radius of cutting edge Rpeak and flank wear VB could reflect cutting capabilities. It was found that increasing flank wear had regrinding effects on the cutting edge, which affects the peak radius. The degree of burr damage was related to these two parameters. Tool wear changed the surface formation mechanism. Before tool wear, carbon fibers were primarily removed through the micro-brittle fracture, with low surface roughness. The flank face and chips scratched the workpiece like abrasive grains after tool wear, leaving scratches on the surface and increasing surface roughness from 1.27 μm to 2.25 μm.

The influence of steel reinforcements on static rigidity of epoxy granite spindle head for dynamic performance enhancement of machining center: Experiments and finite element simulation

Machine tool structures are subjected to continuous distortions and unwanted vibrations during machining. The structures should have excellent static and dynamic properties to minimize the adverse effects due to vibration. Cast iron is generally used as a structural material for machine tools owing to its higher structural rigidity and moderate damping properties. The lack of desired dynamic properties results in poor surface finish of the machined components. Epoxy granite is a resin mineral-based composite found to provide superior damping ability but it has lesser material stiffness. Steel reinforcements are more appropriate to enhance the static rigidity of epoxy granite structures. The cast iron spindle head of the vertical machining center is considered for the present study. Static structural analysis has been performed by finite element analysis and the results are considered as a benchmark for the design of epoxy granite spindle head. Multiple design configurations of steel reinforcements are evolved through topology optimization to achieve improved stiffness with a higher damping ratio. A model which exhibited higher stiffness with minimum steel has been proposed for fabrication. A 1:2 scaled model of the proposed configuration has been fabricated using epoxy granite. Experimental modal analysis and numerical static analyses have been carried out and the results are compared to those of cast iron spindle head. A significant reduction in mass and deformation of the epoxy granite spindle head by 22% and 57%, respectively, was observed compared to that of cast iron spindle head.

Analysis of chip formation mechanism in turning of AA 7075/SiCp MMCs

Purpose The purpose of this paper is to examine the quality of the turned surface. The quality of the surface produced depends on the nature of the chips, which are produced while turning metal matrix composites. This quality is a function of the machining parameters, tool material, tool configuration and elements of the composites. Design/methodology/approach In this study, the turning of AA7075/15 wt.% SiC (particle size 20–40 µm) composites is investigated. Thirty experiments were conducted, and the chip-formation mechanism in turning AA7075/SiCp composites at various combinations of cutting speeds, feed and depth of cuts was studied. Findings It is observed from the response surface methodology-based experimentation that in turning of coarser reinforcement (particle size 20–40 µm) composites, total gross fracture occurs. This causes small slices of chips and a higher shear plane angle. The nature of chips produced at various combinations of cutting speeds, feed and depth of cuts is different. The chips generated were segmented, spiral in cylindrical form, connected C type, chips with saw tooth, curled chips, washer C type chips, half-curved segmented chips and small-radii segmented chips. Originality/value The novelty of this research is that, so far, very little work has been published on the detailed analysis of chips produced during turning of AA7075/15 wt.% SiC (particle size 20–40 µm) composites.

Cutting Performance and Wear Behavior of Self‐Developed Silicon Nitride Ceramic End Mills with Optimized Structure for High‐Speed Machining of GH4099

Ceramic tool materials possess a wide range of potential in machining nickel‐based superalloys due to their superior wear resistance, high‐temperature hardness, and strong chemical stability. Herein, a structural optimization scheme of self‐developed silicon nitride ceramic end mill based on stiffness enhancement and performance improvement is proposed, and the key geometric angular parameters scope of the self‐developed ceramic end mills are prioritized via the finite‐element simulation method. Through precision grinding manufacturing and sandblasting pretreatment, the cutting performance and tool wear behavior of three optimized self‐developed silicon nitride ceramic end mills (called S4‐1, S4‐2, S4‐3 respectively) are comprehensively analyzed in comparison, including cutting force, milling temperature, surface quality, and tool life. The results indicate that the cutting force and cutting temperature of all the optimized ceramic end mills are effectively restrained compared with the nonoptimized ceramic tool(S4), and the final workpiece surface roughness is significantly reduced. Further, better surface quality can be obtained by optimized ceramic mills. In terms of tool life, ceramic end mill with optimized construction in best can be increased by up to 1.9 times. The wear mechanism and pattern of the three optimized ceramic milling tools are similar, which is adhesive wear, diffusion wear, and notch wear. Overall, the effectiveness of the optimization scheme for ceramic end mill is successfully verified.

