lost wax bonze casting problem

Posted by Jerry Vaughan on October 30, 1998 at 14:19:23:

Years back I built a fairly large foundry setup for casting metal sculpture (>100 lb. bronze). I have recently retired from my laboratory and classroom (physiology, anatomy, zoology) at the University of Tennesse and am returning to aluminum and bronze sculptural casting. I have bought a commercial melting furnace (McEnglevan) and have it running. The aluminum process is going fine but with bronze I am having a poor 50% failure. I am using Si-bronze bought in ingot form. I put wax models in a plaster/sand investment and burnout the molds for about 15 hours raising the temperature of the burnout furnace 100 F. or less per hour until a temperature of 1100 F. is achieved. The problem? About half of the castings are incompletely filled. The mold vents and sprues show metal has filled the molds but the casting is full of lacunae, spaces without metal. Metal is flowing through and reaching the entire mold space but leavings blank spots. The other 50% of trials are quite successful. What do you think might be the source of the problem? I would be pleased to get suggestions frome anyone who might have a possible solution. Thanks very much.

Jerry Vaughan

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