ceramic fiber gives the best insulat- ing properties, achieving 50% greater properties than standard sleeves. “When feeding heavy sections that are heavily machined, sleeves give you about one size smaller riser and will not justify the cost of the sleeve in metal savings,” the respondent wrote. Company B: “We have standard-
ized on exothermic so as to get the best yield, presently at 70-75%.” Te company’s castings have a thickness range of 5 to 7 in., adn a high kinetic energy hammer can remove the stan- dardized 4-in. riser with one blow. Company C: Uses insulating sleeves 90% of the time, unless simulation dictates exothermic would work best. Company D: Tends to use sand
risers when more than one casting is on a mold. When the company does use a riser sleeve, it opts for exothermic, which it has found to be more efficient. Company E: Uses exothermic
sleeves where metal can’t reach with a sand riser or to force a riser to fire to slow solidification for better filling. Company F: Uses insulating
sleeves for risers less than 6 in. and exothermic sleeves for risers more than 6 in. when pouring carbon, low alloy and corrosion resistant steels. Company G: Uses pour weight to
determine whether to use a sand riser or exothermic sleeves. Company H: Makes small castings and uses exothermic sleeves only. Company I: Uses exothermic
sleeves up to 24 in. and insulating brick beyond. Company J: Mostly uses insulating
sleeves, but will use exothermic sleeves when more metal is needed in the riser. Company K: Uses exothermic
sleeves on all risers 6 in. or greater and insulating sleeves or vents on risers 4 in. or smaller. Company L: Uses semi-insulating
sleeves for risers 4 in. or greater and exo- thermic sleeves on risers less than 4 in. Company M: Bases the use of exo-
thermic or insulating sleeves on pour weight and yield. It uses a sand riser whenever possible to save costs. Company N: mainly uses insulat-
ing sleeves on risers between 2 and 10 in. and exothermic sleeves on risers greater than 10 in.
May 2011 MODERN CASTING | 41
“When feeding heavy sections that are
heavily machined, sleeves give you about one size smaller riser and will not justify the cost of the sleeve in metal savings.”
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