• Journal of the Korean Society of Manufacturing Process Engineers
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• v.7 no.3
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• pp.67-74
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• 2008

Polycrystalline diamonds(PCD) tools are widely used in machining a large variety of advanced materials. However, the manufacture of PCD tool blanks is not an economical process. The shaping of PCD blanks with conventional machining methods(such a grinding) is long, labor-intensive process. This paper reports experimental investigation of the influence of electrical machining conditions on the metal removal rate of WEDM of PCD. Experimental results show that the longer pulse-on time and the shorter pulse-off time increase the metal removal rate and worsen the surface quality. The smaller grain size of diamond yields the metal removal rate and shows the better surface quality. Higher electrical conductivity of water yields worse surface roughness.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2001.10a
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• pp.172-178
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• 2001

Titanium alloys have lightness, high strength and good corrosion resistant characteristics, and broadly used in manufacturing parts for military and aerospace industries. And these alloys also are recognized for organism materials comparatively and used as fixing ones in the human body. Nevertheless thess alloys have excellent properties such as corrosion resistance, heat resistance, and good tensile strength, it is difficult to machine by traditional methods because of high hardness and chemically activated property. So higher tool wear is expected when cutting by tools. Therefore, it is required nontraditional machining process. And the mechanical characteristics such as surface structure and shape, hardness and bending strength are studied for wire electrical discharge machined and surface ground titanium alloys for various heat-treated conditions.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.3
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• pp.215-222
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• 2014

This paper presents an experimental study of a vibration-assisted dry micro-wire electrical discharge machining (${\mu}$-WEDM) utilized in high precision and micro-manufacturing area. The assisted vibration was applied to the workpiece using a piezoelectric actuator, and high pressure air was injected directly into the machining gap through a nozzle. Investigation experiments were performed to estimate the importance of input parameters and it was observed from experiment results that the width (kerf) of the cutting slot and the machining time were significantly affected by the air injection pressure and input energy. Moreover, it was also observed that there exists an optimal relationship between the machining time and input parameters including the air pressure and vibration frequency and amplitude. Central composite design based experiments were also carried out, and empirical models of the machining time and cutting slot kerf have been developed using the response surface methodology to analyze and optimize the process.

• Journal of Mechanical Science and Technology
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• v.17 no.6
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• pp.816-824
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• 2003

In this study, variations of cutting performance with pulse time, open circuit voltage, wire speed and dielectric fluid pressure were experimentally investigated in Wire Electrical Discharge Machining (WEDM) process. Brass wire with 0.25 mm diameter and AISI 4140 steel with 10 mm thickness were used as tool and work materials in the experiments. The cutting performance outputs considered in this study were surface roughness and cutting speed. It is found experimentally that increasing pulse time, open circuit voltage, wire speed and dielectric fluid pressure increase the surface roughness and cutting speed. The variation of cutting speed and surface roughness with cutting parameters is modeled by using a regression analysis method. Then, for WEDM with multi-cutting performance outputs, an optimization work is performed using this mathematical models. In addition, the importance of the cutting parameters on the cutting performance outputs is determined by using the variance analysis (ANOVA).

• Transactions of the Korean Society of Machine Tool Engineers
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• v.15 no.6
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• pp.15-21
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• 2006

This work deals with the electrical conductivity of dielectric on output parameters such as metal removal rate and surface roughness value of a carbon steel(SM25C) and sintered carbides cut by wire electrical discharge machining (WEDM). Dielectric has several functions like insulation, ionization, cooling, the removal of waste metal particles. The presence of minute metal particles(debris) in spark gap contaminates and lowers the breakdown strength of dielectric. And it is considered that too much debris in spark gap is generally believed to be the cause of arcing. Experimental results show that increases of cobalt amount in carbides affects the metal removal rate and worsens the surface quality as a greater quantity of solidified metal deposits on the eroded surface. Lower electrical conductivity of the dielectric results in a lower metal removal rate because the gap between wire electrode and workpiece reduced. Especially, the surface characteristics of rough-cut workpiece and wire electrode were analyzed too. Debris were analyzed also through scanning electron microscopy(SEM) and surface roughness tester. Micro cracks and some of electrode material are found on the workpiece surface by energy dispersive spectrometer(EDS).

