The influence of unsteady effects on the evacuation of air through vents in pressure die casting processes is analyzed. A model is proposed which considers the air flow as one-dimensional and adiabatic, and which retains friction effects. Venting conditions for wide ranges of the relevant dimensionless parameters are analyzed for both atmospheric and vacuum venting systems. The model is solved numerically using the method of characteristics and its results are compared with those obtained for quasi-steady models. It is shown that wide ranges of operating conditions can exist in practical situations, for which unsteady effects, neglected in previous models, are important and must be taken into account to determine the air mass entrapped at the end of the filling process. The selection of parameters which will reduce the amount of trapped air and thus porosity in manufactured parts is also discussed.
Influence of Unsteady Effects on Air Venting in Pressure Die Casting
Contributed by the Fluids Engineering Division for publication in the JOURNAL OF FLUIDS ENGINEERING. Manuscript received by the Fluids Engineering Division August 12, 1999; revised manuscript received June 11, 2001 Associate Editor: U. Ghia.
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Herna´ndez, J., Lo´pez, J., and Faura, F. (June 11, 2001). "Influence of Unsteady Effects on Air Venting in Pressure Die Casting ." ASME. J. Fluids Eng. December 2001; 123(4): 884–892. https://doi.org/10.1115/1.1412234
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