Overall Evaluation Criteria Research Articles

Machining efficiency and geometrical accuracy on micro-EDM drilling of titanium alloy

ABSTRACT In the current study, micro-electric discharge drilling (µEDD) is conducted on a titanium grade 2 alloy using a tungsten carbide (WC) tool electrode of 496 µm diameter. Capacitance, voltage, and feed rate are selected as machining variables to conduct the experiments based on the full factorial experimental design method. Overcut, material removal rate (MRR), circularity, and hole taper are considered as performance measures. Furthermore, overall evaluation criteria (OEC) is utilized for multiple-objective optimization by allotting varying and equal weight percentages to each response measure. The results of OECs are compared with a revolutionary heuristic multi-objective genetic algorithm (MOGA), resulting in a similar optimal parametric combination and close response measures are obtained. Micrographic investigation demonstrates that at lower capacitance and voltage levels, there is less burr formation, recast layer, and circularity error. Moreover, FESEM and EDS analyses are employed to investigate the machined surface topology and elemental composition respectively.

Machinability characteristics of titanium diamond using EDM and its parametric optimization

ABSTRACT The current research aims at analyzing the machining performance measures of titanium diamond using electro-discharge machining (EDM) process. The selected control variables are peak current and pulse-on-time (Ton) while maintaining a 50% to 75% duty factor during experimental runs. The output responses considered for this operation are material removal rate (MRR), tool wear rate (TWR) and average surface roughness (Ra). A full factorial design (L16) has been employed to execute the current investigation. Analysis of variance along with overall evaluation criteria (OEC) is also carried out for determining the optimal input parametric combination. The work is further supported by mean effect plots and 3D performance plots for visual illustration of outputs. Analyzed results show that current has the most impact on MRR and Ra, while Ton has the most impact on TWR. The obtained results show MRR of 7.753 mg/min (highest), TWR of 0.02 mg/min (lowest) and Ra of 5.46 µm at the optimum parametric combination. Moreover, x-ray diffraction (XRD), scanning electron micrograph (SEM), and energy-dispersive x-ray (EDX) analysis also help in identifying different phases of material on machined work surface.

Investigation on the Effect of Impeller Design Parameters on Performance of a Low Specific Speed Centrifugal Pump Using Taguchi Optimization Method

In order to investigate the effect of blade design on pump performance, a CFD analysis was carried out, and the results were compared with experimental performance data of a low specific speed radial pump, which presents a good agreement. After model verification, the effect of impeller geometrical parameters includes blade outlet angle, wrap angle, and width at the exit, was investigated on the pump’s performance. Moreover, these parameters were chosen on three levels using an L9 orthogonal standard array of the Taguchi optimization method. The efficient levels of variables were calculated using the analysis of variance (ANOVA) method. The results revealed that impeller width at exit and blade outlet angle is the most effective pump shaft power and efficiency parameters. To minimize power, the optimal levels are the outlet angle of 27∘∘, wrap angle of 150∘∘, and width at the exit of 9 mm. Further, an outlet angle of 23∘∘, a wrap angle of 155∘∘, and a width at the exit of 9 mm lead to maximum pump efficiency. According to the validation simulations, an increase of 2.4% inefficiency and a minimum power of 3.9KW were achieved. The Overall Evaluation Criteria (OEC) technique revealed that considering 23∘∘, 160∘∘, and 9 mm for outlet angle, wrap angle, and width at the exit, minimum shaft power, and maximum pump efficiency will be achieved. ANOVA introduced width at the exit as the most governing parameter of pump performance characteristics.

