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Company R: “Yield is a driv-


ing factor for use of riser sleeves. Alloy does play a part in choosing a riser wall material.” Te metalcaster uses either exothermic or insulating sleeves but sticks to insulating sleeves containing no aluminum on low alloy steels to avoid aluminum pickup. Te position and application of the riser with respect to the ease of molding has an influence on when to use a sand riser or riser sleeve. Company S: Uses only exothermic


sleeves when necessary due to effi- ciency of riser size. Company T: Mainly uses exother-


Fig. 2. Open riser trials showed a larger pipe in the risers with insulating sleeves(bottom). Company O: Uses only exothermic


sleeves due to material and section size. It has developed proprietary riser materials with its supplier. Company P: Uses exothermic


sleeves on risers between 3 and 10 in., half exothermic sleeves for 11-12-in.


risers, and insulating sleeves for risers larger than 12 in. Company Q: Uses only exothermic


sleeves for its blind risers. For open risers, it uses insulating sleeves for risers less than 6 in. and exothermic sleeves for risers greater than 6 in.


mic sleeves but might use insulating sleeves where under riser cracks appear due to aluminum pickup from an exothermic sleeve. Company U: Uses only exothermic


sleeves for its ability to feed at longer distances than with a sand riser.


Raymond Monroe is executive vice president and Malcolm Blair is vice president-technology of the Steel Founders’ Society of America, Crystal Lake, Ill.


42 | MODERN CASTING May 2011


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