• Title/Summary/Keyword: vacuum process

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Variations of Form Accuracy in the Process of Metal Cast Prototyping using Rapid prototype, Vacuum casting and Ceramic Mold (쾌속조형과 진공주형 및 세라믹 몰드를 이용한 금속 주조 시제품 제작 공정에서의 형상정밀도 변화)

  • Kim, Gi-Dae
    • Journal of the Korean Society for Precision Engineering
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    • v.24 no.6
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    • pp.131-137
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    • 2007

  • In metal casting process, it is very difficult to predict the form accuracy of cast part and reduce repeatability error. In this study, the variations of form accuracy were measured in the process of metal cast prototyping, where RP part is manufactured from CAD model in the first, and then, wax part is cast in the vacuum environment using the RP part as master model, and finally metal prototype is cast using ceramic mold and the wax part as pattern. To investigate the variations of form accuracy, the averages and standard deviations of error distribution of the parts measured by 3D scanner were compared. It was observed that the biggest shrinkage is generated during the extraction of wax part in the second step and the biggest deterioration of form accuracy is generated during the metal part casting in the last step.

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Comparison of Drying Characteristics of Square Timber by Heated Platen and Radio-frequency/Vacuum Drying (큰 정각재의 가열판과 고주파 진공건조간 건조특성의 비교)

  • Jung, Hee-Suk;Kang, Wook;Lee, ChuI-Hyun
    • Journal of the Korean Wood Science and Technology
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    • v.30 no.2
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    • pp.108-114
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    • 2002

  • Red pine(Pinus densiflora) square timbers with 14.0 cm and 16.5 cm of face size and 24 m long were dried in a vacuum-press kiln and in a radio-frequency/vacuum(RF/V) kiln to compare drying rate, moisture content(MC) distribution and specific energy. RF/V drying rate was higher than vacuum-press drying rate. The effect of size of cross section on the RF/V drying rates were more pronounced than those of vacuum-press drying. The longitudinal- and the transverse MC distribution of dried square timber showed convex profile for the vacuum-press drying and concave profile for the RF/V drying. Moisture gradient of width direction was similar to the thickness direction in vacuum-press dried square timber and was more slight than that of the thickness direction in the RF/V dried large square timber. The specific energy consumption curve increased as MC decreased. Specific energy(kWh/kg of water evaporated) of the vacuum-press process required more than that of the RF/V process.

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