Rethinking Repair & Relining Procedures


Through detailed evaluation and analysis of its operations, one iron casting facility resolved issues related to its coreless induction furnaces. ROBERT WANDEL, MOTOR CASTINGS CO., MILWAUKEE, AND ERNEST BENION SR., CONSULTANT, MILWAUKEE


F


or most of its 95 years in operation, Motor Cast- ings Co., Milwaukee, relied on cupolas in its melting operation. In


the last 20 years, though, the job shop transitioned to two 15-ton, medium frequency, coreless induction furnaces to melt and pour compacted graphite, ductile and gray iron.


Still, over the years, Motor Cast-


ings’ in-house methodology for furnace maintenance remained based on repairing cupolas and not specifi- cally tailored to coreless induction furnaces. A contractor was used to facilitate efficient bricking, relining and repairs. Although Motor Cast- ings assumed the contractor used proper relining techniques, the ques- tion remained: “How do we know we are getting maximum life out of the linings?” Te answer had been either, “Tis


is how we’ve always done it,” or “Tis is what I was trained to do.” Motor Castings realized it lacked the internal knowledge necessary for coreless fur- nace repairs, which led to its pursuit of a culture change. Tis article looks at the case study to see how the Wiscon- sin metalcaster arrived at its solutions.


Three Process Improvements Historically, Motor Castings’ melt


Coreless induction furnaces can benefit from optimized maintenance and repair practices. 30 | MODERN CASTING August 2014


department drained the furnaces at the end of each operating day and inserted 10,000 lbs. of cold charges (pig iron and steel scrap) for the following day’s production. Te furnaces normally are empty by 5 p.m., put into a low- kilowatt hold cycle and switched to full power between 8 and 10 p.m. A computerized system puts the furnace on hold at a temperature of 1,600F (871C). Te melt department sup- ports a green sand molding line and two chemically bonded lines, one with


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