• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2010.05a
• /
• pp.41-42
• /
• 2010

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2009.06a
• /
• pp.227-228
• /
• 2009

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.16 no.4
• /
• pp.62-68
• /
• 2017

Since the aircraft parts industry is a high-value-added industry, mass production order production, and the hundreds of thousands. Therefore, parts produced However, since these parts require high reliability and stability, a high degree of precision is required. In Korea, there on the roughness of the machined surface in cutting process. However, research on the surface roughness characteristic obtained by which is widely used for aircraft parts is still insufficient in Korea. The purpose of this study is to investigate the effect of turning tool rotation speed and X axis feed rate on the surface roughness of cutting tools in CNC lathes during cutting of aluminum alloy 7075.

• Journal of Powder Materials
• /
• v.17 no.4
• /
• pp.302-311
• /
• 2010

In this research, the refinement behavior of the coarse magnesium powders fabricated by gas atomization was investigated as a function of milling time using a short duration high-energy ball milling equipment, which produces fine powders by means of an ultra high-energy within a short duration. The microstructure, hardness, and formability of the powders were investigated as a function of milling time using X-ray diffraction, scanning electron microscopy, Vickers micro-hardness tester and magnetic pulsed compaction. The particle morphology of Mg powders changed from spherical particles of feed metals to irregular oval particles, then platetype particles, with increasing milling time. Due to having HCP structure, deformation occurs due to the existence of the easily breakable C-axis perpendicular to the base, resulting in producing plate-type powders. With increasing milling time, the particle size increased until 5 minutes, then decreased gradually reaching a uniform size of about 50 micrometer after 20 minutes. The relative density of the initial power was 98% before milling, and mechanically milled powder was 92~94% with increase milling time (1~5 min) then it increased to 99% after milling for 20 minutes because of the change in particle shapes.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 1997.10a
• /
• pp.243-247
• /
• 1997

기존의 복합 Turning Center 보다 비구심상태에서의 가공, 3축밀링가공 및 3축/4축 동시 Milling가공 등의 특징을 갖고 복잡한 형상과 기능을 갖도 있는 부품 생산용 각형 FMS/C의 기본기계가 될 다기능 복합가공기[최대가공경 310mm *최대가공길이600mm, 6축제어(4축동시가공), ATC Magazine 20개, 주축18.5KW, 제2주축 15KW 회전수36-1,600RPM의 강력, 고속, 정밀 다기능 복합가공기]를 제2차 선도기술개발사업을 통해 개발을 추진하고 있다.

• Korean Journal of Computational Design and Engineering
• /
• v.10 no.6
• /
• pp.455-464
• /
• 2005

This paper discusses the methods of computing tool-paths for machining free-form surfaces on 3-axis CNC machines in die and mould making. In computational view this paper describes the characteristics and issues of the geometric information and the shape, which make computing tool-paths difficult. Important points that should be considered in devising a computing method are also discussed. A newly implemented method is explained and compared with an old method for a commercial CAM system. The implemented method is used in a commercial CAM system and the computing time for an example is presented.

• Journal of the Korean institute of surface engineering
• /
• v.29 no.5
• /
• pp.415-423
• /
• 1996

Thin film technologies for fabricating SQUIDs involve etching and deposition procedures with the proper substrate materials and $YBa_2Cu_3O_{7-d}$ (YBCO) as the high $T_c$ superconductor. YBCO were prepared on various substrates of MgO, $SrTiO_3$, and $LaAlO_3$ by using off-axis magnetron sputtering methods and annealing in-situ. The parameters of film fabrication processes had been optimized to yield good quality films in terms of the critical temperature $T_c$ and the critical current density $J_c$. The optimized processes yielded $T_C$>90K along with $J_c$>$10_6A$$extrm{cm}^2$ at 77K and>$2\times10_7A/Cm^2$ at 5K. We fabricated step-edge type dc-SQUIDs and directly coupled magnetometers, producing step edges on MgO(100) substrates by etching with Ar-ion beam, depositing YBCO material on them, then patterning them by using ion-milling technique. Circuitizing washer-shape SQUIDs to possess a pair of step-edge junctions of 2-5$\mu$ line width with a high angle>$50^{\circ}C$ , we examined their I-V characteristics thoroughly and Shapiro steps clearly as we irradiate microwaves of 8-20 GHz frequency.

• Korean Journal of Computational Design and Engineering
• /
• v.9 no.3
• /
• pp.246-252
• /
• 2004

Presented in this Paper is a Micro Machining Service .(MIMS) based on the World Wide Web technologies. In order to ensure easy access to the service, the web browsers are used as the user interface. The pan geometry as an STL file is uploaded with process parameter for 3-axis CNC milling. Depending on the predefined user level, novice or expert, the user interface requires different parameters for process planning. An STL-based CAM resides in the server and automatically provides NC codes upon user's request. Tool-paths for scanning and pencil-cut, which are interference-free and precise, are created by the curve-based polyhedral machining method. A couple of sample parts were fabricated by a micro endmill with 127 fm diameter. From the tests, the parts fabricated by scanning followed by pencil-cut resulted in less error(within 2%) than the parts machined only by scanning tool-path.

• Progress in Superconductivity
• /
• v.1 no.2
• /
• pp.146-150
• /
• 2000

Step edge Josephson junctions in c-axis oriented $YBa_2Cu_3O_7$ films were fabricated on $CeO_2$ buffered sapphire substrates. The step angle was controlled in the wide range of $20^{\circ}\sim75^{\circ}$ by the Ar ion milling technique. I-V curves of junction fabricated on the thickness ratio of $\sim$0.8 and the step angle of $35^{\circ}$ were exhibited RSJ-like behavior with $I_CR_N$ product of $\sim250{\mu}A$ and critical current density of $\sim2\times10^4A/cm^2$ at 77 K. Critical current of step edge junction was increased linearly with decreasing temperature but the normal resistance was almost constant. Total samples of step edge Josephson junction was satisfied a scaling behavior of $I_CR_N{\propto}(J_C)^{0.5}$.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.10 no.6
• /
• pp.1157-1163
• /
• 2009

In order to improve in quality and productivity using the CNC machine tools, it has been endeavored to elevate production process by adding supplementary axes(2 axes) to 2,3 axial CNC machine tools. It is because the movement between the progress of work in processed goods is remarkably decreased more than that of general CNC machine tools that productivity improvement with precision maintenance can be improved. VBScript in CAD/CAM is applied to utilize CNC machine tools added supplementary axes so that Multi-axial &Multi-process manufacturin g program can be conveniently drawn up. However, there is generally much skilful work and operation by the manual program of CAD(2.5D) and CNC machine tools in the filed. As a result of conducting an experiment by COM-filing VBScript at the spot of Insert Tip for milling Face Cutter in CAD/CAM Software(2.5D), it was not only timesaving to draw up program but also more convenient than complicated Multi CAD/CAM Software to approach and possible to program various products instantaneously.