• Journal of the Korean Society for Precision Engineering
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• v.17 no.4
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• pp.48-68
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• 2000

The high-speed machining technology of difficult-to-cut material is needed to achieve the high-efficiency of die manufacturing. The high-speed machining is applied in automobile, airplane and electricityㆍelectro industry etc, because it can improve machining efficiency and productivity with high speed, high power and high rotation. In this study, high speed machinability, tool wear characteristics and its monitoring, characteristics of damaged layer, machinability of difficult-to-cut material, characteristics of a free curved surface and method of CAD/CAM system were introduced to acquire the shortening of machining time, the improvement of machining efficiency and the high quality of machined surface. Therefore, we establish the stabilization condition of difficult-to-cut material machining and present the optimal cutting condition for high-efficiency cutting.

• Journal of the Korean Society for Precision Engineering
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• v.1 no.2
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• pp.41-46
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• 1984

The machinability of calicium-deoxidized steel is studied in turning by being compared with that of Fe-Si deoxidized steel under a given set of cutting condition. Tool life, cutting force and cutting mechanism are examined on a few sorts of steel. It is found that adhesive layer "Belag" is developed on the cemented carbide tool and the peak value is observed at the cutting speed of 300m/min followed by gradual increase in the thickness of Belag with the increase of cutting speed. the maximum thickness of Belag is also shown at the feed of 0.3mm/rev. On the other hand, the tool life of carbide tool is more favorable than that of high speed steel (SKH 9) in cutting calcium- deoxidized steel. It is considered that the steel deoxidized with Ca-Si shows better machinability a little than that with Fe-Si. However, the cutting force and the shear angle of the former are similar to those of the latter in turning.n turning.

• 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 $1450^\circC$.

• The Korean Journal of Ceramics
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• v.5 no.1
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• pp.19-24
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• 1999

The influences of TiB2 additions to the β-sialon on mechanical propeties and electrical discharge machinability were investigated. Samples were prepared by adding 15, 30 and 45 vol.% TiB2 particles as a second phase to a β-sialon matrix. The β-sialon-TiB2 composites were sintered by hot pressing in a nitrogen atmosphere at 1800℃ with pressure of 30 MPa. The fracture toughness of the composites was increased with TiB2 content except 45 vol.% TiB2 composite. The crack propagation and crack deflection were observed with a SEM for etched samples after vicker's indentation. The composites containing more than 30 vol.% TiB3 had resistivity lower than 10-3 Ω㎝. The electrical discharge machining (EDM) of composited was conducted with two kind of machines such as die-sinker and wire cutter. The machinability was evaluated with the cutting rate surface roughness after machining.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.5
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• pp.88-93
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• 2012

This paper describes the machinability of the sintered carbide and tool-die steel(STD-11) by electric discharge drilling with various tubular electrodes which have multi-holes. Various types of electrode which have different diameters and materials are used with the application of continuous direct current and axial electrode feed. Inner part of electrodes are inserted with smaller tubes or Y-channel or bar. In ED-Drilling, the dielectric flushed down the interior of the rotating tube electrode, in order to remove machining debris from the hole. As result of experiments, the bigger the diameter of the electrode is, the lower the material removal rate is. Machinability of copper electrode is higher than that of brass. In machining of sintered carbide, to use oil is better than distilled water as dielectric.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.2
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• pp.146-153
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• 1998

NC machines with 4 or 5 axes are capable of various tool approach motions, which makes interference-free and high machinablity machining possible. This paper deals with how to integrate these two advantages (interference-free and high machinability machining) in multi-axes NC machining with a ball-end mill. Feasible tool approach region at a point on a surface is first computed, then among which an approach direction is determined so as to minimize the cutting force required. Tool and spindle volumes are considered in computing the feasible tool approach region, and the computing time is improved by trans-forming surface patches into minimal enclosing spheres. A cutting force prediction model is used for estimating the cutting force. The algorithm is developed so as to be applied to 4- or 5-axes NC machining in common.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1996.10a
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• pp.75-78
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• 1996

End Milling is avilable for machining the variable shape of products and has been widely applicated in many industries. To manufacture precise products a surface roughness has to be noticable as a improtant parameter. In end milling the research for tool wear has been insufficient because the tool shape and the cutting geometry are complicated. In this paper the pattern of endmill wear is investigated and the machinability is evaluated. As finding out the characteristics of cutting force and surface roughness the effect of endmill wear on machinability is investigated.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.05a
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• pp.987-990
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• 2000

In modern manufacturing industry such as aerospace, vehicle and die/mold industry, the high hardness malarial which is remarkable in aspects of durability is effectively used. The high-speed and precision machining technology has been applied in these fields. In this study, efficient sensors in high-speed machining by observing similar tendency through comparing cutting force with AE signal, gap sensor signal and accelerometer signal are selected, and machinability of high-speed machining is experimentally evaluated. We performed a basic research for sensing system construction to monitor a machine tool and machining condition.

• KSTLE International Journal
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• v.3 no.1
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• pp.17-22
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• 2002

Roughing of tool steel in its hardened state represents a real challenge in the die and meld industry and process improvement depends on research of tool material, coating technique, and lubrication. However, roughing of hardened steels generates extreme heat and without coolant flooding, tool material cannot withstand the high temperature without choosing the right tools with proper coating. This research conducted milling tests using coated ball end mills to study effects of cutting conditions and geometric parameters of ball end mills on the machinability of hardened tool steel. KP4 steel and STD 11 heat treated steels were used in the dry cutting as the workpiece and TiAIN coated ball end mills with side relief angle of 12$^{\circ}$ was utilized in the cutting tests. Cutting forces, tool wear, and surface roughness were measured in the cutting tests. Results from the experiments showed that 85 m/min of cutting speed and 0.32 mm/rev of feed rate were optimum conditions for better surface finish during rough cutting and 0.26mm/rev with the same cutting speed are optimum conditions in the finish cutting.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.04a
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• pp.258-263
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• 2000

Under the optimal cutting conditions, determined the machinability difference of cutting tools are by two major factors. One is the geometric shape of the cutting tool, and the other is the tool materials or heat treatment or coating of the cutting tool. In this research, we evaluated the machinability of cutting tools with conventional HSS and P/M(powder metallurgy) which was made from the different of materials and manufacture processes. Tool wear, surface roughness, cutting force and squareness of machined workpiece were evaluated.