WORLD CLASS PRODUCER OF MILL ROLLS AND STEEL CASTINGS. A leading manufacturer of high alloy cast steel backup rolls and large steel castings for the world-wide metals industry. WHEMCO-Steel Castings has been an integral part of the steel industry since 1898. With plants in Midland, PA and West Homestead, PA, WHEMCO-Steel Castings is a world class producer of heavy custom steel castings for the global steel making, metalworking, mining, material handling and power generation industries.