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.30 no.5
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• pp.301-306
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• 2017

Wire electrical discharge machining (WEDM) process was evaluated to slice Silicon (Si) for various applications. Specifically, various Si workpieces with various resistances, such as single and multi crystalline Si bricks and wafers were used. As conventional slicing processes, such as slurry-on or diamond-on wire slicing, are based on mechanical abrasions between Si and abrasive, there is a limitation to decrease the wafer thickness as well as kerf-loss. Especially, when the wafer thickness is less than $150{\mu}m$, wafer breakage increases dramatically during the slicing process. Single crystalline P-type Si bricks and wafers were successively sliced with considerable slicing speed regardless of its growth direction. Also, typical defects, such as microcracks, craters, microholes, and debris, were introduced when Si was sliced by electrical discharge. Also, it was found that defect type is also dependent on resistance of Si. Consequently, this study confirmed the feasibility of slicing single crystalline Si by WEDM.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1902-1906
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• 2003

Micro-milling is an efficient method for fabricating micro structures because of its high machining rate compared with other non-conventional micro machining processes. But it is not easy to make a micro milling tool with less than 50 $\mu\textrm{m}$ in diameter by conventional machining. In this study, the characteristics of a micro milling tool fabricated by wire electrical discharge machining (WEDM) were studied. The workpiece is copper and stainless steel. The effects of some machining conditions such as feed rate, depth of cut, and a shape of tool were studied. The tools with D-shape and square shape in cross section were tested for machining micro grooves and 3D structures.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.11 no.6
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• pp.10-16
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• 2002

Titanium alloys have the characteristics of lightness, high strength and good corrosion resistant and are broadly used in manufacturing parts for military and aerospace industries. These alloys are also recognized for organism materials comparatively and used as fixing ones in human body. Nevertheless titanium alloys have excellent properties, it is difficult to machine by traditional methods because of high hardness and chemically activated property. So higher tool wear is expected when cutting by conventional tools, so it is required nontraditional machining process. Finally, the mechanical characteristics such as surface roughness, shape and hardness on studied for wire electrical discharge machined and pound surfaces of titanium alloys for different heat-tested conditions.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.10
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• pp.1800-1808
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• 2003

This work deals with the electrical conductivity of dielectric on output parameters such as metal removal rate and surface roughness value of a carbon steel(SM25C) and sintered carbides cut by wire-electrical discharge machining(W-EDM). Dielectric has several functions like insulation, ionization, cooling, the removal of waste metal particles. The presence of minute particles(gap debris) in spark gap contaminates and lowers the breakdown strength of dielectric. And it is considered that too much debris in spark gap is generally believed to be the cause of arcing. Experimental results show that increases of cobalt amount in carbides affects the metal removal rate and worsens the surface quality as a greater quantity of solidified metal deposits on the eroded surface. Lower electrical conductivity of the dielectric results in a lower metal removal rate because the gap between wire electrode and workpiece reduced. Especially, the surface characteristics of rough-cut workpiece and wire electrode were analyzed too. Debris were analyzed also through scanning electron microscopy(SEM) and surface roughness tester. Micro cracks and some of electrode material are found on the workpiece surface by energy dispersive spectrometer(EDS).

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.956-959
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• 2001

In die and mould industry, major material such as cemented carbide is broadly used for increasing the life time and decreasing the cost. It is also required the development for the skills of wire-cut electrical discharge machining(WEDM), but the WEDMed surface was found to be worst due to the attached components of wire. Precision machining method like lapping is necessary for obtaining high quality surface. The lapping compound such as Al2O3 and SiC and cast iron lap can be used for lapping process. The components of Cu and Zn were found WEDMed surface of the specimen. As the result, the low quality of precision was obtained and the heat damage layer of the specimen was occurred. The value of surface hardness was deteriorated, and therefore finish process was required.