• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.141-144
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• 2003

This paper proposes an analytical model of off-line feed rate scheduling to obtain an optimum feed rate for high speed machining. Off-line feed rate scheduling is presented as an advanced technology to regulate cutting forces through change of feed per tooth, which directly affects variation of uncut chip thickness. In this paper, the feed rate scheduling model was developed using a mechanistic cutting force model using cutting-condition-independent coefficients. First, it was verified that cutting force coefficients are not changed with respect to cutting speed. Thus, the feed rate scheduling model using the cutting-condition-independent coefficients can be applied to set the proper feed rates for high speed machining as well as normal machining. Experimental results show that the developed fred rate scheduling model makes it possible to maintain the cutting force at a desired level during high speed machining.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.5
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• pp.63-69
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• 2007

The high speed machining has been widely applied to manufacture dies and machine elements in industrial field. Especially, 5-axis milling has been employed to produce a wide range of turbine blades, impellers and complex molds. In this study, the machining characteristics of injection molds were investigated according to tool tilting angles in 5-axis milling. The cutting force and surface roughness were investigated with various tool tilting angles. When the tool tilting angle was over than 10 degree, the characteristics of cutting force and surface roughness were improved in machining of Al alloy.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.36-40
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• 1996

The high-speed machining is one of the most effective technology to improve productivity. Because of the high speed and high feedrate, high-speed machining can give great advantages for the machining of dies and moulds. In this paper, high-speed milling for HP-4 die material was carried out with coated tungsten carbide ball endmill. In the high-speed machining, the cutting force and surface roughness of workpiece show very various characteristics at different cutting conditions. Especially surface roughness of workpiece depends largely on pick feed and feed per revolution of ball endmill. In the condition that pick feed and feed per revolution are equal, better surface roughness is measured. By obtaining good surface roughness at high speed, efficiency of machining can be increased.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.8
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• pp.139-145
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• 1996

Tapping is one of the most widely used machining operations. There are several methodes of producing external screw threads, e.g. turning, milling with single or multiple cutter, rolling, and grinding, but the methods available for cutting enternal threads are less numerous, and for threads in small holes, tapping is employed almost exclusively. In this study, the tap with the various geometry has been developed in order to tap special workmaterial at considerably higher cutting speed than that of the conventional HSS tap. The experimental tests are run with various cutting speed by using a piezo type tool dynamometer to measure tapping torque. Tapping torque is affected by the design of the tap, which seems to be due to internal friction and shearing of the metal. It is clarified that the process of chip formation strongly depends on rake angle, relief angle, angle of twist.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.648-652
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• 1996

Grinding Center(GC)는 머시닝센터가 갖는 드릴링, 태핑 등의 절삭가공의 수행은 물론 주축의 고속화, 이송계의 고정밀화를 토대로 연삭숫돌의 절삭성 회복과 다듬질면의 거칠기를 확보하기 위한 기계로서 Dressing/Truing장치, 기상계측 장치, CNC기능을 구비하여 테이블과 공구간에 3차원의 상대운동을 시킴으로써 평면연삭, 내면연삭, 홈연삭, 캠연삭 등의 복잡한 형상의 연삭가공에 대해서도 공정을 집약화 할 수 있는 기계이다.(중략)

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.166.2-166.2
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• 2016

최근 생산 장비의 발달로 인해 절삭공구, 전기전자 부품, 항공 및 자동차 부품 생산에 필요한 생산 장비의 수명연장, 고속 절단 및 고성능화가 중요시 되면서 우수한 내구성, 내마모성 및 고온 안정성을 갖는 기계부품 및 공구를 요구하게 되었다. 내마모성을 가지는 표면을 얻기 위해서는 TiN, TiC, AlN, Al2O3, CrN, ZrO2와 같은 경도 높은 물질을 증착하여 특성을 개선시키는 방법이 있다. 특히 AlN은 비교적 우수한 경도와 고온 안정성을 가지고 있어, 생산 장비의 고속 절단 및 반복되는 정밀 작업으로 인한 열충격과 마모를 완화시키는 역할을 하는 코팅재로 사용하기 적합하다. 본 실험에서는 RF-magnetron sputtering 방법을 이용하여 AlN 박막을 파워 150W, 질소가스 분압비에 따라 25%, 50%, 75%, 100%의 조건으로 금속기판 위에 증착하였다. 금속 기판 위에 제작된 AlN막은 XRD (X-ray Diffraction)을 사용하여 배향성을 확인하였고, HM-220 (Micro-vickers hardness tester)을 사용하여 AlN박막의 경도를 측정하였으며, SEM (Scanning Electron Microscope), AFM (Atomic Force Microscope)을 이용하여 표면의 구조와 거칠기를 측정하였다. 이 실험을 통하여 우수한 물성과, 치밀한 조직의 AlN박막이 고속 절삭 공구, 유공압 실린더, 베어링과 같은 금속부품의 코팅소재로 적용가능 할 것으로 기대된다.

• 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.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.242-242
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• 2004

다양하게 변화하는 소비자의 요구에 만족하기 위해 제품 디자인의 빠른 변화가 요구되며 이에 따라 빠르게 3차원 형상을 구현하는 기술이 필요하게 되었다. 일반적으로 사용되는 적층 방식의 쾌속 조형기술은 고가의 재료비 및 운영비, 기능성 파트 제작의 어려움, 표면에 적층 무늬가 존재 등의 문제점이 존재한다. 그러나 기계 가공 방식의 경우 다양한 재료의 가공이 가능하고 높은 형상 정밀도가 유지되는 장점이 있다. 특히, 폼을 이용하여 3차원 형상을 구현하는 방법은 현업에서 많이 사용되고 있다.(중략)

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.24 no.6
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• pp.274-278
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• 2014

Machining performance is often limited by chatter vibration at the tool-workpiece interface. Chatter vibration is a type of machining self-excited vibration which originated from the variation in cutting forces and the flexibility of the machine tool structure. Cutting tooling method is one of major factor to chatter vibration in turning process. Even though lots of cutting tooling methods are developed and used in machining process, precise analysis of cutting tooling effect in view of chatter vibration behavior. This study presents numerical and experimental approaches to verify and effects of various cutting tooling geometry and clamping method on the onset of chatter vibration. Acquired knowledge from this study will apply the optimal geometry design of cutting tooling and adjusting of machining process.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.8
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• pp.24-31
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• 2001