Simple Solutions That Work! Issue 6

There has always been a negative stigma against using fluxes during the melting of irons in induction foundries. The refractories used in induction furnaces, such as silica-based linings, were less tolerant to chemical attack from fluxes. In many ferrous melt shops, Lime/ Fluorspar (CaF2) additions are commonly used whether for desulphurization, phosphorus reduction, deoxidation, coke cleansing or improving metal cleanliness. Recent changes in flux formulations (the reduction or elimination of chlorides and fluorides in fluxes), have achieved positive successes in induction melting and pouring operations. In the past, these furnaces were typically removed from service prematurely because of the inability to effectively and safely remove stubborn slag and insoluble build-up. During the last 50 years, the melting of various ferrous alloys in coreless induction furnaces has changed significantly. During the same period, while ductile iron production and hybrid steels have experienced continued growth, the quality of metallic charge such as “pig iron”, carbon steel and other iron-units has steadily deteriorated. The result: slag related melting problems have become widespread in recent years, lending to slower melting rates and less efficient use of the coreless furnace. Whether it is a medium frequency or main frequency furnace, there has been an increase in insoluble build-up formation. A small iron foundry that had success utilizing flux additions in a 500 pound medium frequency coreless induction furnace to combat slag build-up is shown in the accompanying example below. DAVID WILLIAMS, ROD NARO ASI INTERNATIONAL, Inc. ARTICLE TAKEAWAYS: 1. Fluxes for melting iron in induction furnaces to combat slag 2. Preventing insoluble build-up deposition in coreless induction furnaces SYSTEMS INTEGRATION 24 CORELESS FLUXING BENEFITS FOR FERROUS FOUNDRIES