Metcalf Pouring Superalloy at GE from Oct 1955 to June 1956
General Electric was looking for melters with experience with superalloy melting. My partner who had taught me how to melt left General Motors to work at General Electric. He helped me get the better paying position after only six months with General Motors. The new job was operation of a one ton vacuum induction-melting furnace. Their main contract was with the Allison Division of General Motors to produce metal for the turboprop engine for the Electra aircraft.
My job was to load the proper mix of pure metals into the furnace and push the button. I also had to load and unload the molds into which the liquid metal was poured for cooling. The equipment was just too fancy to do the simple job of melting and pouring in a controlled environment. The facility was not designed for the poor furnace operator that had to climb in and out of the chamber to accomplish the task. The precision valves and seals were always getting jammed with metal shot that was thrown from the metal surface during melting.
The job at GE taught me why and how to melt metal in a vacuum to produce the metals needed for the jet age. The new steels required for the jet age contain materials that burn to slag and leave inclusions in the metal if melted in normal furnace operation in air. When the melting operation was carried out in a vacuum the metal had a much better quality. The equipment was a simple induction furnace that was mounted in a large steel chamber. The air was removed from the chamber with vacuum pumps, so the metal could be melted and poured without the effect of air.
The GE furnace was designed to allow several melts to be made before vacuum was released in the melting chamber. This was accomplished using a mold chamber that was separated by a valve under the pouring point for the liquid metal. Molds were raised to the lip of the furnace by a long polished rod that passed through a sliding vacuum seal. There was a turntable with six positions in the mold chamber. High level management from GE headquarters attended the first production melt and I was the furnace operator. The alloy contained manganese that boiled and coated the sight glass during the melt so it was hard for the visitors to see the liquid metal. They departed just before the pouring operation. I knew there were four molds loaded on the six positions by the previous shift but I did not know where they were. I decided that number one must be full so I sent it up to pour. The only thing I could see was the red color of the melt and as bad luck would have it I dumped liquid metal on that beautiful polished shaft. My first design contribution to vacuum melting was a suggestion to use a four-inch gate valve so the sight glass could be changed if necessary.
My hands-on experience allowed me to understand what was needed from the operational point of view and to talk and think like an expert on this subject without understanding the metallurgy.
Hunting was very popular in Michigan and everybody wanted the four-day weekend off at Thanksgiving. I babysat the furnace twenty-four hours per day and earned enough to buy a good used car.