Modeling of Air Venting in Pressure Die Casting Process

2004 ◽  
Vol 126 (3) ◽  
pp. 577-581 ◽  
Author(s):  
A. Nouri-Borujerdi ◽  
J. A. Goldak
Keyword(s):  
Friction Factor ◽  
Die Casting ◽  
Casting Process ◽  
Area Ratio ◽  
Air Pressure ◽  
Temperature Dependent Viscosity ◽  
Air Mass ◽  
Choked Flow ◽  
Dependent Viscosity ◽  
Pressure Die Casting

In this study an analytical model has been developed to describe air pressure and residual air mass variations in pressure die casting for atmospheric venting. During injection of molten metal into a die cavity, air is evacuated from the cavity through vents. In this study, the influences of air velocity and friction factor due to temperature dependent viscosity and vent roughness change have been investigated. The results of the model show that there is a critical area ratio over which a quasi steady state is reached, therefore, the air pressure in the cavity remains constant. In addition, for each area ratio there is a critical/minimum time ratio below which outlet Mach number is not large enough to create choked flow. In this case, the rate of outflow air mass is not maximum. Finally, the results of the model addresses that the friction factor depends on hydraulic diameter of the vent and assuming a constant value for it is not valid.

Heat Transfer in Turbulent Pipe Flow for Liquids Having a Temperature-Dependent Viscosity

1978 ◽  
Vol 100 (2) ◽  
pp. 224-229 ◽  
Author(s):  
O. T. Hanna ◽  
O. C. Sandall
Keyword(s):  
Heat Transfer ◽  
Friction Factor ◽  
Pipe Flow ◽  
Turbulent Pipe Flow ◽  
Fluid Viscosity ◽  
Temperature Dependent ◽  
Temperature Dependent Viscosity ◽  
Analytical Approximations ◽  
Constant Viscosity ◽  
Dependent Viscosity

Analytical approximations are developed to predict the effect of a temperature-dependent viscosity on convective heat transfer through liquids in fully developed turbulent pipe flow. The analysis expresses the heat transfer coefficient ratio for variable to constant viscosity in terms of the friction factor ratio for variable to constant viscosity, Tw, Tb, and a fluid viscosity-temperature parameter β. The results are independent of any particular eddy diffusivity distribution. The formulas developed here represent an analytical approximation to the model developed by Goldmann. These approximations are in good agreement with numerical solutions of the model nonlinear differential equation. To compare the results of these calculations with experimental data, a knowledge of the effect of variable viscosity on the friction factor is required. When available correlations for the friction factor are used, the results given here are seen to agree well with experimental heat transfer coefficients over a considerable range of μw/μb.

Predicting heat extraction due to boiling in the cooling channels during the pressure die casting process

2000 ◽  
Vol 214 (3) ◽  
pp. 465-482 ◽  
Author(s):  
L D Clark ◽  
I Rosindale ◽  
K Davey ◽  
S Hinduja ◽  
P J Dooling
Keyword(s):  
Heat Transfer ◽  
Forced Convection ◽  
Die Casting ◽  
Casting Process ◽  
Nucleate Boiling ◽  
Heat Extraction ◽  
Film Boiling ◽  
Cooling Channels ◽  
Die Casting Process ◽  
Pressure Die Casting

The effect of boiling on the rate of heat extraction by cooling channels employed in pressure die casting dies is investigated. The cooling effect of the channels is simulated using a model that accounts for subcooled nucleate boiling and transitional film boiling as well as forced convection. The boiling model provides a continuous relationship between the rate of heat transfer and temperature, and can be applied to surfaces where forced convection, subcooled nucleate boiling and transitional film boiling are taking place in close proximity. The effects of physical parameters such as flow velocity, degree of subcooling, system pressure and bulk temperature are taken into account. Experimental results are obtained using a rig that simulates the pressure die casting process. The results are compared with the model predictions and are found to show good agreement. Instrumented field tests, on an industrial die casting machine, are also reported. These tests show the beneficial effects of boiling heat transfer in the pressure die casting process, including a 75 per cent increase in the production rate for the test component.

High-Pressure Die-Casting Process Modelling Using Neural Networks

2006 ◽  
pp. 182-198 ◽  
Author(s):  
M. Imad Khan ◽  
Saeid Nahavandi ◽  
Yakov Frayman
Keyword(s):  
High Pressure ◽  
Process Parameters ◽  
Current Knowledge ◽  
Die Casting ◽  
Process Condition ◽  
Industrial Process ◽  
Casting Process ◽  
High Pressure Die Casting ◽  
Die Casting Process ◽  
Pressure Die Casting

This chapter presents the application of a neural network to the industrial process modeling of high-pressure die casting (HPDC). The large number of inter- and intradependent process parameters makes it difficult to obtain an accurate physical model of the HPDC process that is paramount to understanding the effects of process parameters on casting defects such as porosity. The first stage of the work was to obtain an accurate model of the die-casting process using a feed-forward multilayer perceptron (MLP) from the process condition monitoring data. The second stage of the work was to find out the effect of different process parameters on the level of porosity in castings by performing sensitivity analysis. The results obtained are in agreement with the current knowledge of the effects of different process parameters on porosity defects, demonstrating the ability of the MLP to model the die-casting process accurately.

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