Pulse-off Time Research Articles

Preparation of Alumina Thin Films by Reactive Modulated Pulsed Power Magnetron Sputtering with Millisecond Pulses

This paper aims to investigate the quality of thin alumina films deposited on glass samples using magnetron sputtering in the reactive modulated pulsed power mode (MPPMS) and evaluate the process productivity. The aluminum target was sputtered in Ar/O2 gas mixtures with different fractions of oxygen in the total gas flow, in the fixed pulsed voltage mode. The pulse-on duration was varied between 5 and 10 ms, while the pulse-off time was 100 or 200 ms. The dependences of mass deposition rate and discharge current on the oxygen flow were measured, and the specific deposition rate values were calculated. Prepared coatings had a thicknesses of 100–400 nm. Their quality was assessed by scratch testing and by measuring density, refractory index, and extinction coefficient for different power management strategies. The strong influence of pulse parameters on the coating properties was observed, resulting in a maximum density of 3.6 g/cm3 and a refractive index of 1.68 for deposition modes with higher duty cycle values. Therefore, adjusting the pulse-on and pulse-off periods in MPPMS can be used not only to optimize the deposition rate but also as a tool to tune the optical characteristics of the films. The performance of the studied deposition method was evaluated by comparing the specific growth rates of alumina coatings with the relevant data for other magnetron discharge modes. In MPPMS, a specific deposition rate of 200 nm/min/kW was obtained for highly transparent Al2O3, without using any dedicated feedback loop system for oxygen pressure stabilization, which makes MPPMS superior to short-pulse high-power impulse magnetron sputtering (HiPIMS) modes.

Experimental investigation of wire electrical discharge machining parameters on WE43 magnesium alloy

The influence of wire electrical discharge machining (WEDM) factors on the WE43 magnesium alloy is experimentally investigated in this work. Voltage, peak current, pulse-on time, and pulse-off time, are some of the factors taken into consideration in the study. The goal of the study is to understand how the output responses like material removal rate (MRR), surface roughness (SR), and development of recast layers are affected by the factors like voltage, peak current, pulse-on time and pulse-off time. The experimental set-up used a wire electrical discharge machine with a brass wire electrode and a workpiece made of the WE43 magnesium alloy. The L27 orthogonal array was used to alter the selected parameters through a series of experiments. The findings of the experimental investigation showed a strong link between the output responses and the electrical discharge machining (EDM) parameters. Peak current was discovered to have a direct correlation with the rate of material removal, with greater currents resulting in faster machining. SR and MRR were affected by pulse-on time and pulse-off time. Voltage had a direct impact on the development and thickness of the recast layer, with higher voltages favoring thinner recast layers.

Modeling and analysis of process parameters in EDM of Ni35Ti35Zr15Cu10Sn5 high-temperature high entropy shape memory alloy by RSM Approach

The Electrical Discharge Machining (EDM) technique demonstrates proficiency in fabricating precise and intricate geometries, especially in challenging-to-machine materials like high-entropy shape memory alloys. Analyzing and optimizing machining parameters are crucial for their direct impact on mechanical properties and overall product efficiency. The main responses chosen to evaluate the processes are material removal rate (MRR), electrode wear rate (EWR), and surface roughness (Ra). At the same time, the associated machining conditions were discharge current (Ip), pulse-on time (Ton), and pulse-off time (Toff). EDM is a multi-response process; therefore, the method of Response Surface Methodology (RSM) is utilized to assess the influence of machining parameters on Ni35Ti35Zr15Cu10Sn5 (at%) high-temperature high entropy shape memory alloy (HT-HE-SMA) using a copper electrode. Based on a center composite design (CCD), experiments were analyzed using Minitab19 software. To identify the most influential parameters, a thorough analysis of variance (ANOVA) at various significance levels (5%) was performed, checking the sufficiency of all fitted second-order regression models. Discharge current, pulse-on time, and pulse-off time were identified as significant factors that affect output (MRR, EWR, and Ra). The model adequacy of the current experimental investigation is perfect, with determination coefficients (R2) of 97.82% for MRR, 95.36% for EWR, and 99.53% for Ra.

