Investigation of Heat Transfer at the Mold/Metal Interface in Permanent Mold Casting of Light Alloys

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Accurate modeling of the metal casting process prior to creating a mold design demands reliable knowledge of the interfacial heat transfer coefficient at the mold metal interface as a function of both time and location. The phenomena concerned with the gap forming between the mold and the solidifying metal are complex but need to be understood before any modeling is attempted. The presence of mold coatings further complicates the situation. A commercial casting was chosen and studied in a gravity permanent mold casting process. The metal/mold interfacial heat transfer coefficient (IHTC) was the focus of the research. A simple, direct ... continued below

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Pehlke, Robert D. & Berry, John T. December 16, 2005.

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Accurate modeling of the metal casting process prior to creating a mold design demands reliable knowledge of the interfacial heat transfer coefficient at the mold metal interface as a function of both time and location. The phenomena concerned with the gap forming between the mold and the solidifying metal are complex but need to be understood before any modeling is attempted. The presence of mold coatings further complicates the situation. A commercial casting was chosen and studied in a gravity permanent mold casting process. The metal/mold interfacial heat transfer coefficient (IHTC) was the focus of the research. A simple, direct method has been used to evaluate the IHTC. Both the simulation and experiments have shown that a reasonably good estimate of the heat transfer coefficient could be made in the case studied. It has been found that there is a good agreement between experiments and simulations in the temperature profiles during the solidification process, given that the primary mechanism of heat transfer across the gap in permanent mold casting of light alloys is by conduction across the gap. The procedure utilized to determine the interfacial heat transfer coefficient can be applied to other casting processes. A recently completed project involving The University of Michigan and Mississippi State University, together with several industrial partners, which was supported by the USDOE through the Cast Metals Coalition, examined a number of cases of thermal contact. In an investigation which gave special consideration to the techniques of measurement, several mold coatings were employed and results presented as a function of time. Realistic conditions of coating thickness and type together with an appropriate combination of mold preheat and metal pouring temperature were strictly maintained throughout the investigation. Temperature sensors, in particular thermocouples, play an important part in validating the predictions of solidification models. Cooling curve information, as well as temperature gradient history both in the solidifying metal and within the mold are invariably required to be validated. This validation depends upon the response of the sensor concerned, but also on its own effect upon the thermal environment. A joint university/industry team has completed an investigation of the invasive effects of thermocouples upon temperature history in permanent molds determining the degree of uncertainty associated with placement and indicating how the time-temperature history may be recovered. In addition to its relevance to the all important study of thermal contact of the casting with metallic molds, the observations also impact the determination of heat flux and interfacial heat transfer coefficients. In these respects the study represents the first of its kind that has tackled the problem in depth for permanent mold castings. An important ramification of this investigation has been the errors likely to be encountered in mold temperature measurement with thin section aluminum castings, especially with respect to the plans for thermocouple placement. A comparison between the degree of uncertainty experienced in sand molds compared with that found in permanent molds reveals that the associated problems have a lesser impact. These conclusions and the related recommendations have been disseminated to industry and the technical community through project reports and publications.

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  • Report No.: 02ID14236
  • Grant Number: FC36-02ID14236
  • DOI: 10.2172/861448 | External Link
  • Office of Scientific & Technical Information Report Number: 861448
  • Archival Resource Key: ark:/67531/metadc792940

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Office of Scientific & Technical Information Technical Reports

Reports, articles and other documents harvested from the Office of Scientific and Technical Information.

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Creation Date

  • December 16, 2005

Added to The UNT Digital Library

  • Dec. 19, 2015, 7:14 p.m.

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  • Jan. 9, 2017, 10:57 a.m.

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Pehlke, Robert D. & Berry, John T. Investigation of Heat Transfer at the Mold/Metal Interface in Permanent Mold Casting of Light Alloys, report, December 16, 2005; United States. (digital.library.unt.edu/ark:/67531/metadc792940/: accessed July 17, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.