Optimizing Main Process Parameters When Conducting Powder-Mixed Electrical Discharge Machining of Hardened 90CrSi

In the current study, an optimization process of powder-mixed electrical discharge machining (PMEDM) process when machining cylindrically shaped parts made of hardened 90CrSi steel is reported. In this study, SiC powder was mixed into the Diel MS 7000 dielectric solution. Additionally, graphite was chosen as the electrode material. The multi-objective functions were minimizing the surface roughness (SR) and electrode wear rate (EWR) and maximizing the material removal rate (MRR). The used input parameters of the optimization process included the powder concentration, the pulse-on time, the pulse-off time, the pulse current, and the servo voltage. A combination between the Taguchi method and the grey relation analysis (GRA) method with the support of Minitab R19 software was used to design the experiment and analyze the results. It was found that the optimal set of process parameters that can satisfy the above responses are Cp of 0.5 g/L, Ton of 8 µs, Toff of 8 µs, IP of 5 A, and SV of 4 V.

EFFICIENCY OF ORGANIC AND INORGANIC PESTICIDES AGAINST STORED GRAIN INSECT PESTS

The insect pests cause substantial loss of grains in the field and during storage of food grains that worth millions of rupees. Hence, in order to manage stored grain insect pests a combination of organic and inorganic pesticide control materials was selected to check the efficiency against red flour beetle (Tribolium castaneum) and pulse beetle (Callosobruchus chinensis). Total 10 treatments were used, eight different organic bio-pesticides (neem seed, neem leaves, naswar, tobacco, eucalyptus, citrus, dhatura and mint) and one inorganic (naphthalene balls) and control used at 32 ± 2°C and 70 ± 5% RH. The results indicated that three doses of all treatments were used as 5, 10 and 20gm in 50gm grains. Overall, maximum (4.33 ± 1.00%) mortality of red flour beetle was observed using neem seed powder and no (0.0 0 ± 00%) mortality was observed in minte leaves powder. In case of pulse beetle, the maximum (5.07 ± 0.87%) mortality was observed using neem seed powder and minimum (0.66±0.22%) using citrus leaves powder. Maximum (16.26 ± 0.03) antifeedant efficiency of red flour beetle was observed in control group and minimum (6.46±0.65) antifeedant efficiency of red flour beetle was found in dhatura leaves powder at all tested concentrations. Maximum (14.23 ± 0.13) antifeedant efficiency of pulse beetle was determined in control group and and minimum (1.00 ± 0.04) was observed for naphthalene balls at all tested concentrations. Maximum (94.67%) repellency against red flour beetle was observed using neem seed powder and minimum (62.00%) was found in naphathalene balls as compared with their controls. Maximum (81.32%) repellency against pulse beetle was observed using naswar powder and minimum (63.34%) repellency was determined using neem leaves powder as compared with their control group. We concluded that 20% of neem seed powder concentration proved effective to suppress the population of both red flour beetle and pulse beetle.

Performance characterization of powder mixed wire electrical discharge machining technique for processing of Ti6Al4V alloy

Precision machining characteristics with high-dimensional accuracy make the material more adaptable towards the applications. The present study employs the powder mixed wire electrical discharge machining process to machine Ti6Al4V alloy material. In spite of limited drawbacks and enhanced output in the powder mixed wire electrical discharge machining process, the present problem has been formulated for improving the machining efficiency of Ti6Al4V. The impact of suspended powder characteristics on responses, that is, material removal rate and surface roughness, is examined throughout the process. The current investigation also focuses on the interaction effect of machining constraints along with Al2O3 abrasive mixed dielectric to achieve economical machining output for the Ti6Al4V material. An effort has been presented to obtain optimal solutions using the different methodologies, namely response surface methodology, grey relation analysis, and particle swarm optimization. The study reveals that discharge energy is deeply influenced by the peak current and pulse off time followed by powder concentration in the powder mixed wire electrical discharge machining process. The maximum material removal rate of 6.628 mm3/min and average surface finish of 1.386 μm are the outcome of the present study for a set of optimal machining settings, that is, pulse off time ( Toff) of 7.247 μs, pulse on time ( Ton) of 30 μs, peak current ( Ip) of 2 A, and powder concentration of 4 g/L. Finally, the proposed model has been verified that the hybrid particle swarm optimization technique has the highest adequate capability to achieve maximum output. Thus, the approach offered an enhancement on performance measures of Ti6Al4V alloy in the powder mixed wire electrical discharge machining process.