Machinability study of Al and Mg-based metal matrix composites using wire-EDM

In this investigation, a machinability study of the fabricated aluminium (Al) and magnesium (Mg) based MMCs is done using the Wire-EDM process. Initially, Al and Mg-based MMCs are fabricated with Silicon Carbide (SiC) reinforcements particles by the bottom pouring type stir casting process. After that, successful machining of both Al and Mg-based MMCs is carried out using Wire-EDM. The lowest value of machining time and kerf width for both Al/SiC and Mg/SiC MMCs are observed (0.1732 min, 0.3270 mm) and (0.1980 min, 0.2970 mm) respectively. The highest value of material removal rate 71.6651 mm3/min and 53.1313 mm3/min are achieved correspondingly for the Al and Mg-based MMCs. Overall evaluation criteria (OEC) values are calculated for all machining conditions to find out the mean effect of all process parameters simultaneously. The highest calculated OEC value of 75.00 and 84.45 are observed intended for Al/SiC and Mg/SiC respectively.

Investigation of powder mixed electrical discharge machining and process parameters optimization using Taguchi based overall evaluation criteria

Electrical Discharge Machining is a type of nontraditional process can be used for machining of hard materials and making of complicated shape.In EDM, the important parameters are tool, workpiece and dielectric liquid. Dielectric liquid is used to enhance ionization during the process. Powder Mixed EDM (PMEDM) is preferred for enhance the process efficiency. In this work, nano alumina (Al2O3) powder is added to the dielectric liquid and the process parameters effects are investigated. Input parameters considered are pulse on time, pulse off time and current. Output parameters considered are rate of material removal, surface quality and wear in electrode. Nano powders are mixed in the ratio of 2% to the EDM oil during the operation with dielectric fluid weight ratio. Process parameters are optimized using Taguchi based Overall Evaluation Criteria (OEC). The result revealed thatPMEDM is enhanced the process efficiency.

Optimization of photochemical machining process for fabrication of microchannels with obstacles

ABSTRACT The microchannels are one of the most prominent components used in Lab on a chip device for mixing applications. For effective mixing, microchannels with obstacles are commonly used. Design and fabrication of a microchannel with obstacles (micro features) is a crucial one. By considering this motivation, a study on optimization of control parameters for fabrication of different microfeatures on copper and brass using photochemical machining (PCM) is carried out. The control parameters such as etchant concentration, etching temperature and time were considered to measure material removal rate (MRR), surface roughness (Ra) and the edge deviation (ED). In order to have better PCM performance, MRR desired to be higher, while Ra and ED are desired lesser. To obtain optimum conditions for attaining the higher MRR with lesser ED and Ra, Overall Evaluation Criteria (OEC) was articulated. Further, characterization has been carried out employing scanning electron microscopy. Finally, as an application of the study, different master molds of microchannels without and with triangular, semi-circular, and square obstacles were fabricated and using these molds, Polydimethylsiloxane (PDMS) microchannels were fabricated employing soft lithography technique. On the basis of fluid flow analysis, fabricated microchannels found to be suitable for the various microfluidic applications.

Experimental analysis and parametric optimization of drilling process for ferrous clay composite using GRA-PCA approach

The use of materials mixture with non-metallic ingredients composed by powder metallurgy (PM) are getting increased attention in many industries. The newly developed composite material is mainly applied to the structural parts in the many industries. PM parts machining is still a challenge and known as difficult-to-cut metals for manufacturers because of the many factors mainly porosity, Nano particles and complex microstructure. In this work, the mechanical properties like density and porosity along with the machinability in drilling of a newly developed sintered powder metallurgy (P/M) components having Nano-particles of bentonite clay as machinability enhancer is evaluated by a standard twist drill. The impact of this paper aims to reveal the key cutting phenomena i.e. generation of thrust forces, quality of surface roughness, and new insight into the machining mechanism of sintered material. The parameters involved in the machinability study are as speed, feed rate and Nano-particles of bentonite clay for controlling the parametric variables on the response parameters. The speed has the major (95%) effect on the thrust force where the clay percentage has the major (84%) effect on the surface roughness. The less thrust force and low surface roughness have been achieved at 5% clay with 910 rpm and 1% clay with 2265 rpm, respectively. Further, the hybrid grey relational analysis along with principal component analysis (GRA-PCA) has been carried out to find the optimum condition. The less thrust force (Ft) and low surface roughness (Ra) has been found at 1% clay and 910 rpm. The confirmation of optimal process parameters has been made with overall evaluation criteria (OEC) and found the same optimum condition. The X-ray diffraction despises homogeneous mixture of clay in ferrous clay composite. The SEM analysis exposed the presence of clay particles and plastically deformed area during drilling of ferrous clay composite. Thus, this analysis show that the 1% of Nano-particles of bentonite clay is helpful as porosity fillers or machinability enhancer at low speed and within acceptable mechanical properties.