Surface Modification of Magnesium Alloy AZ91D Using Nanopowder Mixed Electrical Discharge Machining for Biodegradable Implant.

Powder-mixed electrical discharge machining (PMEDM) enhances the effectiveness of the electric discharge machining process. It has been used on the Mg alloy AZ91D to address biodegradation concerns in implants. By combining nano-conductive powder particles with the dielectric fluid, PMEDM creates a functional surface. Process parameters like pulse on time, pulse off time, peak current, and powder concentration are examined to optimize material removal rate (MRR), surface roughness (SR), and white layer thickness (WLT). The optimization of input parameters was completed using the Taguchi L9 technique and further analyzed using ANOVA technique that illustrates Ton and pulse-off time as more significant process parameters for powder mixed electric discharge machining as compared with electric potential and peak current. The optimal surface roughness value is found to be 2.215 μm at 3A pulse current and 15 μs Toff time which suggest the material to be suitable for implants.

Multiple Polynomial Regression Model for Predicting Surface Roughness of Titanium Alloy in Electrical Discharge Machining

This study investigated the experimental work of titanium alloy in the die-sinking electrical discharge (EDM) machining process to enhance surface integrity (surface roughness) by applying regression-based modeling. Furthermore, a multiple polynomial regression (MPR) model was developed to predict surface roughness responses under optimized conditions. The effects of EDM parameters, such as pulse-on time (ON), pulse-off time (OFF), peak current (IP), and servo voltage (SV), on surface roughness were studied. The experiment was conducted using a two-level full factorial design with four center points. Roughness was measured using a surface roughness tester (Formtracer SJ-301). The significant cutting parameters for surface roughness were determined using analysis of variance (ANOVA). The results showed that increasing the servo voltage significantly reduced the surface roughness by 46.48%. The developed model also predicted surface roughness values lower than those observed in the experimental data, with an R2 value of 0.608.

Optimization of input parameters on WEDM of AZ61-15wt.% Zr C composites via Taguchi technique for sustainability in transportation sectors

Sustainability in the transportation sector in terms of materials entails many major areas aimed at reducing environmental effect and promoting sustainability over the long haul. Choosing materials that are lightweight, minimizes fuel usage and emission levels from vehicles. In this investigation, Wire Electrical Discharge Machining (WEDM) behavior of AZ61-15wt%ZrC composites was studied. The AZ61-15wt%ZrC composites were made using the stir casting technique. The specimen was created using the WEDM technique from the manufactured composite. By adjusting the input parameters of Current (I) amps, pulse-ON time (T-ON), wire feed rate (WFR), and pulse-OFF time (T-OFF) in s, at four different levels, the manufactured samples were machined via WEDM. L16 orthogonal array was employed in the Taguchi method of experiment design. Analysis of Variance [ANOVA] was utilized to find which process parameter had the greatest impact on output variables like Material Removal Rate [MRR] and Surface Roughness [SR]. WFR is found to be a substantial input parameter on MRR and T-ON on SR, contributing 32.71% and 74.98% respectively.

EXPERIMENTAL INVESTIGATION AND OPTIMIZATION OF WIRE EDM PROCESS TO CREATE DIFFERENT GEOMETRICAL PROFILES IN METAL MATRIX COMPOSITES

Machining of accurate geometrical profiles like triangles, squares or circles with good surface finish and high productivity in metal matrix composites is required for various industrial applications. Thermoelectic principle-based wire electric discharge machine (WEDM) can be conventionally used to overcome the difficulty which occurs during the machining of composites due to the presence of hard abrasive particles. Therefore, in this investigation, three geometrical profiles possessing equal perimeters were produced in 5 mm thick aluminum metal matrix composites (AMMCs) by WEDM. In order to analyze the effect of reinforcements three different AMMCs containing Al6061 as a matrix were produced by stir casting method. The fabricated composites, respectively, contain 10% alumina ([Formula: see text]), 10% silicon carbide (SiC) and a mixture of 5% [Formula: see text] with 5% SiC. The individual effect of various input parameters like pulse-on time ([Formula: see text] = 30-50 [Formula: see text]s), pulse-off time ([Formula: see text] = 6–12 [Formula: see text]s), current ([Formula: see text] = 1–5 A) and geometrical shapes (circle, triangle, and square) on cutting velocity (CV) and surface roughness (SR) were investigated. Furthermore, parametric analysis using regression models was also performed to evaluate the simultaneous effect of two interacting parameters on CV and SR. The study reveals that in the case of hybrid composite, CV decreases with [Formula: see text] and SR is always higher for triangular profiles when [Formula: see text] and [Formula: see text] change. The regression plots indicate that the interaction effect of [Formula: see text] × [Formula: see text] plays a major role in CV for all three composites. Multiobjective optimization using a composite desirability approach reveals a marginal increase in CV (8.58%) and a significant reduction (57.72%) in SR at optimal input parameters for Al6061–10% SiC. The morphological analysis at optimal input parameters indicates a significant reduction in resolidified metal drops and microcraters.

