• 소성∙가공
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• 제15권1호
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• pp.57-64
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• 2006

High speed milling experiment on the hardened mold steel (CALMAX at hardness of HRC 55) is carried out using small diameter ball endmills. Tool lift and wear characteristics under the various machining parameters are investigated Effect of dynamic runout on the wear of the tool is also studied. For most of the cases, catastrophic chipping of tool edge is not observed and uniformly distributed wear on the flank surface of the tool is obtained. It is found that lower rate of tool wear is obtained as the cutting speed is increased. Also, high pick feed rate is found to be more favorable in terms of the tool wear and material removal rate.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2005년도 금형가공,미세가공,플라스틱가공 공동 심포지엄
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• pp.114-120
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• 2005

High speed milling experiment on the hardened mold steel (CALMAX at hardness of HRc 55) is carried out using small diameter ball endmill. Tool lift and wear characteristics under the various machining parameters are investigated. Effect of dynamic runout on the wear of the tool is also studied. For most of the cases, catastrophic chipping of tool edge is not observed and uniformly distributed wear on the flank surface of the tool is obtained. It is found that lower rate of tool wear is obtained as the cutting speed is increased. Also, high pick feed rate is found to be more favorable in terms of tool wear and material removal rate.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.553-556
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• 2003

End-milling have been used in the industrial world because it is very effective to the manufacture of mechanical parts with various shape. Recently the end-milling processing is needed the high-precise technique with good surface roughness and rapid time in aircraft, automobile part and molding industry. Therefore this study carried to decide the optimum cutting condition for surface roughness and rapid manufacturing time using design of experiment and ANOVA. From the results of experimentation, surface roughness have an effect on cutting direction, spindle speed and depth of cut. And then the optimum condition used Taguchi design is upward cutting in cutting direction, 600rpm in spindle speed, 240mm/min feed rate, 2mm in axial depth of cut and 0.25mm radial depth of cut. By using design of experiment, it is effectively represented shape characteristics of working surface in end-milling.

• 한국식품과학회지
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• 제8권1호
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• pp.1-5
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• 1976

1. 통일벼의 도정에 있어서 현백율은 회전 950 rpm, 로울러입도 36 mesh, 90% 유량일 때 수율이 좋고 정미능력은 회전 1050 rpm, 로울러입도 40 mesh, 유량 100%일 때가 가장 좋다. 2. 통일쌀의 단백질함량은 기존 품종보다 약 1% 높았다. 3. 도정에 따라 지방, 회분 섬유 비타민 $B_1$, $B_2$ 성분의 변화가 가장 심하였고 10분도미에 비하여 7분도미로 할 경우 지방은 10% 비타민 $B_1$은 30%, $B_2$는 20%의 손실을 막을 수 있었다.

• 한국기계가공학회지
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• 제16권4호
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• pp.24-29
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• 2017

This paper provides an experimental analysis on the breakage of the coated tool using the face-milling cutter of the machining center due to changes in the cutting speed and the feed rate. The experimental studies were conducted using STS 304 materials and the damage to the tool was analyzed according to the change in machining time. The experiments confirmed that the cutting speed and feed rate affected the tool damage and the mechanical impact and thermal shock were determined to severely damage the tool. From the production engineering point of view, it has been experimentally investigated that the increased feed rate significantly influences the material removal rate more than the increased cutting speed.

• 한국세라믹학회지
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• 제34권6호
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• pp.668-676
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• 1997

Al2O3/SiC nanocomposites are fabricated through intensive ball milling to mix fine SiC particles uniformly with the Al2O3 powder. Another role of milling is to reduce particle sizes by crushing particles as well as agglomerates. However, balls are worn during ball milling and the sample powder mixtures pick up to weight loss of the balls. In this study, pressureless sintering was performed to obtain Al2O3/SiC nanocomposites. It was found that the wear rate of zirconia balls during milling was considerable, and the zirconia addition after even a few hours of ball milling could increase the sintering rates of the nanocomposites significantly. Thus, addition of ZrO2 changed the sintering behaviors as well as mechanical properties of Al2O3/SiC nanocomposites.