Using Entropy Weight and Over All Evaluation Criteria Optimize the Parameters in EDM of Al–20 Wt. % SICP MMC

The paper has been described one of the recent effective optimization technique i.e. Over all Evaluation Criteria (OEC) to controlling the process parameter during Electrical discharge machining (EDM) of Al – 20 wt.% SiCP metal matrix composite (MMC). The MMC is one of the advance material in compare to the conventional material. To exploit the industrial application of this material with EDM it needs to optimize the process parameter for reliable and economical production of this process. For that the experiment is carried out by Central composite design (CCD) method by considering the input process parameters like peak current, pulse on time and flushing pressure and the output are material removal rate, tool wear rate, radial over cut and surface roughness (Ra). In order to optimize the process parameter a combine effect of Entropy weight measurement method and Over all Evaluation Criteria (OEC) is used to get a single numerical index. Finally, the present work.is is carried out by confirmation test to analyse the desirable approach of the selected model.

Experimental study on Titanium diamond by fabricating micro-holes using Micro-EDM with Taguchi’s method and response surface method

Titanium alloys are very hard to machine materials, which can be machined effectively by using advanced manufacturing processes. Electro discharge machining (EDM) process is one of the most efficient methods of machining electrically conductive materials. EDM is focused more on the precision and accuracy of the machined parts. This particular work focuses on the machinability study of titanium diamond using micro-EDM. Input parameters such as voltage, capacitance, feed rate and tool rotation speed (TRS) are varied and their effects are analyzed by evaluating responses such as material removal rate (MRR), machining time (MT), overcut (OC) and circularity error (CE). X-ray diffraction (XRD) analysis of the material is also conducted to observe the material phases and elements. The observed responses are simultaneously optimized by formulating overall evaluation criteria (OEC) for generating the optimal value of process parameters. Further, the analysis of variance (ANOVA) provides the influence of input parameters on each output response. The variation of different response measures with respect to input parameters is shown through 3D response surface plots. It is observed in micro EDM that the MT decreases with the increase in voltage, capacitance, feed rate and TRS, whereas MRR and OC increase with an increase in voltage and capacitance. In the case of CE, it decreases with the increase in voltage and it increases with the increase in capacitance.

SELECTIVE AREA DEPOSITION FOR PATTERN GENERATION IN EDM USING MASKING TECHNIQUE

This paper describes about selective deposition of material for pattern generation. The process is carried out using masking technique and by deposition of constituent material of powder metallurgical (P/M) green compact tool at selected area of aluminium work surface in Electro Discharge Machining (EDM) process. The process is carried out to generate line pattern with a hard layer of tungsten and copper at the selected area. Thus, it can improve surface integrity of aluminium substrate while maintaining its overall lightness. P/M tool, positive polarity of tool and hydrocarbon dielectric are used to achieve appreciable amount of material transfer from tool to work surface. The average deviation of material deposition from predefined boundary line is evaluated as edge roughness of the pattern. Taguchi Design of Experiment is used to perform Analysis of Variance (ANOVA) and Overall Evaluation Criteria (OEC) for its parametric study. The surface roughness is obtained in the range of 4.7–10.55[Formula: see text][Formula: see text]m and edge roughness in the range of 36.49–56.82[Formula: see text][Formula: see text]m in various working conditions. However, surface roughness of 4.00[Formula: see text][Formula: see text]m and edge roughness of 21.47[Formula: see text][Formula: see text]m are achieved at the optimum condition.