Electrodeposition of Reactive Aluminum-Nickel Coatings in an AlCl3:[Emim]Cl Ionic Liquid Containing Nickel Nanoparticles

The electrodeposition of reactive aluminum-nickel dispersion coatings was performed by pulsed direct current (PDC) onto copper substrates in the ionic liquid 1.5:1 AlCl3:[EMIm]Cl (1-Ethyl-3-methylimidazolium chloride). A cathodic current density of 15 mA/cm2 was used with two different frequency (f)/duty cycle (r c) combinations, i.e., f= 0.33 Hz/ r c= 0.33 (t on= 1 s, t off= 2 s) and f= 0.05 Hz/ r c= 0.5 (t on= 10 s, t off= 10 s). Several electrochemical techniques like Cyclic Voltammetry, Electrochemical Impedance Spectroscopy and Open Circuit Potential measurements were used besides X-Ray Diffraction, Confocal Microscopy, Scanning Electron Microscopy, Atomic Absorption Spectroscopy and 27Al/1H Nuclear Magnetic Resonance in order to shed more light on the mechanism of Ni particle incorporation into the Al metal matrix. We could show that particle incorporation at the beginning of the deposition mainly takes place via particle adsorption at the substrate. As the thickness of the coating increases, it seems that the main mechanism for particle incorporation is via the reduction of Al2Cl7 - ions adsorbed at the particles surface. Three different Ni NPs concentration were tested in this work: 5, 10 and 20 g/L. Although a considerable high incorporation of Ni NPs has been achieved from the IL electrolyte containing the highest concentration of Ni NPs (i.e. ~ 33 wt.% from a 20 g/L of Ni NPs bath), a high concentration of NPs in the ionic liquid resulted having a negative effect in terms of quality of the coatings, due to local cathodic passivation, or solidification of the electrolyte in a poorly conductive compound. This phenomenon has been related to the increase in viscosity originating from the decrease in rotational mobility of the [EMIm]+ cation, as detected by 1H NMR. Despite this fact, almost equivalent amounts of Ni and Al (Ni ~ 45 wt.% and Al ~ 44 wt.%) have been detected by energy-dispersive X-ray spectroscopy mapping in some areas of the coatings prepared with longer pulse off-time (f = 0.05 Hz, t off= 10 s). Such a layer composition would be convenient for the targeted application. Nevertheless, more studies related to the homogeneity of the deposits, as well as ignition tests, must be performed to evaluate the suitability of the coatings to trigger a self-propagating reaction.

Experimental Investigations of Using Aluminum Oxide (Al2O3) and Nano-Graphene Powder in the Electrical Discharge Machining of Titanium Alloy.

In the present study, a comprehensive parametric analysis was carried out using the electrical discharge machining of Ti6Al4V, using pulse-on time, current, and pulse-off time as input factors with output measures of surface roughness and material removal rate. The present study also used two different nanopowders, namely alumina and nano-graphene, to analyze their effect on output measures and surface defects. All the experimental runs were performed using Taguchi's array at three levels. Analysis of variance was employed to study the statistical significance. Empirical relations were generated through Minitab. The regression model term was observed to be significant for both the output responses, which suggested that the generated regressions were adequate. Among the input factors, pulse-off time and current were found to have a vital role in the change in material removal rate, while pulse-on time was observed as a vital input parameter. For surface quality, pulse-on time and pulse-off time were recognized to be influential parameters, while current was observed to be an insignificant factor. Teaching-learning-based optimization was used for the optimization of output responses. The influence of alumina and nano-graphene powder was investigated at optimal process parameters. The machining performance was significantly improved by using both powder-mixed electrical discharge machining as compared to the conventional method. Due to the higher conductivity of nano-graphene powder, it showed a larger improvement as compared to alumina powder. Lastly, scanning electron microscopy was operated to investigate the impact of alumina and graphene powder on surface morphology. The machined surface obtained for the conventional process depicted more surface defects than the powder-mixed process, which is key in aeronautical applications.

