Simple Solutions That Work! Issue 8

SUMMARY A new, innovative solution to channel induction furnace inductor performance is available. Actual installations have demonstrated the effectiveness of the concept. Use of pre-formed, pre-fired, ceramic shapes offer a variety of serious economic advantages: • Refractory sintering is less critical as the forms are pre-fired • Less startup downtime as wash heats are never needed and there is no burnout or melt-out • Smoother, denser surface means lower potential for erosion • Tiny pore size means lower metal penetration • Longer campaign life LOOP FORM DESIGN OPTIONS If we are comfortable that the pertinent furnace design is correct, simple duplication of the current loop will dictate the interior shape of the ceramic loop form. The ceramic loop form is best provided in a one piece assembly which limits the gaps that could be potential areas for metal penetration. Note that in the ceramic loop form example shown, the cross section of the loop design is rectangular, while others have circular cross sections. Elliptical cross sections are also employed. The thermal expansion of the pre-fired forms taken together with a properly chosen back-up material will leave the form in compression and allow the two materials to work together. The proprietary process produces shapes to very close, controlled dimensional accuracy, and the practicality of the installation procedure for the CeraLoop loop forms is proven. During installation, the shapes may be held in place with conventional steel strapping while refractory is rammed, or vibrated behind it. A major design consideration involves the wall thickness of the forms. The production process is capable of thin walls, and this, of course, has economic benefits. Closer analysis, however, suggests that the thickness should be dictated by the aggressiveness of the metal being poured. Metal penetration can be measured for the given metal and ceramic combination, and the thickness should slightly exceed the expected penetration. The chemistry of the pre-fired ceramic loop form can be adjusted to suit the characteristics of the metal melted and held. Typically, these would be alloys of iron, aluminum, copper, and zinc. Likewise, there are options for the design of the ceramic shapes, such as wall thickness, component connection and cross section. 30 Figure 4. CeraLoop™ ceramic loop form Contact: PHILIP GEERS [email protected]