Optimal Combination Of Process Parameters Research Articles

Investigate the Optimal Combination of Process Parameters for EDM by Using a Grey Relational Analysis

Electro-discharge machining (EDM) is a non-conventional machining process which has the ability to machine hard, difficult-to- machine materials and the parts with complex internal shapes by using precisely controlled sparks that occurs between an electrode and a work piece in the presence of a dielectric fluid. This spark removes material from both the electrode and work piece. So, Material removal rate (MRR) and Tool wear rate (TWR) both are of crucial importance in this process. The objective of this paper is to investigate the optimal combination of process parameters for ‘maximum MRR and minimum TWR’ on mach inability of carbon fiber epoxy composites with copper-cadmium tool by using a grey relational analysis method. Peak current (Ip), gap voltage (Vg), pulse on time (Ton) and duty cycle (η) are four major process parameters with suitably three levels. L9 standard orthogonal array has been used to perform the experiment. There are multiple performance characteristics so by using multi-objective optimization technique that is grey relational analysis, the optimal value of MRR and TWR are obtained. Grey relational grade which is obtained by applying grey relational analysis is used to identify the optimal combination of process parameters.

Multi-objective Optimization of Titanium Alloy through Orthogonal Array and Grey Relational Analysis in WEDM

Abstract Wire electro discharge machining (WEDM) operations are dynamic in nature and process responses are related with simultaneous variation of parameters during experiments. To make the process reliable and to study the effects of the process parameters on different responses such as surface roughness (Ra), cutting rate and material removal rate (MRR), attempts have been made to carry out experiments considering the WEDM process parameters. Taguchi method, which is a design of experiments (DoE) method, has been applied to the present experiment followed by Grey Relational Analysis. The signals to noise (S/N) ratio plots are analyzed to study the effect of the process parameters. The adequacy of the above analysis has been tested through the implementation analysis of variance (ANOVA). Next, multi-objective optimization of the response analysis is performed. As the Taguchi methodology is unable to perform multi-objective optimization of the response characteristics, combined approach of orthogonal array and Grey Relational Analysis (GRA) are carried out. Optimal combination of process parameters has been proposed in the machining of titanium alloy in order to achieve minimum surface roughness (Ra), higher cutting rate (CR) and higher material removal rate (MRR). Finally, confirmation tests are carried out to verify the findings.

Effect of Solubilisation on the High-temperature Formability of AA6016 Sheets

The paper investigates the formability beh viour and post-forming characteristics of AA6016 sheets in a range of temperatures and strain rates typical of hot stamping. Since the as-delivered condition of the blanks was the T4 treatment, the blanks were subjected to two different thermal cycles before testing: one implying the material solubilisation and subsequent cooling and deformation at the testing temperature, and the other with ut any solubilisation. The influence of the s lubilisation on the material flow stress, true strain at fracture, and post-forming mechanical and surface characteristics is highlighted. The optimal combination of process parameters assuring the best formability and surface characteristics is identified, validating the results through hot carried out on a real component.

Investigation on Electrochemical Machining of EN31 Steel for Optimization of MRR and Surface Roughness Using Artificial Bee Colony Algorithm

In this paper, artificial bee colony (ABC) algorithm is employed to find out the optimal combinations of process parameters in ECM of EN 31 steel for maximum material removal rate (MRR) and minimum surface roughness (Ra). Experiments are carried out to establish an empirical relationship between process parameters and responses using response surface methodology (RSM). Four process parameters viz. electrolyte concentration, voltage, feed rate and inter-electrode gap are considered in this study. The developed second order response equations from RSM are used as the objective function in ABC algorithm. The optimum combination of process parameters are obtained from the analysis and the corresponding value of maximum MRR and minimum Ra are also obtained separately. Then a multi-objective optimization is implemented to calculate the best solutions formaximum MRR and minimum surface roughness simultaneously using ABC. Confirmation tests are carried out to check the validity of the study. It is seen that the results of confirmation tests show a good agreement with the predicted results. Also, variations of responses with process parameters are studied using 3D surface plots. Finally, the surface morphology is studied with the help of scanning electron microscopy (SEM).

