• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.04a
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• pp.494-499
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• 2003

This paper concerns the static, dynamic and thermal characteristics analysis of a high-speed spindle system for horizontal machining centers with 45mm x50,000rpm. The spindle system is designed based on the angular contact ceramic ball bearings, built-in motor, oil-air lubrication method and oil jacket cooling method. The structural and thermal analysis models of spindle system are constructed by the finite element method. The static and dynamic characteristics are estimated based on the static deformation, modal parameter, mode shape and frequency response function, and the thermal characteristics are estimated based on the temperature rise, temperature distribution and thermal deformation. The analysis results illustrate that the designed spindle system has excellent structural and thermal stabilities

• Transactions of the Korean Society of Machine Tool Engineers
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• v.10 no.5
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• pp.130-136
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• 2001

The purpose of this study is an evaluation of flat end mills to develop appropriate tools for the high speed machining. First of all, several flat end mills which are produced by different makers are selected to analyze the performances of the tools. Experimental works are also executed to measure cutting farce, tool wear and surface roughness for different cutting conditions. And then the results are compared and analyzed for developing optimal cutting tool in the high speed condition.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1338-1343
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• 2007

High-efficient machining, which means cutting a part in the least amount of time, is the most effective tool to improve productivity. In this study, a new feed optimization method based on the cutting power regulation was proposed to realize the high-efficient machining in turning process. The cutting area was evaluated by using the Boolean intersection operation between the cutting tool and workpiece. And the cutting force and power were predicted from the cutting parameters such as feed, depth of cut, spindle speed, specific cutting force, and so on. Especially, the reliability of the proposed optimization method was validated by comparing the predicted and measured cutting forces. The simulation results showed that the proposed optimization method could effectively enhance the productivity in turning process.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.12 s.189
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• pp.38-45
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• 2006

In this work, optimal finish machining condition considering total time for mold or electrode manufacturing was investigated. First, manual finishing time according to the machining condition was analyzed for the work material. The effect of runout and phase shift of tool path on surface finish was also considered in those analyses. Secondly, optimal manual finishing processes were determined for various machining conditions. Finally, finish machining time and corresponding manual finishing time were taken into account for the estimation of the total time of manufacturing mold. Though small feed per tooth and pick feed reduced the manual finishing time, the finish machining time increased in such conditions. With a machining condition of feed per tooth of 0.2 mm and pick feed of 0.3 mm, the minimum total time of manufacturing mold was achieved in our machining condition.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.7
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• pp.642-649
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• 2012

This paper deals with a copper die casting induction motor which has several advantages of motor performance. The developed motor is used as spindle motor in machining center. The dynamic characteristic analysis of rotor is dealt with for precision machining. The critical speed of rotor considering rotation and gyroscopic effect should be above operating speed, 18,000 rpm, and have a 201 % sufficient separation margin. Also, the 3-D unbalance vibration response analysis is performed and enabled the prediction of the expected vibration amplitude by unbalance in high speed. The unbalance vibration responses of each position on the rotor are satisfied with allowable vibration displacement of API 611 standard according to balancing G grade(G 0.4, G 2.5, G 6.3). Copper die casting high speed induction motor is successfully developed and verified by experiment.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.5
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• pp.29-34
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• 2012

This study describes the selection of optimum machining conditions for a high-hardness resin by using a large 5-axis machine. The experiments were conducted to examine the main factors that affect the surface roughness, such as the spindle speed, axial and radial depths of the cut, and pattern of the cutter path. To analyze the experiment results, the factor with the biggest impact on machining was determined using the smaller-the-better characteristic of the Taguchi method; the effectiveness of the experiment was then confirmed by verifying the selected optimum machining condition.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.5
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• pp.142-147
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• 2012

Machining tool conditions directly affect to quality of product and productivity of manufacturing. Many researches performed for tool condition monitoring in machining process to improve quality and productivity. Conventional methods use characteristics of signal for cutting force, motor current consumption, vibration of machine tools and machining sound. Recently, diameter of machining tool is become smaller for minimizing of mechanical parts. Tool condition monitoring using conventional methods are relatively difficult because micro machining using small diameter tool has low machining load and high cutting speed. These days, the direct monitoring for tool conditions using vision system is performed actively. But, vision system is affected by external conditions such as back ground of image and illumination. In this study, minimizing technology of external conditions using distribution analysis of image data are developed in micro machining using small diameter drill and tap. The image data is gathered from vision system. Several sets of experiment results are performed to verify the characteristics of the proposed machining technology.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.12
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• pp.5412-5419
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• 2011

The need is growing for high-speed spindle because various equipment are becoming more precise, miniaturization and high speed with the development of industries. Air-lubricated dynamic bearings are widely used in the optical lithographic manufacturing of wafers to realize nearly zero friction for the motion of the stage. Air-lubricated dynamic bearing can be used in high-speed, high-precision spindle system and hard disk drive(HDD) because of its advantages such as low frictional loss, low heat generation, averaging effect leading better running accuracy. In the paper, numerical analysis is undertaken to calculate the performance of air-lubricated dynamic bearing with herringbone groove. The static performances of herringbone groove bearings which can be used to support the thrust load are calculated. Electrochemical micro machining($EC{\mu}M$) which is non-contact ultra precision machining method has been developed to fabricate the air-lubricated dynamic bearing and optimum parameters which are inter electrode gap size, concentration of electrolyte, machining time are simulated using numerical analysis program.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.2
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• pp.1-6
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• 2008

In recent years, developments in the semiconductor and electronic industries have brought a rapid increase in the use of large size silicon wafer. For further improvement of the ultra precision surface and flatness of Si wafer necessary to high density ULSI, it is known that polishing is very important. However, most of these investigation was experiment less than 300mm diameter. Polishing is one of the important methods in manufacturing of Si wafers and in thinning of completed device wafers. This study reports the machining variables that has major influence on the characteristic of wafer polishing. It was adapted to polishing pressure, machining speed, and the slurry mix ratio, the optimum condition is selected by ultra precision wafer polishing using load cell and infrared temperature sensor. The optimum machining condition is selected a result data that use a pressure and table speed data. By using optimum condition, it achieves a ultra precision mirror like surface.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.4 no.4
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• pp.61-68
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• 1995

TiC-Al2O3 composite ceramics has high hardness, high strength, high wear and corrosion resistance. Therefore, composite ceramics have been concerned significantly with some excellent properties and many functions as new industrial materials to the industry at large. In present research, experiments are carried out to obtain the machinability and machining properties by EDM. As a result, the most suitable machining conditions of TiC-Al2O3 composite ceramics was that the pulse duration is 10-60$mutextrm{s}$, the peak current is 10-16A. The machining speed and the wear of the tool electrode increased with the increase in peak current.