• Journal of the Korean Society for Precision Engineering
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• v.12 no.3
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• pp.5-14
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• 1995

In recent years, the automization of cutting machine tools has been developed very fast. Hance, the in-process detection of cutting condition is very important for automatic manufacturing system in factory. Acoustic Emission(AE) has been widely used in monitoring the cutting conditions, because of high sensitivity of AE signal and low cost of AE equipment. This experimental study deals with the relations between AE signal, cutting force charcteristics and tool wear in the machining of SUS304. Face milling operation is used for the analysis between tool wear and AE signal.

• International Journal of Precision Engineering and Manufacturing
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• v.9 no.2
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• pp.63-68
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• 2008

Hard and brittle materials, such as Ni- and Ti-based alloys, glass, and ceramics, are very useful in aerospace, marine, electronics, and high-temperature applications because of their extremely versatile mechanical and chemical properties. One Ni-based alloy, Inconel 718, is a precipitation-hardenable material designed with exceptionally high yield strength, ultimate tensile strength, elastic modulus, and corrosion resistance with outstanding weldability and excellent creep-rupture properties at moderately high temperatures. However, conventional machining of this alloy presents a challenge to industry. Ultrasonic vibration cutting (UVC) has recently been used to cut this difficult-to-machine material and obtain a high quality surface finish. This paper describes an experimental study of the UVC parameters for Inconel 718, including the cutting force components, tool wear, chip formation, and surface roughness over a range of cutting conditions. A comparison was also made between conventional turning (CT) and UVC using scanning electron microscopy observations of tool wear. The tool wear measured during UVC at low cutting speeds was lower than CT. UVC resulted in better surface finishes compared to CT under the same cutting conditions. Therefore, UVC performed better than CT at low cutting speeds for all measures compared.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.20 no.2
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• pp.162-168
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• 2011

In this research, nitrogen plasma source ion implantation(PSII) of non-coated tungsten carbide endmill tools was conducted with low heat treatment for increasing wear resistance. After the low heat treatment of PSIIed tools to give a homogeneity of wear resistance, the surface modification of tools was analyzed by hardness test, surface roughness and cutting forces. As for the resultant cutting forces, low heat treatment in temperature of $400^{\circ}C$ and $500^{\circ}C$ is stable because of low cutting resistance. The 20-minutes heat treated tool at spindle speed 25000rpm has superiority of surface roughness, Ra of $0.420{\mu}m$ and was found to have good wear resistance. The higher hardness value was obtained by increasing temperature from $300^{\circ}C$ to $600^{\circ}C$ for PSIIed tools with low heat treatment. As the PSIIed tools under 10minutes at temperature of $600^{\circ}C$ have the highest hardness as Hv of 2349.8, It was analyzed that temperature processing give much influences on hardness.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.15 no.5
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• pp.79-84
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• 2006

In modem manufacturing, many products that have geometrically complicated features, including three-dimensional sculptured surfaces, are designed and produced. In the production of these complex-shaped mechanical components, e.g. automobile dies, molds, and various engineering applications, the ball-end milling process is one of the most widely used NC machining processes that consists of roughing, semi-finishing and finishing. In semi-finishing, cusps remained after roughing according to the used tools that have two patterns of stairs and wave shapes. These cusp shapes have air-cut in cutting and instability caused by high cutting speed that affects the cutting characteristics such as cutting force and tool wear. Cutting characteristics are measured and analyzed through cutting force, FFT analysis of cutting force and tool wear along cutting length according to low tool paths with same metal removal rate. As a results of the experiments, this study suggests the optimal conditions of tool path and cutting direction. This approach for the cutting characteristics of semi-finishing provides a useful aid for the productivity and efficiency improvements of NC machining processes.

• International Journal of Precision Engineering and Manufacturing
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• v.5 no.3
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• pp.35-42
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• 2004

This research describes that the cutting characteristics and tool wear behavior in the micro cutting of three kinds of wear resistant cemented carbides (WC-Co; V40, V50 and V60) using PCD (Poly Crystalline Diamond) and PCBN (Poly crystalline Cubic Boron Nitride) cutting tools by use of the SEM (Scanning Electron Microscope) direct observation method. The purpose of this research is to present reasonable cutting conditions from the viewpoint of high efficient cutting refer to a precise finished surface and tool wear. Summary of the results is as follows: (1) The cutting forces tend to increase as the increase of the weight percentage of WC particles, and the thrust forces was larger than the principal forces in the cutting of WC-Co. These phenomena were different from the ordinary cutting such as cutting of steel or cast iron. (2) The cutting speed hardly influenced the thrust force, because of the frictional force between the cutting tool edge and small WC particles at low cutting speed region such as 2$\mu\textrm{m}$/s. It seemed that the thrust cutting force occurred by the contact between the flank face and work material near the cutting edge. (3) The wear mechanism for PCD tools is abrasion by hard WC particles of the work materials, which leads diamond grain to be detached from the bond. (4) From the SEM direct observation in cutting the WC-Co, it seems that WC particles are broken and come into contact with the tool edge directly. This causes tool wear, resulting in severe tool damage. (5) In the orthogonal micro cutting of WC-Co, the tool wear in the flank face was formed bigger than that in the rake face on orthogonal micro cutting. And the machining surface integrity on the side of the cutting tool with a negative rake angle was better than that with a positive one, as well as burr in the case of using the cutting tool with a negative rake angle was formed very little compared to the that with a positive one.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.1 s.178
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• pp.80-88
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• 2006