Wear Behavior of Electroless Ni-P Coatings in Brine Solution and Optimization of Coating Parameters

Abstract The present paper studies the wear behavior of electroless Ni-P coating in brine medium and optimization of the coating process parameters for minimum wear using Taguchi method based on L27 orthogonal array. The study is carried out using different combinations of four coating process parameters, namely, concentration of nickel source (A), concentration reducing agent (B), bath temperature (C) and annealing temperature (D). The wear tests are conducted with a pin-on-disk Wear & Friction Monitor. The optimum combination of process parameters for minimum depth of wear is obtained. ANOVA is performed to find out the significance of the coating parameters and their interactions. The surface morphology and composition of coatings are studied with the help of scanning electron microscopy (SEM), energy dispersed X-ray (EDX) analysis and X-ray diffraction (XRD) analysis. It is found that Ni-P coating is amorphous in as-deposited condition but gradually turns crystalline with heat treatment. The worn surface morphology reveals abrasive as well as corrosive wear mechanism.

Friction performance of electroless Ni-P coatings in alkaline medium and optimization of coating parameters

The present paper studies the friction performance of electroless Ni-P coating in alkaline medium (10% NaOH solution) and optimization of the coating process parameters is performed for minimum friction using Taguchi method based on L27 orthogonal array. The study is carried out using different combinations of four coating process parameters, namely, concentration of nickel source (A), concentration reducing agent (B), bath temperature (C) and annealing temperature (D). The friction tests are conducted with a pin-on-disk tribometer. The optimum combination of process parameters for minimum friction is obtained. Also, analysis of variance (ANOVA) is performed to find out the significant contribution of each coating process parameters and their interactions. ANOVA reveals that bath temperature has the maximum contribution in controlling the friction behaviour of Ni–P coating. The surface morphology and composition of coatings are studied with the help of scanning electron microscopy (SEM), energy dispersed X-ray (EDX) analysis and X-ray diffraction (XRD) analysis. It is found that the Ni-P coating is amorphous in as-deposited condition but gradually turns crystalline with heat treatment.

Application of Artificial Bee Colony Algorithm for Optimization of MRR and Surface Roughness in EDM of EN31 Tool Steel

The objective of this paper is to find out the combination of process parameters for optimum surface roughness and material removal rate (MRR) in electro discharge machining (EDM) of EN31 tool steel using artificial bee colony (ABC) algorithm. For experimentation, machining parameters viz., pulse on time, pulse off time, discharge current and voltage are varied based on central composite design (CCD). Second order response equations for MRR and surface roughness are found out using response surface methodology (RSM). For optimization, both single and multi-objective responses (MRR and surface roughness: Ra) are considered. From ABC analysis, the optimum combinations of process parameters are obtained and corresponding values of maximum MRR and minimum Ra are found out. Confirmation tests are carried out to validate the analyses and it is seen that the predicated values show good agreement with the experimental results. This study also investigates the influence of the machining parameters on machining performances. It is seen that with an increase in current and pulse on time, MRR and surface roughness increase in the experimental regime. Finally, surface morphology of machined surfaces is studied using scanning electron microscope (SEM) images.

Multiple Process Parameter Optimization of WEDM on AISI304 Using Utility Approach

Wire EDM is an exceptionally precise, efficient and economical manufacturing route in many applications, allowing customers to design parts for optimum function, without the many restrictions of other metal working process. This paper describes the development of multi-characteristic optimization technique using Utility concept to predict and select the optimal setting of machining parameters of Wire EDM on AISI304 material. Multi characteristic optimization was performed for MRR,SR and DD by using utility concept to find out the optimal process parameter setting .The level of significance of the machining parameters for their effect on the output response were determined by using analysis of variance(ANOVA). The experiment has been done using Taguchi orthogonal array L27. Each experiment was carried out with different conditions of input parameters. The input parameters used for optimization are pulse on time, pulse off time, servo voltage, wire feed, wire tension, and di-electric pressure. The response table and ANOVA for overall utility value were established and the best combination of parameters was obtained. The results revealed that optimum combination of process parameters for multi process parameter optimization, by using utility approach was of, pulse on time level1, pulse off time level 2, servo voltage level1, water pressure level3, wire feed level3 and wire tension level 3.

