• 대한기계학회논문집A
• /
• 제34권10호
• /
• pp.1499-1505
• /
• 2010

유연성 공구를 가진 자기연마는 고경도 소재 및 자유곡면 형상 표면의 나노메터급 가공이 가능한 강점을 지닌다. 이러한 자기연마에서 자기연마입자는 시간적, 비용적 측면에서 단순 혼합형 입자가 유리하다. 그러나 단순혼합형 입자는 가공 중 공구로부터 쉽게 이탈하게 되어 가공 시간이 증가 할수록 매우 낮은 가공 효율을 가진다. 따라서 본 연구에서는 단순 혼합형 입자에 오일을 대신하여 실리콘 겔을 매개물로 사용하는 자기연마 입자를 연구하고 그 특성을 분석하였다. 그 결과 자기력 향상과 별개로 입자간 응집력을 높여 입자의 이탈을 줄여 표면거칠기의 향상에 효과가 높음을 확인 하였다. 그리고 실험계획법을 이용하여 고경도 소재인 텅스텐 카바이드의 실리콘 겔 자기연마에서 각 공정변수가 표면거칠기의 향상에 미치는 특성을 평가하고 이를 최적화 하였다.

• 한국정밀공학회지
• /
• 제21권12호
• /
• pp.37-43
• /
• 2004

The performance of magnetic abrasive finishing fur surface is evaluated by the characteristic curve. The characteristic curve is generated by experiment in surface finishing. For experiment, new magnetic inductor is designed and manufactured. 15 kinds of powders are provided to find the relationship between powder characteristic and finishing performance. As powder, Fe-TiC. Polymer-TiC and Fe-NbC are used with different size. The size of abrasives and location are also important factor for the performance. From characteristic curve, two index are obtained, which specify the initial finishing performance and endurance of finishing performance. It is proved that the performance index can be applied to select proper powder for efficient deburring. It is shown that the characteristic curve can be used as good tools for evaluating powder performance in surface finishing and deburring.

• 대한기계학회논문집A
• /
• 제24권11호
• /
• pp.2786-2795
• /
• 2000

Recently, the technology for internal polishing is needed for ultra-clean machining for the prevention of corrosion and pollution of parts is the area of high technology industries such as semiconductor, electronics, telecommunication optics, aerospace, and motors. In this study, an internal polishing system using the magnetic force was developed for the production of ultra-clean tubes with averaged surface roughness ranging from 0.2㎛ to 0.05㎛ or less, and magnetic abrasives composed of WC/Co powder were developed, After finding the optimal condition on each, machining characteristics using newly developed abrasive were analyzed. Form the results obtained by experimental design method, the optimal polishing condition was analyzed and, thhereafter internal polishing was done.

• 한국재료학회지
• /
• 제11권10호
• /
• pp.907-911
• /
• 2001

In order to improve the grindability of magnetic abrasive, Fe-WC magnetic abrasives were made by a plasma melting method after ball milling at various times. This study aims to investigate homogeneously distributed hard phases in Fe matrix and strong bonding between the Fe-matrix and the hard phase. According to XRD, SEM and OM observation, Fe-WC magnetic abrasive powders exhibit the best grindability by plasma melting for 30h ball milling. As a result of magnetic abrasive polishing, the surface roughness, R_{max}$ 5.0$\mu\textrm{m}$, before magnetic abrasive polishing, was reduced to R_{max}$ 2.4$\mu\textrm{m}$. The new magnetic abrasive polishing process is thought to be the useful methods for the automation of three dimensional surface polishing.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2001년도 춘계학술대회 논문집
• /
• pp.960-963
• /
• 2001

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 vibrated and a workpiece is rotated only is tried in a non-ferromagnetic pipe(SUS304), and its finishing characteristics is experimental results, it is found that the vibration effects of magnetic poles on the finishing characteristics are large in internal finishing.

