Papers by Keyword: Micro Hole

Abstract: The current research focuses on the viability of rotating, single tubular brass electrodes undergoing shallow cryogenic treatment (at -140°C) before micro-drilling austenitic stainless steel SS316L with the electrical discharge machining process. In order to study and achieve a better rate of material removal and a lower rate of electrode wear, the Taguchi L18 experimental matrix representing the four variables, current, duty cycle, capacitance level, and gap voltage was examined. Regular tap water served as the dielectric fluid to uphold the sustainability concept of the machining experiments and an integrated hybrid approach incorporating CRITIC (criteria importance through inter-criteria correlation) weight determination method and MOORA (multi-objective optimization by the ratio analysis) was applied for decision making. The weight fractions (significance) for MRR and EWR were found to be 0.5532 and 0.4467, respectively and the MOORA method converted multiple objective parameters into a single objective function with weight fractions assigned to each of them. An ideal parameter combination highlighting the dominant significance of duty cycle, pulse current, capacitance level and gap voltage with corresponding values of 70%-18A-1-34V was obtained and the results were substantiated with relevant confirmation experiments. The highest MRR achieved is 10.0961 mm³/min and the lowest EWR is found to be 3.9640 mm³/min. Moreover, the electrode tip regions, the micro holes, and the surrounding workpiece surfaces were also thoughtfully scrutinized and contrasted using scanning electron micrographs (SEM), which validates the worth and significance of cryogenically frozen electrodes in successful micro-drilling of SS316L material.

Abstract: Electromagnetic micro-punching is a novel micro-punching process in which metal foil occur plastic deformation until shear fracture under magnetic impact load. In this paper, electromagnetic micro-punching process was investigated on T2 copper foil. Effects of discharge energy, foil thickness and discharging time on micro punching were discussed. The results show that micro holes were successfully pierced with the discharge energy more than 5.0 kJ on copper foil of 20 μm in thickness. Foil thickness is the main factor in electromagnetic micro-punching with the discharging energy of 7.2 kJ. In addition, increasing discharging time can punch micro hole on thicker foil. The micro holes with diameter of 0.4-1.4 mm were successfully punched on 20 μm copper foil in thickness with discharge energy of 7.2 kJ.

Abstract: Electrochemical micro machining is a critical micro machining technology. The purpose of this paper is to study the effect of ethylenediaminetetraacetic acid (EDTA) complex electrolyte in electrochemical micro machining (ECM) of stainless steel. The micro machining of stainless steel is difficult by electrochemical machining, especially in machining deep micro holes, because of an oxide layer formed on the surface. In this paper, ECM of stainless steel in EDTA complex electrolyte was researched. The influence of electrochemical machining parameters such as pulse duration, electrolyte composition to machine stainless steel was investigated. The results showed that EDTA can enhance the stability of electrochemical machining and the electrolyte is eco-friendly.

Abstract: In order to fabricate micro holes by EDM process, microelectrodes with high accuracy of form are needed. At present, micro electrodes are generated by grinding and/or on-machine EDM operations and then it is well known that efficient productivity of micro electrodes cannot be realized. Controlling method of thrust force for micro shaft is already proposed. Applying this method, thrust force is controlled to be 0 in turning operation, therefore microelectrodes are generated efficiently. Actually, microelectrode which diameter is less than 0.1 mm can be easily machined in short time. high-precision micro hole machining requires microelectrodes with high cylindricity. In this study, turning method for microelectrodes with high cylindricity is discussed.

Abstract: Electrochemical machining (ECM) is an anodic dissolution process of metal as anode ion by ion, and micro-ECM is a promising micromachining method at micro to meso-scale. Thus, a micro-ECM setup was developed to fabricate micro parts and explore the feasibility of micro-ECM at micro to meso-scale, including the design of high-frequency micro-energy pulse power supply. By using the detection unit of machining state and optical encoder, a closed loop control system for micro-ECM was developed. Under low concentration of passivating electrolyte, low machining voltage, micro rotating electrode and high-frequency short-pulse current, the machining gap can be reduced to about 10μm. The influence factors of the additives and the rotation of micro electrode on micro ECM were analysed by experiments. A micro-hole about 30μm in diameter was drilled by the rotating micro electrode.

Abstract: A new turning method to control the thrust force to be zero has already been proposed in our laboratory, and it is shown that micro shafts which diameters are less than 1 mm can be generated stably and repeatedly by applying this turning method. As an application of this turning method, a generating method of electrodes of micro electric discharge machining, EDM, for micro holes is proposed. When drilling a micro hole by EDM using an electrode with high aspect ratio, machined chip is difficult to be exhausted. Therefore, machining time has a tendency to be long and the electrode consumption becomes large. Standing in such a viewpoint, a new method to exhaust the chip smoothly by forming the micro electrode geometry is proposed in this paper. As the results of this study, it is confirmed that the machining time of micro holes can be shorted and the consumption of electrode can also be decreased experimentally.

Abstract: In this paper a method of ultrasonic elliptical vibration cutting has been applied to precision boring of micro hole due to its superior performances such as low cutting force, high quality surface finish and long tool life. A transducer with the longitudinal excitation is carried out to machining(boring) micro hole of 1Cr18Ni9Ti workpiece. The cutting force and surface quality are studied in detail.The workpiece with surface roughness of Rz 0.4μm is achieved.The results showed that the ultrasonic elliptical vibration transducer can be applied rationally in micro hole precision boring.