Pulse Off Research Articles

Multi-objective optimization of machining variables for wire-EDM of LM6/fly ash composite materials using grey relational analysis

Abstract With the enhancement in science and technology, necessity of complex shapes in manufacturing industries have become essential for more versatile applications. This leads to the demand for lightweight and durable materials for applications in aerospace, defense, automotive, as well as sports and thermal management. Wire electric discharge machining (WEDM) is an extensively utilized process that is used for the exact and indented shaped components of all materials that are electrically conductive. This technique is suitable in practically all industrial sectors owing to its widespread application. The present investigation explores WEDM for LM6/fly ash composites to optimize different process variables for attaining performance measures in terms of maximum material removal rate (MRR) and minimum surface roughness (SR). Taguchi’s L27 OA design of experiments, grey relational analysis, and analysis of variance (ANOVA) were employed to optimize SR and MRR. It has been noted from ANOVA that reinforcement (R) percentage and pulse on time are the most influential aspects for Grey Relational Grade (GRG) with their contributions of 28.22 and 18.18%, respectively. It is found that the best process variables for achieving the highest MRR and lowest SR simultaneously during the machining of the composite are gap voltage of 30 V, pulse on time of 10 µs, pulse off time of 2 µs, wire feed of 8 m/min, and R of 9%. The predicted GRG is 0.84, and the experimental GRG value is 0.86. The validation experiments at the optimized setting show close agreement between predicted and experimental values. The morphological study by optical microscopy revealed a homogenous distribution of reinforcement in the matrix which enhances the composite’s hardness and decreases the density.

Effect of pulsed electric field processing on the quality characteristics and enzyme activity of tender coconut water.

Tender coconut water (TCW) is a natural drink rich in natural electrolytes, minerals, salts and sugars; it has good health benefits. But, its shelf-life is very limited because of the active nature of enzymes present in it when exposed to air. Therefore, the processing of TCW is necessary to inactivate the enzymes. So, this study aims to observe the effect of various process parameters of pulsed electric field (PEF) on the quality parameters of TCW. For the treatment of TCW with PEF, a full-factorial design of experiments was followed with process parameters such as three levels of electric field intensity (8, 12, and 16 kV/cm), two levels of pulse width (PW) (50 and 70 μs), and six levels of the number of pulses (2000 to 12,000 pulses) were considered at a constant pulse OFF time of 75 ms. PEF treatment did not significantly change pH, total soluble solids, and viscosity. However, it significantly affected vitamin C, colour, and total and reducing sugars. PEF treatment significantly enhanced the total phenolic content and antioxidant activity by 23.17% and 42.49%, respectively. At the same time, significant inactivation of polyphenol oxidase (100%) and peroxidase (60.2%) was observed at PEF treatment conditions of 16 kV/cm, 70 μs PW, and 12,000 pulses. Moreover, no significant change in the sensory acceptability of PEF-treated TCW (16 kV/cm, 70 μs PW, 12,000 pulses) when compared to the untreated/fresh TCW, which is a promising sign.

Experimental Analysis of Spiral Finishing Process on EDM Drilled Hole in Titanium

It is quite evident that some of the experimental research works have been carried out by researchers in the area of spiral polishing using abrasive for surface finishing improvement but most of the experiment has been employed on Steel or Alloy Steel as a material. Very few number of research works have been performed by researchers across the globe on the Spiral Polishing Method of Titanium holes made by Electrical Discharge Machining (EDM). Therefore, experimental investigations were carried out in the area of Spiral Polishing and Finishing of EDM-drilled holes of various materials to meet the desired goal of demands on the surface quality. This experimentation aims to develop a novel method with spiral polishing using abrasive flow finishing. To explore the search investigation and find out the better surface finishing for through holes made on EDM, the process parameters have been designed using the Taguchi L16 orthogonal array with input parameters such as Current (I), Pulse on time (Ton), and Pulse off time (Toff). The addition of Boron Carbide Powder with Handwash, Glycerine, Shampoo, and Liquid Soap is used to decrease the Surface Roughness (Ra) with a ratio of 5 : 1. The Taguchi technique is used to assess the P/M process parameter setting for a given signal to noise (S/N) ratio.

