• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.2
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• pp.311-316
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• 2008

Powder type Ag system insert metals were manufactured by ball milling process. The variables of milling process were constant except the milling time. The milling times were selected for 24, 48 and 72 hours. The insert metals made by milling process were evaluated by performing scanning electron microscope, DSC(differential scanning calorimetry) analyses, spreading test and further in terms of wettability test. The selected insert metals that have the good characteristics compared to commercial insert metals were applied to make the brazed joints. The characterizations of those brazed joints were also conducted by microstructural observations. The results indicated that milling time of 48 hours for making powder type insert metals was the best condition showing the good spreadibility, low wetting angle. The brazed joints that applied the 48 hours milled insert metal were very sound condition indicating the stable microstructure in spite of containing small amount of porosity and the microhardness value of the joint was about 138VHN.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.04a
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• pp.21-26
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• 2004

This research presents a modeling and a manufacturing method of insert type milling cutters such as face cutter, flat endmill and ball endmill. The methods introduced in this paper adopts the multi-tasking 5-axis machining that is increasing machining accuracy of holder and position accuracy of bolting points. So this can be used in the basic document of the total package program that involves modeling and manufacturing module in various insert cutters.

• Journal of Biosystems Engineering
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• v.42 no.2
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• pp.112-116
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• 2017

Purpose: The purpose of this study was to analyze the milling characteristics of white rice depending on the guide angles of the cutting roller's induced guide, as well as to verify optimum milling conditions for the cutting-type milling machine. Methods: Brown rice, which was produced in Cheongju-si, Chungcheongbuk-do, Republic of Korea, in 2014, was used as the experimental material. The milling characteristics of white rice were measured under six different guide angle levels of the cutting roller, which were none, $0^{\circ}$, $5^{\circ}$, $10^{\circ}$, $15^{\circ}$, and $20^{\circ}$. The quantity of brown rice for each experiment was 500 kg, and the milling characteristics were measured according to the whiteness, rice temperature, cracked rice ratio, broken rice ratio, and energy consumption. Results: The whiteness of white rice maintained a uniform level, indicating at range of $38{\pm}0.5$, regardless of the cutting roller guide angles under all conditions. The rice temperature rise during milling was found to be rather low, at $13.9^{\circ}C$ and $13.6^{\circ}C$ at $10^{\circ}$ and $15^{\circ}$ guide angles, respectively. The cracked rice ratio after milling was 18.67%-19.47%, and the broken rice ratio was 0.68% at a $10^{\circ}$ guide angle, which is the lowest in comparison to other guide angles. Energy consumption was lower when the guide was used compared to that with-out the use of the guide. The energy consumption tended to increase as the cutting roller guide angle increased. Conclusions: From the above results, we conclude that the cutting roller guide angles of $0^{\circ}$ and $10^{\circ}$ are suitable for producing high quality rice during milling with a cutting-type milling machine.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.4
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• pp.167-172
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• 2005

In this paper. micro electrochemical machining (ECM) for micro structure fabrications is presented. By applying ultra short pulses. the chemical reaction can be restricted only to the region very close to the electrode. Micro ECM is applied to machining micro structures through electrochemical milling process becasuse it doesn't suffer from tool wear. Using this method. 3D micro structures were machined on stainless steel. It was found that micro machining is possible with good surface quality in the low concentration electrolyte,0.1 M H₂SO₄. In ECM, as the machining depth increases, better flushing of electrolyte is required for sufficient ion supply. Layer-by-layer milling is advantageous in flushing. However, layer-by-layer milling causes taper of structures. To reduce the taper, application of a disk-type electrode was introduced. By electrochemical milling, various 3D micro structures including a hemisphere with 60 ㎛ diameter were fabricated.

• Transactions of the Korean hydrogen and new energy society
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• v.8 no.4
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• pp.181-185
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• 1997

The electrochemical properties of the $AB_2$-type (Zr-Ti-V-Ni-Cr-Co-Mn) metal hydride electrodes prepared by ball milling with $AB_5-type\{(LM)Ni_{3.6}Al_{0.4}Co_{0.7}Mn_{0.3}\}$(LM : Lanthanum-rich mischmetal) alloy powder as a surface activator were investigated. By ball milling with $AB_5$ type alloy powder, the activation of $AB_2$ type metal hydride electrode was accelerated resulting in an increase of discharge capacity from 35% to 85% of the maximum capacity at the first cycle. As the amount of surface activator increased the activation rate increased, whereas the discharge capacity increased with 10wt% and decreased with 20wt% addition of the surface activator. When the amount of the surface activator was kept constant as 10wt%, the discharge capacity and the activation rate increased with ball milling time up to 20 hours. However beyond 20 hours of ball milling time, they decreased drastically due to the nano-crystallization or amorphorzation of the alloy powder.

