This tour was conducted on November 24, 2003 at Conbraco Industries, Conway, SC plant. They did sand casting and ceramic shell casting. Of most interest to us was the ceramic shell casting, and the steps are outlined below.
First, wax molds are created. They had a machine that made theirs, and we made ours by hand. Once made, they were attached to a wax tree by means of slightly melting the wax.
After treeing the molds were ready to be dipped in ceramic. Here are our molds:
The trees were carried by overhead conveyor belt to the slurry machines. The object was to coat the trees in a ceramic that would be thin enough to capture detail, but thick enough to hold the hot metal.
The ceramic molds were fired to burn out the wax (hence the name 'Lost Wax' or 'Investment' casting) and to harden the ceramic shell. The preheat furnace takes the ceramic shell to around 1900oF.
The metal is poured in at around 2800oF. Some of these pictures are from the sand casting line, but others are from the ceramic shell line. The ceramic shells are placed in a bed of sand and after the metal is poured, a chunk of hexane is tossed in and a hood lowered over the sand and shell. The hexane consumes the oxygen and reduces oxydation.
The shells are allowed to cool and then hit with a sledge hammer to remove the ceramic material. The pieces are separated from the tree and finished with a grinding wheel.
Random pictures
