• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.988-991
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• 2001

Plastically deformed layer influences the mechanical property of the mechanical element such as creep hardening, microscopical crack and stress corrosion destruction. Therefore, the property so called the surface integrity has to be considered, and the machined surface including plastic deformation, distribution of stress has to be conducted quantitatively. This paper explains the orthogonal cutting, and made an orthogonal cutting model using the finite element method, then analyzed cutting power, plastic deformation of workpiece. It introduces the developed subsequent recrystallizations technique for measurement of the plastic strain of machined surface, and verified the technique.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.2 no.3
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• pp.69-75
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• 2003

Plastically deformed layer influences the mechanical property of the mechanical element such as creep hardening, microscopical crack and stress corrosion destruction. Therefore, the property so called the surface integrity has to be considered, and the machined surface including plastic deformation, distribution of stress has to be conducted quantitatively. This paper explains the orthogonal cutting, and made an orthogonal cutting model using the finite element method, then analyzed cutting power, plastic deformation of workpiece. It introduces the developed subsequent recrystallizations technique for measurement of the plastic strain of machined surface, and verified the technique.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.04a
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• pp.646-650
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• 1996

In this paper, A hydrostatic bearing spindle for high precision machining and a motor built-in spindle for high speed machining are developed toobtain the high precision machining accuracy of the prototype lathe. The sliding bearing with fluoric resin (turcite) pad is adopted for improving the damping charateristics of guide ways. The funning accuracy of moving elements isestimated to confirm the validity of application on the prototype; the high precision CNC lathe. The surface roughness of Cupper and Aluminum machined by the hydrostatic spindle are 0.07 .mu. m and 0.10 .mu. mRmax. The surface roughness of Aluminium machined by the built-in spindle are 0.10 .mu. mRmax. From this results, it is venified that the prototype lathe is effective to high precision maching.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1992.10a
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• pp.115-120
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• 1992

Mirror-surface machining is very important machining technology to manufacture optical parts. especially brittle materials. In case of optical plastics, it is produced through both grinding and polishing till now. New machining method which is more efficient and contributed to the protection of the environmental pollution is, therefore, studied. In this , experimental results and an analysis of surface roughness in ultrasonic vibration cutting of optical plastic (CR-39) which is used for optical lens is presented. In results, a comparison of the micro-structure of machined surfaces produced by cutting with ultrasonic vibration and conventional turning is presented by analyzing S.E.M. photograph. Also, wavelength spectrum analysis is performed to investigate the surface-characteristics machined by ultrasonic vibration cutting.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1995.10a
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• pp.68-75
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• 1995

The milling process is one of the most important metal removal processes in industry. Due to the complexities inherent to the cutter insert geometry and the milling cutter kinematics, these processes leave an analytically difficult to predict texture on the machined surface's hills and valleys. The instantaneous uncut chip cross sectional area may be estimated by the relative position between the workpiece and the cutter inserts. furthermore, since the cutting forces are proportional to the instantaneous uncut chip cross sectional area, the cutting forces in face milling operations can not be estimated easily. A new simulation program which is based upon the numerical method has been proposed to estimate the cutting force components, with the ability to predict the machined surface texture left by the face milling operation.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.20 no.6
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• pp.729-734
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• 2011

The full sintering process of zirconia has some extent of shrinkage and the custom abutment design should consider the pre-compensation volume of the shape. In this paper, we concentrated to reveal the asymmetric sintering characteristics. The circular profile of all six samples were measured using the three dimensional coordinate machine. After the full sintering process, the profiles were measured again. The roundness were compared to those of the original shapes and the percent of shrinkage were calculated. On the other hand, surface roughness was also investigated after the full sintering process. The final average surface roughness was improved by the sintering of the machined zirconia surface.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.1
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• pp.21-26
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• 1993

A study on the fatigue fracture at electro discharge machined(E.D.M) surface has been made with special emphases on the microstructure variation and the residual stress distribution at the E.D.H heat affected zone. Results obtained are summarized as follows. (1) E.D.M brings about a variation of microstructure in heat affected zone, structures of molten, quenching, tempering are formed in order of formation from E.D.M surface. (2) Residual stress generated by E.D.M reduces the fatigue strength of the material through the influencing fatigue crack initiation and growth. (3) Magnitude of the residual stress existed in a microscopic area is approximately estimated by a COD measurement method which was originally suggested by authors.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.30 no.3
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• pp.54-61
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• 2007

Machining processes produce high accurate metallic parts in metal working industries. Lubrication for machining enhances quality of machined surface and it prolongs the life of cutting tools. Since lubricant is poisonous to human body and environment, it causes occupational diseases for workers and air pollution in environment. Because of these problems generated, developed countries do not permit the excessive usage of lubricant in machining shops. This research focuses on the development of MQL machining technique that consumes minimal amount of lubricant, which reduces possible outbreak of occupational diseases and air pollution. This research sets experimental equipments for MQL machining. Experiments for this study are designed with major machining parameters in MQL. Through the analysis of experiments, this paper presents the optimal machining parameters.

• 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
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• v.14 no.6
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• pp.1515-1522
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• 1990

Ultra precision cutting should be satisfied with two conditions of Mirror Like and shape grade, and especially Mirror Like depends on surface roughness. In this study, in order to develop Mirror Cutting for Al alloy, this was done with edge form of single crystal diamond tool divided into R type and S type. Surface roughness machined by S type tool is more satisfactory than by R type tool, being the lowest value of 13.8nm. In addition, Mirror surface can reach above 90% of reflection rate by both R type and S type tool, but machined surface by R type tool has much more fine fracture portions rather than by S type tool. Even though feed rate decreases from 5.mu.m to 1.mu.m, surface roughness doesn't show improvement.