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  • Title/Summary/Keyword: finish machining

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Development of Electrode Guide of Super-drill EDM and Electrical Discharge Machining of Small Hole for High Precision Semiconductor Die (초정밀 반도체 금형 제작을 위한 슈퍼드릴 방전가공기 전극가이드 개발과 미세홀 방전가공)

  • Park, Chan-Hae;Kim, Jong-Up;Wang, Duck-Hyun;Kim, Won-Il
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.4 no.3
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    • pp.32-38
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    • 2005
  • Electrical discharge machining is the method of using thermal energy by electrical discharge. Generally, if the material of workpiece has conductivity even though very hard materials and complicated shape which are difficult to cut such as quenching steel, cemented carbide, diamond and conductive ceramics, the EDM process is favorable one of possible machining processes. But, the process is necessarily required of finish cut and heat treatment because of slow cutting speed, no mirror surface, brittleness and crack due to the residual stress for manufactured goods. In this experimental thesis, the super EDM drilling was developed for high precision semiconductor die steel and for minimization of leadframe width. It was possible to development of EDM drilling machine for high precision semiconductor die with the electrode guide and its modelling and stress analysis. The development of electrode with the copper pipe type was conducted to drill the hole from the diameter of 0.1mm to 3.0mm with the error of from 0.02mm to 0.12mm. From the SEM and EDX analysis, the entrance of the EDM drill was found the resolidification of not only the component of tungsten but also the component of copper.

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Characteristics of Wire EDM for Cold Die Steel due to the Different Wire Electrode Component (전극선 성분 변화에 따른 냉간금형용강의 와이어방전가공 특성)

  • Wang, Duck-Hyun;Jeong, Sun-Sung
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.2 no.2
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    • pp.98-105
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    • 2003
  • In the experimental study, wire EDM was conducted for cold die steel by changing the Wire electrode, peak discharge current and number of finish cut. From the micro structure analysis of SEM photographs, the size of irregular welded and added component on the EDMed surface is decreasing and size of EDMed plane surface is increasing as the decreasing peak current and increasing number of finish cut. From the analysis of coating effect, Zn component is highly contained in Br and Zn Wire EDMed surface and copper component is highly contained in Br and Al wire EDMed surface. Hardness values are Increasing as the increasing peak current and decreasing the number of finish cut The value of hardness is decreasing as Cu, Al, Zn and Br wire electrode because of the residual austenite effect of solid solution copper on solidification, and finally EDMed surface has the highest hardness values for every wire electrode. Yield strength values becomes larger and bending strength values become smaller due to the increasing the hardness. These results are increased as increasing brittleness with hardness.

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Performance Characteristics of CVD Diamond Cutting Tools

  • Oles, E.J.;Cackowski, V.J.
    • The Korean Journal of Ceramics
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    • v.2 no.4
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    • pp.203-211
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    • 1996
  • CVD diamond tools are becoming more widely used in industry as an economic alternative to polycrystalline diamond (PCD) for machining non-ferrous and non-metallic materials. Although CVD diamond-sheet tools have been on the market for several years, diamond-coated carbide inserts have become available only recently, with the successful resolution of long-standing adhesion problems. Diamond coating morphology on the rake surface of the tool affects chip formation favorably, whereas a microscopically rough, faceted morphology on the flank surface of the tool produces a rough workpiece finish. Workpiece finish can be improved by using a coated tool with a larger nose radius. The tool life provided by diamond-coated tools(~30 μm thick) can meet or exceed that of PCD tools, depending on the characteristics of the workpiece material. When using diamond-coated carbide tools in milling, a sharp-edged PCD tool should be used in the wiper position of the cutter to minimize workpiece roughness and burr formation.

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Influence of Electrical Conductivity of Dielectric on Machinability of W-EDM (방전액의 전도율이 와이어방전가공성에 미치는 영향)

  • Kim, Chang-Ho;Hur, Kwan-Do;Kwon, Taek-Hwan
    • Proceedings of the KSME Conference
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    • 2001.06c
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    • pp.64-70
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    • 2001
  • This work deals with the electrical conductivity of dielectric and cobalt percentage on output parameters such as metal removal rate and surface roughness value of sintered carbides cut by wire-electrical discharge machining (W-EDM). To obtain a precise workpiece with good quality, some extra repetitive finish cuts along the rough cutting contour are necessary. Experimental results show that increases of cobalt amount in carbides affects the metal removal rate and worsens the surface quality as a greater quantity of solidified metal deposits on the eroded surface. Lower electrical conductivity of the dielectric results in a higher metal removal rate as the gap between wire electrode and workpiece reduced. Especially, the surface characteristics of rough-cut workpiece and wire electrode were analyzed too. To obtain a good surface equality without cracks, 4 finish-cuts were necessary by reducing the electrical energy and the offset value.

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A Study on Cutting Tool Selection Techniques for Rough and Finish Turning Operations (선삭가공에서 황삭 및 정삭용 절삭공구선정방법에 관한 연구)

  • 김인호
    • Korean Journal of Computational Design and Engineering
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    • v.3 no.4
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    • pp.236-242
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    • 1998
  • This paper presents a development of computer aided cutting tool selection techniques for rough and finish turning operations. The developed system,. which is one of important activities for computer aided operation planning, firstly implements operation sequencing. Then, from relations of the size of machined area, recommended finishing allowance and maximum depth of cut, a main machining method is selected, a number of cut is calculated, cutting tools including toolholders and inserts are selected, and values for cutting parameters are determined. A cutting tool selection procedure is proposed for toolholders and inserts of ISO code in rough cutting, and some important parameters such as holder style, tool approach angle, tool function and its direction are described in detail. In order to demonstrate the validity of the system a case study is performed.