Characterization of tannin based colorimetric indicator and its application on fish packaging

This study aims to determine characteristics of the gel-type colorimetric indicator at various pH and under different storage conditions, then determine the indicator characteristic in the packaging of fish fillets during storage. The gel-type color indicator was synthesized with a concentration of 1%, 3%, and 5% gambir powder. The FT-IR spectra of the color indicator showed the presence of tannin functional groups, namely C=C aromatic rings, C-C phenolic, and C-H groups, respectively at wavenumbers 1517-1519, 1440-1475, and 752-761 1/cm. Moreover, the coefficient value of the Red-Green-Blue (RGB) of the indicator was changed over pH and did not appear to be consistent. Based on the Analysis of Variance (ANOVA) test, the concentration of gambir powder and duration of color indicator storage, respectively, had a significant effect (P <0.05) on the value of the RGB coefficient. The color indicator exposed to sunlight had a smaller RGB coefficient value than the RGB coefficient value of the indicator stored at room temperature and 5-7°C. The application of color indicators with a 1% Gambir powder concentration in fish fillet storage has been tested for 5 days at a temperature of 5-7°C. They showed that the RGB coefficient value of the indicator was proportional to changes in the pH value of fish fillets but not in line with changes in Total Volatile Based Nitrogen (TVBN) of fish fillets.

Multi-Objective Optimization of Process Parameters for Powder Mixed Electrical Discharge Machining of Inconel X-750 Alloy Using Taguchi-Topsis Approach

The paper investigates the influence of boron carbide powder (B4C) mixed in dielectric fluid on EDM of Inconel X-750 alloy. The process parameters selected as discharge current (Ip), pulse on time(Ton), pulse off time(Toff), boron carbide(B4C) powder concentration to examine their performance responses on Material Removal Rate (MRR), Surface Roughness(Ra) and Recast Layer Thickness (RLT).In this study, o examine the process parameters which influence the EDM process during machining of Inconel X-750 alloy using combined techniques of Taguchi and similarity to ideal solutions (TOPSIS).Analysis of variance (ANOVA) was conducted on multi-optimization technique of Taguchi-TOPSIS. ANOVA results identified the best process parameters and their percentages. It developed the mathematical equation on Taguchi-TOPSIS performance characteristics results. The multi optimization results indicated that Ip and Toff are more significant parameters; V, and Ton parameters are less significant. Finally, surface structures were studied at optimized EDM conditions by using scanning electron microscope (SEM).

The Advanced Performance of Microbial Consortium for Simultaneous Utilization of Glucose and Xylose to Produce Lactic Acid Directly from Dilute Sulfuric Acid Pretreated Corn Stover