• Food Engineering Progress
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• v.21 no.2
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• pp.110-115
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• 2017

This study aimed to identify milling characteristics depending on the number of a cutting roller's air vent and blowing velocity to remove rice bran by the cutting type milling machine which can minimize the conventional milling process. The level of whiteness was found to be $38{\pm}0.5$ in all the conditions, showing consistent whiteness levels during milling. The rice temperatures turned out to be 15.4 and $14.6^{\circ}C$ which were rather low-level under the conditions of the cutting roller with 3 vents and blowing velocities of 35 and 40 m/s respectively. Cracked rice ratio was 2.13% under the conditions of the cutting roller with 3 vents and a blowing velocity of 35 m/s. Broken rice ratio showed the range of 0.762-0.869%, reflecting a low level. Turbidity after milling was decreased, as blowing velocity became faster. Energy consumption for milled rice production was decreased, as blowing velocity became faster. The optimum milling condition for cutting type milling machine depending on air vent number of cutting roller and blowing velocity was found to be 3 vents and 35 m/s.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.04a
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• pp.394-397
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• 2004

This paper presents a simple analytic method using 2D simulation program for predications of cutting force and machining temperature in dry type milling process. And also, comparison of cutting force and machining temperature obtained from experiment and simulation work is accomplished to distinguish of suitability.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.2
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• pp.196-205
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• 2004

The cutting characteristics and the deformed layer of nitrogen(N)-added type 316LN stainless steel were comparatively investigated to type 316L stainless steel. The cutting force, the surface roughness(Ra) and the tool wear in face milling works were measured with cutting conditions, and the deformed layers were obtained from micro-hardness testing method. The cutting resistance of type 316LN was similar to type 316L in spite of its high strength. The surface roughness of type 316LN was superior to type 316L for all the cutting conditions. In particular, in the high cutting speed above 345m/min, the surface roughness of the two stainless steels was closely same. The deformed layer thickness of the two stainless steels was generated in the 150$\mu\textrm{m}$-300$\mu\textrm{m}$ ranges, and its value of type 316LN was lower than that of type 316L. This is due to the high strength properties by nitrogen effect. It was found that type 316LN was higher in the tool wear than that type 316L, and flank wear was dominant to crater wear. In face milling works of type 316LN steel, tool wear is regarded as a important problem.

• Journal of the Korean Magnetics Society
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• v.24 no.1
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• pp.1-10
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• 2014

$Co_2Z$-type barium ferrites ($Ba_3Co_2Fe_{24}O_{41}$) were synthesized using variation method. First, M-type, $Co_2Y$-type and $Co_2Z$-type synthesized by hydrothermal method. Second, M- and Y-type precursors for synthesis of $Co_2Z$ hexaferrite by hydrothermal and ball milling method. the morphology, structure and magnetic properties of the barium ferrite particles were characterized using XRD, FESEM, VSM, impedance. As a result, Single phase of M-type and $Co_2Y$-type were obtained. Manufactured powders of M+Y ball milling, M+Y hydrothermal were similar to single phase of $Co_2Z$-type hexaferrite, all powders were obtained theoretical magnetization (50 emu/g). The largest initial permeability were obtained $Co_2Z$ hexaferrite synthesized by reagent precusor, With increasing calcination temperature was lowered the initial permeability. In another synthesis didn't almost that little change could be found.

• Korean Journal of Materials Research
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• v.24 no.11
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• pp.591-598
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• 2014

In this research, magnesium powder was prepared by gas atomizing. Refinement behaviors of magnesium powder produced under different conditions were investigated using a mechanical milling (attrition milling) process. Analyses were performed to assess the characterization and comparison of milled powder with different steel ball sizes and milling times. The powders were analyzed by field emission scanning electron microscope, apparent density and powder fluidity. The particle morphology of the Mg powders changed from spherical particles of feed metals to irregular oval particles, then plate type particles, with an increasing milling time. Because of the HCP structure, deformation occurs due to the existence of the easily breakable C-axis perpendicular to the base, which results in producing plate-type powders. An increase in ball size and the impact energy of the magnesium powder maximizes the effect of refinement. Furthermore, it is possible to improve the apparent density and fluidity according to the smoothness of the surface of the initial powder.