To determine the effects of typical manufacturing parameters on the flow of liquid metal and the formation of defects in gray iron lost foam castings, statistically designed experiments were used to develop a model with which to predict metal velocity and defects. In addition, a set of patterns with different coating thicknesses was evaluated to see the effects of decreased air flow rates on metal velocity and formation of defects. The statistically designed experiments were constructed to determine the relative effects of coating permeability or air flow rate, pouring temperature, foam density, and carbon equivalent (C.E).
When the designed experiments used coatings with extreme differences in permeability, the metal velocity was controlled almost exclusively by the coating permeability, or air flow rate. Only small increases in velocity were obtained by increasing the pouring temperature and carbon equivalent. The formation of carbon defects was increased by a higher coating permeability and a high carbon equivalent. No significant and consistent effect of the four variables on the occurrence of penetration defects was observed.
The experiment was redesigned to use coatings with small permeability differences. Higher pouring temperatures and lower air flow rates caused a small increase in velocity, but little effect of foam density and carbon equivalent were observed. Higher pouring temperature and lower carbon equivalent reduced carbon defects, while low air flow rate and high pouring temperature reduced penetration.
Use of multiple layers of coating significantly reduced the air flow rate and, consequently, the metal velocity. The lower air flow rate and velocity also reduced both penetration and surface defects.
Askeland, Donald R.
Ramsay, Christopher W.
Materials Science and Engineering
M.S. in Metallurgical Engineering
University of Missouri--Rolla
ix, 61 pages
© 1997 Jeremy Joseph Green, All rights reserved.
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Green, Jeremy Joseph, "Effects of typical manufacturing parameters on the flow of liquid metal and the formation of defects in gray cast iron lost foam castings" (1997). Masters Theses. 1668.
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