• Journal of the Korean Society of Manufacturing Process Engineers
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• v.7 no.2
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• pp.23-30
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• 2008

As a basic machining process, turning is a widely used machining process in which a single-point cutting tool removes material from the surface of a rotating material. A common method of evaluating machining performance is to measure the surface roughness. In a turning operation, it is important to select cutting conditions for achieving high cutting performance. As a rule, cutting conditions can be classified into feed rate, depth of cut and insert radius. While cutting process even though cutting conditions are optimized, the average roughness can be deterioration due to wear of the cutting tool edge. In this study, the aim is to maintain the average roughness even though the cutting condition is irregularly changing within the predictable range due to the working environment. First, the surface roughness model influenced by cutting conditions is constructed based on the experimental results in a turning operation, Second, applying the sliding mode control theory to the turning operation model which is composed of the surface roughness model and the motor transfer function, the surface roughness is closed to the desired value. Finally, the effectiveness of this approach is demonstrated through the computer simulation.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1997.04a
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• pp.82-87
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• 1997

In order to make unmanned machining systems with satisfactory performances, it is necessary to incorporate appropriate condition monitoring systems in the machining workstation to provide the required intelligence of the expert. This paper deals with condition monitoring for tool wear and fracture during turning operation. Developing economic sensing and identification methods for turning processes, sound pressure measurement and digital signal processing technique are proposed. The validity of the proposed system is confirmed through the large number of cutting tests.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.6 no.3
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• pp.36-43
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• 1997

In order to make unmanned machining systems with satisfactory performances, it is necessary to incorporate appropriate condition monitoring systems in the machining workstations to provide the required intelligence of the expert. This paper deals with condition monitoring for tool wear and breakage during turning operation. Developing economic sensing and identification methods for turning processes, sound pressure measurement and digital signal processing technique are proposed. The validity of the proposed system is confirmed through the large number of cutting tests.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.1
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• pp.82-88
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• 2009

Ultra-precision turning is highly needed to manufacture molds for precision lens. In this study, micro-turning combined with elliptical vibration cutting (EVC), which is known to enhance micro- machining quality, was investigated by installing a rotary stage into the micro-grooving machine. From machining experiments involving materials of copper, brass, and aluminum and single and poly crystalline diamond tools, it was found that EVC produced thinner and curlier chips and that better surface finish could be achieved, compared with conventional turning, owing to prohibition of formation of burrs and built-up edges. Therefore, we found EVC micro turning could be readily utilized to manufacture precision mold.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.24 no.6
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• pp.274-278
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• 2014

Machining performance is often limited by chatter vibration at the tool-workpiece interface. Chatter vibration is a type of machining self-excited vibration which originated from the variation in cutting forces and the flexibility of the machine tool structure. Cutting tooling method is one of major factor to chatter vibration in turning process. Even though lots of cutting tooling methods are developed and used in machining process, precise analysis of cutting tooling effect in view of chatter vibration behavior. This study presents numerical and experimental approaches to verify and effects of various cutting tooling geometry and clamping method on the onset of chatter vibration. Acquired knowledge from this study will apply the optimal geometry design of cutting tooling and adjusting of machining process.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.12
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• pp.47-54
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• 2008

Hard turning process can be defined as a single-point machining process carried out on "hard" materials. The process is intended to replace or limit traditional grinding operations that are expensive, environmentally unfriendly, and inflexible. The purpose of this study is to achieve a systematic understanding of machining characteristics and the effects of machining parameters on cutting force, tool wear shape and chip formation by the outer cutting of a kind of wear resistant tungsten carbide V30. Hard turning experiments were carried out on this alloy using the PCD (Poly Crystalline Diamond), cBN (cubic Boron Nitride) and PcBN (Polycrystalline cubic Boron Nitride) cutting tools. The PcBN and the usual cBN tools were used to be compare with the PCD tool and the dry turning was carried out. The PcBN is attractive as the tool material which replaces the PCD. The tool wear width and cutting force were measured, and the worn tool and chip were observed. The difference of the tool wear mechanism among the three tool materials was investigated.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.12
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• pp.198-203
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• 1999

In this study, chip-tool friction and shear characteristics of cold drawn free machining steels in turning were assessed. To do this, a newly developed equivalent oblique cutting model was adopted. And for comparison with those of free machining steels, chip-tool friction and shear characteristics of conventional carbon steels were also investigated. The Pb-S free machining steel shows superior machinability to others. In case of the Bi-S free machining steel, the shear stress and the specific friction energy are relatively lower than those of conventional carbon steels, but its shear strain is relatively high, so it does not show any remarkable improvement of machinability.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.3
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• pp.19-23
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• 2012

Glassy carbon is widely used for high temperature melting process such as quartz due to its thermal stability. For utilizing Classy Carbon to glass mold press(GMP) optical lens, brittleness of Glassy Carbon is main obstacle of ultraprecision machining. Thus authors investigated ductile machining of Glassy Carbon adopting turning and grinding process respectively. From the experiments, ultraprecision turning surfaces resulted brittle crack in all machining conditions and ultraprecision grinding surfaces showed semi-ductile mode in small undeformed chip thickness conditions.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.20 no.4
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• pp.382-385
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• 2011

There is an immense need to obtain nanometric surface finish on optical glass owing to the advantage of improved performance of the components. But owing to brittleness and hardness, optical glass is one of the materials that is difficult to ultra-precision turning. According to the hypothesis of ductile mode machining, regardless of their hardness and brittleness, will undergo a transition from brittle to ductile machining region below a critical undeformed chip thickness. Below this threshold, it is suggested that the energy required for plastic formation. Thus, plastic deformation is the predominant mechanism of material removal in machining these materials in this mode. An experimental study is conducted diamond cutting for machining BK7 glass. The investigation presents the feasibility of achieving nanometric surface and the understanding the mechanism of cutting glass, proving the cutting edge radius effect.

• Journal of ILASS-Korea
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• v.10 no.2
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• pp.10-17
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• 2005

The proposed research has been performed to know the characteristics of cutting fluid aerosol formation using Dual-PDA system in machining process. The cutting fluid aerosol size and concentration is common attributes that quantify the environmental intrusiveness or air quality contamination. The atomized cutting fluid aerosols can be affected to human health risk such as lung cancer and skin irritations. Even though cutting fluid can be improved the machining quality and productivity in a carefully. its use must be controlled and optimized carefully. This experimental works using Dual-PDA were performed to analyze the cutting fluid aerosol behaviors and characteristics in turning process using precise aerosol particle measuring system. The obtained experimental results profovide basic knowledge to develop the environmentally conscious machining process. This results cail be provided as a basis to estimate and control the hazardous cutting fluid aerosol in machining process.