• Journal of the Korean Society for Precision Engineering
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• v.31 no.5
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• pp.395-401
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• 2014

Development of five axis tool grinding machine and CAD/CAM systems increase tool design flexibility. In this research, investigated are cutting characteristics of ball-end mill with different helix angle. Special WC ball-end mills with $0^{\circ}$, $10^{\circ}$, $20^{\circ}$, $30^{\circ}$ helix angles are designed and used in various cutting tests. Machining performance according to helix angle variation is evaluated from cutting forces, surface roughness, tool wear, produced chip shape, and vibration characteristics. The ball-end mill with $10^{\circ}$ helix angle shows the best cutting performance due to appropriate chip load distribution and smooth chip flow. This research can be used for cutting edge geometry optimization and novel design of ball-end mill.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1996.03a
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• pp.41-46
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• 1996

In this study, unsintered and pre-sintered low purity alumina ceramics were machined with various tools to clarify the machinability, optimum tool materials and optimum cutting conditions. The main conclusions obtained were as follows. (1)In the case of dry cutting, the sintered diamond and natural diamond tools exhibit better performance in machining of the ceramic pre-sintered at lower temperature, and the tool lives of both tools in machining the ceramics pre-sintered at high temperature becomes extremely short. (2)The performance of CBN tool becomes better in dry machining of the ceramics pre-sintered at higher temperature. (3)When the pre-sintered ceramics were wet machined with sintered diamond, the tool life becomes considerably long, and higher cutting speed can be used than in the case of the CBN and ceramic tools, the tool lives becomes shorter at wet cutting than at dry cutting, especially exhibiting extremely short tool life in wet cutting with ceramic tool.

• Geomechanics and Engineering
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• v.31 no.3
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• pp.249-263
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• 2022

The specially-shaped Polycrystalline Diamond Compact (PDC) cutter is widely used in drill bit design due to its advantages of high rock cutting efficiency, strong impact resistance and long service life in hard and abrasive formation drilling. A detailed understanding of rock cutting behavior of worn specially-shaped PDC cutter is essential to improve the drilling efficiency and decrease the drilling costs. In this paper, the theoretical models of two new principles (loading performance (LP) and cutting performance (CP)) are derived for evaluating the cutting process of worn specially-shaped cutter, the theoretical models consider the factors, such as cutter geometry, aggressiveness, stress state, working life, and rock cutting efficiency. Besides, the numerical model of heterogeneous granite is developed using finite element method combined with Voronoi tessellation, the LP and CP of 12 kinds of worn specially-shaped PDC (SPDC) cutters are analyzed. The results found that the mechanical specific energy (MSE) of worn cutters first increase and then decrease with increasing the cutting depth, and the MSE increase with the increase of back rake angle except for Conical cutter and Wedge-shaped cutter. From the perspective of CP, the worn PDC cutters are more suitable for the smaller cutting depths, and the back rake angle has little effect on the CP of the specially-shaped worn PDC cutters. Conical cutter, Saddle-shaped cutter and Ellipse-shaped cutter have the highest CP value, while Rhombus-shaped cutter, Convex cutter and Wedge-shaped cutter have the lowest value in selecting cutters. This research leads to an enhanced understanding of rock-breaking mechanisms of worn SPDC cutters, and provides the basis to select of specially-shaped PDC cutters for the specific target formation.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.04a
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• pp.341-346
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• 2004

Performance Evaluation of end mills for high speed cutting has been performed in a view of dynamic characteristics and noise-vibration under operation. The tools tested in this research consist of three foreign country made and one korean made. In addition, numerical models using finite element method are established, which are confirmed by experimental results. The evaluation results has been feedback for developing high performance end mills fur high speed cutting tools.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.04a
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• pp.478-483
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• 2003

Performance Evaluation of end mills for high speed cutting has been performed in a view of dynamic characteristics and noise-vibration under operation. The tools tested in this research consist of three foreign country made and one korean made. In addition, numerical models using finite element method are established, which are confirmed by experimental results. The evaluation results has been feedback fur developing high performance end mills for high speed cutting tools.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.2
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• pp.443-448
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• 2010

