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In micro electrical discharge machining (micro-EDM), the precision fabrication of cylindrical micro rods is difficult to achieve with a high processing efficiency. In order to overcome this challenge, this paper proposes a new processing method, which is denoted as twin-mirroring-wire tangential feed micro electrical discharge grinding (TMTF-WEDG). The machining principle, characteristics, and realization of the new method are firstly introduced. Then, the advantages of TMTF-WEDG in terms of machining efficiency and accuracy are demonstrated. The experimental results have shown that the machining efficiency can be increased to more than 70% in comparison with conventional tangential-feed wire electrical discharge grinding. It has also been proved that a minimum removal of material corresponding to a reduction of less than 1 μm in the diameter of a micro rod can be obtained by TMTF-WEDG. This considerably helps in improving the accuracy and repeatability of the machining process. A deviation of less than 1 μm on the diameter of a micro rod has been obtained in a length range of 800 μm. The process repeatability in machining five micro rods has been established to be below 2 μm. The proposed method is therefore of great significance for improving the machining efficiency and ensuring a high precision in the shaping process of cylindrical micro rods.

This paper discusses the development of a numerical model and its comparison with the analytical model to predict the wire deflection in WEDG. The movement of wire between upper and lower guides creates vibration during the machining process which can create micro deflection of the wire. The Finite Element Analysis model [FEA] for the wire deflection is analyzed and compared with the analytical model. The deflection of the wire due to the input current may affect the machining of micro parts, which will be used for further research in micro machining and also will help us to choose the parameters such as current, spark gap, wire feed, and the speed of the workpiece during micro machining with WEDG. The FEA results for various forces were compared with the analytical results and found that the developed numerical model results are in good agreement.

The paper gives an overview of designing of rotary axis for WEDM and fabrication of the same. WEDG the combination of WEDM with grinding a Hybrid Machining Process, WEDM has lot of advantages so all the Hybrid Machine are use the help of WEDM but here WEDG is used to produce the micro components like probe and micro electrodes. One such combination is wire electrical discharge grinding (WEDG), which is commonly used for micro-machining of fine and hard rods. Here the workpiece need the tendency to rotate where the wire is pass through based on spark erosion principle the rod can be grinded to our required small and precise diameters like 0.4mm, the existing WEDM can only used to produce through holes with the help of this we can able to reduce the components diameters and lengths WEDG also has an ability to produce micro components with high aspect ratios the rotation of workpiece is taken cared of with the help of spindle that coupled with AC motor., {"references":["Liao Y. S., Chien S. T., Lin C. S. (2005), Development of a high precision tabletop versatile CNC wire EDM for making intricate micro parts, J. Micromachanics Microengineering, 15: 245-253","Schoch A., Foster A., Menz W. (2005) Micro wire EDM for high aspect ratio 3D microstructuring of ceramics and metals, Microsyst Technol 11:250-253","Yan M. T., Huang C. W., Fang C. C., Chang C.X. (2003) Development of a prototype micro-wire EDM machine, J.Mater. Process Technol 149:99-105","Yan M., Chien H. (2007), Monitoring and control of the micro wire-EDM process, Int. J Mach Tools Manuf 47:148-157","Rees. A, Brousseaua. E, Dimova. S. S, Gruberb.H, Paganettib,I, (2008) Wire electro discharge grinding: surface finish optimization, JMulti-Material Micro Manufacture","Chris Morgan, Shelby Shreve ,Ryan Vallance..R, (2003), PRECISION OF MICRO SHAFTS MACHINED WITH WIRE ELECTRO-DISCHARGE GRINDING,","Proceedings of the ASPE Winter Topical Mtg on Machines and Processes for Micro-Scale, Meso-Scale Fabrication, Metrology and Assembly","Uhlmann. E, Piltz. S, Oberschmidt. D,(2008) Machining of micro rotational parts by wire electrical discharge grinding, Prod. Eng. Res. Devel. 2:227–233","Masuzawa T, Fujino M and Kobayashi K.(1985) Wireelectro-discharge grinding for micro-machining, CIRP Annals, 34:1: 431-434.","Anjali V. Kulkarni, V. K. Jain, (2004) Microfabrication using Electrochemical Spark [p4]","Pradhan.B.B B. B, Masanta.M, Sarkar.B.R, Bhattacharyya.B (2008) Investigation of electro-discharge micro-machining of titanium super alloy, Int J Adv Manuf Technol 41:1094–1106","Janardhan.V, Samuel. G. L, (2010) Pulse train data analysis to investigate the effect of machining parameters on the performance of wire electro discharge turning (WEDT) process, International Journal of Machine Tools & Manufacture, 50: 775–788.","Jun Qu, Albert J. Shih, Ronald O. Scattergood, (2002) Development of the Cylindrical Wire Electrical Discharge Machining Process, Part2: Surface Integrity and Roundness, Transactions of the ASME 708 / Vol.124"]}

Выполнено компьютерное моделирование методом конечных элементов электромагнитных процессов в роторе синхронного турбогенератора 300 МВт в двухмерной постановке при продолжительной несимметричной нагрузке. Исследовано влияние материала пазовых клиньев на добавочные потери в роторе без учета контактных явлений. Показано, что применение титановых клиньев является предпочтительным по сравнению с дюралюминиевыми клиньями. 2D FEM computer simulation of electromagnetic processes in a 300 MW synchronous turbogenerator rotor under long-time unbalanced load is carried out. Effect of slot wedge material on additional losses in rotor with neglect of contact phenomena is studied. It is demonstrated that utilization of titanium wedges is preferable in comparison with duralumin ones.