Performance analysis of EDM parameters on silicon nitride-titanium nitride composite for improving geometrical tolerances: an integrated GRA-RSM approach

ABSTRACT In the modern context, ceramic composites are being developed not just for increased strength and hardness but also for the ability to manufacture difficult to machine geometries that can use Electrical Discharge Machining. Sparking parameters such as current (I), pulse on time (Ton), pulse off time (Toff), and dielectric flushing pressure (P) are improved with multi-response factors such as material removal rate, Electrode Wear Rate, and Geometrical Errors. The results of the confirmation experiments indicate that machining time was decreased from 12.517 to 10.121 min, Material Removal Rate was increased from 0.0183 to 0.0215 g/min, Electrode Wear Rate was reduced from 0.0024 to 0.0002 g/min, circularity was decreased from 0.175 mm to 0.098 mm, cylindricality was decreased from 0.761 to 0.541 mm, and perpendicularity was decreased from 1.071 to 0.085 mm. By optimizing the data to its optimum level, the gray relational grade has been enhanced to 0.16464. Consequently, the experimental findings suggest that gray relational analysis can be effectively employed to optimize the machining settings of Spark Electrical Discharge Machining for various performance aspects.

Experimental investigation to assess the surface integrity in WEDM of Al-based hybrid composite material

Aluminum-based hybrid composites are used in various engineering applications due to their unique properties, such as high strength, good wear resistance, excellent corrosion resistance, and low density. Aluminum metal matrix (AMMC) composites reinforced with ceramic particles can be more difficult to machine than traditional aluminum alloys because of their increased hardness and abrasiveness. Wire electric discharge machining is a non-traditional machining process that uses a thin metal wire, typically made of molybdenum, brass or tungsten to cut through a workpiece using electrical discharge sparks. This process is useful for precision machining of complex shapes and profiles in hard or difficult to machine materials. WEDM is a commonly used process for cutting Al-SiC-ZrO2 HAMMCs due to their hardness and difficulty in machining using conventional techniques. The present study examines the relationship between machining parameters like pulse on time (TON), pulse off time (TOFF), peak current (IP) and wire feed (WF) and material removal rate (MRR) and surface roughness ( Ra) for Al-SiC-ZrO2 in WEDM. The Box-Beckham Design was used to plan the experiments, and response surface method was employed to develop the models. The pulse duration, TOFF, IP, and quadratic terms of [Formula: see text] and [Formula: see text] are the most influential factors of the MRR. The TON, IP and interaction term (TON × IP), and [Formula: see text] were the most significant factors for Ra. Multi-response optimization of process parameters was obtained using the desirability function approach. Furthermore, the machined samples were analyzed for surface integrity using SEM techniques. The prediction from this model validated the confirmation results.

Effect of pulse time (Ton), pause time (Toff), peak current (Ip) on MRR and surface roughness of Cu–Al–Mn ternary shape memory alloy using wire EDM

Shape memory and super elasticity are two outstanding properties of Cu–Al–Mn SMAs together with additional copper-based shape memory alloys that make them superior to NiTi alloys. It's quite hard to machine Cu–Al–Mn SMA. The machinability properties of Cu–Al–Mn SMAs during Wire Electrical Discharge Machining (WEDM) were experimentally investigated using molybdenum wire as the electrode material. Material Removal Rate (MRR) and Surface Roughness (SR) are two machining qualities that are studied in relation to the combinational values of pulse time (Ton), pause time (Toff), and peak current (Ip), which are selected as the changeable input process factors. From the experimental investigation, it was found that both MRR and Ra values were increased with an increase in pulse on time(Ton), pulse off time(Toff), and peak current (IP)values. Because the wire electrode contains maximum current under these conditions, it is easy to remove more material at the tool and work material interface, resulting in moderate surface finish. Surface quality was higher on samples machined at low energy input than it was on samples machined at high energy input. This SEM micrograph clearly shows that a lower pulse on time produces a superior surface quality.SEM images and the analysis of the machined surface morphology on the surface of the CAM7 alloy clearly showed that the machined surface of the alloy had a lower surface roughness value at a lower Ip-2A and was associated with a higher surface roughness value at a higher Ip-6A, as well as a lot of uncleared debris and blow holes.