• Journal of Biosystems Engineering
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• 제26권5호
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• pp.469-474
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• 2001

Milling the rice with low moisture requires more energy, produces more cracked rice, and results in reducing taste of cooked rice. Accordingly, it is necessary to add moisture to the rice with low moisture to obtain optimum moisture level for milling and taste of rice. This study was performed to evaluate the influence of initial moisture content and absorption rate on rice crack, milling energy and whiteness of milled rice and to obtain the information for design of rewetting system mounted on stirring device in grain bin. The tests were conducted for the four levels of initial moisture content in the range of 11.4 to 14.5%(w.b.) and six levels of absorption rate in the range of 0.04 to 1.0%, w.b./hr. In the case of lower moisture content below 12%(w.b.), crack ratios of brown rice were remarkably high regardless of initial moisture contents. Therefore, it was found that rough rice below 12%(w.b.) in initial moisture content could not rewetted by spraying water without crack generation of low level. Absorption rate must be below 0.3%, w.b./hr to maintain crack ratio increase of less than 1% regardless of initial moisture contents. In the case of allowable crack ratio increase of 2% and 5%, it was found that the maximum absorprion rate was respectively 0.6%, w.b./hr and 1.0%, w.b./hr in the initial moisture content of above 13.5%(w.b.). Rewetting the rough rice in moisture content of 11.4 to 14.5%(w.b.) to 14.3 to 16.9%(w.b.) decreased milling energy consumption by 15.9 to 22.3%. The effect of energy saving was higher in the samples of higher initial moisture content. Whiteness of milled rice was decreased by 0.5 to 1.5.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.1902-1906
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• 2003

Micro-milling is an efficient method for fabricating micro structures because of its high machining rate compared with other non-conventional micro machining processes. But it is not easy to make a micro milling tool with less than 50 $\mu\textrm{m}$ in diameter by conventional machining. In this study, the characteristics of a micro milling tool fabricated by wire electrical discharge machining (WEDM) were studied. The workpiece is copper and stainless steel. The effects of some machining conditions such as feed rate, depth of cut, and a shape of tool were studied. The tools with D-shape and square shape in cross section were tested for machining micro grooves and 3D structures.

• 한국생산제조학회지
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• 제25권1호
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• pp.83-88
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• 2016

Because of the increasing tool cost for cutting hard-to-cut materials, abrasive water jet (AWJ) milling recently has been regarded as a potential alternative machining method. However, it is difficult to control the depth and width of cut in AWJ milling because they vary depending on many AWJ cutting parameters. On 27 conditions within a limited range of pressure, feed rate, and abrasive flow rate, AWJ cutting was conducted on titanium, and depth profiles were measured with a laser sensor. From the depth profile data, depth and width of cut were acquired at each condition. The relationships between depth and parameters and between width and parameters were derived through regression analysis. The former can provide proper cutting conditions and the latter the proper pick feed necessary to generate a milled surface. It is verified that pressure mostly affects depth, whereas abrasive flow rate mostly affects width.

• 대한금속재료학회지
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• 제49권6호
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• pp.454-461
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• 2011

In this study, the relationship between corrosion resistance and microstructural characteristics such as grain size reduction, preferred orientation, and homogenous distribution of elements and impurity by mechanical milling of magnesium powder was investigated. Mechanical milling of pure magnesium powder exhibited a complex path to grain refinement and growth together with preferred orientation reversal with milling time. It was also found that anisotropic formation of dislocation on the basal plane of magnesium was initially the dominant mechanism for grain size reduction. After 60 hrs of milling, grain coarsening was observed and interpreted as a result of the strain relaxation process through recrystallization. In spite of the finer grain size and strong (002) texture developed in the sample prepared by spark plasma sintering at $500^{\circ}C$ for 5 min after mechanical milling for 2hrs, the sample showed a higher corrosion rate. The results from this study will be helpful for better understanding of the controlling factor for corrosion resistance and behaviors of mechanical milled magnesium powders.