• 한국공작기계학회논문집
• /
• 제18권1호
• /
• pp.22-28
• /
• 2009

In order to optimize the polishing process, Run to Run control scheme has been applied to the micro mold polishing in this study. Also, to fully understand the effect of parameters on the surface roughness a design of experiment is performed. By linear approximation of main factors such as gap and rotational speed of micro quill, EWMA (Exponential Weighted Moving Average) gradual mode controller is adopted as a optimizing tool. Consequently, the process converged quickly at a target value of surface roughness Ra 10nm and Rmax 50nm, and was hardly affected by unwanted process noises like initial surface quality and wear of magnetic abrasives.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2008년도 춘계학술대회 논문집
• /
• pp.371-372
• /
• 2008

• 한국생산제조학회지
• /
• 제19권2호
• /
• pp.184-190
• /
• 2010

Recently, the polishing process using magnetorheological fluids(MR fluids) has been focused as a new ultra-precision polishing technology for micro and optical parts such as aspheric lenses, etc. This method uses MR fluid as a polishing media which contains required micro abrasives. In the MR polishing process, the surface roughness and material removal rate of a workpiece are affected by the process parameters, such as the properties of used nonmagnetic abrasives(particle material, size, aspect ratio and density, etc.), rotating wheel speed, imposed magnetic flux density and feed rate, etc. The objective of this research is to predict MRR according to the polishing conditions based on the multiple regression analysis. Three polishing parameters such as wheel speed, feed rates and current value were optimized. For experimental works, an orthogonal array L27(313) was used based on DOE(Design of Experiments), and ANOVA(Analysis of Variance) was carried out. Finally, it was possible to recognize that the sequence of the factors affecting MRR correspond to feed rate, current and wheel speed, and to determine a combination of optimal polishing conditions.

• 한국안전학회지
• /
• 제26권2호
• /
• pp.13-19
• /
• 2011

The magnetic polishing is the useful method to finish using magnetic power of magnet. That method is one of precision polishing techniques and has an aim of the clean technology using for the pure of gas and inside of the clean pipe. The magnetic abrasive polishing method is not so common for machine that it is not spreaded widely. There are rarely researcher in this field because of non-effectiveness of magnetic abrasive. Therefore, in this paper deals with development of the magnetic abrasive using Sr-Ferrite. In this development, abrasive grain GC used to resin bond fabricated low temperature. And Sr-Ferrite of magnetic abrasive powder fabricated that Sr-Ferrite was crused into 200 mesh. The XRD analysis result show that only GC abrasive and Sr-Ferrite crystal peaks detected which explains resin bond was not any more chemical reaction. From SEM analysis it is found that GC abrasive and Sr-Ferrite were strong bonding with each other by bond. The magnetic polishing is performed by polishing the surface of pipe by attracting magnetic abrasives with magnetic fields. This can be widely applied for finishing machinery fabrications such as various pipes and for other safety processes. In this paper, we could have investigated in to the changes of the movement of magnetic abrasive grain. In reference to this result, we could have made the experiment which is set under the condition of the magnetic flux density, polishing velocity according to the form of magnetic brush.

• 한국자기학회지
• /
• 제6권1호
• /
• pp.28-35
• /
• 1996

자기 테이프 제조용 초미립 자성 철 분말의 분산 거동을 파악하기 위하여 vinyl계 바이더, polyurethane 바인더, 윤활제등 첨가제 종류 및 양에 따른 분산 거동 및 물리특성들을 조사하였다. 분산성은 바인더의 funtional group의 종류, 자성체와 바인더의 비율등에 크게 영향을 받았으며 적정 조건의 선택으로 분산성은 종래보다 20% 증가하 였다. 이에 따라 자기 특성중 포화 자화는 종래의 경우보다 200 Gauss 증가하였으며, 전자 변환 특성중 휘도 S/N (signal to noise ratio)은 2dB 증가하였다. 적절한 윤활제의 종류및 양에 따라 tape의 마찰계수는 0.15 감소하였으며, 이에 따라 tape의 내구성중 휘도 S/N 열화특성이 4dB 이상 향상되었다.