The evaluation of machining performances and surface roughness of TZM-molybdenum superalloy processed by silicon carbide powder mixed EDM process using RSM and ANOVA

In the present era, the concept of Industry 4.0 plays a significant part in improving the efficiency, quality, and utilization of resources by automation and enabling intelligent operations in manufacturing processes. As a result, there is a requirement to develop an environment that improves efficiency as well as quality in order to accomplish net zero in manufacturing. The objective of powder mixed electric discharge machining (PMEDM) is to enhance the quality of the surface and machining efficiency of traditional electrical discharge machining. The PMEDM method was applied to TZM-molybdenum superalloy in the present investigation by incorporating silicon carbide particles into the dielectric medium. Powder concentration, peak current, pulse on time, pulse off time, and gap voltage were the considered input variables for the investigation. The impacts of the input variables on the surface of the specimen’s roughness and the rate of material removal (MRR) were examined. The experiment model was built using response surface methodology. To find out if the input factors were significant with regard to each response, an analysis of variance (ANOVA) was performed. Powder concentration, pulse current, gap voltage, and pulse on time are found to be the important input variables for both surface roughness and MRR based on ANOVA analysis.

Optimization of wire electrical discharge machining parameters of AA6063/Al2O3 nanocomposite processed by multi axial forging using Taguchi technique

AbstractThe aluminium based matrix composites have excellent mechanical properties to use in automobile, aerospace, aviation, and military industries. The aluminium based matrix composite possesses desired characteristics like specific strength, excellent rigidity and wear resistance. The stir casting technique was used to fabricate the nanocomposite of AA6063 alloy reinforced with 5 weight % nano aluminium oxide particulate. To improve the microhardness of as cast and aluminium based nanocomposites, multiaxial forging was performed up to three passes for grain refinement. Wire electrical discharge machining was used to machine both as cast and “AA6063/Al2O3” (zero and three multi axial forging pass). The machining characteristics of samples were statistically examined using the Taguchi technique. The material removal rate in three multiaxial forging pass nanocomposite sample increased as peak current increases. However, increasing the pulse off time resulted in the lowest material removal rate. The surface roughness was found to be higher in the nanocomposite sample in comparison to as cast. The machining on nanocomposite multiaxial forged sample has a greater impact as compared to as cast. After machining, scanning electron microscopy was used to examine the surface morphology. The presence of different elements in the castings was validated using energy dispersive X‐ray spectroscopy.

MICRO-EDM OF TI–6AL–4V USING VARIOUS TOOL MATERIALS: MULTI-RESPONSE OPTIMIZATION AND SURFACE CHARACTERIZATION

In this paper, experimental analysis was performed during micro-electrical discharge machining (micro-EDM) of titanium alloy Ti–6Al–4V (grade 5) using three types of tools viz. copper (Cu) tool, tungsten carbide (WC) tool, and synthetic graphite (Gr) grade three tool. The main process parameters were taken as (a) pulse on time ([Formula: see text]), (b) pulse off time ([Formula: see text]), (c) voltage (V), and (d) capacitance (C). The output responses were taken as the material removal rate (MRR) and tool wear rate (TWR). Taguchi method coupled with grey relational analysis (GRA) (L[Formula: see text] orthogonal array) technique was applied to optimize the input process parameters for both the responses. Scanning electron microscopy (SEM) analysis of the workpiece and tool was also performed to investigate the morphology of the machined surface and tool surface. Energy-dispersive spectroscopy (EDS) analysis was performed to investigate the elemental composition of the machined surface. The experimental finding reveals that tungsten carbide is the most suitable tool material for machining the chosen workpiece for obtaining optimal MRR and TWR. The optimum condition for the copper tool was found as 180[Formula: see text]V, 1000[Formula: see text]pf, 10[Formula: see text][Formula: see text]s ([Formula: see text]), and 10[Formula: see text][Formula: see text]s ([Formula: see text]). Meanwhile, the optimum parametric condition for tungsten carbide and graphite tools was found to be the same as 240[Formula: see text]V, 100[Formula: see text]pf, 20[Formula: see text][Formula: see text]s ([Formula: see text]), and 5[Formula: see text][Formula: see text]s ([Formula: see text]).

