• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.104-107
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• 2002

Direct Metal Manufacturing (DMM) is a new additive process that aims to take die making and metalworking in an entirely new direction. It is the blending of five common technologies : lasers, computer-aided design (CAD), computer-aided manufacturing (CAM), sensors and powder metallurgy. The resulting process creates parts by focusing an industrial laser beam onto a tool-steel work piece or platform to create a molten pool of metal. A small stream of powdered tool-steel metal is then injected into the melt pool to increase the size of the molten pool. By moving the laser beam back and forth, under CNC control, and tracing out a pattern determined by a computerized CAD design, the solid metal part is built line-by-line, one layer at a time. DMM produces improved material properties in less time and at a lower cast than is possible with traditional fabrication.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.824-828
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• 2002

Twin screw extruders are the heart of the polymer processing industry. The single most important mechanical element of a screw extruder is the screw. The proper design of the geometry of the excluder screw is of crucial importance to the proper functioning of the extruder. If material transport instabilities occur as a result of improper screw geometry, even the most sophisticated computerized control system cannot solve the problem. For this purpose, Tool shape design for the screw flights cutting in twin screw extruder.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.2
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• pp.89-96
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• 2000

This paper describes the characteristic of die finishing to obtain smooth surface using electro-chemical grinding after cutting process. Electro-chemical grinding is possible under lower load and tool wear comparing with those in the mechanical grinding. Conventionally, if the metal bonding material of the grinding wheel is directly t contacted with workpiece, the current is circulated without electrolytic phenomena. Sometimes, electrical discharge is occurred between tool and workpiece. To cope with this problem, the metal-resin bonded pellet was used in this study. This pellet is composed of optimal volume of metal and resin powders and its characteristics are changable with the each volume of powders. Finally, high efficient die finishing is realized using metal resin bonded pellet in electro-chemical grinding.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.327-330
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• 2004

Laser aided direct metal deposition (LADMD) process offers the ability to make a metal component directly from 3-D CAD dimensions. A 3-D object can be formed by repeating laser cladding layer by layer. The key of the build-up mechanism is the effective control of powder delivery and laser power to be irradiated into the melt-pool. A feedback control system using optical sensors is introduced to control laser power and powder mass flow rate. Using H13 tool steel and $CO_2$ laser system, comprehensive analysis are executed to test the efficiency of the system. In addition, the dimensional characteristics of directed deposited material are investigated with the parameters of deposition thickness, laser power, traverse speed and powder mass flow rate.

• IE interfaces
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• v.12 no.3
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• pp.374-381
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• 1999

In this paper, we propose an architecture of the DNC system for Shop Floor Control/Point of Production(SFC/POP). The DNC system to be presented this paper retrieves line-up sheets which include the drawing information, making a index database for line-up sheets, NC programs and tool adjustment data. And it is interface with a raw material, jig and tool information. Also, the DNC system transmits operation information to real workers rapidly, and supports realtime monitoring by collecting the state information of machines directly. In the analysis and design phases, this paper models realtime events using the state transition diagrams. In the implementation phase, we use the ORACLE DBMS(Database Management System) as the DBMS and Developer 2000 and Microsoft Visual C++ 5.0 as the programming tools.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.7
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• pp.2182-2195
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• 1996

Densification characteristics and behavior of tool steel powder compact during high temperature forming processes were investigated under pressure less sintering, sinter forging and hot isostastic pressing. In pressureless sintering, full density was obtained at a closely controlled temperature near the solidus of the material. Finite element calculations from constitutive model for densification by power law creep and diffusional flow were compared with experimental data. Agreements between theoretical calculations and experimental data were good in hot isostatic pressing but not as good in sinter forging.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.10 no.4
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• pp.109-114
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• 2011

An impeller is difficult to machine because of severe collision due to the complex shape, overlapping and twisted shape that form impeller blades. So, most CAM software companies have developed CAM module for manufacturing impeller in addition to their CAM software. But it is not still easy for inexperienced users to machine impellers. The purpose of this paper is the development of automatic CAM module for manufacturing impeller(E-ICAM) which is based on visual basic language and it is used CATIA graphical environment in order to be easily machining impellers. Automatic CAM module for manufacturing of impellers generates tool path, and proposes recommended cutting condition according to the material of stock and tool. In addition, it has also included a post processor for 5-axis control machining. Therefore the user can easily machine impellers using this automation module.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2001.10a
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• pp.172-178
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• 2001

Titanium alloys have lightness, high strength and good corrosion resistant characteristics, and broadly used in manufacturing parts for military and aerospace industries. And these alloys also are recognized for organism materials comparatively and used as fixing ones in the human body. Nevertheless thess alloys have excellent properties such as corrosion resistance, heat resistance, and good tensile strength, it is difficult to machine by traditional methods because of high hardness and chemically activated property. So higher tool wear is expected when cutting by tools. Therefore, it is required nontraditional machining process. And the mechanical characteristics such as surface structure and shape, hardness and bending strength are studied for wire electrical discharge machined and surface ground titanium alloys for various heat-treated conditions.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.961-964
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• 1995

For geometric accuracy in the net shape machining, the problem of tool deflection should be resolved in some fashion. In particular, this is crucial in finish cut operation where slim tools are used. The purpose of this paper is to verify the validity and effectiveness of the prediction model of the machined surface. Experimental results are presented for the cut of steel material with HSS endmill of diameter 6mm on machining center. The results shows that 1) the machining error due totool deflection is serious even in the low cutting load, 2) by using the mechanistic simulation model with experimental coefficients, the machining error was predicted with maximum prediction error of 10% which was significantly reduced to the desired level by the path modification method.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.1
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• pp.47-52
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• 2005

In this paper, the effect of TiN-coating on product quality such as dimensional accuracy and surface roughness is experimentally investigated. A punch of SKD11 material in cold forging an automotive bearing shaft and its related process found in a cold forging company are selected as the test example. The effect of TiN-coating is revealed in a quantitative manner. It is to be noted that TiN-coating is effective in controlling the dimensional accuracy and surface roughness as well as in increasing tool lift.