• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.9 no.6
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• pp.111-117
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• 2000

The plastically deformed layer in a machined surface must be considered in precision machining process. Therefore the analysis of the machined surface, including the plastic deformation and strain distribution should be carried out quantitatively. The subsequent recrystallization technique was presented for analysis of the plastically deformed layer in the machined surface, and the technique was successfully applied to determine the plastic strain in the machined surface. This investigation is to evaluate the plastic strain in the distance 0.1mm from the machined surface, and in particular, to find the effect of shear angle, shear strain, cutting energy etc. on the plastic strain.

• Journal of the Korean Society for Precision Engineering
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• v.11 no.5
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• pp.153-160
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• 1994

In this study, residual stress and surface roughness were investigated experimentally to evaluate surface integrity on surface layer machined by CBN, ceramics and WC cutting tools. When machining difficult-to-cut material (hardened STD11 steel $H_{R}$C 60), residual stresses remaining in machined surface layer were mainly compressive. The increase of flank wear caused a shift of the compressive residual stress maximum to greater workpiece depths, but the changes did not penetrate the workpiece beneath a depth of 300 .mu. m. Surface roughness was influenced considerably by variations of the cutting speed and feed. In machining hard material, CBN and A1$_{2}$ $O_{3}$ ceramics cutting tool materials proved significantly superior to mixed ceramics A1$_{2}$ $O_{3}$-TiC and WC in evaluation of surface integrity.y.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.4
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• pp.141-147
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• 1998

A plastically deformed layer in the precision machined surface affects in various forms the physical properties of machined components such as the fatigue strength, the dimensional instability, microcracks and the stress corrosion cracking. These physical properties, so called surface integrity, are very important for designing highly stressed and critically loaded components. Typical plastic strains in the precision machined surface are very difficult to measure, since they are located within a very short distance from the surface and they change very rapidly. A new way is suggested to determine the residual strain in plastically deformed materials by analyzing the plastically deformed layer after a subsequent recrystallization process. This investigation is to explore a new technique for measuring plastic strain in machining applications, and in particular, to and the effect of cutting parameters(rake angle, depth of cut, specific cutting energy), on the plastic strains and strain energy.

• Journal of the Korean Society for Precision Engineering
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• v.5 no.4
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• pp.59-65
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• 1988

This paper describes the transmutation layer of CNC Wire electrical discharte machined surface. In order to analayze and invesigate transmutation layer of the carbon tool steel, workpieces was heat-treated by quenching, tempering, normaling. The obtained results are summarized as follows. 1. The result showed that wire electrical discharge machined surface region was transmuted into the recdast layer in the range of about 10${\mu}$m deep by resolidification and next zone was transmuted into the heat affected zone in the range of about 15${\mu}$m deep by high temperature. 2. The hardness of the recast layer and heat affected zone was decreased on its machined surface. 3. The more wire feedrate was increased, the more electrical discharge machine gap was decreased.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.1
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• pp.80-85
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• 2007

High speed cutting is a machining process which cuts materials with the fast movement and rotation of a spindle in a machine tool. High speed cutting leaves a plastically deformed layer on the machined surface. This deformed layer affects in various forms to the surface roughness of machined parts such as the dimensional instability, the micro crack. The surface roughness is called surface integrity which is very important in precision cutting. This paper aims to study on the machined surfaces characteristics of aluminum alloy and brass by AFM(Atomic force microscope) measurement. The objective is contribution to ultra- precision cutting by exhibit foundation data of surface roughness and tool wear when parts are cutting with diamond tool at the factory.

• Journal of Institute of Convergence Technology
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• v.2 no.2
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• pp.25-29
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• 2012

Micro machining technologies have been required to satisfy various conditions in a high-technology industry. Micro electrochemical process is one of the most precision machining methods. Micro electrochemical process has been divided into electrochemical etching through protective layer and electrochemical machining using ultrashort voltage pulses. Micro shaft can be fabricated by electrochemical etching. The various protective layers such as photo-resist, oxide layer and oxidized recast layer have been used to protect metal surface during electrochemical etching. Micro patterning on metal surface can be machined by electrochemical etching through protective layer. Micro hole, groove and structures can be easily machined by electrochemical machining using ultrashort voltage pulses. Recently, the groove with subnanometer was machined using AFM.

• Journal of the Korean Society for Precision Engineering
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• v.10 no.3
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• pp.47-56
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• 1993

Typical plastic strains in the machined surface are very difficult to measure, since they are located within a very short distance from the surface and they change very rapidly. There is an alternative way to determine the residual strain in plastically deformed materials by measuring the grain size after a subsequent recrystallization precess. Although, this technique has been successfully applied by several researchers to find the plastic zone around notches and cracks in various materials and welding beads, few works have been reported using the recrystallization method to determine the residual strains in machined surface. Therefore, the purpose of this investigation is to explore the effectiveness of the recrystallization technique in machining applications and in particular, to find the effect of cutting parameters, i.e., depth of cut, rake angle, on the plastic strains. As the result, the recrystallization technique was succesfully applid to determine the plastic strain in machined surface.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.04a
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• pp.326-331
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• 2000

In this study, residual stress was investigated experimentally to evaluate damaged layer in high-sped machining. In machining difficult-to-cut material, residual stress remaining in machined surface was mainly speared as compressive stress. The scale of this damaged layer depends upon cutting speed, feed per tooth and radial cutting depth. Damaged layer was measured by optical microscope. The micro-structure of damaged layer was a mixed maternsite and austenite. depth of damaged layer is increased with increasing of cutting temperature, cutting force and radial depth. On the other hand, that is slightly decreased with decreasing of cutting force. The increase of tool wear causes a shift of the maximum residual stress in machined surface layer.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1991.11a
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• pp.54-58
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• 1991

It is well known that metal cutting leaves a plastically deformed layer in the machined surface. This residual phenomenon affects in various forms the physical properties of machined components such as the fatigue strength, the dimensional instability, microcracks, and the stress corrosion cracking. These physical properties, so called surface integrity, are very important for designing highly stressed and critically loaded components. Typical plastic strains in the machined surface are very difficult to measure, since they are located within a very short distance from the surface and they change very rapidly. There is an alternative way to determine the residual strain in plastically deformed materials by measuring the grain size after a subsequent recrystallization process. Although, this technique has been successfully applied by several researchers to find the plastic zone around notches and cracks in various materials and welding beads, few works have been reported using the recrystallization method to determine the residual strains in machined surface. Therefore, the purpose of this investigation Is to explore the effectiveness of the recrystallization technique in machining applications, and in particular, to find the effect of cutting parameters, i.e., depth of cut and rake angle on the plastic strains.

• Tribology and Lubricants
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• v.11 no.5
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• pp.31-39
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• 1995

The surface integrity of a machined surface is an important factor that dictates several performance characteristics of a metal part. In this paper, the surface integrity aspects are presented specifically with respect to the tribological properties of steel. Test specimens were prepared under varying conditions to induce different levels of surface deformation and hardness. Sliding and rolling experiments were performed to assess the friction and wear characteristics of these specimens using a pinon-disk type tribotester and a plate-on-ball type set-up. It is reaffirmed that heat treated steels possess superior sliding and rolling fatigue resistance than raw steel. However, for the case of raw steels machined under varying conditions, the harder specimen resulted in higher wear. This result is attributed to the presence of surface cracks that were induced during machining. The results of such findings will aid in the optimization of surface preparation process for tribological applications of steel.