A Hybrid Design of Experiment Approach in Analyzing the Electrical Discharge Machining Influence on Stir Cast Al7075/B4C Metal Matrix Composites

The present work centers on aluminum-based metal matrix composites (AMCs), synthesized via stir casting and then processed by electrical discharge machining (EDM) in the case of Al7075 as a matrix and 6 wt.% boron carbide (B4C) as reinforcement. A design of experiment (DoE) approach, powered by hybrid optimization techniques (such as the entropy weight method (EWM), grey relational analysis (GRA) incorporated Taguchi method) was used to investigate the relationship between current (I), pulse ON time (Ton), pulse OFF time (Toff), and electrode gap (Gap) as input parameters and the material removal rate (MRR), tool wear rate (TWR), and surface roughness (SR) as response parameters. The results showed that an I = 140 A, Ton = 120 ms, Toff = 50 ms, and Gap = 0.4 mm combination gives the best response parameters of MRR = 0.5628 mm3/min, TWR = 0.0048 mm3/min, and SR = 4.4034 μs.

Multi-Objective Parametric Optimization of Micro-Electro Discharge Machining of Hastelloy C276 Super Alloy Using Response Surface Methodology and Particle Swarm Optimization

The need for the application of superalloys in aerospace industries in recent years has increased owing to its benefits such as extensive load-bearing capability under high temperatures. Hastelloy is one such superalloy that is extensively utilized in the aerospace sector because of its good corrosion and heat resistance among the other nickel-based superalloys. In this work, the investigation is conducted to understand the effects of input process parameters such as voltage, pulse off time (Toff), and pulse on time (Ton) on the response variables, namely Material removal rate (MRR), Tool wear rate (TWR), Overcut (OC), and Taper Ratio (TR) during micro-EDM of Hastelloy C276. For micro drilling the Hastelloy C276 material, a copper electrode with a diameter of 0.5 mm is utilized. To investigate the connections between the input and output characteristics, a technique known as the Response Surface Methodology (RSM), which is a collection of mathematical and statistical methodologies, is applied. The experimental runs are carried out with the help of the RSM-based Box-Behnken design (BBD). The experimental outcomes were computed, and ANOVA was used to identify the most influential variables. In addition, particle swarm optimization (PSO) was utilized to optimize the results, which were compared to the Response surface methodology approach. The outcomes of the PSO-optimized results revealed a strong correlation between expected and experimental outcomes over the RSM approach.

Investigation of machining rate and surface roughness in wire EDM of Al6063/WC/ZrO2 composite using response surface methodology

The aim of the current work is to explore the machinability behavior of Al6063/WC/ZrO2 metal matrix composites (MMC) produced through a stir casting process through wire electrical discharge machining (WEDM) process. In order to examine the effects of process parameters such as voltage (V), pulse on time (Ton) and pulse off time (Toff) on material removal rate (MRR) and surface roughness (SR), the experiments were conducted by adapting Response Surface Methodology (RSM) in conjunction with the central composite design (CCD). A second-order regression model has been developed to predict the response parameters and an analysis of variance (ANOVA) was performed to validate the significance of the models. Using the desirability function approach, the parameters were set for the highest MRR and the minimum SR value. The prediction was within a tolerable average error range. A total of 19 sets of tests were developed to obtain six possible solutions. The most suitable solution among these six has been found by a confirmatory experiment. The results indicate that voltage and its interactions have significantly affected both the responses than Ton and Toff. Overall, it can be said that the study of the Al6063/WC/ZrO2 MMCs using WEDM process parameters demonstrated improved casting and machining qualities.

