• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1134-1135
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• 2006

A revolutionary "Active Braze Coated Diamond" (ABCD) has been developed for bonding diamond grits firmly in the metal matrix. The molten braze is wetted and reacted with diamond to form strong chemical bond at the interface so that the diamond does not become knocked out of tools. The ABC is a nickel alloy that can form metallurgical diffusion bondswith the metal matrix. In essence, ABCD turns diamond into a metal grain so that the diamond tools can be made by conventional powder metallurgical process without being concerned about the poor bonding between matrix metal powder and the diamond as before.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.951-954
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• 2000

This paper presents a new cutting method, i.e. diamond cutting, aided by electrolysis, in order to cut ferrous materials with diamond tools. Diamond cutting is widely applied in manufacturing ultraprecision parts such as magnetic disk, polygon mirror, spherical/non-spherical mirror and copier drum, etc. because of the diamond tool edge sharpness. In general, however, diamond cutting cannot be applied to cutting steels, because diamond tools wear excessively in cutting iron based materials like steel due to their high chemical interaction with iron in high temperature. In order to suppress the diffusion of carbon from the diamond tool and to reduce increase of cutting force due to size effect, we attempt to change chemically the compositions of iron based materials using electrolysis in a limited part which will be soon cut. Through experiments under several micro-machining and electrolysis conditions, cutting using electrolysis, compared to conventional cutting, was found to result in a great decrease of the cutting force, a better surface and much less wear tool.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.1
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• pp.120-130
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• 1993

Generally, the machinability of materials that have a good mechanical properties is poor. For materials having a high strength, high toughness, high strength in high temperature and wear resistance, it is difficult to remove a chip from work materials. These properties are well shown in a Nickel, so this metal is used in machine materials, semi-conductor industry, metal mold and optical fields etc. But it is limitted in use because of high cost and poor machinability. In this study, the cutting of pure Nickel was conducted to examine wear of CBN, poly crystal diamond (PCD) and single crystal diamond (SCD) tools. From the result, the CBN tool is superior to poly crystal diamond tools or single crystal diamond tools in terms of tool wear and tool wear is predictable from experimental data base.

• 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.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.362-365
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• 2005

Currently Chemical Mechanical Planarization (CMP) has become an essential step in the overall semiconductor wafer fabrication technology. Especially the CMP pad conditioner, one of the diamond tools, is required to have strong diamond retention. Strong cohesion between diamond grits and metal matrix prevents macro scratch on the wafer. If diamond retention is weak, the diamond will be pulled out of metal matrix. The pulled diamond grits are causative of macro scratch on wafer during CMP process. Firstly, some results will be reported of cohesion between diamond grits and metal matrix on the diamond tools prepared by three different manufacturing methods. A measuring instrument with sharp cemented carbide connected with a push-pull gauge was manufactured to measure the cohesion between diamond grits and metal matrix. The retention force of brazed diamond tool was stronger than the others. The retention force was also increased in proportion to the contact area of diamond grits and metal matrix. The brazed diamond tool has a strong chemical combination of the interlayer composed of chrome in metal matrix and carbon which enhance the interfacial cohesion strength between diamond grits and metal matrix. Secondly, we measured real-time data of the coefficient of friction and the pad wear rate by using CMP tester (CETR, CP-4). CMP pad conditioner samples were manufactured by brazed, electro-plated and sintered methods. The coefficient of friction and the pad wear rate were shown differently according to the arranged diamond patterns. Consequently, the coefficient of friction is increased according as the space between diamonds is increased or the concentration of diamonds is decreased. The pad wear rate is increased according as the degree of diamond protrusion is increased.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.11a
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• pp.181-182
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• 2007

• Journal of the Korean Society for Precision Engineering
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• v.13 no.1
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• pp.78-83
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• 1996

This paper presents the characteristics of surface roughness and cutting force in ultraprecision cutting of aluminium alloy using natural diamond tools whose edge radii are smaller than those of tools made of other materials. The feed rate and depth of engagement were set to be a micrometer order. After measuring the surface roughness of machined surface and cutting force for each cutting condition, the relations between the surface quality and its condition were investigated qualitatively. If the feed rate was under a certain limit, the machined surface quality was deteriorated unexpectedly. This is supposed to have happened due to vibration leading its condition to abnormal one. In a certain situation the machined surface roughness by a natural diamond tool was inferior to that made by a carbide tool whose cutting edge radius is larger. This is supposed to be caused by not normal machining but burnishing effect.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.875-876
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• 2006

For dry machining of mineral materials the Institute of Materials Engineering pursues a novel thermal protection shield concept for diamond tools, in which thermal insulating materials in diamond composite structures act as heat shield, which protects diamonds in deeper layers against high temperature and graphitisation. Before the effectiveness of this concept could be investigated suitable composites have to be manufactured. In this paper the powder metallurgical production processes of diamond-alumina-cobalt-composites with varying alumina and cobalt particle sizes, their microstructures and porosities are described. It could be observed that the distribution of small-sized alumina particles ($<70{\mu}m$) in the cobalt matrix is uniform and the porosity of the composite decrease.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.2 s.191
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• pp.33-40
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• 2007

In this study, presintered and full sintered low purity alumina ceramics were machined with various tools to clarify the effect of cutting fluid in machinability. The main conclusions obtained were as follows. When the presintered ceramics were wet machined with sintered diamond tool, the tool wear becomes extremely large, and higher cutting speed can be used than in the case of full sintered ceramics. The productivity of wet cutting with the sintered diamond tool is much higher than that of dry cutting. In the case of the CBN and ceramic tools, the tool wear were smaller at wet cutting than at dry cutting, especially exhibiting considerably larger grooved tool wear in wet cutting with ceramic tool.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.3
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• pp.284-291
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• 2013

Micro cutting of titanium alloy by polycrystalline diamond (PCD) tools was studied. Micro electro discharge machining (MEDM) was used to fabricate customized micro shaping tools from PCD blank. The tool was used to machine micro grooves on Ti alloy and the effects of depth of cut and machining length on tool wear, burr and surface roughness were studied. The shaping tool has cutting edge of a few ${\mu}m$. The crater size of the tool surface was increased with increasing capacitance of EDM machining conditions, which was used to control the surface roughness of the machined micro grooves.