Optimization of MRR and Surface Roughness in PAC of EN 31 Steel Using Weighted Principal Component Analysis

Abstract In this paper, an attempt has been made to optimize the process parameters for multi-responses (material removal rate, MRR and surface roughness) in plasma arc cutting (PAC) of EN 31 steel using weighted principal component analysis (WPCA). For surface roughness characteristics, five different surface roughness parameters (centre line average roughness: R a , root mean square: R q , skewness: R sk , kurtosis: R ku and mean line peak spacing: R sm ) are considered. Three process parameters viz. gas pressure, arc current and torch height are considered. The experimental plan is based on Taguchi L 27 orthogonal array (OA). To convert the multi-responses problem to a single response optimization problem, WPCA is applied to compute a multi-response performance index (MPI) and then MPI has been optimized using Taguchi method. The optimum combination of process parameters has been found for maximum MRR and minimum surface roughness and verified through a confirmation test. Also, ANOVA is carried out and it is seen that the gas pressure is the most significant factor followed by arc current.

Comparison of DEA Rank based Method with Assignment Weightage Method in Optimizing the Process Parameters for Dissimilar Friction Stir Welded Aluminium Alloys

This paper presents a novel approach for the optimization of welding parameters on dissimilar friction stir welded joints between AA6061T-651 and AA7075T-651 aluminium alloys with multiple responses based on comparing DEA Rank based Method with Assignment weightage Method. These two methods have a series of steps from of proposed approach which are capable of decreasing uncertainty caused by engineering judgement in the Taguchi method. Experiments are conducted by varying the welding parameters related to three pin profiles. In this study, welding parameters namely rotational speed, welding speed and pin profiles are optimized with the considerations of multi responses such as ultimate tensile strength and hardness. L9 Orthogonal array was taken to conduct the experiments with the range 800-1000rpm for rotational speed and with welding speed from 90-110mm/min. The two methods show a good convergence with the experimental and the optimum process parameters combinations where the maximum ultimate tensile strength and the hardness are obtained.

Process Parameter Optimization for Better Hydro-Forming Performance of a Trailing Arm Tube

This work presents the tube forming characteristics of a trailing arm which the whole forming processes are arranged through pre-bending twice and hydro-forming once. This work utilizes the finite element method to simulate the hydro-forming process of the trailing arm by changing the process parameters, such as velocity of left and right punches and internal hydraulic pressure, etc. The effects of process parameters on the distribution states of the tube wall-thickness, distribution of equivalent stresses and strains, and formability of the forming arm are thus investigated. Taguchi method, orthogonal array and factor response are then applied together to determine the optimal process parameter combinations corresponding to two single-quality objects, minimum tube wall-thickness and maximum equivalent stress, with nominal-the-best and smaller-the-better, respectively. It shows that the velocity of the right punch for the billet material axial feeding supplement should be larger than that of the left punch preventing the uneven bursting of the tube-wall on right-end. The analysis of variance also shows that left punch velocity is a major contribution parameter for tube wall-thickness while that primarily affects the equivalent stress is the internal pressure.

Statistical multi-objective optimization of electrical discharge machining parameters in machining titanium grade 5 alloy using graphite electrode

In industrial applications, particularly in aero, marine and medical industries, titanium has received great attention as a useful material and electrical discharge machining as its machining process. Selection of optimal machining parameters in a multi-objective environment is essential for specific workpiece and tool material combination, which is the concern of industries to improve the overall productivity at less cost. In this article, optimization of critical electrical discharge machining parameters such as pulse current, on time of pulse, off time of pulse and tool geometry depending on the responses such as titanium machining rate, graphite wear rate, surface roughness and deviation between entry and exit while machining titanium grade 5 alloy with graphite tool electrode at negative polarity is presented. Taguchi’s L27 orthogonal array was used to design the experiment with interaction between factors. The weighing method was used to integrate different objectives into one performance. The optimal combination of process parameters was found statistically using signal-to-noise ratios. Significance was checked by analysis of variance. Optimum parameters were found to be pulse current 15 A, on time of pulse 50 µs, off time of pulse 200 µs and cylindrical tool geometry. Resultant percentage improvements in different responses were presented.