Synergistic Reinforcement of Si3N4 Based Ceramics Fabricated via Multiphase Strengthening under Low Temperature and Short Holding Time.

Si3N4 ceramic as a tool material shows promising application prospects in high-speed machining fields; however, the required high mechanical properties and low-cost preparation of Si3N4 ceramic tool materials restrict its application. Herein, synergistic reinforced Si3N4 ceramic tool materials were fabricated by adding β-Si3N4 seeds, inexpensive Si3N4 whiskers and TiC particles into coarse commercial Si3N4 powder (D50 = 1.5 μm), then sintering by hot-pressing with low temperature and short holding time (1600 °C-30 min-40 MPa). The phase assemblage, microstructure evolution and toughening mechanisms were investigated. The results reveal that the sintered Si3N4 ceramics with synergistic reinforcement, compared to those with individual reinforcement, present an enhancement in relative density (from 94.92% to 97.15%), flexural strength (from 467.56 ± 36.48 to 809.10 ± 45.59 MPa), and fracture toughness (from 8.38 ± 0.19 to 10.67 ± 0.16 MPa·m1/2), as well as a fine Vickers hardness of 16.86 ± 0.19 GPa. Additionally, the various reinforcement modes of Si3N4 ceramics including intergranular fracture, crack deflection, crack bridging and whiskers extraction were observed in crack propagation, arising from the contributions of the added β-Si3N4 seeds, Si3N4 whiskers and TiC particles. This work is expected to serve as a reference for the production of ceramic cutting tools.

A Machine Learning Perspective to the Investigation of Surface Integrity of Al/SiC/Gr Composite on EDM

Conventional mechanical machining of composite is a challenging task, and thus, electric discharge machining (EDM) was used for the processing of the developed material. The processing of developed composite using different electrodes on EDM generates different surface characteristics. In the current work, the effect of tool material on the surface characteristics, along with other input parameters, is investigated as per the experimental design. The experimental design followed is an RSM-based Box–Behnken design, and the input parameters in the current research are tool material, current, voltage, pulse-off time, and pulse-on time. Three levels of each parameter are selected, and 46 experiments are conducted. The surface roughness (Ra) is investigated for each experimental setting. The machine learning approach is used for the prediction of surface integrity by different techniques, namely Xgboost, random forest, and decision tree. Out of all the techniques, the Xgboost technique shows maximum accuracy as compared to other techniques. The analysis of variance of the predicted solutions is investigated. The empirical model is developed using RSM and is further solved with the help of a teaching learning-based algorithm (TLBO). The SR value predicted after RSM and integrated approach of RSM-ML-TLBO are 2.51 and 2.47 µm corresponding to Ton: 45 µs; Toff: 73 µs; SV:8V; I: 10A; tool: brass and Ton: 47 µs; Toff: 76 µs; SV:8V; I: 10A; tool: brass, respectively. The surface integrity at the optimized setting reveals the presence of microcracks, globules, deposited lumps, and sub-surface formation due to different amounts of discharge energy.