EDM Electrode Design and Analysis to Enhance Process Performance

Electric discharge machining (EDM) is regarded as one of the most energy-efficient manufacturing processes for exceptionally accurate processing of any electrically conductive material, regardless of mechanical properties. EDM is a non-contact process utilized in various industries, including aerospace, industrial, instruments, molds, dies, and medical tools; also, it is beneficial for hard materials with simple or proficient geometries and shapes. Although EDM is for machining "difficult to machine" metals, such as those used in the mold and die industries, metal properties indicate potential capability in the domain of surface modification due to the electrical spark between the tool and the work material. This paper investigates the machining of Alloy steel X210 by using the most affecting parameters and how electrode angles contribute to responses, as MRR, Electrode wear ratio, and surface finish, which the manufacturing industry uses to make die tools, molds, automotive parts, and other products. Electrodes with angles of 0o and 90o are used to machine workpieces using WEDM (dk7740). Electrode Angle, peak discharge current, pulse-on time, and pulse-off time were controllable parameters in this study. While all other criteria are constant, variables have been studied. The effects of the four aspects on the four variables were statistically analyzed using ANOVA by MINITAB. Regression models for the responses were developed. Regression mathematical models have been developed for Alloy steel X210 workpieces to increase productivity and industry results.

Multi objective optimization of EDM process parameters for HCHCr steel

Electric discharge machining (EDM) or spark machining involves controlled erosion of electrically conducting materials by an interrupted, repetitive electric spark creating discharge between the cathode- tool and anode- work-piece, separated by a dielectric fluid medium. The objective of this work is to study the influence of machining characteristics during EDM of high carbon and high chromium steel (HCHCr) with copper electrode. EDM of HCHCr steel is conducted according to Taguchi orthogonal array (OA) design of experiment to evaluate the material removal rate (MRR), tool wear rate (TWR) and surface finish (Ra).The experiments are conducted on die-sinking EDM with varying current, voltage, and pulse-on-time to measure the above responses. Finally, the multi objective optimization technique namely principal component analysis (PCA) is used for optimizing the process parameters. The experimental results indicate the optimum parameters as: current 9 Amps, pulse-on time 15 µs and pulse-off time 10 µs.

A Comprehensive Investigation into the Material Removal Capability of Powder Mixed Wire Electric Discharge Machining

The powder mixed electric discharge machining (PMEDM) has demonstrated promising results in the machining of difficult-to-cut materials including metal matrix composites (MMCs). Adding powder particles to the dielectric fluid used in electric discharge machining (EDM) improves material removal rate (MRR) and surface quality of the machined item. This study presents a thorough overview of research works on PMEDM for the machining of MMCs, concentrating on the impacts of different process parameters on the MRR and surface quality, such as powder concentration, pulse on-time, and Pulse off-time. The study also notes the process's obstacles and limits, as well as opportunities for further research.
 Previous research has shown that PMEDM can greatly increase the MRR and surface quality of machined MMCs when compared to regular EDM. The addition of powder particles to the dielectric fluid has been found to improve machining zone cleansing and cooling, decreasing tool wear and enhancing machining precision.

