• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 춘계학술대회 논문집
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• pp.552-556
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• 1997

The Direct Metal Prototyping(DMP), one of the rapid prototyping technologies, allows the manufacturing of three-dimensional metallic parts using metal powders directly from the CAD data. Laser power and scanning speed are the most important variables of the process. The objective of this study is to obtain the design data for laser power and scanning speed to bond metal powders effectively using the finite element method. To obtain the design values, a numerical analysis considering two-dimensional heat transfer during the sintering of metal powder layers of the process was performed. The laser beam has been modeled to have directionality in its heat flux distribution, i. e., in the scanning direction a Gaussian beam mode distribution has been assumed and in the thickness direction a square beam mode distribution. The three-dimensional irregular distribution of metal powders of the powder layer is idealized as two-dimensional distribution in which metal powders are located regularly and periodically on the plate. In this study the design values of laser power vs scanning speed have been obtained. Temperature distribution and temperature variation of the powder layers with respect to time have been predicted. The commputed dsign data will be useful in determining the initial conditions of the process.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 춘계학술대회 논문집
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• pp.763-766
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• 2000

The Rapid Prototyping and Tooling technology has been developed. However, most commercial ones currently use resins or waxes as the raw materials. These days. the direct metal deposition methods are researched as a true rapid prototyping and tooling technology. A fundamental study on rapid prototyping and tooling with wire welding technology using $CO_2$ laser radiation was carried out in this paper. The main focus is to develop a simple commercial rapid prototyping and tooling system with the exiting laser welding technology. The process is investigated as a function of laser parameters and process variables. Basic parts were fabricated as out-put and their microstructure, hardness and tensile strength are examined for the reliability. In addition, Its advantages and disadvantages are discussed as a rapid prototyping and tooling system.

• 한국정밀공학회지
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• 제17권10호
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• pp.56-62
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• 2000

A fast and precise technique to make 3-dimensional object which is called direct metal shaping process is processed. It is very useful technique in design and inspection. Using this developed system, a solid object is made. In experiment, test parts are built by varying three factors, laser power, scan path, scan speed. This process used device, which is different from the widely used in rapid prototyping in that powder feeding device is used. Spraying powder directly at the focused laser beam and then three dimensional object is made by the deposit of melted metal powder. The optimum scanning path is found to be zigzag path, which had little thermal affection on base metal. As a result of these experiments, it was found that optimum scanning speed is 15mm/sec laser power is 50W. This constructed 3-dimensional object could be used in mold manufacturing directly.

• Journal of Welding and Joining
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• 제17권3호
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• pp.1-7
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• 1999

• 한국정밀공학회지
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• 제18권1호
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• pp.104-110
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• 2001

The rapid prototyping and tooling technology has been developed. However, most commercial ones currently use resins or waxes as the raw materials. These days, the direct metal deposition methods are being investigated as new rapid prototyping and tooling technology. A fundamental study on rapid prototyping and tooling with wire welding technology using CO2 laser radiation was carried out in this paper. The main focus is to develop a simple commercial rapid prototyping and tooling system with the exiting laser welding technology as output and their microstructure, hardness and tensile strength are examined for the reliability. In addition, its advantages and disadvantages are discussed as a rapid prototyping and tooling system.

• 한국주조공학회지
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• 제20권5호
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• pp.330-335
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• 2000

Functional metal prototypes are often required in numerous industrial applications. These components are typically needed in the early stage of a project to determine form, fit and function. Recent R/P(Rapid Prototyping) part are made of soft materials such as plastics, wax, paper, these master models cannot be employed durable test in real harsh working environment. Parts by direct metal rapid tooling method, such as laser sintering, by now are hard to get net shape, pores of the green parts of powder casting method must be infiltrated to get proper strength as tool, and new type of 3D direct tooling system combining fabrication welding arc and cutting process is reported. But a system which can build directly 3D parts of high performance functional material as metal park would get long period of system development, massive investment and other serious obstacles, such as patent. In this paper, through the rapid tooling process as silicon rubber molding using R/P master model, and fabricate wax pattern in that silicon rubber mold using vacuum casting method, then we translated the wax patterns to numerous metal tool prototypes by new investment casting process combined conventional investment casting with rapid prototyping & rapid tooling process. With this wax-injection-mold-free investment casting, we developed new investment casting process of fabricating numerous functional metal prototypes from one master model, combined 3-D CAD, R/P and conventional investment casting and tried to expect net shape measuring total dimension shrinkage from R/P pare to metal part.

• 한국레이저가공학회지
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• 제3권3호
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• pp.21-29
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• 2000

For the direct metal shape processing the powder feed device which is different from the widely used in rapid prototyping. is developed, The three dimensional object is shaped with the melting metal powder. The developed research has applied to rapid prototyping in ultraprecision for MEMS and medical science fields required of rapid manufacture of complex shape. The goal of this study make 3D model which has precision accuracy. Powder spreading apparatus has been more improved because that the control of powder spread is very important in layer manufacturing. It consists of the vibration motor, nozzle and tube which supplies various metal powder. This apparatus could control the spreading velocity that could control powder spreading thickness. Laser on/off switch was adapted because laser scanning velocity must be preserved constantly to prevent heat transformation of laser overheating. The error between sintered thickness md experimental one occurred by shrinkage in sintering melting process. The problem of heat transformation was solved by On/Off switching system.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.521-522
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• 2006

Laser additive direct deposition of metals is a new rapid manufacturing technology, which combines with computer aided design, laser cladding and rapid prototyping. The advanced technology can build fully-dense metal components directly from CAD files with neither mould nor tool. Based on the theory of this technology, a promising rapid manufacturing system called "Laser Metal Deposition Shaping (LMDS)" is being developed significantly. The microstructure and mechanical properties of the LMDS-formed samples are tested and analyzed synthetically. As a result, significant processing flexibility with the LMDS system over conventional processing capabilities is recognized, with potentially lower production cost, higher quality components, and shorter lead time.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.250-251
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• 2006

It is known that powder characteristics including particle size and distribution, particle shape, and chemical composition are important parameters which influence direct laser sintering of metal powders. In this paper, we introduce a first order kinetics model for densification of steel powders during laser sintering. A densification coefficient (K) is defined which express the potential of different powders to be laser-sintered to a high density dependent on their particle characteristics.

• 한국정밀공학회지
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• 제16권6호
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• pp.52-57
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• 1999

Funtional metal prototypes are often required in numerous industrial applications. These components are typically needed in the early stage of a project to determine form, fit and function. Recent R/P(Rapid Prototyping) part are made of soft materials such as plastics, wax, paper, these master models cannot be employed durable test in real harsh working environment. Parts by direct metal rapid tooling method, such as laser sintering, by now are hard to get net shape, pores of the green parts of powder casting method must be infiltrated to get proper strength as tool, and new type of 3D direct tooling system combining fabrication welding arc and cutting process is reported by song etc. But a system which can build directly 3D parts of high performance functional material as metal part would need long period of system development, massive investment and other serious obstacles, such as patent. In this paper, through the rapid tooling process as silicon rubber molding using R/P master model, and fabricate wax pattern in that silicon rubber mold using vacuum casting method, then we tranlsated the wax patterns to numerous metal prototypes by new investment casting process combined conventional investment casting with rapid pototyping & rapid tooling process. with this wax-injection-mold-free investment casting, we developed new investment casting process of fabricating numerous functional metal prototypes from one master model, combined 3-D CAD, R/P and conventional investment casting and tried to expect net shape measuring total dimension shrinkage from R/P part to metal part.