• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.5
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• pp.1147-1154
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• 1990

Micro-hole drilling by EDM and production of fine rods for the tool electrode or other purpose have become very important in industry. This paper suggests a new method for production of very fine rods by ultrasonic-assisted chemical machining and describes the machining characteristics of micro-hole drilling by EDM. For fine rods, copper wires of initial diameter of 250.mum are used and successfully machined into a diameter of less than 30.mum with good repeatability. The ultrasonic agitation not only accelerated the material removal rate uniformly, but also produced smooth surfaces of fine rods. To drill the micro-hole, kerosene and pure water is used as a dielectric. From the experiment, water is superior to kerosene with respect to surface roughness of inlet and outlet of hole and machined surface as well as electrode wear. However, due to the electrochemical reaction of water, small pits are remained on the workpiece surface.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.8 s.185
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• pp.195-202
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• 2006

High-speed machining (HSM) with excellent quality and dimensional accuracy has been widely used to create 3D structures of metal and plastics. However, the high-speed machining process is not suitable for the rapid realization of 3D thin-walled product because it consumes considerably long time in fixturing process of a work piece. In this paper, an effective rapid manufacturing process is proposed to fabricate 3D thin-walled products directly using HSM, phase change filling and ultrasonic welding. The filling process is useful to hold the thin-walled product during the machining step. The ultrasonic welding process is introduced to make one piece product from two piece parts that are machined by HSM and filling process. The proposed rapid manufacturing (RM) process has been shown that the RM process enables to fabricate the 3D thin-walled products using ABS plastics and aluminum metals from 3D CAD data to functional parts.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1853-1856
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• 2003

Multi-layer printed circuit board(PCB) is being used widely for the product with relatively complex circuits such as TV, VTR and FAX. With the rapid enlargement of electronic and IT industry, the hole machining technology on multi-layer PCB is increasingly required to improve. Thus, the micro drilling with ultrasonic vibration can be a good method for hole machining. Unlike conventional drilling, ultrasonic vibration applied drilling introduces less wear and fracture of not only tool but also internal surface of workpiece due to little cutting resistance, thus, machinability can be improved. The experiment is conducted through the comparison between the results of conventional drilling and ultrasonic micro drilling as well as among each results by the variation according to not only feed rate of drill but also amplitude and frequency of ultrasonic vibration. The multi-layer PCB consists of 6 layers and ${\Phi}$0.3 diameter drill was used. As a result, it was found that the state of internal surfaces of holes on multiple layer PCBs is improved by the application of ultrasonic vibration.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.625-628
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• 2005

For precise micro-grooving and surface machining, ultrasonic cyclic elliptical cutting is proposed using two parallel piezoelectric actuators. The piezoelectric actuators are energized by sinusoidal voltages of varying phase which is essenstial to generating elliptical cutting. Experimental setup is composed of ultrasonic motor, single crystal diamond cutting tool, and precise motorized xyz stage. It is confirmed experimentally that the cutting performance, in terms of the cutting force, the burr formation, and the discontinuous chip formation is improved remarkably by applying ultrasonic elliptical vibration cutting.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2002.11a
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• pp.79-87
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• 2002

An attempt to automate the surface finishing process of the die and mould has been carried out. An UMB(Ultrasonic Micro Burnishing) equipment which brought the micro plastic cold deformation to the 3D sculptured surface of mold and dies by ultrasonic vibration and static load, was developed and installed at the head stock of a vertical machining center. To be satisfied with the required surface roughness and hardness, the DB based program was also developed and applied. This equipment composes of UMB equipement, CNC vertical machining center, CAD/CAM system and the DB based program fer optimal condition. UMB processing effect was obtained from initial value Ral.25 and Hk337 to Ra0.085 and Hk521 and similar result was shown in industrial mould application.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.151-152
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• 2013

• Journal of the Korean Society for Precision Engineering
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• v.30 no.12
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• pp.1237-1243
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• 2013

This study has focused on the effect of ultrasonic vibration table in ELID grinding process of aluminum nitride ceramics. Aluminum nitride ceramics has superior physical and chemical properties and widely used in IC, LSI substrate, package and so on. To achieve the high effective machining of brittle and high strength ceramics as like aluminum nitride, machining method combined ELID grinding and ultrasonic vibration has been adopted in this study. From the experimental results, material removal rate, MRR has been increased maximum 36 percent and spindle resistance has been decreased in using ultrasonic table. Surface roughness of ground surface became a little worse in using ultrasonic table but was somewhat improved in feed direction.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.2 no.1
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• pp.32-38
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• 2003

Engineering ceramics have many unique characteristics both in mechanical and physical properties such as high temperature hardness, high thermal, chemical and electrical resistance. However, its machinability is very poor in conventional machining due to its high hardness and severe tool wear. In the current experimental study alumina($Al_2O_3$) was ultrasonically machined using SiC abrasives under various machining conditions to investigate the material removal rate and surface quality of the machined samples. Under the applied amplitude of 0.02mm, 27kHz frequency, three slurry ratios (abrasives water by weight) of 11, 13 and 15 with different tool shapes and applied pressure levels, the machining was conducted. Using the mesh number of 240 abrasive, slurry ratio of 11 and static pressure of $25kg/cm^2$, maximum material removal rate of $18.97mm^3/mm$ was achieved with mesh number of 600 SiC abrasives and static pressure of $30kg/cm^2$, best surface roughness of $0.76{\mu}m$ Ra was obtained.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.12
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• pp.1347-1352
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• 2011

Recently, as the aged population grows around the world, many medical instruments, devices, and their fabrication processes are developing. Among the devices, a drug delivery stent is a good example for precision machining. Conventional drug delivery stent has problem of the remaining polymer because the drug is coated on the surface with it. If the drug is impregnated into the micro hole array on the stent surface, the polymer can be perfectly eliminated. Micro sized holes are generally fabricated by laser machining however, the fabricated holes do not have an enough aspect ratio to contain the drug or a good surface finish to deliver the stend to blood vessel tissue. To overcome these problems, we propose a vibration-assisted machining mechanism with PZT (Piezoelectric Transducers) for abrication of micro sized holes better. The results indicated that the burr size can be significantly decreased with vibration assisted in nanosecond pulse laser drilling test.

• Journal of Mechanical Science and Technology
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• v.20 no.2
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• pp.227-233
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• 2006

Engineering ceramics have many unique characteristics both in mechanical and physical properties such as high temperature hardness, high thermal, chemical and electrical resistance. However, its machinability is very poor in conventional machining due to its high hardness and severe tool wear. In the current experimental study, alumina $(Al_2O_3)$ was ultrasonically machined using SiC abrasives under various machining conditions to investigate the material removal rate and surface quality of the machined samples. Under the applied amplitude of 0.02mm, 27kHz frequency, three slurry ratios of 1:1, 1:3 and 1:5 with different tool shapes and applied static pressure levels, the machining was conducted. Using the mesh number of 240 abrasive, slurry ratio of 1:1 and static pressure of $2.5kg/cm^2$, maximum material removal rate of $18.97mm^3/min$ was achieved. With mesh number of 600 SiC abrasives and static pressure of $3.0kg/cm^2$, best surface roughness of $0.76{\mu}m$ Ra was obtained.