Evaluation of response characteristics using sensitivity analysis and TLBO technique of powder mixed wire EDM of Ti6Al4V alloy

The development of Powder Mixed Wire Electric Discharge Machining (PMWEDM) aims to enhance both precise dimension and surface quality, making it a more efficient method for the cost-effective production of precise dies and tools compared to conventional Wire Electric Discharge Machining (WEDM. This approach effectively eliminates the need for secondary operations. The present study is focused on the parametric influence of surfactant with powder mixed WEDM process parameters during die corner cutting on Ti6Al4V material in the presence of surfactant and powder with dielectric. A sensitivity analysis was conducted to determine the significant influence of machining parameters and powder properties in conjunction with the dielectric. To empirically explore these variables, a central composite full factorial design based on response surface methodology was utilized. The design involved varying the pulse on-time (Ton) within the range of 30–90 µs, pulse off-time (Toff) within 3–11 µs, gap voltage (GV) within 40–80 V, and powder concentration (PC) within 2–10 g/L. The mathematical model was developed to predict the responses such as corner inaccuracy (CI) and surface roughness (SR) using RSM. The results conclude that the sensitiveness of powder concentration is highest. Apart from this, positive sensitiveness towards surface roughness is determined for three inputs: pulse on time, pulse off time, and powder concentration. In comparison, powder concentration shows positive sensitiveness towards corner inaccuracy. An artificial intelligence technique namely, Teaching learning-based optimization (TLBO) algorithm has been used to determine the best output. The minimum output for both responses, i.e. corner inaccuracy of 12982.67 µm2 and surface roughness of 1.199 µm, was obtained using TLBO technique. Further improvement for surface finish and corner accuracy in addition powder (3 g/L) with dielectric in WEDM process is found to be a value of 50.77% and 23.01%, respectively, compared with conventional WEDM process. SEM was employed to observe and analyze the topographical changes that occurred during powder mixed and without powder mixed in WEDM process.

INVESTIGATION OF ELECTROEROSION MACHINING PERFORMANCE OF METAL MATRIX COMPOSITE MATERIALS PRODUCED USING STIR AND INDIRECT SQUEEZE METHOD

In this study, metal matrix composite (MMC) materials were made with an aluminum matrix (AA7075 alloy) and reinforcement silicon carbide (SiC) elements using molten metal stir and indirect squeeze casting. SiC was used as a reinforcing element in the making of MMC material in different amounts (10%, 14%, and 18%) by mass. Electro Discharge Machining (EDM), cut depth (0.5 mm), three different pulse-on times, three different discharge current values, and a fixed pulse-off time (20 s) were used to machine MMC materials. The effects of machining parameters on machining time, average surface roughness, hole diameter, and material wear difference after machining were studied. As a result of the study, the composite material with 75 [Formula: see text]s pulse-on time, 6A current value, and 10% reinforcement element had the lowest machining time, the largest hole diameter, and the smoothest average surface. These machining parameters and materials also had the shortest machining time (5 min). Based on the signal-to-noise ratios, the best parameters for average surface roughness, hole diameter, Processing time, and material wear amount (MMC, discharge current value, and impact time) were found to be [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text], respectively. Based on the ANOVA results, the [Formula: see text]2 values for the average surface roughness, hole diameter, machining time, and material wear loss value were 99.3%, 98.7%, 77.8%, and 97.3%, respectively.

THE COMPARATIVE EFFECT OF WIRE ELECTRODES ON WIRE BREAKAGE FREQUENCY AND CUTTING RATE IN WEDM OF INCONEL 706

Non-traditional machining methods like wire electric discharge machining (WEDM) appear to be an ideal choice for machining high strength super alloys like Inconel 706, because of their capability to generate intricate profiles with high accuracy. However, wire breakages are a common problem in the WEDM process and adversely affect the productivity, accuracy, and surface quality. Therefore, the aim of this work is to investigate and comprehend the phenomenon of wire breakage using Inconel 706 as work material and brass wire, diffused brass wire, and zinc-coated brass wire as electrode materials. Six process parameters—pulse-on time, pulse-off time, peak current, spark gap voltage, wire feed rate, and wire tension—have been varied experimentally to determine their effect on the frequency of wire failure. According to the findings, the zinc-coated brass wire breaks with the lowest frequency when compared to the other two. Additionally, an ideal range of input variables has been proposed for efficient WEDM of Inconel 706 without unexpected wire breakages. This range can also be utilized for further research work related to modeling and optimization in WEDM of Inconel 706.