An experimental investigation of F53 super duplex stainless steel using wire cut EDM process

This research focuses on the machinability of F53 super duplex stainless steel using the Wire Electrical Discharge Machining (WEDM) process. F53 Super Duplex Stainless Steel is known for its exceptional corrosion resistance and mechanical properties. It is a popular choice for critical applications in various industries, such as offshore, chemical, and petrochemical. The wire EDM process is chosen for its ability to achieve precise and intricate cuts in hard-to-machine materials like super duplex stainless steel. This study considered important process variables like wire feed rate, servo voltage, pulse-on and pulse-off time, and material removal rate and surface roughness as output responses. Box Behnken method is used to analyse all possible interactions between input and output variables are taken into account, and three different levels of parameter conditions are adopted. It was found that MRR increased by 51.30 % with a gradual increase in pulse on time and applied wire feed and SR decreased by 62.86 % gradually with increasing servo voltage and pulse off time. The optimized values are found to be Ton = 11 µs, WF = 13 m/min, SV = 40 V and Toff = 8 µs. The microhardness study confirms the formation of the melted layer on the machined surface. This research contributes to a deeper understanding of the wire EDM process's applicability to the challenging material properties of F53 super duplex stainless steel, offering insights for the manufacturing and engineering industries aiming to improve the efficiency and precision of machining operations for this advanced material.

Process parameters optimization and performance analysis of micro-complex geometry machining on Ti6Al4V

The aeronautical industry relies on high-performance equipment that demands materials with exceptional engineering attributes, such as the Ti6Al4V alloy. However, the complexity of the parts used in these applications presents challenges related to stack-up tolerances during assembly. Therefore, conventional machining processes are not economically viable due to their two-step nature solution (machining and surface treatment) and their inability to achieve the required accuracy level, particularly given the alloy’s hard-to-cut nature. In this matter, wire electric discharge machining (WEDM) emerges as an attractive alternative for fabricating complex geometries. This research focuses on evaluating the potential of the WEDM process for machining micro-complex profiles. A comprehensive range of process parameters, including servo voltage (Vs), pulse on time (Ton), pulse off time (Toff), and wire speed (Ws), are studied using a Taguchi-based design of experiments. The results are analyzed through parametric significance analysis, parametric control analysis, surface morphological analysis using scanning electron microscopy, and modified layer analysis. Additionally, both mono-objective and multi-objective process optimization techniques are employed to achieve superior accuracy and speed. The findings indicate that Ton and Ws have the most significant influence on both cutting speed and spark gap, whereas Vs and Toff play a crucial role in determining the accuracy index. In addition, adequate flushing, reduced wire speed (economically viable), and stability of the spark are recommended to attain a lower spark gap and higher accuracy. The confirmatory experiments show that the optimal parametric conditions of Vs = 60 V, Toff = 30 μs, Ton = 8 μs, and Ws = 6 mm/s provide the highest speed of 3.4 mm/min, minimum spark gap of 0.344 mm, and accuracy index of 98.72%. The findings will contribute to enhancing manufacturing efficiency, precision, and cost-effectiveness in the aeronautical industry, meeting the demand for high-quality components with tight tolerances.

MRI AND BLOOD-BASED BIOMARKERS ASSOCIATED WITH SURGICAL MANAGEMENT IN CHILDREN AND ADULTS WITH SMALL BOWEL CROHN'S DISEASE

