• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1579-1582
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• 2005

Polishing is cutting process that polished workpiece by relative motion of abrasive grain between polishing tool and workpiece. According to relative motion forms(polishing patterns) of abrasive grain, the surface quality is different. Then, polishing patterns are important essential in polishing process. In work field, polishing patterns are determined by an expert of experience. Therefore, to work effective polishing, it is necessary that evaluate polishing characteristics for polishing patterns. And, polishing machine is made with cartesian coordinate robots, we estimate polishing characteristics by measurement of surface roughness.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.10
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• pp.58-67
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• 1997

Generally, die polishing process occupies about 30 .approx. 50% of the whole die manufacturing time. However, die polshing has not been automated yet, since it needs a great deal of experience and skill. This study aims at development of an expert system for die polishing which gives such optimal parameters as tool and polishing conditions. Through experiments, polishing characteristics such as surface roughness, stock removal and scratch were analyzed quantitatively for each polishing tool, and a knowledge base for the expert system was established. Evaluation tests show that the developed system works well to suggest the optimal polishing conditions and it is very promising.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.5
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• pp.761-766
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• 2012

Abrasive fluid jet polishing processes have been used for the polishing of optical surfaces with complex shapes. However, unstable and unpredictable polishing spots can be generated due to the fundamental property of an abrasive fluid jet that it begins to lose its coherence as the jet exits a nozzle. To solve such problems, MR fluid jet polishing has been suggested using a mixture of abrasives and MR fluid whose flow properties can be readily changed according to imposed magnetic field intensity. The MR fluid jet can be stabilized by imposed magnetic fields, thus it can remain collimated and coherent before it impinges upon the workpiece surface. In this study, MR fluid jet polishing characteristics of fused silica glass were investigated according to injection time and magnetic field intensity variations. Material removal rates and 3D profiles of the generated polishing spots were investigated. From the results, it can be confirmed that the developed MR fluid polishing system can be applied for stable and predictable precise polishing of optical parts.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.311-315
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• 2001

This paper presents the result of basic study about corrective polishing for arbitrary surface figure. In this study, we researched polishing characteristics on the working condition of optical glass. The abrasive size, relative velocity and working pressure were selected major factors that affect polishing process. The Preston's equation which is the representative model of polishing process was used to model the unit removal shape. The Preston's coefficient and unit removal function were calculated from the polished surface. Applying these results, we have shown that the systematic corrective polishing of arbitary figure is feasible through experiments and analysis.

• Tribology and Lubricants
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• v.32 no.2
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• pp.56-60
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• 2016

Sapphire has a high hardness and strength and chemical stability as a superior material. It is used mainly as a material for a semiconductor as well as LED. Recently, the cover glass industry used by a sapphire is getting a lot of attention. The sapphire substrate is manufactured through ingot sawing, lapping, diamond mechanical polishing (DMP) and chemical mechanical polishing (CMP) process. DMP is an important process to ensure the surface quality of several nm for CMP process as well as to determine the final form accuracy of the substrate. In DMP process, the material removal is achieved by using the mechanical energy of the relative motion to each other in the state that the diamond slurry is disposed between the sapphire substrate and the polishing platen. The polishing platen is one of the most important factors that determine the material removal characteristics in DMP. Especially, it is known that the geometric characteristics of the polishing platen affects the material removal amount and its distribution. This paper investigated the material removal characteristics and the effects of the polishing platen groove in sapphire DMP. The experiments were preliminarily carried out to evaluate the sapphire material removal characteristics according to process parameters such as pressure, relative velocity and so on. In the experiment, the monitoring apparatus was applied to analyze process phenomena in accordance with the processing conditions. From the experimental results, the correlation was analyzed among process parameters, polishing phenomena and the material removal characteristics. The material removal equation based on phenomenological factors could be derived. And the experiment was followed to investigate the effects of platen groove on material removal characteristics.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1836-1839
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• 2003

This paper describes the surface polishing characteristics of a flat and free surface ferromagnetic substance(SM45C) that magnetic abrasive polishing processed. The effects of the various working factors on the surface roughness are clarified by experiments respectively, such as magnetic flux density. rotation speed of magnetic head. working gap, feed rate of workpiece. diameter of magnetic abrasives. and shape of workpiece. On the basis of these experiments, the polishing mechanism is discussed and the characteristics of the polishing process are described. In addition, it is found experimentally that die ＆ mold surfaces are also polished precisely by this process

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.20 no.5
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• pp.632-638
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• 2011

Recently, it has been studying for the polishing process of micro parts widely. However, present MR polishing system, it is difficult to minimize electromagnet and to polish sphere or slope parts. Then, it can not be obtained demanded surface quality. In this study, material removal characteristics of BK7 glass using round endmill type MR polishing system were investigated through series of experiment. The experiments were investigated by changing imposed polishing conditions, such as rotational speed and polishing depth. As a results, very high material removal was obtained at 0.7mm gap distance, 1,980rpm.

• Transactions of Materials Processing
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• v.22 no.2
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• pp.74-79
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• 2013

The ultra-precision polishing method using MR fluid has come into the spotlight for polishing metals and optical materials. The MR fluid jet polishing process can be controlled using a change of viscosity by an imposed magnetic field. The MR fluid used for polishing process is a mixture of CI particles, DI water, $Na_2CO_3$ and glycerin. The efficiency of polishing depends on parameters such as polishing time, magnetic field, stand-off distance, pressure, etc. In this paper, the MR fluid jet polishing was used to polish nickel and brass mold materials, which is used to fabricate backlight units for 3-D optical devices in mobile display industries. In MR jet polishing, ferromagnetic materials like nickel can decrease the polishing efficiency by interaction with the cohesiveness of the MR fluid more than non-ferromagnetic materials like copper. A series of tests with different polishing times showed that the surface roughness of brass (Ra=1.84 nm) was lower than that of nickel (Ra=2.31 nm) after polishing for 20 minutes.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.04a
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• pp.27-33
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• 2004

Electro-theological fluid is recently used for the micro polishing of 3-dimensional micro-aspherical lens. It's also used for polishing small area defects on the wide flat wafer. Since ER fluid shows a behavior of viscosity changing under certain electric fields. micro polishing efficiency may be enhanced for certain cases. In this paper, a perfluorinated carbonyl fluoride oil based ER fluids was used to improve surface polishing rate and submicron-scale accuracy. As the polishing electrodes, micro size cylindrical tools had been used for maximizing the electric field. An experimental device, which was applied for micro polishing a number of wafers of 4inches in size and other workpiece. was made on a precision polishing system. It consisted of a steel electrode. a wafer fixture. l0㎃ current and DC 5㎸ power supply unit, and a controller unit. From the Experiments. the ER fluid is applicable for micro polishing of small parts.

• Proceedings of the Safety Management and Science Conference
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• 2004.11a
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• pp.189-195
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• 2004

It compared quality characteristics for the stone surface treatment system and its products. With the result, the flame burner equipment was mainly used to the surface treatment of granite, but it occurred greatly the high temperature, the rock fragment, the noise and dust. For the other side, the whetstone polishing machine for the polishing was a maintenance for the specific physical properties of stone, and it did not occur the stone fragment and the dust. The durability of the stone products due to the flame burner was investigated with that it falls to $20\sim25\%$ more than the surface treatment by the whetstone polishing. Share's hardness of the polishing products in the durability test showed more greatly index than the flame burner and conventional product. The polishing products of Pochon stone in the case of the abrasion resistance showed great more $15\%$ than the general products, more $9\%$ than the products by the flame burner.