Background: Lignocellulosic feedstocks have attracted much attention as an alternative carbon source for lactic acid (LA) production with the advantages of ready availability, sustainability, and renewability. However, the production of LA from lignocellulose faces at least two major technical obstacles. The inhibitors derived from pretreatment of lignocellulose inhibit the growth of microorganism used in downstream hydrolysis and fermentation processes. In addition, most LA producers cannot to ferment pentose sugars and have carbon catabolite repression (CCR) effect. Microbial consortium with great robustness can use complex feedstocks displaying high bioconversion efficiency and has received great attention nowadays.Results: in this study, a thermophilic LA producing consortium DUT50 was enriched and employed to enhance the utilization of corn stover (CS). Enterococcus was the dominant family, accounting for 93.66% abundance in DUT50, and the abundance of Lactobacillus, Bacillus, Lactococcus and Trichococcus, accounted for 2.68% in total. This consortium was highly resistant to inhibitors up to 10.90 g/L derived from pretreatment of CS, metabolized hexose and pentose simultaneously without CCR effect. Based on consortium promising features, an efficient process of simultaneous saccharification and co-fermentation (SSCF) was developed to produce LA from acid-pretreated corn stover. The economical route avoided the operations of solid–liquid separation and detoxification. The key influential factors, including dry biomass and cellulase loading, corn steep liquor powder concentration, and the pre-hydrolysis time were investigated and optimized. The highest LA titer of 71.04 g/L with a yield of 0.49 g/g-CS was achieved at a dry biomass loading of 20% (w/v). This is the reported highest LA production from non-detoxified acid-pretreated corn stover via the SSCF process without wastewater generation. The interaction mode of Enterococcus was collaboration while the low abundance of Lactobacillus and Bacillus might metabolize xylose efficiently via the pentose phosphate pathway.Conclusions: Our results demonstrated the potential advantage of symbiosis and provided a feasible and economical route to produce LA from lignocellulosic biomass in industrial scale.

Multi response optimization of PMEDM of Ti6Al4V using Al2O3 and SiC powder added de-ionized water as dielectric medium using grey relational analysis

In the present work, surface characteristics of powder mixed electro-discharge machining (PMEDM) process are investigated using alumina and carborundum abrasive powder added dielectric fluid for titanium alloy Ti6Al4V. Deionized water is utilized as dielectric to accomplish an environmentally safe machining climate, and limit the emanation of harmful substances. Pulse ON/OFF time (TON/TOFF), discharge current (IP), and powder concentration (PC) are selected as process variables to reconnoiter characteristics of performance like surface finish, rate of material removal, and tool wear. The multi-response optimization has been performed using grey relational analysis (GRA) to establish the optimal parametric combination of process variables that gives the finest surface quality and minutest tool wear. The investigation results divulge that discharge current (IP) and powder concentration (PC) have the most significant effect on material removal rate (MRR), tool wear rate (TWR), and surface finish. The surface characteristics were evaluated by scanning electron microscope for the optimal parameters combination. The minutest value of surface roughness and tool wear rate is achieved at IP: 06 amps, TON: 05 µS, TOFF: 96 µS, and PC: 0.50 g/L. The optimized set of parameters would help process engineers to attain improved machining performance of PMEDM, economically along with desired surface characteristics.

Performance Evaluation of SiC Powder Mixed Electrical Discharge Machining: A Case of Wire Cut Mode with Re-Circulating Molybdenum Wire

Review of the available literature on powder mixed electrical discharge machining (PMEDM) indicates, that most of the research has been done for “die sinking machining mode” whereas the “wire cut machining mode” has not received due attention despite being an important process variant. This work employs Silicon Carbide (SiC) powder mixed dielectric fluid for machining of AISI D2 in “wire cut” mode with re-circulating molybdenum wire (an economic and chemically stable proposition as tool). The effect of five process parameters (powder concentration, peak current, pulse on time, nozzle flushing pressure and stand-off distance) have been evaluated on surface roughness, kerf width, material removal rate and wire wear ratio using Taguchi’s approach. It is found that for surface roughness, higher current and low to moderate concentration levels (2 to 4g/l) deteriorate surface quality; higher values of pressure and stand-off distance are also seen to adversely affect it. For material removal rate, pulse on time as well as its interactions with powder concentration and current, are statistically significant. A higher pulse on with smaller and moderate powder concentrations (2g/l and 4g/l) reduces MRR. For wire wear ratio, current is the sole significant factor (PCR of ~ 65%). SEM analysis of the machined workpiece for the maximum MRR condition quantifies recast layer as ~ 19microns. An indirect comparison with the reported values for non-powdered EDM process indicates that for the similar wire (molybdenum), the use of SiC powder maintains the surface roughness and kerf values, for a much harder D2 material used in this work.