Machinability of Silicon and German Silver in Micro Electrical Discharge Machining: a Comparative Study

This paper introduces an experimental investigation of micro hole drilling on two different categories of material such as silicon and german silver using micro electrical discharge machining (μEDM) process. The conductivities of the two materials are of different levels; silicon being a semiconductor has relatively much lower electrical conductivity as compared to german silver which is an alloy of copper, nickel and zinc. The tool electrode used is tungsten rod of 518 μm diameter. Responses like material removal rate (MRR), taper angle (TA), circularity error (CE) and overcut (OC) have been calculated and their variation with respect to the process parameters such as capacitance and voltage are evaluated. In both the materials, the values of all the responses increases with an increase in both voltage and capacitance. German silver is observed to have a higher MRR and OC than that of silicon while silicon has a higher TA for the same values of process parameters. The CE of silicon is higher at lower capacitance while it is higher for german silver at higher capacitance. From the analysis of variance (ANOVA), it is observed that both the voltage and capacitance played a significant role in all the responses. An optimum condition of micro hole drilling of both the materials is achieved by formulating overall evaluation criteria (OEC), which combines all the response parameters into a single index. In most of the cases, OEC of german silver is found to be higher than silicon, thus justifying the superior machinability performance of german silver. From the ANOVA of OEC, the role of capacitance is found to be more significant as compared to the voltage.

A comparative assessment of micro drilling in boron carbide using ultrasonic machining

ABSTRACTIn the present work, machining of boron carbide (B4C) has been performed using ultrasonic machining (USM) with the same material as abrasive particles. A comparative assessment of machining of B4C with that of glass and brass has also been carried out by drilling microholes using USM. The experimentation has been conducted according to Taguchi L9 orthogonal array. The effect of feed rate, slurry concentration, and grit size has been evaluated on the performance measures such as material removal rate, overcut, circularity error, taper angle and tool wear rate. Additionally, overall evaluation criteria (OEC) has been formulated to evaluate the combined performance measures. After ANOVA feed rate became the most significant parameters affecting OEC for all the materials. The machining of B4C has been found to be possible but lacks in the machining rate in comparison with that of glass and brass. Least tool wear rate has been found in case of glass whereas minimum overcut, circularity error and taper angle have been observed for brass. The quality of the drilled holes in B4C is better as minimal surface chipping and burr formation has been observed.

Effects of Reynolds and Froude dimensionless numbers on geometry of silica powders: simultaneous optimization using overall evaluation criteria technique

Specific surface area, mean pore diameter, and pore volume are among the most important geometrical properties, which can be controlled by the sol-gel mixing parameters during the silica synthesis. In this paper, these geometrical parameters were simultaneously optimized by overall evaluation criteria (OEC) technique in the Taguchi method. The optimum conditions were obtained at Reynolds dimensionless number (Re) of 250,000, Froude dimensionless number (Fr) of 0.034, acid dripping time (θ) of 60 min and acid normality (N) of 8, which resulted in BET specific surface area, BJH pore diameter and pore volume of 473.12 m2g−1, 5.21 nm, and 0.861 m3g−1, respectively. Analysis of variance demonstrated that only Re had a significant effect on the OEC values with 76.3% of contribution. The samples were characterized by SEM, BET–BJH analyses. Morphological observations confirmed the considerable effects of N, Re, and Fr on geometrical properties such as particle shapes, N2 adsorption–desorption isotherms and pore size distribution.

Effect of non-electrical parameters in fabrication of micro rod using BEDG

ABSTRACTThis paper presents an experimental study of fabrication of micro rods by block electrical discharge grinding (BEDG) process, with the aid of an assisting block electrode. The effect of non-electrical parameters such as feed rate (FR) and tool rotation speed (TRS) is investigated, by considering brass rod of 1.8 mm diameter as workpiece and rectangular block of brass as tool material. Machining time (MT), average diameter (AD), and standard deviation in diameter (SDD) of rod are the evaluated response measures. The process parameters are optimized for lower MT, AD, and SDD. Further, overall evaluation criteria (OEC) have been formulated for simultaneous optimization of all the response measures. From analysis of variance (ANOVA), it is ascertained that FR significantly influences MT, whereas TRS significantly influences both AD and SDD. The topography of the micro rods has been characterized by optical microscopy and scanning electron microscopy (SEM) analysis. With optimum parameters of OEC (), a micro rod with AD of 156.86 µm and SDD of 7.54 µm is fabricated successfully, which suggests that fairly linear micro rod can be fabricated by optimizing the non-electrical parameters in BEDG process.

