PARAMETRIC OPTIMIZATION OF Al-SiC 12 % METAL MATRIX COMPOSITE MACHINING BY ELECTRICAL DISCHARGE MACHINE
In the present study, pure aluminium alloy is mixed with 12% SiC on weight basis to fabricate the metal matrix composite (MMC) material. The objective of this paper is to investigate the effect of process parameters such as pulse on time(Ton), peak current (Ip) and flushing pressure (Fp) on metal removal rate (MRR), tool wear rate (TWR) and surface roughness (SR) during electrical discharge machining (EDM) of Al-SiC12% MMC .The experiment is followed by Central composite design (CCD) method under different combination of process parameters .In this paper Response surface methodology (RSM) is used to develop the mathematical model and to correlate the process parameters with the response. Also Analysis of Variance (ANOVA) technique is used to check the significance of the model and confirmation test is conducted to compare the experimental data with the predicted data to identify the effectiveness of the proposed method. From the main effective plot it is found that peak current is the most significant parameter among the other. Further the morphology study of the composite is carried out by the Field emission Scanning electron microscope (FESEM) of the surface after machining to make a relation with the model.
Machining parameter optimization for EDM machining of Mg–RE–Zn–Zr alloy using multi-objective Passing Vehicle Search algorithm
Abstract Mg alloys are known for their specific strength, stiffness, damping capacity, EMI shielding. Particularly, Rare earths added Mg alloys find applications in the gear box casing, transmission housing, engine mount, ribs, frames, instrument panels due to their improved corrosion resistance, pressure tightness, specific strength and creep strength. Reemergence of Mg alloys in the aircraft structural applications demands for advanced machining processes such as EDM to fabricate complex geometry parts. In this study, parametric multi-objective optimization of EDM on Mg–RE–Zn–Zr alloy is carried out using the novel meta-heuristic algorithm – Passing Vehicle Search (PVS). The input parameters considered are pulse-on (Ton), pulse-off (Toff) and peak current (A). Response surface method (RSM) is implemented through the Box–Behnken design to formulate a mathematical model for Material Removal Rate (MRR), Tool Wear Rate (TWR) and Roundness of holes. The accuracy of theoretical model has been established using the confirmation runs. Using the weighted sum method, the multi-objective PVS calculated optimal solutions for different weights to generate 2-D and surface pareto fronts. These pareto fronts were evaluated for performance determination of PVS using novel and established metrics such as spacing, spreading, hypervolume and pure diversity. The values of performance metrics indicate acceptable nature of the graphs and such analysis would facilitate better comparisons of solutions to select algorithms for optimization. Finally, decision making is illustrated with the help of level diagrams to draw up practical inferences for designing production plans and providing the best choice of machining parameters according to their preferences.
An Ultrasensitive Analytical Method Based on Chemiluminescence Sensing Electrochemical Parallel Catalytic Reaction Event
An ultrasensitive electrochemiluminescence (ECL) method on the combination of electrochemical parallel catalytic reaction and chemiluminesence signal sensing was proposed for improving ECL analytical characteristics using vanadate(V) as a representative. Vanadate(V) could be electrochemically reduced to generate vanadate(II) which could be chemically oxidized by potassium periodate to regenerate vanadate(V) and give parallel catalytic wave effect. Then, the reduced product of potassium periodate could react with butyl-rhodamine B to emit a sensitive chemiluminescence signal. The chemiluminescence intensity was correlative with vanadate(V) concentration. The investigation on the electrochemical reaction rate constant (k0) confirmed that the speed of electrochemical reaction was faster than that of the subsequent chemiluminescence reaction. The possibility of the combination of electrochemical parallel catalytic reaction with chemiluminescence signal sensing was proved. The similar ECL behaviors could be observed at zirconia nanowires-Nafion modified electrode. Because of the separation and enrichment effect of the modified electrode on vanadate(V), the selectivity and sensitivity was further improved greatly. Based on these findings, a new concept on the combination of electrochemical parallel catalytic reaction and chemiluminesence signal sensing was proposed and an ultrasensitive ECL method for the determination of vanadate(V) was developed at zirconia nanowires-Nafion modified electrode. Under the optimum experimental conditions, the ECL intensity was linear with the concentration of vanadate(V) in the range of 2.0×10−12 mol/L–2.0×10−10 mol/L. The detection limit was 8.0×10−13 mol/L, which was more than 6 orders of magnitude lower than that observed by electrochemical current transduction for electrochemical parallel catalytic reaction at zirconia nanowires-Nafion modified electrode.