Experimental and Numerical Investigation of Vacuum Investment Casting on Heat Transfer and Part Quality of Brass

Anastasia Vasileiou, Dimitrios I. Pantelis, George C. Vosniakos

Research output: Chapter in Book/Report/Conference proceedingChapterpeer-review

Abstract

Vacuum casting is widely used as an investment casting method for small parts of
complex geometry. Selection of casting conditions for acquiring sound castings is not a
trivial process. In modern casting machines, the application of pressure directly after
completion of melt pouring is used to ensure proper filling of the very fine details of the
casting tree. The present work concerns examination of casting conditions of brass on a
modern vacuum-pressure casting machine, in order to reveal their influence on part
quality. A parametric investigation was carried out with respect to pressure in the upper
chamber and vacuum in the lower chamber of the machine. The obtained cast samples
were examined with optical microscopy in order to identify possible defects, while image
analysis was used in order to quantify porosity in each sample. In addition, casting
simulation software was exploited to enhance process knowledge. The major issue in
obtaining realistic results from simulation was the determination of the interfacial heat
transfer coefficient (HTC). This was achieved using experimental cooling curves,
obtained with K-type thermocouples during casting under pre-defined conditions. The
heat transfer coefficient, once estimated in each case from the corresponding simulations,
was, then, used in further typical casting scenarios. These scenarios were analyzed with
commercially available casting simulation software. The purpose was to determine the
influence of casting parameters on mould filling time, porosity and solidification time.
Original languageEnglish
Title of host publicationAdvances in Mechanical Engineering Research Volume 2
Place of PublicationNew York
PublisherNova Science Publishers
Chapter7
Pages209-232
Number of pages24
Volume2
ISBN (Electronic)978-1-61122-393-4
Publication statusPublished - 2010

Keywords

  • vacuum-pressure casting
  • Investment casting
  • heat transfer coefficient
  • porosity

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