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Technology continues to evolve.

The need for foundries to improve their production efficiencies and reduce overall costs has not been lost on the operations.

This year's Melting Methods & Materials sessions featured both new research on cupola operations and practical approaches to improve induction melting.

V. Sahajwalla presented the results of an AFS/University of Michigan research project he worked on with R.D. Pehlke. Sahajwalla reported on methods to mathematically model carbon transport in a cupola to determine scrap and coke bed factors that affect the carbon content of iron.

The study evaluated the carbon dissolution from coke and the carbon loss through oxidation by gas and slag phases. A mathematical model, verified experimentally, successfully predicts the tapped metal's carbon content in a given melt on the basis of physical and chemical fundamentals.

The work confirms that cast iron and steel charges melt at different heights in the cupola. Cast iron with a melting point of about 1150C melts higher in the furnace compared to steel, which has a melting point near 1500C. The model assumes that droplets of cast iron and steel fall through the cupola separately and do not mix until the last stage of the melting process.

According to R. Gee, Stanton, PLC, Nottingham, England, the soaring cost of energy, recycling pressures and emissions restrictions are changing the liningless, water-cooled cupolas of European foundries. More of the foundries are using refractory linings above the tuyeres to protect tuyeres against the shock of the first charge and to produce hotter iron in the melt zone.

Gee noted that new types of low-cement gunning castables and self-flowing castables, which are under development, promise to reduce even more refractory installation time and prolong refractory life.

Improving the energy efficiency in a coreless induction heel melter was the concern of K. Copi, Exolon-ESK, Savannah, Georgia, who offered four ways to minimize heat loss.

He advocates keeping furnace tops clean and level; maintaining refractory integrity in the lid; keeping lift cylinders clean; and reducing lid-open time during charging, sampling and slagging by using the largest charge and tap size possible.

Efforts to improve furnace electrical efficiency should focus on finding the optimum preheat time, maintaining it and getting as much output as possible from the fewest melters, Copi said.

Although induction furnaces grow old with use, they do not have to become obsolete. Continual updating of good equipment leads to improved reliability, lower maintenance costs, increased output without capital expenditures, and expanded productivity.

That was the conclusion of a paper by W. Duca, Duca Remanufacturing, Boardman, Ohio, and W. Powell, Waupaca Foundry, Waupaca, Wisconsin, that dealt with the cost and productivity gains wrought by upgrading a 30-ton vertical channel furnace.
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Title Annotation:96th AFS Casting Congress Milwaukee; production techniques of foundries
Publication:Modern Casting
Date:Jun 1, 1992
Words:444
Previous Article:Regulations take new turn.
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