Wire Electrical Discharge Machining of AISI304 and AISI316 Alloys: A Comparative Assessment of Machining Responses, Empirical Modeling and Multi-Objective Optimization

This research investigates the multi-response of both material removal rate (MRR) and surface roughness (Ra) for the wire electrical discharge machining (WEDM) of two stainless steel alloys: AISI 304 and AISI 316. Experimental results are utilized to compare the machining responses obtained for AISI 316 with those obtained for AISI 304, as previously reported in the literature. The experimental work is conducted through a full factorial experimental design of five running parameters with different levels: applied voltage, transverse feed, pulse-on/pulse-off times and current intensity. The machined workpieces are analyzed using an image processing technique in order to evaluate the size of cut slots to allow the calculation of the MRR. Followed by the characterization of the surface roughness along the side walls of the slots. Different mathematical regression techniques were developed to represent the multi-response of both materials using the MATLAB regression toolbox. It was found that WEDM process parameters have a fuzzy influence on the responses of both material models. This allowed for multi-objective optimization of the regression models using four different techniques: multi-objective genetic algorithm (MOGA), multi-objective pareto search algorithm (MOPSA), weighted value grey wolf optimizer (WVGWO) and osprey optimization algorithm (OOA). The optimization results reveal that the optimal WEDM parameters of each response are inconsistent to the others. Hence, the optimal results are considered a compromise between the best results of different responses. Noteworthily, the multi-objective pareto search algorithm outperformed the other candidates. Eventually, the optimal results of both materials share the high voltage, high transverse feed rate and low pulse-off time parameters; however, AISI 304 requires low pulse-on time and current intensity levels while AISI 316 optimal results entail higher pulse-on time and current levels.

Analyzing the Relationship between the Chemical Composition and the Surface Finish of Alnico Alloys in EDM.

The purpose of this study was to determine whether the chemical compositions of Alnico alloys had any effects on the electrical discharge machining (EDM) performance and the surface finish. This article compares the behavior of three different Alnico alloys in electrical discharge machining. The experiments were conducted under different conditions using a BP93L EDM machine (ZAP BP, Końskie, Poland), applying an additional rotary motion to the electrode. A Box-Behnken experimental design was employed to analyze the influence of three factors, i.e., the spark current, the pulse-on time, and the pulse-off time, at three levels for three Alnico alloys. The material removal rate (MRR) was calculated for the different process parameters. After the EDM, the surface roughness was studied using a Talysurf CCI Lite non-contact profiler (Taylor-Hobson, Leicester, UK). The next step of the experiments involved preparing metallographic specimens to be observed by means of scanning electron microscopy (SEM) and optical microscopy (OM). Measurements of the nanohardness were also performed. The experimental data were then analyzed using Statistica software version 10 (64-bit) to determine and graphically represent the relationships between the input and output parameters for the three Alnico alloys. The chemical compositions of the Alnico alloys affected the thickness of the white layer (higher cobalt content, lower white layer thickness) and the material removal rate. The higher the cobalt content, the thinner the white layer and the lower the material removal efficiency. Moreover, the cobalt content in Alnico alloys influenced the shape of the precipitates; these ranged from spheroidal (13% Co) to mix-shaped (21.3% Co) to flake-shaped (32.2%). The hardness of the resulting white layer was 874 HV at10 mN.

Improvement on the wire EDM characteristics of zirconia filled Al7050 (Al-Zn-Cu-Mg) alloy composite using Taguchi coupled TOPSIS method

Wire electrical discharge machining (WEDM) is an cutting edge non-traditional techniques for producing complicated 3D forms in rigid materials with greater dimensional accuracy. The aim of the investigation was, to predict the WEDM characteristics of ZrO2 ceramic addition of Al7050 alloy composite by employing Taguchi coupled Technique for order preference by similarity to ideal solution (TOPSIS) approach. The work material was manufactured by stir casting process utilizing 12 wt.% of ZrO2 particulates in Al7050 alloy matrix. The experimental work was carried out as per the L9 (33) orthogonal array design by taking input parameters like pulse current ( Ip), pulse on-time ( Ton) and pulse off-time ( Toff), respectively. The impact of the WEDM parameters on the material removal rate (MRR) and surface roughness (SR) were determined by analysis of variance (ANOVA). Based on the TOPSIS approach, the higher MRR (0.32251 g/min) with lesser SR (3.982 µm) were achieved at the ‘ Ip’ of 25 amps, ‘ Ton’ of 115 µs and ‘ Toff’ of 60 µs. ANOVA results explored that the ‘ Ton’ was identified as the primary impact factor on MRR and SR, subsequently by ‘ Ip’ and ‘ Toff’ with contribution of 44.23%, 36.53%, and 12.16%, respectively. Moreover, the surface topography of the machined composite surface was analyzed through scanning electron microscopy (SEM). It was clearly revealed the formation of surface defects such as craters, micropores, cracks and also the appearance of a recast layer on the machined surface.