Synergistic effect of Ag and MoS2 on high-temperature tribology of self-lubricating NiCrBSi composite coatings by laser metal deposition

To increase the performance of the tool materials operating at high temperatures (HT), the protection of the surface from wear is usually needed. Conventional lubricants pose problems due to their degradation and harmful effects on human health; therefore, self-lubricating materials are of great importance. In the current work, self-lubricating NiCrSiB millimeter-thick composite coatings with the addition of solid lubricants Ag and MoS2 were fabricated on stainless steel substrates using laser metal deposition. Upon microstructural analysis, it was revealed that the addition of MoS2 resulted in a uniform distribution of Ag throughout the coating thickness owing to a unique phenomenon of silver encapsulation. Further, the coatings were subjected to sliding wear tests against an alumina counterbody at a load of 5 N, a speed of 0.1 m s−1, and a distance of 500 m under a unidirectional condition in a ball-on-plate configuration. The tests were performed from 20 to 800 °C. The results show that self-lubricating composite coatings demonstrate an exceptional performance up to 800 °C. Significant friction (best at 800 °C ⁓0.25) and wear (best at 600 °C ⁓4.3 times less) reduction for Ag + MoS2 added coating is seen. It was revealed that the presence of CrxSy and Ag on the wear track delivered lubrication at temperatures ≤400 °C while, a glazed tribolayer rich in silver molybdate phase (along with CrxSy, MoO3) was an effective lubricant at 600 and 800 °C. The results are reported in comparison to the unmodified Ni-based alloy.

Effects of graphene pull‐out on the interfacial mechanical properties of alumina/graphene nanocomposite ceramic tool materials: Molecular dynamics analysis and material preparation

AbstractThe interfacial mechanical properties of the alumina/graphene (Al2O3/GR) nanocomposite ceramic tool materials were studied by molecular dynamic simulations. The effects of pull‐out velocity of graphene, system temperature, vacancy defect, and wrinkled graphene on the interfacial mechanical properties were investigated. Results show that a large interfacial shear stress (382 MPa) exists between the Al2O3/GR interface. The maximum pull‐out force and interfacial shear stress increase with increasing graphene pull‐out velocity. The increase of temperature reduces the maximum pull‐out force and interfacial shear stress. Moreover, the load transfer capacity is reduced and the creep of the matrix occurs. These factors reduce the fracture toughness of the Al2O3/GR nanocomposites. A moderate amount of vacancy defects in graphene increases the interfacial pull‐out force and shear stress of Al2O3/GR nanocomposite ceramic tool. Compared with Al2O3/GR nanocomposite ceramic tools, the interfacial interaction energy and shear stress of pleated graphene and Al2O3 were increased by 13.87% and 41.08% respectively, with better toughening and reinforcement. The results are of significance in further understanding of the interfacial mechanical properties at the nanoscale and then beneficial to improve the mechanical properties and engineering performance of Al2O3/GR composite ceramic materials.

Enhancing Electric Discharge Machining Performance by Selecting Electrode Design and Geometrical Parameters for Square, Triangular, and Hexagonal Profiled Holes

Manufacturing of dies, molds, and their allied components requires the machining of holes with different profiles. Electric discharge machining (EDM) die-sinking is a crucial process used in the dies and molds manufacturing industry. By nature, EDM die-sinking is a relatively slow process in terms of material removal rate (MRR) and there are high amounts of tool material loss in terms of tool wear rate (TWR) which directly influence dimensional accuracies and surface roughness (SR). Therefore, the process is continuously evolving to address these limitations. The present research is aligned in this direction such as to bring improvements in MRR, TWR, and SR through modifications to the conventional electrode design and its geometrical parameters. Traditional designs of EDM electrodes have a uniform cross-section through the tool’s entire length and have only one geometrical parameter, i.e., the tool’s cross-section. To improve the EDM performance, traditional designs are completely modified by introducing several geometrical parameters such as relief angles, land thickness, cross-sectional area, shank height, circular relief, and non-circular relief, etc. Electrode designs are employed to mill non-circular profiles including triangular, square, and hexagonal shaped holes. The EDM performance measures strongly depend on the tool’s geometrical parameters (design type, relief angle, land thickness), machining profile (circular, square, triangle, hexagon), as well as the height/depth of the machining feature. By selecting proper tool designs and corresponding geometrical parameters, the EDM performance measures can be improved significantly.