• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 추계학술대회 논문집
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• pp.857-860
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• 1997

The purpose of this research was to study the influence of machining characteristics for aluminum alloys. The effect of metallic microstructural variables on the measures of machinability of aluminum alloys has no been adequately investigated. Machining Characteristics are influenced significantly by mechanical characteristics, composition and structure of material etcs. For improvement of machining characteristics, various studies are reported. In this paper, composition elements add to aluminum alloys within the limit of sustaining mechanical characteristics of metallic material. We have analyzed dynamic characteristics of cutting resistance, tensile strength value, hardness value etcs.

• 대한기계학회논문집
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• 제18권5호
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• pp.1096-1105
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• 1994

A hypereutectic Aluminum-Silicon Alloy is widely used in the parts of automobile because of high-resistance and good strength. In this study, the cutting of hypereutectic A1-Si alloy for economical production was investigated by simulation. Tool life and the extraction rate of Si particles is inversely proportional to the depth of cut. When decreasing the depth of cut, the reduction of single crystal diamond tool cost and tool change time is achieved.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2007년도 추계학술대회 논문집
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• pp.134-135
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• 2007

Graphite and MoS2 were added respectively as a lubricant to improve the cutting efficiency of micro blades which contains diamond abrasive. Strength, fracture toughness, and life span of micro-blades were observed to decrease with the increase in diamond abrasive and lubricant content. Wearing mode of micro-blades and the cutting efficiency were also found to be affected by the content of diamond abrasive and the addition of lubricants.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2001년도 춘계학술발표회 초록집
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• pp.46-47
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• 2001

• Geomechanics and Engineering
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• 제31권3호
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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.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2018년도 춘계학술대회 논문집
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• pp.129-129
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• 2018

Hard coating application is effective way of cutting tool for hard-to-machine materials such as Inconel, Ti and composite materials focused on high-tech industries which are widely employed in aerospace, automobile and the medical device industry also Information Technology. In cutting tool for hard-to-machine materials, high hardness is one of necessary condition along with high temperature stability and wear resistance. In recent years, high-entropy alloys (HEAs) which consist of five or more principal elements having an equi-atomic percentage were reported by Yeh. The main features of novel HEAs reveal thermodynamically stable, high strength, corrosion resistance and wear resistance by four characteristic features called high entropy, sluggish diffusion, several-lattice distortion and cocktail effect. It can be possible to significantly extend the field of application such as cutting tool for difficult-to-machine materials in extreme conditions. Base on this understanding, surface coatings using HEAs more recently have been developed with considerable interest due to their useful properties such as high hardness and phase transformation stability of high temperature. In present study, the nanocomposite coating layers with high hardness on WC substrate are investigated using high entropy alloy target made a powder metallurgy. Among the many surface coating methods, reactive magnetron sputtering is considered to be a proper process because of homogeneity of microstructure, improvement of productivity and simplicity of independent control for several critical deposition parameters. The N2 is applied to reactive gas to make nitride system with transition metals which is much harder than only alloy systems. The acceleration voltage from 100W to 300W is controlled by direct current power with various deposition times. The coating layers are systemically investigated by structural identification (XRD), evaluation of microstructure (FE-SEM, TEM) and mechanical properties (Nano-indenter).

• 한국분말재료학회지
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• 제15권5호
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• pp.359-364
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• 2008

To satisfy the demand of higher cutting performance, mechanical properties with tungsten carbide (WC-Co) tool materials were investigated. Hardness and transverse rupture strength with WC grain size, Co content and density were measured. Compared to H, K, and S manufacture maker as tungsten carbide (WC-Co) tool materials were used for high-speed machining of end-milling operation. The three tungsten carbide (WC-Co) tool materials were evaluated by cutting of STD 11 cold-worked die steel (HRC25) under high-speed cutting condition. Also, tool life was obtained from measuring flank wear by CCD wear measuring system. Tool dynamometer was used to measure cutting force. The cutting force and tool wear are discussed along with tool material characteristics. Consequently, the end-mill of K, H manufacture maker showed higher wear-resistance due to its higher hardness, while the S maker endmill tool showed better performance for high metal removal.

• 한국표면공학회지
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• 제45권1호
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• pp.37-42
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• 2012

$WS_2$ powder was added to the Cu/Sn bond metal of diamond micro-blades for machining of semi-conductor and IC chips to improve cutting efficiency. The effect of $WS_2$ additive on cutting efficiency was investigated and compared with the micro-blades with $MoS_2$ developed in previous research. Flexural strength, frictional coefficient, and wear resistance of blades decreased with $WS_2$ but wear depth increased. It was found that the blades including $WS_2$ consumed less momentary energy than the blades containing $MoS_2$ during dicing test. Micro-blades containing $WS_2$ exhibited lower flexural strength than the blades with $MoS_2$ resulting from higher amount of sintering defects relevant to the less effectiveness of $WS_2$ on fluidity. The effect of $WS_2$ and $MoS_2$ on fluidity during sintering was analyzed in terms of mismatching degree between the longitudinal direction of lubricant particles and the perpendicular direction to the compact loading. The blade with 8.1 vol.% of $WS_2$ showed the best cutting efficiency.

• 한국공작기계학회논문집
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• 제17권2호
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• pp.38-44
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• 2008

Titanium and its alloys, due to their superior properties of high specific strength and excellent corrosion resistance, are increasingly used in living applications in the 21century. The applications in aerospace and medical industries demand machining process more frequently to obtain a desired product. But unfortunately, this material is one of the most difficult-to-cut. In the turning process of titanium alloys, the key point for successful work is to select proper tool materials and cutting conditions. This study suggests a guidance for selecting the tool materials and the cutting speeds to improve tool life and surface integrity in Ti-6Al-4V titanium turning process. The experiments investigate the change of surface roughnesses, cutting forces and flank wear with various cutting parameters of tool materials, depth of cuts and feeds. As the results, K10 type of insert tip was assured as the best for turning of Ti-6Al-4V titanium alloy.

• Tribology and Lubricants
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• 제12권4호
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• pp.52-59
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• 1996

The results of the electrical contact conductivity of multi-contact spots accounting the surface roughness and the non-conductive films of different origins such as air, water, cutting oil, and machining oil are presented. The array of metal spheres compressed between two flat plates has been used for simulation of the contact behavior of multiple contact of solids, under normal loading. Measurement of electrical contact resistance has been made using the equipment providing the adequate accuracy in the range of micro Ohms. The data on electrical contact resistance have been compared with theoretical predictions using the multiple contact model of constriction resistance. The effect of single spot number and array on conductivity of contact has been evaluated. The results of the experiments show that the contact resistance are closely related to the number of loading cycles, form of surface roughness, and presence of non-conductive films that reduce the size of the real electrical contact spots.