In this study, unsintered and presintered low purity alumina ceramics were machined with various tools to clarify the machinability and the optimum cutting conditions. The main conclusions obtained were as fellows. Machined with ceramic tool, the ceramics presintered at the temperature range of $1000\~1100^{\circ}C$ showed the best machinability due to the adhesion formed in weared surface within a certain cutting speed range. In the above combination and conditions, the ceramic tool showed the highest productivity through all experiments. The life of CBN tool was longer in machining of the ceramics presintered at $1000^{\circ}C$ than in the case of that presintered at $600^{\circ}C$, but the diamond tool showed adverse tendency. In machining of the ceramics presintered at $1000^{\circ}C$, the ceramic tool exhibits the longest tool life in high speed, the tool lives became extremely worse in the order of CBN tool and diamond tool. However, in the case of the ceramics presintered at $600^{\circ}C$, the diamond tool shows the longest tool life, the tool lives was much worse in the order of CBN tool and ceramic tool.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.11
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• pp.93-101
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• 1997

Ever since the nonlinearity of machine tool dynamics was established, researchers attempted to make use of this fact to devise better monitoring, diagnostics and control system, which were hitherto based on linear models. Theory of chaos which explains many nonlinear phenomena comes handy for furthering the analysis using nonlinear model. In this study, measuring system will be constructed using multi-sensor (Tool Dynamometer, Acoustic Emission) in end milling process. Then, it will be verified that cutting force is low-dimensional chaos by calculating Lyapunov exponents. Fractal dimension, embedding dimension. And it will be investigated that the relation between characteristic parameter calculated from sensor signal and tool wear.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.16-21
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• 2002

The high speed machining center(HMC) has been widely applied to manufacture a die and trial product in many machine industry. Because the evaluation fer the HMC is not sufficiently performed and the efficient cutting conditions aren't selected, a great loss has been caused in the cost aspect. In this study, the need of preliminary running time and unstable spindle speed is presented from the analysis of acceleration in idling. The Machinability fur the TiAlN coated flat end mill and STD11( $H_{R}$C60) is evaluated from the trends of tool wear and cutting force according to cutting conditions and slenderness ratio and a low response of tool dynamometer in high speed is proved. The resonance spindle speed is identified through the tool wear and natural frequency test.t.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.1
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• pp.39-46
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• 2005

In this study, unsintered, presintered and full-sintered low purity alumina ceramics were machined with various tools to clarify the machinability and the optimum cutting conditions. The main conclusions obtained were as follows. (1) Machined with alloy steel tool, the machinability of the presintered ceramics becomes better with the decrease of presintering temperature, but that of unsintered ceramics(white body) was extremely poor. (2) In the case of carbide, K01, the tool life in machining the white body was the longest, and the machinability of presintered ceramics becomes poorer with the increase of the presintering temperature. (3) The K01 tools exhibit longer life than the P10 tools in machining both the white body and the ceramics presintered at $1450^\circC$ or higher temperatures, but the P10 tools shows longer tool life than the K10 tools in machining of the ceramics presintered at temperatures below $1450^\circC$.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.4
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• pp.104-111
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• 2008

The objective of this study is to evaluate micro end-milling characteristics and tool wear behavior of AlN-hBN composites. First, AlN based composites with hBN contents in the range of 10 to 20vol% were prepared by hot-pressing. Vickers hardness and flexural strength of the prepared composite specimens were measured and compared according to the vol% of hBN variations. Then, cutting force variations were measured and analyzed using a tool dynamometer during the micro end-milling experiments; and machined surface shapes and roughness were investigated using a 3D non-contact type surface profiler. After micro end-milling, worn tools were investigated using a tool microscope and SEM images. From the experimental results, it can be observed that the cutting forces decreased, and surface qualities were improved with increasing hBN contents. At low content of hBN, tool chipping was observed; and tool wear rate decreased with increasing hBN contents. The results of this study insist that proper machining conditions, including tool wear behavior investigation, should be determined for the micro end-milling of AlN-hBN composites for its further application.