Development of analytical models for tip, root, and end relieving of spur gears by pulsed electrochemical finishing process

This paper describes analytical modelling for the non-contact tip, root, and end relieving of spur gears and their associated volumetric material removal rate (MRR) by the pulsed electrochemical finishing (PECF) process. The models were developed using Faraday’s law of electrolysis and involute geometry of spur gears. The developed models are validated experimentally using the innovatively designed and developed cathode gears and experimental apparatus by varying voltage, pulse-on time, and pulse-off time at four levels each. It found that minimum prediction errors for the developed models for the amount of tip, root, and end relief are 0.8%, 0.3%, and 1.3%, respectively, and minimum prediction error for models of volumetric MRR of tip, root, and end relief are 6.9%, 0.6%, and 9.8% respectively. A study of microgeometry along the profile and lead direction of spur gear confirmed that the PECF process not only successfully imparted tip, root, and end relief but also reduced their arithmetical average roughness and maximum height by 61.1% and 62.5% for tip relief, 67.7% and 67.8% for root relief, and 63.8% and 66.6% for end relief respectively. It also removed hob cutter marks and cracks revealed from the comparison of surface morphology of spur gear flank surfaces before and after tip, root, and end relieving. Maximum values of % reductions in maximum height and arithmetical average roughness occurred for pulse-on and pulse-off times as 3 and 4 ms (i.e., 43% duty cycle). The developed models will be very useful in designing or predicting the amount of tip, root, and end relief that can be imparted for a given modification duration. Conversely, they can be used for parametric optimization of the PECF process and to compute the required duration for the PECF process to impart the desired amount of tip/root/end relief to spur gears.

PREDICTION OF SURFACE ROUGHNESS IN WIRE CUT ELECTRIC DISCHARGE MACHINING OF AL-FE-SI ALLOY COMPOSITES USING TAGUCHI TECHNIQUE AND REGRESSION ANALYSIS

Wire cut electric discharge machining (WCEDM) is a flexible and more essential for the precise machining of hard materials like composites and super alloys. In order to improve the surface texture as the main focus of the WCEDM process, the expansion of the fundamental procedural perceptive is very important. This paper mainly focuses on the prediction of surface quality of Al-Fe-Si alloy (AA8011) matrix composites during the WCEDM process. For the fabrication of composites, the varying proportions (0, 5, 10 and 15 wt.%) of ZrO2 ceramic particle were incorporated with AA8011 matrix alloy by using stir casting method. In the machining studies, to investigate the effects of reinforcement (wt. %) and the WCEDM process parameters, namely pulse current (amps), pulse-on time ([Formula: see text]s) and pulse-off time ([Formula: see text]s) on machining performance like surface roughness (SR) of the proposed composites. Based on the selection of parameters and their levels, an L16 (44) orthogonal array was most suitable for conducting the WCEDM experiments. A Taguchi technique was employed in this study to determine the optimal conditions of machining parameters through the signal-to-noise (S/N) ratio analysis. The result shows that the minimum SR is achieved at 5 wt.% of reinforcement, 6 amps of pulse current, 110 [Formula: see text]s of pulse-on time and 50 [Formula: see text]s of pulse-off time, respectively. Analysis of variance (ANOVA) results revealed that the reinforcement wt.% has the primary significant factor on SR, trailed by pulse-on time and pulse current, respectively. Furthermore, the regression equation was also developed to predict the SR and that values well agree with the experimental SR.