Abstract BACKGROUND Despite advances in medical therapy, many children and adults with ileal Crohn’s Disease (CD) progress to fibrostenosis requiring surgery. Prior studies have identified circulating and imaging biomarkers associated with strictures, although their associations with need for surgery are not well-established. PURPOSE We aimed to identify MRI and circulating biomarkers associated with the need for surgical management in chidlren and adults with ileal CD. METHODS This prospective, multi-center study included pediatric and adult CD cases undergoing ileal resection (n=50), and CD controls receiving medical therapy (n=83). Noncontrast research MRI examinations measured bowel wall three-dimensional magnetization transfer ratio normalized to skeletal muscle (normalized 3D MTR), modified Look-Locker inversion recovery (MOLLI) T1 relaxation, intravoxel incoherent motion (IVIM) diffusion-weighted imaging metrics, and the simplified magnetic resonance index of activity (sMaRIA) (Figure 1). Circulating biomarkers included CD64, ECM1, and GM-CSF autoantibodies (Ab). Clinical variables, including demographics, anthropometrics, and routine clinical laboratory data (e.g., CRP, fecal calprotectin), also were obtained at the research visit. Associations between MRI and circulating biomarkers and need for ileal resection were tested using univariate and multivariable LASSO regression. RESULTS Mean participant age was 23.9±13.1 years. Disease duration and treatment exposures did not vary between the groups. Univariate biomarker associations with ileal resection included log GM-CSF Ab (odds ratio [OR]=2.87; p=0.0009), normalized 3D MTR (OR=1.05; p=0.002), log MOLLI T1 (OR=0.01; p=0.02), log IVIM perfusion fraction (f) (OR=0.38; p=0.04), and IVIM apparent diffusion coefficient (ADC) (OR=0.3; p=0.001). MRI and circulating biomarker Tukey box plots are presented in Figure 2. The multivariable model for surgery based upon AICc criteria included age (OR=1.03; p=0.29), BMI (OR=0.91; p=0.09), log GM-CSF Ab (OR=3.37; p=0.01), normalized 3D MTR (OR=1.07; p=0.007), sMaRIA (OR=1.14; p=0.61), luminal narrowing (OR=10.19; p=0.003), log CRP (normalized) (OR=2.75; p=0.10), and hematocrit (OR=0.90; p=0.13). CONCLUSION After accounting for clinical and MRI measures of severity, normalized 3D MTR and GM-CSF Ab are associated with need for surgery in ileal CD. GM-CSF autoantibodies and MRI biomarker sequences may be useful for guiding management decisions in CD patients. Figure 1 Research MRI images from a surgical Crohn’s disease patient with stricturing behavior involving the terminal ileum. A and B. Coronal and axial fat-saturated T2-weighted single-shot fast spin-echo (SSFSE) images show wall thickening and luminal narrowing of the terminal ileum (arrows) with more proximal bowel dilation measuring greater than 3 cm. C. Axial 3D magnetization transfer images – MT pulse on (bottom image, arrow), MT pulse off (top image, arrow). D. Axial modified Look-Locker inversion recovery (MOLLI) T1 relaxation image (arrow). E. Representative axial intravoxel incoherent motion diffusion-weighted images with increasing b-values (left to right, arrows). Figure 2 Variation in circulating and imaging biomarkers in Crohn’s disease patients with medical and surgical management. Ctrl: non-IBD healthy controls; Med: CD patients with nonsurgical medical management; Surg: CD patients with surgical management.

An investigative study on the parameters optimization of the electric discharge machining of Ti6Al4V

<abstract> <p>This investigative study explored the field of electrical discharge machining (EDM), with a particular focus on the machining of Ti6Al4V, a titanium alloy that finds widespread application in aerospace, airframes, engine components, and non-aerospace applications such as power generation and marine and offshore environments. Ti6Al4V presents difficulties for conventional metal cutting techniques because of high cutting forces, poor surface integrity, and tool wear. This has led to the adoption of unconventional techniques like EDM. However, problems like high electrode wear rates, low material removal rates, long machining times, and less-than-ideal surface finishes still exist, especially in large-scale applications. By addressing the particular difficulties associated with large-scale electrical discharge machining and by putting forth a multi-objective optimization strategy, this research makes a substantial contribution to the field. With an emphasis on the optimization of input parameters like pulse on time (T<sub>on</sub>), pulse off time (T<sub>off</sub>), voltage (HV), and current (LV), which are critical in large-scale industrial applications, the study attempts to evaluate the optimal parameter states that simultaneously accomplish multiple goals during the machining process. This work is the first to simultaneously optimize all relevant output responses, such as material removal rate (MRR), electrode wear rate (EWR), machining time (Tm), surface roughness (Ra), and base radius. Previous studies have concentrated on one or two output responses. To optimize MRR, EWR, Tm, Ra, and base radius, the experiments were carefully planned using design of experiment (DOE) and response Surface methodology (RSM). Regression analysis and ANOVA are two statistical techniques that were used with Minitab 15 to help interpret experimental data and build a solid regression model specifically for Ti6Al4V. Throughout the experiment, a variety of input factor settings were employed, and the responses to those were noted. The following parameters were used to obtain the experimental data: current (LV) at 30 and 50 A, voltage (HV) at 0.3 and 0.7 V, pulse on time (T<sub>on</sub>) at 4 and 6.5 µs, and pulse off time (T<sub>off</sub>) at 5.5 and 6.5 µs. T<sub>on</sub> and current are the most significant variables that influence most of the output responses. By addressing the simultaneous optimization of multiple output responses, this investigative study not only sets a new standard in the field but also identifies current bottlenecks and offers solutions.</p> </abstract>

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.

