• International Journal of Precision Engineering and Manufacturing
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• v.9 no.1
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• pp.3-6
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• 2008

Electrical discharge machining (EDM) is one of the most widespread nonconventional machining processes. Recently, a low-power micro-EDM process was introduced using a cylindrical electrode. Since its development, micro-EDM has been applied effectively to micromachining, and because the device setup for this process is simple, it is suitable for a microfactory that minimizes machines to fabricate small products economically in one system. In the EDM process, however, the electrode is also removed along with the workpiece. Therefore, the electrode shape and length vary as machining progresses. In this paper, a control method using a high speed realtime voltage measurement is proposed to regulate the rate and amount of material removed. The proposed method is based on the assumption that the volume of the workpiece removed in a single discharge pulses is nearly constant. The discharge pulses are monitored and controlled to regulate the amount of material removed. For this purpose, we developed an algorithm and apparatus for counting the number of discharge pulses. Electrode wear compensation using pulse number information was applied to EDM milling in a microfactory, in which a slight tilt of the workpiece may occur. The proposed control method improves the machining quality and efficiency by eliminating the inaccuracies caused by electrode wear and workpiece tilt.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.57-60
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• 2002

The high precision spindle is essential fer mass and low cost production of aspherical glass lens. Especially, in the grinding process of micro glass lens the performance of the spindle determine the machined surface quality. For the aspheric micro glass lens grinding, we design and make a high precision spindle. We use air bearings for high speed and low motion errors of the spindle. And the driving mechanism is an air turbine to remove heat generation. In this study, we make basic performance requirements of the spindle through benchmarking. And we confirm the requirements by basic machining test. We test air consumption, static stiffness, run-out and vibration of the spindle.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.46-51
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• 2002

A grinding technology is very essential to finish the surface of IT and BT industrial application parts such as wafer, optical connection part and lenses etc. However the finding machine has bead depended on imports. Especially, it is completely imported for machining high precision part relevant to domestic electric and communicational industries. The amount to import grinding machine is about $110milions. It takes about 35% of total import amount of all the machine tools. A domestic finder manufacturer is a very small-scaled bussinessman and research facilities is poor. Recently, it is increasing to demand high speed and precision grinding technology because it brings cost down and value added up. Its further study will be something related to inteligent grinding system fur value added and high precision part. It will make domestic grinding technology to its advanced country level.

• International Journal of Precision Engineering and Manufacturing
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• v.1 no.1
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• pp.118-126
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• 2000

Die-casting burr to casting process is removed by post-process for assembly and quality control of product. Though robot has been widely used for deburring job before. CNC exclusive machine is currently developed for high power, high speed machining and quick tool change. Deburring tool path with complex 3D curve type is defined to make out deburring NC program. But there is no efficient method to define it currently used methods with teaching probe on machine. In this study the efficient method to make out deburring NC program is developed. 5-axis digitizing machine is used to receive data of deburring path. And the post process for NC program generation is developed in consideration of the machining conditions. The developed system is not dependent on the skill of operator and has the advantage to maintain the flexibility of job to modify NC program due to the wear of tool and aging of the die casting.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.445-449
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• 2001

The tool wear that is developed by long-term machining in mold manufacturing with machining center makes a severe influence to the accuracy and the surface roughness. In this reason, tool-wear supervising system which has guaranteed high accuracy and high speed is needed to improve the measurement quality. Touching probe and touch sensor are widely used to measure the tool profile at on-machine measurement. In this paper, using the newly developed electric touch point measuring system, the Automatic Tool Compensation System is developed to correct the error of tool diameter resulted from the wear, and the operating method of this system is also provided.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.1
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• pp.93-100
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• 2000

Die-casting burr due to casting process is removed by post-process for assembly and quality control of product. Though robot has been widely used for deburring job before, CNC exclusive machine is currently developed f3r high power, high speed machining and quick tool change. Deburring tool path with complex 3D curve type is defined to make out deburring NC program. But there is no efficient method to define it currently used methods with teaching probe on machine. In this study the efficient method to make out deburring NC program is developed. 5-axis digitizing machine is used to receive data of deburring path. And the post processor for NC program generation is developed in consideration of the machining conditions. The developed system is not dependent on the skill of operator and has the advantage to maintain the flexibility of job to modify NC program due to the wear of tool and aging of the die casting.

• Journal of the Korean Society for Precision Engineering
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• v.11 no.1
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• pp.177-183
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• 1994

The ball-end milling process is widely used in the die/mold industries, and it is very suitable for the machining of free-from surfaces. However, cusps(or scallops) remaining at the machined part along the cutter paths require anothe finish process such as polishing or grinding. In this study, a high sped micro ball-end milling method has been suggested for the finish of free- form surfaces. A new tool path which makes the geometrical roughness of workpiece be constant through the machined surface has been developed. In the high speed machining of micro ball-end muling experimets, the developed tool paths have been successfully applied. And it was concluded that the surface roughness from this finish cuts of micro ball-end milling process was acceptable.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.2
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• pp.228-234
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• 2001

To obtain precise machined surface and high productivity in machining, high speed end milling has beed studied recently. Though high speed end milling is explicitly effective for precision surface generation geometrically, tool deflection, chatter vibration and frequency characteristics of end milling system deteriorate the theoretical surface. In this study, simulation algorithm and programming method are suggested to simulate machined surface using acceleration signal in high speed end milling. This simulation is conducted by considering vibrational effect of spindle system which was not considered by other investigators. Good agreements were obtained between simulated results and experimental results.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.20-23
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• 2002

In silicon wafer manufacturing process, the grinding process has been adopted to improve the quality of wafer such as flatness, roughness and so on. This paper describes the effect of grinding process on the surface quality of wafer. The experiments are carried out by high precision in fred grinder with air bearing spindle. The relationship between the inclination of chuck table and the flatness of wafer is investigated, and the effect of grinding conditions including wheel speed, table speed, and feed rate on damage depth and roughness of wafer is also investigated. The experimental results show that there is close relationship between the inclination of the chuck table and the flatness of wafer, and the grinding conditions within this paper little affect the flatness of wafer and relatively high affect the damage depth of wafer.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.621-625
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• 1996

The feed system of the machine tools is limited by the mechanical transmission elements. However, thanks to the advanced modern technology, those machines are able to equip with linear motors. In this paper, the types and application aspects of linear motor are discussed and a synchronous type of the linear motors has been applied to X-Y table for machining center. The performance shows an outstanding result in terms of the accuracy, speed and stiffness. Machine tool system with linear motors is expected to be more productive machines using linear motor in the near next years.