• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.8
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• pp.110-116
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• 2020

Aircraft hydraulic oil reservoirs made with aluminum 7075 have an anodized coating to enable airtightness and corrosion resistance. To maintain a stable oil pressure, the internal surface roughness of the reservoir should be less than approximately 0.2 ㎛. To this end, precision polishing must be performed. However, ensuring the processing quality is challenging, as most polishing operations are performed manually, owing to which, the inner surface roughness is not uniform, and the product quality is irregular. Therefore, we developed a special superfinishing machine to realize the efficient inner polishing of an aircraft hydraulic oil reservoir, by using an abrasive film to improve the process throughput and uniformity. In the experiment involving the superfinishing of an anodized aluminum 7075 cylinder specimen by using the proposed machine, a higher surface roughness than that achieved in the repetitive manual polishing process could be realized.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.1
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• pp.47-53
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• 2001

Results ar presented of a new process for internal precision finishing of slender fine ceramic pipes using a magnetic field generated by a permanent magnets. For finishing the interior surface of a long pipe, a new type of finishing equipment was developed which can be very easily used in an industrial surrounding. In general, the pipe is so slender that a conventional finishing tool is hardly inserted into the pipe deeply, being impossible to finish. Therefore, a new technology has been considered to finish inside of a slender ceramic pipe by a simple technique. In this experimental, Magnetic Abrasive Machining is applied for the inner surface of silicon nitride fine ceramic pipe using ferromagnetic particles mixed with chromium-oxide powder. It is shown the initial roughness of 2.6㎛ Ry(0.42㎛ Ra) in the inside surface can be precisely finished to the roughness of 0.1㎛ Ry(0.01㎛ Ra). This paper discusses the outline of the processing by the application of magnetic abrasive machining and a few finishing characteristics.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.2
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• pp.72-77
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• 2016

Airplane reservoirs made of Al7075 are coated with an anodizing layer to maintain precision, air tightness and corrosion resistance. It is commonly required that the inner surface roughness of the reservoir be less than an average $0.2{\mu}m$ to maintain stable oil pressure. Even though precision polishing is necessary to achieve this quality it is not easy. Inner surface roughness is not uniform and the quality of the product is irregular because most of the work is done by hand. The purpose of this study is to design an exclusive polishing machine and to determine the standard cutting condition and polishing condition necessary for good inner surface roughness and to improve workefficiency.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.947-952
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• 1997

The magnetic polishing is the useful method to finish using magnetic power of a magnet. The time hasn't been that long since the magnetic polishing method was introduced to korea as one of precision polishing techniques. However, the reasons for not being spreaded widely are the magnetic polishing method don't have mediocrity for machine, the efficiency of magnet-abrasive is confined as a bad polishing, and there are not many researchers in this field. The mechanism of this R&D is dealing with the dynamic state of magnet-abrasive. This paper deals with mediocritizing magnetic polishing device into regular lathe and this experiment was conducted in order to get a best surface roughness with low cost. Beside the subsidiary experiment was performed using the mixed magnet-abrasive with general alumina, barium. This paper introduced the main reason for difficulty using this method in industrial field. It needs more continues research on it. This paper contains the result of experiment to acquire the best surface roughness, not using the high-cost polishing material in processing. The average diameters of magnet-abrasive are the particles of 150 $\mu\textrm{m}$, 250 $\mu\textrm{m}$.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.7
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• pp.14-21
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• 2019

Large-diameter hydraulic devices such as the hydraulic reservoir in aircraft that serves to balance the hydraulic pressure in the various hydraulic devices in the cabin and to store hydraulic oil are operated by the internal piston systems. However, since this operates in an environment with high temperature and humidity, it may cause the inner surface to flake during its operation. Therefore, an anodizing surface treatment is applied to improve the corrosion resistance, abrasion resistance, and smooth operation. However, anodizing increases the surface roughness. Accordingly, the polishing process that improves the surface roughness after anodizing is important. However, the existing polishing process is performed manually, which results in an inefficient process. Therefore, in this study, we selected the optimum polishing conditions for effective polishing using the experimental design to improve the polishing process for the $Al_2O_3$ film that forms after anodization. Through experiments, we confirmed that the surface uniformity after polishing was superior as the feed rate was slower when the same polishing time had been applied.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.6
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• pp.701-708
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• 2011

