• Journal of Mechanical Science and Technology
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• v.18 no.5
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• pp.770-779
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• 2004

This paper describes the micro cutting of wear resistant tungsten carbides using PCD (Poly-Crystalline Diamond) cutting tools in performance with SEM (Scanning Electron Microscope) direct observation method. Turning experiments were also carried out on this alloy (V50) using a PCD cutting tool. One of the purposes of this study is to describe clearly the cutting mechanism of tungsten carbides and the behavior of WC particles in the deformation zone in orthogonal micro cutting. Other purposes are to achieve a systematic understanding of machining characteristics and the effects of machining parameters on cutting force, machined surface and tool wear rates by the outer turning of this alloy carried out using the PCD cutting tool during these various cutting conditions. A summary of the results are as follows: (1) From the SEM direct observation in cutting the tungsten carbide, WC particles are broken and come into contact with the tool edge directly. This causes tool wear in which portions scrape the tool in a strong manner. (2) There are two chip formation types. One is where the shear angle is comparatively small and the crack of the shear plane becomes wide. The other is a type where the shear angle is above 45 degrees and the crack of the shear plane does not widen. These differences are caused by the stress condition which gives rise to the friction at the shear plane. (3) The thrust cutting forces tend to increase more rapidly than the principal forces, as the depth of cut and the cutting speed are increased preferably in the orthogonal micro cutting. (4) The tool wear on the flank face was larger than that on the rake face in the orthogonal micro cutting. (5) Three components of cutting force in the conventional turning experiments were different in balance from ordinary cutting such as the cutting of steel or cast iron. Those expressed a large value of thrust force, principal force, and feed force. (6) From the viewpoint of high efficient cutting found within this research, a proper cutting speed was 15 m/min and a proper feed rate was 0.1 mm/rev. In this case, it was found that the tool life of a PCD tool was limited to a distance of approximately 230 m. (7) When the depth of cut was 0.1 mm, there was no influence of the feed rate on the feed force. The feed force tended to decrease, as the cutting distance was long, because the tool was worn and the tool edge retreated. (8) The main tool wear of a PCD tool in this research was due to the flank wear within the maximum value of $V_{max}$ being about 260 $\mu\textrm{m}$.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.04a
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• pp.317-322
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• 2004

This paper deals with a prediction method of tool life in view of the reliability assessment. In this study, the flank wear was studied among multi-factors deciding the tool wear state. Firstly, tool lift was predicted by correlation between flank wear and cutting time, based on the extended Taylor tool life equation of turning data, including parameters of cutting speed, feed rate, and cutting depth. Secondly, each of cutting conditions of endmilling was equivalently converted to apply ball endmill data to the extended Taylor equation. The web-based reliability prediction program for tool lift is being developed as one of reliability assessment programs to for the machine tools.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.4 no.2
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• pp.31-37
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• 1995

This study is focused on the prediction of appropriate tool life by clarifying the correlation between progressive tool wear and AE signal. when rcutting SM45C by End mill in machining center. First of all, end mill have a problem that position of sensor sticking because it is revolution tool, but I think that it can be bained specific character according to sticking Sensor in the Vise. Consequently, the following results have been obtained; 1. Each cutting speed of feed rate over 0.1mm had a tendency to increase linearly according to the RMSAE 2. The level of AE signal at the same cutting area was more sensitive to depth of cut tharn the variation of feed rate 3. In the range of cutting duringqr about 75minqr atqr cutting speed 27m/min flankqr wear turns up aboutqr 0.21mm, aboutqr 0.29mm in the caseqr of about 65minqr at 33/min, qr hereby RMSAE increased rapidly at 0.2mm flank wear, also AE-HIT and CUM-CNTS.

• 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.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.3-8
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• 1996

To enhance the cutting performance of the tool, single or multilayer coating is applied on the substrate of the tool. Coating material reduces cutting force and heat generation in tool-chip contact zone and enhances resistance against abrasive wear. This paper presents that the effect of different coatings on abrasive wear resistance varies with work material and the flank wear rate is different with depth of cut. Crater wear rate is also found to decrease with higher thermal diffusivity of coating material. It is verified that the estimated thermal diffusivity of multilayer coating has consistent effect on the crater wear.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.14 no.6
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• pp.16-21
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• 2005

The cutting characteristics of hardened steel(AISI 52100) by PCBN tools is investigated with respect to cutting force, workpiece surface roughness and tool flank wear by the vision system. Hard Owning is carried out with various cutting conditions; spindle rotational speed, depth of cut and feed rate. Backpropagation neural networks(BPNs) are used for detection of tool wear. The input vectors of neural network comprise of spindle rotational speed, feed rates, vision flank wear, and thrust force signals. The output is the tool wear state which is either usable or failure. The detection of the abnormal states using BPNs achieves $96.8\%$ reliability even when the spindle rotational speed and feedrate are changed.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.1
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• pp.128-133
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• 2010

The Titanium has many superior characteristics which are specific strength, heat resistance, corrosion resistance, organism compatibility, non-magnetic and etc. and their quantity are abundant. this study performed turning operation of Ti-6Al-4V alloy using the TiAlN Coated Tool which treated Physical Vapor Deposition. Experimental works are also executed to measure cutting force, tool wear, chip figuration and surface roughness for different cutting conditions. As a result of study. Cutting depth influences on the cutting force much more than the feed rate and the value of the cutting force is the most stable at the depth of 1.0mm. And tool wear was serious at over 100m/min of cutting speed and cutting condition was excellent at 1.0mm of cutting depth.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.6 no.1
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• pp.27-33
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• 2007

Hard turning on modern lathes becomes a realistic replacement for many grinding applications. Because CBN tools are expensive, excessive tool wear can eliminate economic advantages of hard turning. This paper describes a study of investigating the cutting force and the characteristics of tool wear in hard turning of hardened steels, AISI 52100. Cutting forces generated using CBN tools have been evaluated. The radial thrust cutting force was the largest among three cutting force components. It increased dramatically as a result of progressive tool wear. On the other hand, the result shows significantly different wear characteristics between high CBN and low CBN. Backpropagation neural network was used for the estimation of tool wear. The networks were achieved the reliability of 96.3% even when the spindle speed and feed rate are changed.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.6
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• pp.79-89
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• 1998

In determining optimal cutting condition for face milling operation, tool wear is an important factor. For the purpose of establishing the relationship between various machining factors and tool wear, cutting tests have been performed. As a result, hardness and chemical composition of workpiece material, chemical composition and grain size of cutting tool and cutting speed have been selected as machining factors. In addition, relationship between feed rate and workpiece hardness has been observed. Prior to utilizing cutting conditions recommended by ‘Machining Data Handbook(MDH)’ as a knowledge base, an analysis for the validity of the MDH has been provided. Based on this analysis, tool life criteria applied by MDH has been modified. Finally, using MDH recommended data for neural network trainning, the results from the trained neural network for optimal cutting condition for some given workpiece and cutting tool can be used as reference cutting conditions.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.74-79
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• 1996

The wear of partially coated pinion cutters under several cutting conditions was studied. In the realm of this experiment, chipping was a dominant tool wear mechanism and flank wear was much larger than crater wear. Under the condition of relatively low rotary feed and low radial feed rate, the wear due to chipping was concentrated at the nose part of pinion cutter. Increasing of rotary feed and radial feed rate alleviated the concentration of chipping at nose and prolonged tool life.