Research on the Technology for DC CMT Welding of AZ31B Magnesium Alloy

Orthogonal experiment method was used on DC CMT welding of AZ31B magnesium alloy sheet. The tensile test was carried out on the CMT5305 microcomputer control universal testing machine .The effect regular of welding current, arc length correction and welding speed on tensile strength and elongation was analyzed and acquired the optimal combination of process parameters. That is, welding current is 62A, arc length correction is +30% and welding speed is 50cm/min. The microhardness test on joints was carried out. Its found that the curve of microhardness is "W" shaped and the micro-hardness of HAZ is minimum and that of weld zone is maximum.

Optimization of process parameters for fabricating functionally gradient WC–Co composites

Functionally gradient WC–Co hardmetals not containing η phase with a Co depleted surface layer can be produced by heat treating WC–Co in a carburizing atmosphere. This study investigates the effect of process parameters of carburizing heat treatment, such as time, temperature, volume fraction of methane in carburizing atmosphere, and flow rate of mixed gases on cobalt gradient structure in functionally gradient WC–Co. Taguchi method is used to formulate the experiment layout, and the range analysis and the analysis of variance are employed to determine the optimal process parameter levels and to analyze the effect of parameters on cobalt gradient structure. The results indicate that the order of significance of the parameters on both thickness and amplitude of cobalt gradient is temperature followed by volume fraction of methane, time and flow rate of mixed gases. Both the thickness and the amplitude of the gradients increase with increasing temperature and time, and decrease with increasing volume fraction of methane, and first increase then decrease with increasing flow rate of mixed gases. Finally, the optimal combination of process parameters for fabricating functionally gradient WC–Co composites is determined.

The multi-objective optimization of medium-speed WEDM process parameters for machining SKD11 steel by the hybrid method of RSM and NSGA-II

In the medium-speed wire electrical discharge machining (MS-WEDM) process, the extremely high temperature and massive electrical discharges in a fraction of 1 s result in the poor surface quality such as high tensile residual stresses, high surface roughness, white layers, and micro cracks. In this paper, an experimental plan for central composite design (CCD) of processing the tool steel (SKD11) has been conducted according to response surface methodology (RSM). The aim is to develop the mathematical model that can correlate the main process parameters of MS-WEDM with machining performance and to seek the optimal parameters on material removal rate (MRR) and 3D surface quality (Sq) by integrated RSM and Non-dominated Sorting Genetic Algorithm-II (NSGA-II). Then, a set of pareto-optimal solutions is obtained. Moreover, from the confirmation experiment, it has been proved that the optimal process-parameter combinations are suitable on the MRR and the 3D surface texture. Eventually, it has also demonstrated that the method of integrated RSM and NSGA-II is an effective way for multi-objective optimization.

An experimental study on the effect of magneto-rheological finishing on diamond turned surfaces

Magneto-rheological materials are a class of smart materials whose rheological properties can be rapidly varied by applying a magnetic field. Magneto-rheological finishing utilizes magneto-rheological fluid, which consists of magnetic particles, non-magnetic abrasives and some additives in water or other carrier to polish the materials. Single-point diamond turning is able to remove hundreds of microns of material and generate surface with micron accuracies. Residual turning marks are the most important factor limiting the performance in diamond turning process. Magneto-rheological finishing has inherent ability to improve micro-roughness, remove subsurface damage and reduce residual stresses induced during diamond turning process. Combining single-point diamond turning and magneto-rheological finishing creates a deterministic process for manufacturing highly finished surfaces. In this article, an attempt has been made to improve the finish of diamond turned surface with magneto-rheological finishing and to investigate the effects of parameters like current, spacing, wheel speed, feed rate and magnetic field on the final surface finish. Based on the parametric study, an optimum combination of process parameters is identified using analysis of variance. Various image processing techniques have been used for the comparison of the surface analysis of diamond turned surfaces and the magneto-rheological finished surfaces.

Optimization of Process Parameters in the Hole Sinking Electrical Discharge Micromachining of Ti-6Al-4V Thin Sheet

The paper describes the multi-objective optimization of hole sinking electrical discharge micromachining (HSEDMM) process considering material removal rate (MRR), tool wear rate (TWR), and hole taper (Ta) as objectives simultaneously. The micromachining parameters considered in the present work are gap voltage and capacitance of capacitor. Eighteen set of experiments are conducted as per L18 orthogonal array and these experimental results are used for further optimization. Optimal combination of process parameters is determined using grey relational analysis that employs grey relational grade as performance indexes. The principal component analysis is applied to evaluate the weighting values corresponding to each performance characteristics so that their relative importance can be properly and objectively described. Optimal combination of the process parameters for the multiperformance characteristics of the hole sinking electrical discharge machining has been found as; gap voltage 140V and 100 pF capacitance of capacitor.