Although Titanium material has superior properties, it belongs to difficult-to-machine materials. The present research applies magnetic abrasive finishing to precision machining of internal-face of titanium pipes, and analyzed & assessed the influence of grinding conditions on magnetic abrasive effects through the removed amount and surface roughness of materials. There was the influence on grinding properties according to change of rotational speed, a total input of mixed powder and an input of grinding liquid, and when the total input, rotational speed and ratio of electrolytic iron versus magnetic abrasives are 8g and 1000rpm, it was most advantageous in aspects of surface roughness and material removal amount, and the grinding liquid remarkably improved the surface roughness and material removal amount only with addition of trace amounts of light oil rather than dry machining conditions. And a result of considering the influence on grinding properties by using an inert gas (Argon gas) for improving grinding properties of the internal-face of titanium pipe, the present research has obtained improvement effects in the removal amount and surface roughness through utilization of an inert gas.

• Journal of the Korean Society of Safety
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• v.17 no.3
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• pp.30-35
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• 2002

The magnetic abrasive polishing is the useful method to finish using magnetic power of a magnet. It's not a long time this method was introduced to korea as one of precision finishing techniques. The magnetic abrasive polishing method is not so common for machine that it is not spreaded widely. The are rarely researcher in this field because of no-effectiveness of magnetic abrasive. The mechanism of this R&D is dealing with the dynamic state of magnet-abusive. This paper deals with mediocritizing magnetic polishing device into regular lathe and this experiment was conducted in order to get the best surface roughness at low cost. We need to continue the research on it. This paper contains the result of experiment to acquire the best surface roughness, not using the high-cost polishing material in processing. The average diameters of magnetic abrasive are the particles of 150$\mu\textrm{m}$, 250$\mu\textrm{m}$.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.166-169
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• 2005

The magnetic polishing is the useful method to finish using magnetic power of magnet. This 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 sanitary pipe for transportation. 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. In this paper. We could have investigated into 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.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.9
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• pp.244-250
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• 2017

The most important aspect determining the completeness of aprosthesis is itsmarginal and internal fit. Alloysare processed using a softening/hardening heat treatment methodin order to improve their mechanical, physical properties and polishing properties. To examinehow the heat treatment method affects the marginal and internal fit of the Ni-Cr alloy core,thirty dental stone models of the abutment of the mandibular left molar were manufactured.The Ni-Cr alloy coreswere manufactured by the dipping method for the experiment and dividedinto three groups; A for no heat treatment, B for softening heat treatment and C for hardening heat treatment. The marginal and internal fitsof all of the groups were measured by the silicone replica technique. A statistical analysis was performed using one-way ANOVA(${\alpha}=0.05$) in order to examine whether there is a significant difference in the average values of the marginal and internal fits among the three groups and it was found that themarginal fits (1, 6) were significantly different (p<0.05), but the internal fits (2, 3, 4, 5) were not significantly different (p>0.05). These results show that Ni-Cr alloys should not be processed bythe heat treatmentmethod.However, they need to be confirmed in further clinical application studies.

• Journal of the Korean Society of Safety
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• v.16 no.3
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• pp.35-40
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• 2001

An internal finishing process applying Magnetic Abrasive Finishing (MAF) was proposed to produce smooth inner surfaces of tubes at a high rate. Since this process uses the tube rotation system, it has been considered applicable only to tubes which are rotatable at high speeds. Here development of the stainless tube(STS 304) rotation system to extend the scope of the application of the internal finishing process applying MAF was made. By the stainless tube(STS 304) rotation system, the abrasive magnetically attracted by the poles is rotated along the inner surface of the tube by magnetic force together with fixed poles, finishing the inner surface of the tube. The main results obtained are as follows : 1) The magnet abrasive finishing minimized influence due to external force because non-contact finishing, 2) The profile of surface roughness decreased very good in 11.4m/min range because abrasive size and speed, 3) The profile of surface roughness by flux density decreased in finishing speed 28m/min, 4) The profile of surface roughness by fled rate decreased in 0.16mm/rev and 0.18mm/rev.