• 한국정밀공학회지
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• 제22권2호
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• pp.202-209
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• 2005

A new effective thick-layered RP process, Transfer-type Variable Lamination Manufacturing using expandable polystyrene foam (VLM-ST) has been developed with thick layers and sloped surfaces. VLM-ST has the innate advantages by virtue of its working principle: high building speed, low cost for introduction and maintenance of VLM-ST apparatus, little staircase surface irregularities of parts. Despite these advantages in VLM-ST, the surface roughness of VLM-ST parts is still inadequate to be used as RP master patterns for rapid tooling (RT). This paper describes the systematic and effective methodology to remove the laminated pattern and improve the surface roughness for VLM-ST parts. From the results of surface finishing of VLM-ST parts, it can be seen that the laminated pattern is completely removed and the surface characteristics such as surface roughness, surface hardness, and paintability are improved.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1994년도 추계학술대회 논문집
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• pp.108-112
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• 1994

The paper describes the effects of magnetic field on the electrochemical polishing process in the view of ionic in the electrolyte. Theoretical background was suggested how magnetic field increases the material removal efficiency and surface finishing ability Magnetic field changes the jonic movement in the electrolyte from linear motion to curved or complex oscillating one, thus increases the electrolytic current density and, as the results, the finishing efficiency.

• 한국세라믹학회지
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• 제46권1호
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• pp.102-107
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• 2009

This study has been focused on an effective surface finishing method combining ELID (ELectrolytic In-process Dressing) and MAP (Magnetic Assisted Polishing) for the nano-precision mirror grinding of glass-lens molding mould. ELID grinding is an excellent technique for mirror grinding of various advanced metallic or nonmetallic materials. A polishing process is also required for elimination of scratches present on ELID grinded surfaces. MAP has been used as polishing method due to its high polishing efficiency and superior surface quality. It also presents some techniques for achieving the nanometer roughness of the hard material such as WC-Co, which are extensively used in precision tooling material.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.1840-1843
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• 2003

The Magnetorheological fluid has the properties that its viscosity has drastic changed under some magnetic fields therefore, Magnetorheological fluids has been used for micro polishing of the micro part( for example, a aspherical surface in a micro lens). The polishing process may appears as follows. A part rotating on the spindle is brought into contact with an Magnetorheological finishing(MRF) fluids which is set in motion by the moving wall. In the region where the part and the MRF fluid ate brought into contact, the applied magnetic field creates the conditions necessary for the material removal from the part surface. The material removal takes place in a certain region contacting the surface of the part which can be called the polishing spot or zone. The polishing mechanism of the material removal in the contact zone is considered as a process governed by the particularities of the Bingham flow in the contact zone. Resonable calculated and experimental magnitudes of the material removal rate for glass polishing lends support the validity of the approach.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.964-967
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• 2002

An internal finishing process by the application of magnetic abrasive machining has been developed as a new technology to obtain a fine inner surface of pipe. In this paper, another method of magnetic abrasive machining in which the N and S magnetic poles are feed and a workpiece is rotated only is tried in a fine-pipe, and its finishing characteristics is experimently investigated by various effective factors such as feeding amplitude. From the experimental results, it is found that the feed effects of magnetic poles on the finishing characteristics are large in internal finishing.

• 한국정밀공학회지
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• 제23권12호
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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.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 춘계학술대회 논문집
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• pp.937-941
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• 1997

Utomatic finishing process requires the development of high efficient and precision abrasive machining method for die and molds. This study describes the evaluation of the finishing characteristics, such as sufrace roughness, topography and material removal depth, of the electrolytic chemical mixed abrasive machining method. Experimental setup is composed of 3 axis machining center, a newly developed finishing attachment with constant pressure, electrode and electrolytic bath. Finally, we achieved a successful result that surface roughness is 0.01 .mu. m Ra and material removal depth is 145 .mu. m after 100 times repeat-finishing using electrolytic (0.8A,30V) mixed abrasive (#400 CBN, #320 Sic) machining method.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.1768-1771
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• 2003

Hard turning replaces grinding for finishing process with expectations of higher productivity and demanded surface quality. Especially for the surface roughness as surface quality demanded in finishing process of hard turning, know-how of machining characteristics of hardened materials by cutting force analysis should be accumulated in company with achievement of precision of elements and high stiffness design technology in hard turning. Considering chip formation mechanism of hardened materials, adequate cutting conditions are selected for machining experiments and cutting forces are measured according to cutting conditions. Increase of cutting forces especially thrust force and increase of dynamic instability could occur in hard turning. Analysis of dynamic characteristics of the cutting forces is executed to investigate relation between dynamic instability and surface roughness in hard turning. Investigation on effects of relative motion of machining system generated by vibration due to dynamic instability shows that ultimate surface roughness could be predicted considering relative motion of machining system with geometrical surface roughness.

• Composites Research
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• 제30권6호
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• pp.416-421
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• 2017

CFRP와 금속간의 접합공정이 개선된 구조용 접착제가 제조되었다. 구조용 접착제에 대한 경화시간, 기지재료의 표면상태 그리고 접착제의 양에 따른 최적의 접합공정 조건을 랩쉐어 실험을 통하여 파악하였다. 적합한 접합조건을 확인하기 위해 이종재료간의 접합 파단면 상태를 반사현미경을 이용하여 평가하였다. 이종재료간 접합력 향상을 위해 접착제의 개선뿐만 아니라 CFRP의 표면처리 또한 중요하였다. 구조용 접착제의 경우 180도 조건에 20분의 경화온도 조건이 최적이였으며, CFRP의 표면 처리에 따라 접합특성이 향상됨을 확인하였다. 이종재료 간 접합을 위해 구조용 접착제의 양은 $1.5{\times}10^{-3}g/mm^2$ 조건일 때 최적이었다. 접합공정의 개선 및 최적화를 통해 기존의 접착력 대비 10% 이상의 물성 강화를 나타냄을 확인하였다.

• 한국기계가공학회지
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• 제3권1호
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• pp.7-14
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• 2004

Machining error is defined the normal distance between designed surface and actual tool path with tool deflection. This is inevitably caused by the tool deflection, tool wear, thermal effect and machine tool errors and so on. Among these factors, tool deflection is usually known as the most significant factor of machining error. Tool deflection problem is analyzed using Instantaneous horizontal cutting forces. The high quality and precision of machining products are required in finishing. In order to achieve these purposes, it is necessary work that decrease the machining error. This paper presents a study on the machining error caused by the tool deflection in ball end milling of 2 dimensional surface. Tool deflection model and simple machining error prediction model are described. This model is checked the validity with machining experiments of 2 dimensional surface. These results may be used to decrease machining error and tool path decision.