• Journal of the Korean Society for Precision Engineering
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• v.29 no.4
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• pp.367-372
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• 2012

The biggest factors that lower the machining accuracy are thermal deformation and chatter vibration. In this article, we introduce the study case of technology that can automatically compensate the errors of these factors of a machine during processing on the machine tool's CNC(Computerized Numerical Controller) in real time. This study is related to the detection and compensation of thermal deformation and chatter vibration that can compensate for faster and produce processed goods with more precision by autonomous compensation. In addition, this study is related to the active control of vibration during machining, monitoring of cutting force and auto recognition of machining axes origin. Thus, we attempt to introduce the related contents of the development we have made in this article.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.5 s.182
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• pp.44-50
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• 2006

This paper describs about the technique of ultra-precision machining for an infrared(IR) camera aspheric mirror. A 200 mm diameter aspheric mirror was fabricated by SPDTM(Single Point Diamond Turning Machine). Aluminum alloy as mirror substrates is known to be easily machined, but not polishable due to its ductility. Aspheric large reflector without a polishing process, the surface roughness of 5 nm Ra, and the form error of ${\lambda}/2\;({\lambda}=632.8\;nm)$ for reference curved surface 200 mm has been required. The purpose of this research is to find the optimum machining conditions for cutting reflector using Al6061-T651 and apply the SPDTM technique to the manufacturing of ultra precision optical components of Al-alloy aspheric reflector. The cutting force and the surface roughness are measured according to each cutting conditions feed rate, depth of cut and cutting speed, using diamond turning machine to perform cutting processing. As a result, the surface roughness is good when feed rate is 1mm/min, depth of cut $4{\mu}m$ and cutting speed is 220 m/min. We could machined the primary mirror for IR camera in diamond machine with a surface roughness within $0.483{\mu}m$ Rt on aspheric.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2004.11a
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• pp.283-288
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• 2004

The measurement of ultra low aspect ratio fluid film thickness is very crucial technique both for the verification of lubrication media characteristics and for the clearance design in many precision components such as MEMS, precision bearings and other slideways. Many technologies are applied to the measurement of ultra low aspect ratio fluid film thickness (i.e. elastohydrodynamic lubrication film thickness). In particular, in-situ optical interferometric method has many advantages in making the actual contact behaviors realized with the experimental apparatus. This measurement method also does the monitoring of the surface defects and fractures happening during the contact behavior, which are delicately influenced by the surface conditions such as load, velocity, lubricant media as well as surface roughness. Careful selection of incident lights greatly enhances the fringe resolutions up to $\~1.0$ nanometer scale with digital image processing technology. In this work, it is found that coaxial aligning trichromatic incident light filtering system developed by the author can provide much finer resolution of ultra low aspect ratio fluid film thickness than monochromatic or dichromatic incident lights, because it has much more spectrums of color components to be discriminated according the variations of film thickness. For the measured interferometric images of ultra low aspect ratio fluid film thickness it is shown how the film thickness is finely digitalized and measured in nanometer scale with digital image processing technology and space layer method. The developed measurement system can make it possible to visualize the contact deformations and possible fractures of contacting surface under the repeated loading condition.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.1105-1108
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• 2001

In these days, according s the increase of technological development the part demension goes up for ultra-precision. It is grinding behavior that is important processing which directly influences by machining accuracy at product quality with the net shape manufacturing. In this study, by using CBN wheel an analysis carried out for workpiece's profiles and its characteristics by measuring grinding force and surface roughness. Workpiece materials were used STD11, SUS304 and STB2 varing condition of feedrate and depth of cut.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.777-780
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• 2005

The global consumption of aspheric surfaces will expand rapidly on the Electronics and Optical Components Information and Communications, Aerospace and Defense, and Medical optics markets etc. We must research on market, technology forecast and analysis of aspheric surfaces that is a principle step of ultra precision machine technology with a base one of optical elements. Especially, F-theta lens is one of the important parts in LSU(Laser scanning unit) because it affects on the optical performance of LSU dominantly. The core is most of important to produce plastic F-theta lens by plastic injection molding method, which is necessary to get the ultra-precision aspheric and non-axisymmetric machine processing technology.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.4
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• pp.297-301
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• 2014

