• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.1052-1055
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• 2001

In micro-drilling of brittle materials including glass, cracks occur at the exit surface. In drilling glass, the main type of crack is cone crack. Cone crack is generated by thrust force acting at the bottom surface of the workpiece. Cone crack size could be reduced by changing cutting conditions, but cone crack still existed. Two methods were proposed to prevent crack formation and perfect hole shapes were obtained. One method is attaching two glass plates with water and the other method is constraining two glass plates. The proposed methods eliminated tensile stress acting on the exit surface of glass and prevented crack propagation.

• 산업기술연구
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• 제19권
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• pp.1-7
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• 1999

This is the pre-study to pile up the basic technique for the electro-discharge machining in the field of micro-drilling. The machined chips are flowed out from the machining area by the flow arisen from the high speed rotation of the electrode. The cylindrical shape electrode, whose diameter is 0.5mm, is clamped by the three point clamping type clamper and the clamper is attached at the front shaft of the high speed rotating DC motor. The current for machining is controlled by pulse width modulation technique and the machining conditions such as frequency and duty ratio are changed to find out the effect of the variables for machined results.

• 한국기계가공학회지
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• 제4권1호
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• pp.18-23
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• 2005

This paper reports experimental results on microdrilling process for silicon parts used in semiconductor equipments. An experimental system was developed consisting of a high speed precision machine, microscope system, and project profile instrument. The experimental results indicate that the amount of chipping at the entrance and exit of micro hole decreases as the spindle speed increases up to 18,000 rpm. At higher spindle speed, however, the amount of chipping increases rapidly. The amount of chipping and infeed rate show proportional relationship up to 20 m/min of infeed rate. Beyond that infeed rate, however, sudden increase in the amount of chipping has occurred.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.231-234
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• 2002

Ultrasonic machining technology has been developed over recent years for the manufacture of cost-effective and quality-assured precision parts for several industrial application such as optics, semiconductors, aerospace, and automobile. Ultrasonic machining process is an efficient and economical means of precision machining of ceramic materials. The process is non-thermal, non-chemical and non-electric and hardly creates changes to the mechanical properties of the brittle materials machined. This paper describes the characteristics of the micro-hole of $\textrm{Al}_2\textrm{O}_3$ by ultrasonic machining with tungsten carbide tool. The effects of various parameters of ultrasonic machining, including abrasives, machining force and pressure, on the material removal rate, hole quality, and tool wear presented and discussed. The ultrasonic Machining of micro-holes in ceramics has been under taken and the machining mechanism in the ultrasonic machining of ceramics based on the fracture-mechanics concept has been analyzed.

• 한국생산제조학회지
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• 제8권5호
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• pp.115-120
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• 1999

This research is a described result of experimental for the parameter's effecting the microhole machining by Nd-Yag laser, The parameters are energy, pulse interval time a kin of assisting gas and its pressure. The result reveals that parameter value of energy 0.08J, pulse 20Hz, interval time of 300 microseconds could be a good machining condition to make upper microhoel that is the diameter range of 50-70${\mu}{\textrm}{m}$. At tat time the assistant gas such air, $O_2$, Ar $N_2$, was appelied. Assistant gas of air makes heat affected zone enlarge due to burning of material surface. Also it makes microhole irregular and damageable. Because of refusion caused by chemical reaction with $Al_2O_3$ ceramic material . The $O_2$(99.9%) has good characteristics to get good drilling and smooth surface on pressure of 0.2kgf/$\textrm{cm}^2$ but it is expensive. Ar, $N_2$ make material crack and burnning and proved that to be unappropriate but, Ar was a better than $N_2$.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.1072-1075
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• 2001

$Al_2O_3$ ceramics are generally used as components in processing equipment, devices or machinery because it can perform some functions better than competing metals or polymers. Many of these applications rely on $Al_2O_3$ ceramics special electromagnetic properties, its relative chemical inertness, hardness, strength and its temperature capabilities. But $Al_2O_3$ ceramics are brittle materials, a fact that may cause problems and at the same time be helpful while machining with laser. This study described a basic study of the input parameters effect on the dimension of the microhole at the $Al_2O_3$ ceramics using Excimer laser. In the laser microhole machining of $Al_2O_3$ ceramics, major input parameters are pulse energy, pulse power, pulse frequency and pulse numbers. In conclusion, we can get a smaller microhole and diameter rate by an appropriate pulse energy, pulse frequency and pulse number.

• 한국정밀공학회지
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• 제13권12호
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• pp.46-53
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• 1996

Micro drilling is one of the most important machining types and its necessity becomes more and more increasing in the whole field of industry. Micro drilling, however, has few the case of practical application, because it requests high techniques : manufacturing micro drill, treating chip, producting precise hole shape and progressing machining effeciency. Micro drilling has a technical problem: drill breakage from the lack of drill rigdity and the interuption of chip. It is, therefore, essential to select the proper cutting conditions and the step fed for the method solving the lack of rigidity and the interruption of chip. Especially, step feed is very efficient to avoid the breakage of drill, but bring about reducing of cutting efficiency. The study on step feed must be requested more than the present in the near future. The purpose of this paper is to investigate experimentally about cutting conditions which affect on tools and round errors and to estimate about the effect of step feed as well as optimal step feed size to solve the breakage of drill.

• 한국정밀공학회지
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• 제22권12호
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• pp.163-169
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• 2005

Micro hole is ode of basic elements for micro device or micro parts. Micro electrochemical machining (ECM) can be applied to the machining of micro holes less than 50 ${\mu}m$ in diameter, which it is not easy to apply other techniques to. For the machining of passivating metals such as stainless steel, machining conditions should be chosen carefully to prevent a passive layer. The machining conditions also affect the machining resolution, In this paper, machining characteristics of micro ECM were investigated according to machining conditions such as electrolyte concentration and pulse conditions. From the investigation, optimal machining conditions were suggested for micro ECM of stainless steel.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.988-992
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• 2002

Ultrasonic machining technology has been developed over recent years for the manufacture of and quality-assured precision parts for several industrial application such as optics, semiconductors, aerospace, and automobile application. The past decade has seen a tremendous in the use of ceramics in structural application. The excellent thermal, chemical and wear resistance of these material can be realized because of recent improvements in the overall strength and uniformity of advanced ceramics. Ultrasonic machining, in which abrasive particles in slurry with water are presented to the work surface in the presence of an ultrasonic-vibrating tool, is process which should be of considerable interest, as its potential is not limited by the electrical or chemical characteristics of the work material, making it suitable for application to ceramics. This paper intends to further the understanding of the basic mechanism of ultrasonic machining for brittle material and ultrasonic machining of ceramics based in the fracture-mechanic concept has been analyzed.

• 한국기계가공학회지
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• 제11권5호
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• pp.99-103
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• 2012

Presently, A glass is widely used in telecommunication system, optoelectronic devices and micro electro mechanical systems. Micro drilling of glass using the laser can save processing cost and improve the accuracy. This paper experiments micro drilling using KrF excimer laser on the pyrex glass of $500{\mu}m$ thickness. We have experiment to find out optimum laser machining conditions of micro drilling of glass and ablation depth and influence by processing parameter suc'h pulse repetition rate, energy density and number of pulses. Pulse repetition rate don't influence ablation depth at the micro drilling of pyrex glass. Energy density influence micro drilling of parallelism and maximum thickness that can be drilled. Ablation depth is most influenced by number of pulses.