An investigation on surface integrity and microstructure behaviour of AISI 304 stainless steel machined by die sinking EDM

Machining of AISI 304 enables the customization of parts to meet specific mechanical and aesthetic requirements, ensuring optimal performance and durability in various applications. In this study, electrical discharge machining (EDM) is introduced to machine AISI 304 stainless steel. To accomplish the desired machining characteristics (MRR, SR), different EDM factors are chosen, such as discharge current, pulse on time, and pulse off time. The experiment is planned using central composite design in response surface methodology (RSM). The impact of EDM variables on metal removal rate (MRR) and surface roughness (SR) is examined through surface plot. Regression coefficient values for MRR and SR are 92.37% and 83.28%, respectively, indicating an empirical relation between the factors and responses. The lack of fit values for MRR and SR were 3.87 and 1.49, respectively, which were lower than the average values. Thus, the developed model was sufficient. It was observed that MRR and SR increases with increase in all parameters, but decreases at higher range of parameters. As current and pulse on time increase, the ionization temperature generated in the machining zone which removed more quantity of materials from the workpiece. Due to ionization temperature, more craters and voids formed which made surface irregular and hard, resulted increased SR. At lower level of discharge current and pulse on time, insufficient spark intensity is developed which made cracks and globules on the surface. The estimated error of actual and expected values for MRR and SR are 7.07% and 5.12% respectively. The desirability of optimization was calculated to be 0.9710, indicating that parameters are within acceptable conditions.

CoCrMo Alaşımının Toz Katkılı Elektrik Deşarj ile İşlenmesinde Malzeme Kaldırma ve Takım Aşınma Hızının Cevap Yüzeyi Modellemesi

Electric discharge machining (EDM) is commonly used in implant manufacturing due to the challenge of machining materials that are widely employed in these applications. The study applies response surface methodology to model the impact of powder concentration and machining parameters in powder mixed EDM of CoCrMo alloys, a prevalent material for implantation. AISI 316L stainless steel was selected as the electrode material, while Ti6V4Al was chosen as the additive powder based on their biocompatibility properties. An experimental design was created using a Taguchi L16 array, which involved selecting 4 levels for each parameter of additive ratio, discharge current, pulse on time, and pulse off time. Regression models were developed for material removal rate (MRR) add tool wear rate (TWR) with satisfactory coefficients of determinations (0.87). Effect of the process parameters on MRR and TWR were analysed by means of 3D response surface plots. As a result of the modeling, it was revealed that discharge current, puls on time positively affected MRR, powder concentrations and puls off time negatively affected it. On the other hand, all of the considered process parameters have increasing effect on TWR.

Effect of processing conditions and electrode materials on the surface roughness of EDM-processed hybrid metal matrix composites

The current investigation aims to investigate the role of four major input parameters, i.e. Current (I), Gap Voltage (V), Pulse off time (Toff), and Pulse duration (Ton) on surface roughness (Ra) of Al–Mg-0.6Si-0.275Cu/SiC10 % hybrid composite samples fabricated by Stir-casting. In addition, paper focuses on the goal to ascertain the impact of distinct tool materials on surface morphology of Al/SiC composite. Further, mathematical models were developed using the L29 orthogonal array in the Stat-Ease Modelling Expert V7.0 software. Thus, to validate the significance of the developed models, an Analysis of Variance was used. Finally, the topography of the specimen's surface (pre and post-machining) was performed using scanning electron microscopy (SEM). The results showed that at a peak current of 5 Amp, Gap voltage of 100V, Pulse on time of 100 μs, and Pulse off time of 40 μs, the lowest surface roughness with brass and copper electrodes was 0.29 μm and 0.32 μm obtained. The Brass electrode yielded 9.3 % lower surface roughness than the copper electrode.