• Applied Microscopy
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• v.36 no.3
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• pp.209-216
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• 2006

Accuracy and precision of the goniometer and the specimen holder should be measured and corrected to improve reliability of 3-D structure analysis using transmission electron microscopy (TEM). In this study, we described the operation principle and performance of the Gatan rotation holder. Through analysis of the images taken inside the microscope, rotation angles were measured within the accuracy of ${\pm}0.42^{\circ}$. For comparison the rotation angles were measured outside the microscope using a home-made measurement tool, which resulted in the accuracy of ${\pm}0.6^{\circ}$. Additionally, we found abnormal specimen drifts during rotation probably due to the unstable engagement between the specimen cup and the rotation belt.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.5
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• pp.60-68
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• 2008

The tool overhang length affects tool deflection and chatter that should be reduced for machined surface quality, productivity and long tool lift. The shortest tool setting algorithm that uses a safe space is proposed and applied with simulation software in NC machining. The safe space in the coordinate fixed in the tool is computed by the virtual machining system that simulates NC machining by stock model, tool model and NC code. The optimal tool assembly that has largest diameter and shortest length is possible using the safe space. This algorithm has been applied over fifty companies for safe and rigid tool setting. The collision accident between holder and stock was reduced from 3 to 0 a year and the productivity was incensed about 15% by using faster feed rate acceptable for shorten tool length.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.6
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• pp.9-14
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• 2007

In this paper, a rotating tool clamping device was developed based on a shape memory alloy(SMA) and its feasibility as a tool holder was experimentally explored. The SMA-based device was able to alter clamping to unclamping through temperature control within 1 second. The means and repeatability(${\sigma}$) of the tool clamping force were 185.5N and 6N respectively and its drifts were less than 3% for an hour. Considering the temperature hysteresis of the SMA-based tool clamping device, it is necessary to heat the SMA ring to around $50^{\circ}C$ after tool change to obtain more clamping force.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.4
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• pp.136-142
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• 1996

Automatic monitoring of cutting process is one of the most important technology in machining. AE sensing technology has been applied to monitoring process and proved to be effective in detecting tool abnor- malities such as tool wear and fracture. In this experimental study. AE signals were detected from the tool holder for continuous and interrupted cutting, which obtained from changing workpice material configuration, under control of constant cutting speed from CNC lathe. From statistical and frequency analysis, the AE signals were analyzed to obtaining the characteristics of continuous and interrupted cutting conditions and tool failure. The Kurtosis values decreased but RMS voltages increased as the cutting speed increased, in both continuous and interrupted cutting. RMS voltage is suddenly increased but Kurtosis value is suddenly decreased when tool failure condition. Power spectrum density of AE signals when tool failure reaches extreme value around 0.065 cycles/ .mu. m.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.10a
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• pp.591-596
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• 1999

Due to the development of CNC machining centers and the complexity of machined part geometry, the ball-end milling became the most widely used the cutting process. Generally, the tool runout defined as the eccentricity of a rotating tool set in the holder involved the spindle runout and the problem of tool runout generated to remove the workpiece is a main factor affecting the machining accuracy. In this paper, the relationship of tool runout(zero-to-peak, P-K) and surface shape on the change of cutting conditions is studied and it is proposed the probability of prediction of surface shape from the in-process tool runout measurements with high response displacement sensor in the ball-end milling

• Design & Manufacturing
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• v.11 no.3
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• pp.19-24
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• 2017

In these days, increase requirement of TEM (Transmission Electro Microscope) in not only scientific field but also industrial field. Because TEM can measure inner-structure of specimen a variety of materials like metal, bio. etc. When use TEM, specimen should be thin about 50nm. So making for thin specimen, use Ion milling device that include specimen holder. The holder generally made of Aluminium Aluminium holder is worn away easily. For this reason, using time of ion milling with aluminum holder is too short. To solve the problem, we replace aluminium holer to molybdenum alloy holder. In this paper, we design molybdenum alloy holer for CAM and modify CAD modeling for effective machining process. So we array a specimen 3 by 4 and setup orientation for one-shot machining process. Next we make a CAM program for machining. we making a decision two machining strategy that chose condition of tool-path method, step-down, step-over. etc. And then conduct machining using CNC milling machining center. To make clear difference between case.1 and case.2, we fixed machining conditions like feed-rate, main spindle rpm, etc. After machining, we confirm the condition of workpiece and analysis the problems case by case. Finally, case.2 work piece that superior than case.1 cutting with WEDM because that method can not ant mechanical effect on workpiece.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.3-8
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• 2002

An intelligent polishing robot automation system is developed. Automatic Tool Change System(A.T.C.), Tool Posture Angle Control, and Robot Program for Polishing Application are developed and integrated into a robotic system that consists of a robot, pneumatic finding tool, and finding abrasives (papers and special films). A.T.C. is specifically designed to exchange whole grinding tool set for complete unmanned operation. Tool Posture Angle Control is developed to give a certain skew angle rather than right angle to tools on the surface for best finishing results. A.T.C. and Tool Posture Angle Control is controlled by a PC and the robot controller. Also, there have been some considerations on enhancing the performance of the system. Some elastic material is inserted between the grinding pad and the holder for better grinding contact. The robot path data is generated automatically from the NC data of previous machining process.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.5
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• pp.1092-1096
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• 1988

This paper presents a research on the development of a system which manages be tool data for the factory using NC machines. The tool information concerning each production stages of the industry is studied in the CIM(Computer Integrated Manufacturing) view point. The system gives the characteristics of the easy and reliable processing of the tool data by the help of menu and graphic functions. The DBMS(Data Base Management System) having relational model is used for the system build-up and is interfaced with CAD system for display of the tool geometry.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.10a
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• pp.153-157
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• 2002

본 연구에서는 선반가공에서 일반적인 선반작업 후 밀링이나 드릴링 가공이 가능한 복합가공기의 역할을 한번에 수행할 수 있는 CNC 공구터렛의 홀더 주축에 대한 수학적 모델링을 통하여 시스템의 횡진동 및 비틀림 진동 해석으로 발생할 수 있는 진동 문제에 대처할 수 있는 방안을 제시 하고자 한다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.11a
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• pp.455-456
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• 2007