Fabrication of an array of micro-fins using Wire-EDM and its parametric analysis

ABSTRACTThe fabrication of micro-fin is very critical due to its higher debility nature. In this paper, a simple methodology is proposed for fabricating an array of micro-fins using 2-Axis wire electric discharge machining process, which gives a faster production rate with good accuracy. Arrays of 625 (25 × 25) micro-fins have been fabricated on stainless steel and copper square rods. The average height of the fabricated fins is 850 µm. The effects of process parameters such as pulse-on-time, pulse-off-time, current, and table feed on performance measures like material removal rate, overcut, and cutting rate have been studied. Taguchi L16 orthogonal array has been employed to conduct the experimentation. Analysis of variance (ANOVA) has been applied to observe the significant process parameters and their contribution to the responses. Moreover, the overall evaluation criteria (OEC) have also been formulated to obtain the best parametric combination. The characterization of fabricated micro-pin-fins has been carried out using scanning electron microscope and energy dispersive X-ray techniques.

Multi-response optimization of 67Ni18Cr5Si4B coating by HVOF spray using Taguchi-OEC technique

High Velocity Oxygen Fuel (HVOF) spray is being widely used in many industries to deposit erosion-resistant coatings or restore the dimension for components. The porosity, adhesion strength, and hardness are the essential properties commonly used to access the quality of coatings and thus the effectiveness of a HVOF spray process. To achieve desired coating properties and reduce production cost, optimization of process parameters in HVOF spray has developed immensely during last decades. Among the spray parameters, particle velocity, powder feed rate and standoff distance contribute a significant influence on the final properties of the coatings. In the present study, experiments of HVOF thermal spray were prepared for the 67Ni18Cr5Si4B alloy powder. The process parameters including spray velocity, powder feed rate and spray distance were optimized for the objectives of adhesion strength, porosity and microhardness of 67Ni18Cr5Si4B coating. Based on the Taguchi method, signal-to-noise (S/N) ratio and overall evaluation criteria (OEC) are determined to solve the optimization problem considering multiple performance characteristics. Moreover, analysis of variance (ANOVA) was conducted to analyse the contribution percentage of each process parameter. The optimal process parameters in HVOF spray of 67Ni18Cr5Si4B were found for the multi-response optimization as velocity of 1000 m/s, powder feed rate of 30 g/min, and spray distance of 0.2 m. The results of ANOVA indicated that the spray distance was the most significant parameter affecting the output spray quality among the investigated process parameters, subsequently to the powder flow rate and velocity of spray. Finally, a confirmatory experiment was carried out to support the accuracy of optimal process parameters.

Process Optimization of Steam Explosion Parameters on Multiple Lignocellulosic Biomass Using Taguchi Method—A Critical Appraisal

