Hot Tops
The automobile business had grown enormously from the start of the Ford Motor Company in 1903. Better car manufacturing required higher quality steel for critical parts. The Republic Steel Corporation and the Timken Company plants in Canton, Ohio, were among the early leaders in the United States in the development of specialty steels by adding various allow elements. Steel plants used substantial amounts of a variety of clay refractory products in melting, pouring and heat-treating steel products. Art Estep asked his friend Pete Daly, who was in charge of the Timken melt shop, “What products do you use that we might make at our Waynesburg factory?” The most promising was the single use clay “hot top.” One hot top was required on top of every ingot mold filled with molten steel. Daily use of the hot tops was in the hundreds in each mill.
Hot tops were typically either round or approximately square hollow tubes, 15 to 30 inches square, 20 inches long with a wall thickness of 2 inches to 3 inches. The ingot mold was cast iron to promote rapid solidification of the molten steel by a high rate of heat transfer from the steel to the mold. The hot top was inserted 3 inches to 5 inches into the top of the mold. It had a slow heat transfer, keeping the metal molten and allowing this metal to flow down into the ingot and fill the centerline cavity created as the steel shrunk, while solidifying in the ingot. Up until this time, sewer pipe presses were used to form clay hot tops. Could these shapes, 20 to 30 inches in diameter, be formed on a 15-inch diameter auger extrusion machine that compressed the extruded column 15-inch into a smaller shape? It hadn’t been done to date and was no easy task.