Rapid advance in information technology requires high performance devices with compact size. Integrated multi-layer electronic element with different functions enables those compact devices to possess various performances and powerful capabilities. In mass production, the multi-layer electronic element is manufactured as a bulk type with a large number of parts for productivity. However, this may cause the electronic part to be damaged in the cutting process of the bulk elements to separate into each part. Therefore the cutting performance of multi-layer element bulk is playing an important role in the view of production efficiency. This study focuses on the cutting characteristics of multi-layer electronic elements. In order to increase the efficiency, the vibration cutting method was applied to the blade cutting machine. Flexure hinge structure, which is an physical amplifier of increasing displacement, was attached to the vibration cutting device for machining efficiency. The behaviors of flexure hinge were modeled with Lagrange equation and simulated with finite element method (FEM). Performance of hinge structure was verified by experimental modal analysis (EMA) for hinge structure to be tuned to the specific mode of vibrations. Cutting experiments of multi-layer elements were conducted with the proposed vibrating cutting module, and the characteristics was analyzed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.6
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• pp.1955-1960
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• 2010

A performance of CNC 3-axis pipe profile-cutting machine we developed was evaluated by measuring and verifying a positioning accuracy of its feeding unit and a cutting shape accuracy of pipe workpiece. The positioning accuracy was verified by comparing moving distance actuated by PLC motion controller with actual one measured by a laser interferometer. The cutting shape accuracy was also verified by comparing a cutting shape obtained through scanning and 3D modeling the pipe workpiece with that through CL data.

• Journal of the Korean Society of Safety
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• v.9 no.4
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• pp.17-28
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• 1994

Chip breaking is important in lathe work for maintaining good surface of the products and safety of operator. The purpose of this study is to investigate the performance of chip breaking and chip shape resulted from the carbide inserts with grooved type and obstruction type chip breaker. Experiments have been performed under the following cutting conditions, (1) constant cutting speed with variable depth of cut and feed rate, (2) constant depth of cut with variable cutting speed and feed rate. Also, the flying distance of chip and it's distribution have been investigated. As a results, good performance of chip breaking can be obtained for small radius of curvature and land width of grooved type chip breaker. And the thickness of chip increase with the increase of feed rate and decrease of cutting speed, and the chip breaking becomes easier with the increase of chip thickness due to the large deformation rate. Obstraction type chip breaker shows better performance of surface roughness than the grooved type. The flying distance of the chips over 90% are less than 1 meter, and the distance decreases as the feed rate decreases.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.857-858
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• 2006

In order to clarify the wear resistance as cutting tools, the effect of oxygen addition on oxidation behavior of the ${\beta}-Si_3N_4$ ceramics with 5 mass% $Y_2O_3$ and 2 or 4 mass% $Al_2O_3$ was investigated by performing oxidation tests in air at $1300^{\circ}$ to $1400^{\circ}C$ and cutting performance tests. From test results, we could conclude that the mechanical properties of ${\beta}-Si_3N_4$ ceramics depending on oxygen introduction are much effective on cutting performance improvements of ${\beta}-Si_3N_4$ ceramics.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1993.10a
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• pp.666-675
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• 1993

In order to prevent bodily injuries frequently suffered in using bush cutters, especially from spattered stones, we developed a unique new cutting system equipped with a fixed blade on top of the rotary blade, and checked into the mowing performance of the cutter. From experimental test of mowing efficiency and measuring test of physical stress (O$_2$ consumption and heartbeat rates) , the new cutting system with a fixed blade proved that it keeps good cutting performance with lower peripheral speed of the rotary blade(22m/sec), compared to that of ordinary cutting blade, yielding more safety in operation. Weight of the cutter head is, however, heavier than that of ordinary machine by about 70% which increased a physical stress on the operator with slightly faster heartbeat rates. In mowing along edge of concrete wall, the operator enjoyed using the cutter with no anxiety , owing to function of the fixed blade.