Xylitol is a low calorie sweetener that can be produced through a bioconversion approach from lignocellulosic biomass that requires pretreatment prior to the bioconversion of xylose to xylitol. Steam explosion (SE) is an industrially scalable pretreatment (PT) process with the potential to liberate xylose monomers, however SE-PT has not been optimised for xylose release from multiple feedstock. The effect of pressure, substrate weight, phosphoric acid loading concentration and residence time on four feedstock (wheat straw (WS), corn stover (CS), Miscanthus (M), and willow (W)) for xylose release and minimal fermentation inhibitor productions (furfural and 5-hydroxymethylfurfural (HMF)) was investigated using the Taguchi methodology for design of experiment (DoE) with variation at four levels (44). An L16 orthogonal array design was utilised and all factors indicated influence on xylose release and inhibitor formation and the resulting xylose rich hydrolysate assessed for bioconversion to xylitol.. The L16 DoE gave hydrolysates containing 75-95% of xylose content in the original biomass, whilst retaining cellulose and lignin components in the fibre. The level of inhibitors were within boundary limits to enable microbial fermentation of the hydrolysates to xylitol. Fine tuning of the overall evaluation criteria (OEC) model imbibing 1.5 kg feedstock in 1.2% w/v orthophosphoric acid, 12 bar(g) and 6 minutes residence time resulted in 90% xylose recovery and production of >1000 L of wheat straw hydrolysate for bioconversion to xylitol. The advantages and limitations of the Taguchi OEC model and further improvements to this process are discussed in a biorefining context

Parametric Optimization for Photochemical Machining of Copper using Overall Evaluation Criteria

This paper focuses on parametric effect study and optimization for photochemical machining of copper. The objective of the study is to analyze the parametric effect of concentration of etchant, temperature, and etching time on material removal rate (MRR) and edge deviation (ED). The photochemical machining of copper has been carried out based on Taguchi L9 array using ferric chloride as etchant. The effect of process parameters on output parameters has been studied using Analysis of Variance (ANOVA). The material removal rate should be high while edge deviation is always desired lesser. For achieving this multi-objective condition, overall evaluation criteria (OEC) have been formulated by assigning equal weight percentage to MRR and ED. The optimum condition predicted by OEC is at a concentration of 600 g/L, temperature of 40°C, and 21 minutes etching time

Fabrication of serpentine micro-channels on glass by ultrasonic machining using developed micro-tool by wire-cut electric discharge machining

A rapid method for fabrication of micro-channel on glass substrates is introduced and investigated in this paper. Wire-cut electro discharge machining (WEDM) and ultrasonic machining (USM) were used as manufacturing processes for machining the micro-tools and micro-channels, respectively. The copper micro-tool was machined using WEDM and the optimal design of the tool was achieved using Taguchi design of experiment. After overall evaluation criteria (OEC) analysis, the optimum conditions were achieved as Ton as 25 μs, Toff as 6 μs, Ip as 1 A, and Wf as 75 mm/s. Further, it was used for fabrication of micro-tools with different profiles such as square, circular, and zigzag. The fabricated micro-tools were used to machine serpentine micro-channels on glass using USM at various power ratings such as 40, 50, and 60%. After machining, net overcut of the micro-channels were found as 74.65, 75.86, and 81.75 μm for square, circular, and zigzag profiles, respectively.

OPTIMIZATION AND SURFACE MODIFICATION OF Al-6351 ALLOY USING SiC–Cu GREEN COMPACT ELECTRODE BY ELECTRO DISCHARGE COATING PROCESS

This paper introduces the surface modification of Al-6351 alloy by green compact SiC–Cu electrode using electro-discharge coating (EDC) process. A Taguchi L-16 orthogonal array is employed to investigate the process by varying tool parameters like composition and compaction load and electro-discharge machining (EDM) parameters like pulse-on time and peak current. Material deposition rate (MDR), tool wear rate (TWR) and surface roughness (SR) are measured on the coated specimens. An optimum condition is achieved by formulating overall evaluation criteria (OEC), which combines multi-objective task into a single index. The signal-to-noise (S/N) ratio, and the analysis of variance (ANOVA) is employed to investigate the effect of relevant process parameters. A confirmation test is conducted based on optimal process parameters and experimental results are provided to illustrate the effectiveness of this approach. The modified surface is characterized by optical microscope and X-ray diffraction (XRD) analysis. XRD analysis of the deposited layer confirmed the transfer of tool materials to the work surface and formation of inter-metallic phases. The micro-hardness of the resulting composite layer is also measured which is 1.5–3 times more than work material’s one and highest layer thickness (LT) of 83.644[Formula: see text][Formula: see text]m has been successfully achieved.