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A Study on the Optimal Cutting Depth upon Surface Roughness of Al Alloy 7075 in High-speed Machining (알루미늄 합금 7075의 표면 거칠기에 미치는 고속가공의 최적 절삭 깊이에 관한 연구)

  • Bae, Myung-Whan;Park, Hyeong-Yeol;Jung, Hwa
    • Transactions of the Korean Society of Automotive Engineers
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    • v.21 no.5
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    • pp.74-81
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    • 2013
  • The high-speed machining in the manufacturing industry field has been widely applied for parts of vehicles, aircraft, ships, electronics, etc., recently, because the effect of cost savings for shortening processing time and improving productivity is great. The purpose in this study is to investigate the effect of cutting depth on the surface roughness of workpiece with the spindle rotational speed and feed rate of high-speed machines as a parameter to find the optimal depth in the finishing for ball end mill of the aluminum alloy 7075 which is used much in aircraft parts. When the cutting depth for the respective feed rate and spindle rotational speed is varied from 0.1 mm to 0.7 mm at intervals of 0.2 mm in the wet finishing of the aluminum alloy 7075 by the insoluble cutting oils and high-speed machining used in the rough machining of previous study, the surface roughness values and the cutting temperature are measured. In addition, the cutting surface shapes of test specimens are observed by optical microscope and compared with respectively. It is found that the surface roughness values and the temperature generated during machining are increased as the feed rate and cutting depth are raised, but those are decreased as the spindle rotational speed is increased.

Characteristics of Tool Deflection when Pencil Cutting with Ball-End Mill (볼엔드밀에 의한 펜슬가송시 공구변형 특성)

  • 윤경석;왕덕현;이윤경;이상훈
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1995.10a
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    • pp.157-160
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    • 1995
  • Pencil cutting can eliminate overload in uncut area caused by large diameter ball-end mill before finish cutting. As ball-end mill for pencil cutting is long and type, it is easily deflected by cutting force. The tool deflection when pencil cutting with thin and long ball-end mill is one of the main reason of the machining errors on a free-form surface. The purpose of the research is to find the characteristics of deflected cutter trajectory by eddy-current sensor.

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A five-axis CAM system for free-surface grinding (금형연마작업을 위한 5축 CAM 시스템)

  • 서석환;이민석;김두형
    • 제어로봇시스템학회:학술대회논문집
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    • 1993.10a
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    • pp.1024-1030
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    • 1993
  • In manufacturing press die with free surface, grinding operation is an important post process for surface finish and dimensional accuracy. With the advancement of NC technology. surface grinding operation is increasingly replaced by the gantry type manipulator. As the mechanics for grinding operation is different from machining operation, conventional CAM system for machining operation is hard to apply. In this. paper, we develop a five-axis CAM system by which an efficient gantry trajectory can be planned and verified. The developed system consists of four conceptual modules; namely CAD, PROCESS. CAM, and ANALYSIS. In the CAD module, the machined surface is represented by CL-data or surface modeler, and process parameters are specified by the PROCESS module. Then, the CAM module generates a series of grinding paths based on the grinding mechanics together with process databases for tool spaces and grinding conditions. The generated paths are verified via ANALYSIS module. Validation via real experiments is left for further study.

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Characteristic of Mirror Surface ELID Grinding of Large Scale Diametrical Silicon Wafer with Rotary Type Grinding Machine (로타리 연삭에 의한 대직경 Si-wafer의 ELID 경면 연삭특성)

  • 박창수;김원일;왕덕현
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.11 no.5
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    • pp.58-64
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    • 2002
  • Mirror surface finish of Si-wafers has been achieved by rotary in-feed machining with cup-type wheels in ELID grinding. But the diameter of the workpiece is limited with the diameter of the grinding wheel in the in-feed machining method. In this study, some finding experiments by the rotary surface grinding machine with straight type wheels were conducted, by which the possible grinding area of the workpiece is independent of the diameter of the wheels. For the purpose of investigating the grinding characteristics of large scale diametrical silicon wafer, grinding conditions such as rotation speed of grinding wheels and revolution of workpieces are varied, and grinding machine used in this experiment is rotary type surface grinding m/c equipment with an ELID unit. The surface ground using the SD8000 wheels showed that mirror like surface roughness can be attained near 2~6 nm in Ra.

Mirror Surface ELID Grinding of Large Scale Diametral Silicon Wafer with Straight Type Wheel (스트레이트 숫돌에 의한 대직경 Si-wafer의 ELID 경면연삭)

  • 박창수;김경년;김원일
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2001.04a
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    • pp.946-949
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    • 2001
  • Mirror surface finish of Si-wafers has been achieved by rotary in-feed machining with cup-type wheels in ELID grinding. But the diameter of the workpiece is limited with the diameter of the grinding wheel in the in-feed machining method. In this study, some grinding experiments by the rotary surface grinding machine with straight type wheels were conducted, by which the possible grinding area of the workpiece is independent of the diameter of the wheels. For the purpose of investigating the grinding characteristics of large scale diametral silicon wafer, grinding conditions such as rotation speed of grinding wheels and revolution of workpiece are varied, and grinding machine used in this experiment is rotary type surface grinding m/c equipped with an ELID unit. The surface ground using the SD8000 wheels showed that mirror like surface roughness can be attained near 2~6nm in Ra.

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