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Do two different and independent methods of estimating the wear rate of a test sample yield the same numerical result? Numerical values of specific wear rates estimated on the basis of alternative methods using a set of dry sliding rotary-pin-on-disk experiments are presented. Wear rates of brass and aluminium alloy pins were estimated using gravimetric and wear scar area methods. Gravimetric and linear displacement methods were used to assess wear rates of ABS plastic and machinable wax pins. Scepticism about the estimated nominal values of wear rates is reduced when alternative assessment methods result in comparable numerical values, or values having the same order of magnitude. This is particularly useful when ranking competing materials for wear rates, when the differences in these rates are small. Uncertainties in individual test sample wear rates, and dispersion in the nominal values of wear rates are also computed to support the aforementioned observations.

A six-layered Al/Al2O3 functionally graded composite material (FGCM) was successfully fabricated via powder metallurgy (PM), with each layer approximately 1.5 mm. thick. The influence of varying Al2O3 volume fractions on the microstructure, hardness and tribological properties (wear rate, specific wear rate, relative wear resistance and coefficient of friction) was systematically evaluated. Grey Relational Analysis (GRA)was effectively utilized for multi-criteria optimization, revealing that, relative wear resistance significantly influences the wear stability of the FGCM. Optimal performance was achieved at an intermediate Al/ Al2O3 fraction (e.g., 30%), resulting in notably enhanced wear resistance. The study demonstrates the efficacy of integrating PM fabrication and GRA optimization in producing FGCMs suitable for demanding applications in automotive and aerospace industries.

The principle of electrical discharge machining is based on electrical discharge which occurs between two electrodes (a cathode and an anode). The cathode is generally represented by workpiece and the anode by electrode tool. An electric discharge between the cathode and the anode occurs always upon fulfillment of basic conditions. A decisive influence has a kind of workpiece and tool electrode materials; spacing between the electrodes, called also gap; properties of dielectric fluid; and the main technological parameter setting. The combination of these parameters generates crater of specific shape on the workpiece and also on the tool electrode. The shape and size of the crater, formed during one electric discharge in die-sinking EDM, have a significant impact on material removal rate and on electrode wear. The aim of the paper is based on experimental measurement to identify the impact of selected process parameters on material removal rate and electrode wear in die-sinking EDM of tool steels EN X210Cr12 with Cu electrode EN CW004A, based on acquired dependencies to perform optimization of these parameters with a view of maximization of material removal rate and minimization of tool wear rate.

Friction coefficient depends on various factors or surface characteristics during tribological testing, and this friction coefficient can be modified by altering the properties of one of the two contacting surfaces. It is crucial to monitor the friction coefficient continuously, not only at the conclusion of the test. This research examined the evolution of friction coefficient of silicon nitride (Si 3 N 4 ) coating and H13 steel over different sliding distances (250, 500, 750, 1000 m). The study assessed surface wear and oxidation through three-dimensional profilometry and SEM/EDX. The findings indicated a reduction in friction coefficient by 22%, a decrease in wear rate by 88%, and a reduction in wear volume by 87% when comparing the silicon nitride coated steel to the uncoated steel. Furthermore, the changes in friction coefficient provided insights into the timing of the complete fracture of the hard coating. Graphical abstract

In the present research, three typical cutting tool wear mechanisms (abrasive wear, adhesive wear, and diffusive wear) were taken into consideration in the FE simulation of cutting tool with a specific user-defined subroutine. Based on the influence of temperature on the cutting tool wear form, a novel wear rate model was built integrating Usui, Takeyama, and Attanasio wear rate equation. The high-speed cutting tests were carried out on Ti6Al4V to determine the proposed wear rate model constant. The cutting forces and rack face wear morphologies obtained from FE simulation match well with those from experimental cutting tests. Finally, the effect of cutting parameters on tool wear was studied by FEM. The simulation results show that the impact of the cutting speed on the cutting tool life is more significant than that of feed rate, and the preferred ranges of cutting speed and feed rate for extending cemented carbide cutting tool in high-speed dry cutting Ti6Al4V are 90–150 m/min and 0.10–0.20 mm/r, respectively.

In the present study, the effect of alumina (Al2O3) nano-powder was investigated for the electrical discharge machining (EDM) of a Nitinol shape memory alloy (SMA). In addition to the nano-powder concentration, other parameters of pulse-on-time (Ton), pulse-off-time (Toff), and current were selected for the performance measures of the material removal rate (MRR), surface roughness (SR), and tool wear rate (TWR) of Nitinol SMA. The significance of the design variables on all the output measures was analyzed through an analysis of variance (ANOVA). The regression model term has significantly impacted the developed model terms for all the selected measures. In the case of individual variables, Al2O3 powder concentration (PC), Toff, and Ton had significantly impacted MRR, TWR, and SR measures, respectively. The influence of EDM variables were studied through main effect plots. The teaching–learning-based optimization (TLBO) technique was implemented to find an optimal parametric setting for attaining the desired levels of all the performance measures. Pursuant to this, the optimal parametric settings of current at 24 A, PC at 4 g/L, Toff at 10 µs, and Ton of 4 µs have shown optimal input parameters of 43.57 mg/min for MRR, 6.478 mg/min for TWR, and 3.73 µm for SR. These results from the TLBO technique were validated by performing the experiments at the optimal parametric settings of the EDM process. By considering the different user and application requirements, 40 Pareto points with unique solutions were generated. Lastly, scanning electron microscopy (SEM) performed the machined surface analysis. The authors consider this to be very beneficial in the nano-powder-mixed EDM process for appropriate manufacturing operations.

