Electrical discharge machining (EDM) of high aspect ratio (AR) micro-holes on materials like Ti-6Al-4 V alloy is challenging. The ineffective removal of the machining by-products from and replenish...

EDM of high aspect ratio micro-holes on Ti-6Al-4V alloy by synchronizing energy interactions

The present article focused on the surface characterization of electric discharge machined duplex stainless steel (DSS-2205) alloy with three variants of electrode material (Graphite, Copper-Tungsten and Tungsten electrodes). Experimentation was executed as per Taguchi L18 orthogonal array to inspect the influence of electric discharge machining (EDM) parameters on the material removal rate and surface roughness. The results revealed that the discharge current (contribution: 45.10%), dielectric medium (contribution: 18.24%) majorly affects the material removal rate, whereas electrode material (contribution: 38.72%), pulse-on-time (contribution: 26.11%) were the significant parameters affecting the surface roughness. The machined surface at high spark energy in EDM oil portrayed porosity, oxides formation, and intermetallic compounds. Moreover, a pin-on-disc wear analysis was executed and the machined surface exhibits 70% superior wear resistance compared to the un-machined sample. The surface thus produced also exhibited improved surface wettability responses. The outcomes depict that EDMed DSS alloy can be considered in the different biomedical and industrial applications.

https://www.mdpi.com/2072-666X/11/10/926/pdf

Surface Characterization and Tribological Performance Analysis of Electric Discharge Machined Duplex Stainless Steel.

The high strength and hard-to-cut materials can be easily machined by using modern machining methods. It is important to introduce the efforts on enhancing the process for improving the machining quality. In the present investigation, an effort was made to analyze the effects of micro-size Al2O3 particles mixed into Kerosene as the dielectric under different powder concentrations on machining titanium alloy in Electrical Discharge Machining (EDM). Response Surface Methodology (RSM) based algorithm utilized to analyze the performance measures by considering machining time with Cost of Goods Manufactured (COGM) method in Powder Mixed Electro Discharge Machining (PMEDM) process. It was found that the micron size powders can significantly help to enhance the surface quality of the Ti-6Al-4V during machining in the PMEDM process. The presence of carbon, oxygen elements and the formation of surface oxides and carbides has been found due to the decomposition of dielectric fluid in the PMEDM process. The lower deep cavities and uniform of PMEDM’s surface have been produced by added Al2O3 powder into the EDM process owing to lower surface cracks density, conductivity.

Investigation of surface quality in Cost of Goods Manufactured (COGM) method of μ-Al2O3 Powder-Mixed-EDM process on machining of Ti-6Al-4V

Machinability Analysis and Optimization of Electrical Discharge Machining in AA6061-T6/15wt.% SiC Composite by the Multi-criteria Decision-Making Approach

7Cr13Mo steel is widely used in many industries given its good properties. However, it has poor wear resistance and difficult-to-cut characteristics. In this study, ultrasonic-assisted and powder-m...

Machining of 7Cr13Mo steel by US-PMEDM process

Polycrystalline diamond (PCD) is widely used for its excellent properties but difficult to be processed by traditional machining methods. Electrical discharge machining (EDM) is regarded as...

Machining characteristics of PCD by EDM with Cu-Ni composite electrode

The demand for integrating and transmitting a large amount of renewable energy over long distances continues to promote the development of high voltage direct current (HVDC) transmissions technology. For the upcoming need of HVDC grids, high voltage DC/DC converters are necessary to interconnect HVDC lines with different voltage levels. This paper proposes a nonisolated bidirectional DC/DC converter based on the capacitive energy transfer (CET) principle. The proposed converter is composed of only one energy buffering arm and two series-connected switches for energy transfer, moreover, one active filtering arm on each DC side to keep the current flowing smoothly and continuously. Thus, the proposed converter features lower cost, higher reliability, and greater potential for practical application. The operation principle and parameter design are shown in detail. The control scheme with equal amplitude mode for energy balancing and voltage/power adjusting is investigated. The feasibility of the proposed converter is verified by simulation results. 

A capacitive energy transfer high voltage DC/DC converter with active filtering arms

Objective: To explore the effect and underlying mechanism of casein kinase 2 interacting protein-1 (CKIP-1) on hepatocyte apoptosis in nonalcoholic fatty liver disease (NAFLD). Methods: Experimental study. An NAFLD cell model was established by inducing human hepatoma cell line, HepG2 cells, with oleic acid (OA). Flag-CKIP-1 expression vector and shRNA-CKIP-1 were transfected into HepG2 cells. Flow cytometry was used to detect the effect of CKIP-1 on the activity and apoptosis of NAFLD hepatocytes. The levels of apoptosis-related proteins were detected by Western blot. CKIP-1 knockout mice in C57BL/6 back-ground were fed with either standard or high-fat diet for 8 weeks. Apoptosis-related signal proteins in NAFLD hepatocytes were detected by immunohistochemistry. Results: After CKIP-1 was transfected into HepG2 cells, the degree of OA induced cell liposis was significantly reduced (P<0.05). Annexin V-FITC/PI flow cytometry showed that CKIP-1 reduced the apoptosis of steatotic hepatocytes. Overexpression of CKIP-1 could significantly inhibit the expression of caspase-3 and caspase-9 and increase the expression of Bcl-2/Bax (P<0.05). Knockdown of CKIP-1 could increase the expression of caspase-3 and caspase-9 (P<0.05). CKIP-1 knockout could further increase the expression of caspase-3 and caspase-9 in NAFLD mice (P<0.01,P<0.05), and further decrease the expression of Bcl-2/Bax (P<0.05). Conclusion: CKIP-1 inhibited the apoptosis of steatotic hepatocytes by up-regulating the expression of apoptosis inhibitor gene, Bcl-2/Bax, and affecting the proteases, caspase-3 and caspase-9.

N. Wang

Papers

Machining characteristics of PCD by EDM with Cu-Ni composite electrode

Machining of 7Cr13Mo steel by US-PMEDM process

A capacitive energy transfer high voltage DC/DC converter with active filtering arms

[Effect of CKIP-1 on hepatocyte apoptosis in nonalcoholic fatty liver disease].