Experimental investigation, intelligent modeling and multi-characteristics optimization of dry WEDM process of Al–SiC metal matrix composite

Dry wire electrical discharge machining (WEDM) is an environmentally friendly modification of the oil WEDM process in which liquid dielectric is replaced by a gaseous medium. In the present work, parametric analysis has been fulfilled while dry WEDM of Al–SiC metal matrix composite. Experiments were designed and conducted based on L27 Taguchi's orthogonal array to study the effect of pulse on time, pulse off time, gap voltage, discharge current, wire tension and wire feed on cutting velocity (CV) and surface roughness (SR). Firstly, a series of exploratory experiments has been conducted to identify appropriate gas and wire material based on the values of cutting velocity. After selection of best gas and best wire, they were used for later stage of experiments. Analysis of variances (ANOVA) has been performed to identify significant factors. In order to correlate relationship between process inputs and responses, an adaptive neuro-fuzzy inference system (ANFIS) has been employed to predict the process characteristics based on experimental observation. At the end, an artificial bee colony (ABC) algorithm has been associated with ANFIS models to maximize CV and minimize SR, simultaneously. Then the optimal solutions that obtained through ANFIS-ABC technique have been compared with numbers of confirmatory experiments. Results indicated that oxygen gas and brass wire guarantee superior cutting velocity. Also, according to ANOVA, pulse on time and discharge current were found to have significant effect on CV and SR. In modeling of CV and SR by ANFIS, it was resulted that the proposed method has superiority in prediction of them in the ranges of factors beyond the training condition. Also, association of ANFIS with ABC can find the optimal combination of process parameters accurately according to the confirmatory experiments.

Investigation of green properties of iron/jet-milled grey cast iron compacts by response surface method

Grey cast iron powder was produced from grey cast iron scraps by jet milling method and mixed with commercial pure iron powder. The morphology of the produced powders and characteristics of the powder mixtures were investigated. The mathematical models were successfully developed to predict green properties of iron/jet-milled grey cast iron compacts using response surface methodology. Using response surface methodology, the effects of the percentage of jet-milled cast iron powder and compaction pressure on green density, green strength, and hardness of the green compacts were analyzed and the optimal combinations of the input process parameters were obtained to maximize the responses. The main and interaction effects of the input process parameters and also the validity of the models were evaluated by using analysis of variance method. Scanning electron microscopy micrographs of the powders and the fracture surfaces were provided to discuss the obtained responses. The results indicated that in addition to fast production rate and economical considerations, the iron/jet-milled grey cast iron powder compacts have adequate green properties for most of the different combinations of the input process parameters.

A removing process for multilayer nano thin-film structures on the hard disk surface

In this investigation, the nanoscale removal of the multilayer metal film structure from the surface of glass hard disk platters is carried out by an electrochemical reaction. The electrolytic process used is assisted by the application of ultrasonic vibration at very high frequency which effectively enhances the speed and efficiency of metal layer removal. The results also show that higher concentrations of electrolyte and higher temperature also increase the rate of metal layer removal. A high electrolyte flow rate accompanied by high energy ultrasonics results in a high etching rate. The closer the anode is to the surface of the workpiece (platter) and the smaller the gap between the two electrodes, the higher is the etching rate. Further enhancement of etching rate can be achieved by using a smaller anode and cathode as well as by using electrodes with smaller edge radii. A high rotational speed of the anode and cathode module also enhances metal removal because it speeds up the flow of electrolyte across the surface of the workpiece to remove dregs and heat. A high current flow increases the rate of etching and allows a higher workpiece feed rate with a resultant increase in speed and overall efficiency. An optimal combination of processing parameters (electrical conditions, electrolyte flow and control, dregs removal, etc.) allows clean and complete removal of the multilayered nano metal film microstructure from the glass hard disk platters. The basic technology for the micro-electrochemical removal of the nano metal film from glass hard disk surfaces has been established. In addition, the results set a benchmark for the extension of basic laboratory equipment, as well as the implementation and commercial application of the method by industry.