This research focuses on the development of carbide-free nanostructured bainitic steel through the process of austempering at 250°C. The selected steels are also patented at 550°C, to get fine pearlitic structure. In austempered steels, microscopic analyses encompassing optical, scanning, transmission electron microscopy and X-ray diffraction revealed the presence of nanoscale bainite, filmy and blocky austenite. In contrast, lamellar pearlite was observed in the patented steels. With increase in the austempering duration, the extent of bainite improved, while the volume percentage of blocky retained austenite (RA) decreased. The tribological performance of high-carbon bainitic steels is compared with patented one of same composition against a tungsten-carbide counter disc. The specific wear rate as well as coefficient of friction decreases with rise in load from 10 to 50 N. The hardening volume of B15VA-1 sample is greater than that of B15VA-2 and P15VA, and it is mainly due to the transformation of blocky RA to strain-induced martensite. The bainitic pins with higher hardness exhibited superior tribological response than the pearlitic ones. SEM analysis of worn surfaces confirmed that at lower load (10 N), abrasive wear occurs, but at higher load (50 N), wear mechanism changes to adhesive along with abrasive in bainitic steel and oxidative wear along with adhesive and abrasive wear in pearlitic steel.

Electrical discharge machining (EDM) is a highly regarded method for producing ultra-precise mechanical parts. In this study, the process parameters of die-sinking EDM using copper electrodes and American Iron and Steel Institute (AISI) P20 tool steel workpieces are optimized for various output responses. The study surveys three input parameters, including Current (I), Pulse on Time (Ton), and Pulse Off Time (Toff). Some statistical methods, such as Taguchi and Analysis of Variance (ANOVA), are applied to find the optimal set of parameters for the output responses, consisting of Material Removal Rate (MRR), Electrode Wear Rate (EWR), and Surface Roughness (SR), and determine the most influential input factor. With the L9 Orthogonal Array (OA), the analytical results demonstrate the optimal parameter set for MRR is I = 6 A, Ton = 120 µs, and Toff = 30 µs, while those optimal values for EWR and SR are I = 2 A, Ton = 120 µs, and Toff = 90 µs and I = 2 A, Ton = 60 µs, and Toff = 30 µs, respectively. The study also indicates that input factor I has the most effect on the output responses, followed by Ton and Toff. Moreover, Grey relational analysis in the Taguchi method is also employed for multi-response optimization. The optimal parameter set for the three output factors is I = 6 A, Ton = 120 µs, and Toff = 60 µs, respectively. In this research, the microstructure and recast layer of the machined surfaces are investigated using optical microscopy as well.

The challenging characteristics of Inconel 617 (IN617), such as its modest modulus of elasticity, heightened chemical reactivity, and low thermal conductivity, pose difficulties in employing conventional machining methods for this material. This complexity is further amplified when considering the specific requirements for applications in aerospace. Consequently, electric discharge machining (EDM) emerges as a preferred approach for working with this alloy. However, inherent challenges within EDM, specifically electrode wear rate (EWR) and dimensional overcuts, limit its efficacy. To address these issues, a comprehensive exploration of the potential of powder-based additives in waste cooking oil (WCO) against cryogenically treated brass electrode material has been undertaken. The investigation holds pivotal importance because the careful choice of an optimal dielectric plays a significant role in affecting the heat input to the electrode, thereby influencing the melting/vaporization and tool wear of the electrode. It is essential to highlight that these considerations have not been adequately addressed in the current body of literature. The experimentation employs the Response Surface Methodology (RSM) experimental design. The findings indicate that the shallow cryogenically treated (SCT) brass electrode exhibited exceptional performance, yielding the lowest values for electrode wear rate (EWR) at 1.49 mg/min and dimensional overcuts (OC) at 0.01 mm. These results are notably superior, surpassing the least values obtained with the deep cryogenically treated (DCT) brass electrode, showcasing a 202.68% improvement in EWR and a 2.33% improvement in OC.

Modern industry is focused on looking for new and effective technologies to manufacture complex shapes from alloys based on nickel and chromium. One of the materials widely used in the chemical and aerospace industry is Hastelloy C-22. This material is difficult to machine by conventional methods, and in many cases, unconventional methods are used to manufacture it, such as electrical discharge machining (EDM). In the EDM process, the material is removed by electrical discharges between a workpiece and a tool electrode. The physical and mechanical properties of the tool electrodes have a direct impact on the process efficiency, machining accuracy, and surface roughness. Currently, there has been a significant increase in the use of graphite as a material for tool electrodes due to the low purchase cost of the raw material, good machinability, and high sublimation temperature. In this work, an experimental investigation of the influence of the grain size of the graphite tool electrode on material removal rate (MRR), tool wear rate (TWR), and surface roughness (Ra) of Hastelloy C-22 was carried out. Two POCO graphite tool electrodes with a grain size of 1 µm (AF-5) and 10 µm (S-180) were used. Based on the experimental studies, empirical models describing the influence of machining parameters on technological indicators and the condition of the surface texture were determined. The research indicates that graphite with a larger grain provides higher process efficiency with high relative wear of the tool electrode. The lowest surface roughness was obtained for graphite with a smaller grain size (AF-5). The analysis of the machining parameters proves that the discharge current and pulse duration are the main factors determining the MRR and Ra values for both AF-5 and S-180 graphite. The time interval is the dominant parameter with regard to the relative wear of the graphite electrode.