The biggest factors, which lower the machining accuracy of machine, are thermal deformation and chatter vibration. In this article, we introduce the development case of a device and technology that can automatically compensate thermal deformation errors of machine during long-time processing on the machine tool's CNC (Computerized Numerical Controller) in real time. In machine processing, the data acquisition of temperature signal in real time and auto-compensation of the machine origin of machine tools depending on thermal deformation have significant influence on improving the machining accuracy and the rate of operation. Thus, we attempts to introduce the related contents of the development we have made in this article : The development of a device that embedded the acquisition part of temperature data, linear regression to get compensation value, compensation model of neural network and a system that compensates the machine origin of machine tool automatically during manufacturing process on the CNC.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2001.10a
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• pp.68-74
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• 2001

This system is composed of fine and coarse apparatus, measurement system and control system. Piezoelectric actuator is designed for fine positioning. We make a study of precision apparatus that is used in the various industrial machine. The study was carried out to develope a precision positioning apparatus, consisting of servo motor and piezoelectric actuator. Coarse positioning using lead screw is drived by servo motor. Control system output a signal from laser interferometer to amplifier of servo motor and piezoelectric actuator after digital signal processing(DSP). Resolution of this apparatus measure with laser interferometer. In this study, design method and control system with ultra precision position apparatus are researched. As the first step, we have estimated for control performance and system stability before an actual apparatus is manufactured by MATLAB with SIMULINK including various functions those are composed of pre-design and system modeling.

• Transactions of Materials Processing
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• v.18 no.2
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• pp.107-111
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• 2009

Temperature variation happens in micro prism roll mold processing system during machining the prism pattern roll mold using manufacturing optical films of LCD (liquid crystal display). This temperature variation induces pitch errors of the prism patterns. The temperature variation displaces the positions of the diamond cutting tool on the roll which was coated by the copper. In order to prevent the pitch errors, the stabilizing the temperature of machining environment is needed. Therefore, the researching on the temperature variation of the ultra-precision roll mold processing system on the machining of micro prism rot 1 mold is needed. In this paper, the temperature variation of micro prism roll mold processing system is researched, the influence is analyzed, and the study for reducing the pitch errors carried out.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.1
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• pp.26-32
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• 2012

Polishing is one of the important methods in manufacturing of Si wafers and in thinning of completed device wafers. This study will report the characteristic of wafer according to processing time, machining speed and pressure which have major influence on the abrasion of Si wafer polishing. It is possible to evaluation of wafer abrasion by load cell and infrared temperature sensor. The characteristic of wafer surface according to processing condition is selected to use a result data that measure a pressure, machining speed, and the processing time. This result is appeared by the characteristic of wafer surface in machining condition. Through that, the study cans evaluation a wafer characteristic in variable machining condition. It is important to obtain optimal condition. Thus the optimum condition selection of ultra precision Si wafer polishing using load cell and infrared temperature sensor. To evaluate each machining factor, use a data through each sensor. That evaluation of abrasion according to variety condition is selected to use a result data that measure a pressure, machining speed, and the processing time. And optimum condition is selected by this result.

• Design & Manufacturing
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• v.14 no.2
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• pp.56-61
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• 2020

Recently, research for machining next-generation micro semiconductor processes and micro patterns has been actively conducted. In particular, it is applied to various industrial fields depending on the machining method in the case of FIB (Focused ion beam) milling. In this study, intends to deal with FIB milling machining technology for ultra-precision diamond tool fabrication technology. Ultra-precision diamond tools require nano-scale precision, and FIB milling is a useful method for nano-scale precision machining. However, FIB milling has a problem of Gaussian characteristics that are differently formed according to the beam current due to the input of an ion beam source, and there are process conditions to be considered, such as a side clearance angle problem of a diamond tool that is differently formed according to the tilting angle. A series of process steps for fabrication a ultra-precision diamond tool were studied and analyzed for each process. It was confirmed that the effect on the fabrication process was large depending on the spot size of the beam and the current of the beam as a result of the experimental analysis.