• Journal of the Korean Society for Precision Engineering
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• v.18 no.9
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• pp.101-109
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• 2001

The simulated die casting process in which the traditional plaster casting process is combined with rapid prototyping technology is being used to produce Al, Mg and Zn die casting prototypes. Because of lower mechanical properties induced by the large grain structure and incomplete filling, conventional plaster casting is not suitable for the simulated die casting process. A plaster casting process with pressurized vibration was developed for the simulated die casting process[5]. In this paper, numerical simulation for the filling stage of the process has been performed to show the effect of the pressurized vibration for complete filling. Treatment of boundary condition based on the finite element method has been proposed for imparted pressurized vibration in the plaster casting process.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.3 s.174
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• pp.769-776
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• 2000

RP(Rapid Prototyping) technology is gaining its popularity in building a prototype in all industries. SLS(Slective Laser Sintering) is one of RP technologies, which is focused on tooling processes as well as three dimension solid model. There are several factors, the length and the cross-sectional area of a part, that have an effect on build setup in SLS process. In this paper, the computation on geometrical relationship is used to slice STL file and to estimate these factors. Based on these values, the build setup parameters such as the heating temperature, the laser power, and the powder cartridge feed rate are determined by neural network approaches. The test results show that the computation time is saved and the neural network approach is able to apply to get the optimal parameters of build process within an acceptable error rate.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.3
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• pp.47-52
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• 2001

Rapid Prototyping(RP) has been widely applied in designing and developing process of new products. RP can reduce the lead time and expense required to bring a new product form initial concept to production. Among several RP process can dramatically reduce the total build time and be applied for fabrication of large-sized and free form object because it uses in LOM the paper thickness is 0.05∼0.38mm as deposition feature segment. In this study, mechanical properties of pattern with LOM system is studied for optimal design of sand mold casting. The main result is that tensile, compressive strength and pattern size are significantly affected by temperature of hot roll.

• Journal of Welding and Joining
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• v.23 no.2
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• pp.47-51
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• 2005

Rapid Prototyping (RP) technology has helped successfully to reduce time and costs since first emerged in 1986. Recently, RP using functional materials like as metal have been researched. However RP using molten metal and brazing material have been struggling to resolve several drawbacks, such as dimensional inaccuracy, poor surface finish and post finishing because occurring shrinkage and warpage at cooling. So, the purpose of this study is to develop a new RP technique using sheet metal and projection welding for reducing several drawbacks in occurring RP using molten metal. And optimum process variables were determined using desist of experiment(DOE).

• Journal of the Korean Society for Precision Engineering
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• v.22 no.10 s.175
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• pp.99-106
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• 2005

This paper presents manufacture of mock-up by HSM and optimization of machining condition for high productivity in the view of manufacturing time and accuracy. The rapid machining of prototypes plays an important role in building mock-up. Rapid Prototyping(RP) is a technology to make prototype. But, it have many problems such as shrinkage. deformation and formation occurred by hardening of resin and stair shaping. On the contrary, high speed machining(HSM) technology has many advantages such as good quality, low cost and rapid machining time. HSM and RP is compared for machining efficiency. Experiments are designed by Latin Square Method and machining condition is optimized and selected by ANOVA. For example, propeller is machined by the surface machining of thin surface parts.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.8
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• pp.46-52
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• 2000

3D Welding and Milling is a solid freeform fabrication process which is based on the combination of welding as additive and conventional milling as subtractive technique. This hybrid approach enables direct building of metallic parts with high accuracy and surface finish. Although it needs further improvements it shows an application potential in rapid tooling of injection mold inserts as the investigation results show. To optimize the process for higher surface quality and accuracy effectively Taguchi method is applied to the experimental investigation. in this way relationships between process parameters and final product qualities such as tensile strength and surface hardness are found with minimal efforts.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.128-131
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• 2005

Structural Dynamics Modification (SDM) is a very effective technique to improve structure's dynamic characteristics by adding or removing auxiliary structures. changing material properties and shape of structure. Among those of SDM technique, the method to change shape of structure has been mostly relied on engineer's experience and trial-and-error process which are very time consuming. In order to develop a systematic method to change structure shape, surface grooving technique is studied and successfully applied to HDD cover model. To check the effectiveness of this surface grooving technique, the grooved HDD cover design was manufactured using rapid prototyping and experimentally tested to prove the effectiveness of the grooving method as one of SDM techniques. And the modal strain energy and eigenvalue sensitivity method for choosing the initial starting point are compared.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.10
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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.