Ingersoll Cutting Tools Drilling a ductile cast iron part might involve using a special three-step indexable drill (top tool) to rough, semifinish and spotface the bore, and a special extendedlength, solid-carbide drill. iron has slowed recently because fire hydrants, for example, are commonly made of the material and the new housing market is in a slump. However, ductile cast iron is still more common than gray iron—at least when it comes to seeking drilling assistance. “I’m seeing more ductile because it is more of a problem than gray,” Cole said. “People don’t call you when they don’t have problems.” About the Author: Alan Richter is editor of Cutting Tool Engineering, having joined the publication in 2000. Contact him at (847) 714-0175 or at alanr@jwr.com. CTE workpieces create less-thanideal conditions for carbide, shortening tool life. In scenarios where lack of rigidity prevents effective application of carbide tools, a tougher HSS substrate might be the solution. “Allied has an HSS spade drill line that allows you to swap out a carbide insert for an HSS insert in the same tool body,” Porter said. He added that an HSS drill is able to cut at feed rates similar to those for carbide, but HSS won’t be able to run at the high spindle speeds appropriate for carbide because HSS cannot tolerate the same heat level. Ductile cast iron is certainly a mature workpiece material, but it continues to replace materials for certain applications. “Ductile iron is becoming more popular,” Ductile Iron Society’s Wood said. “Gray iron is probably suffering.” That’s in part because automakers are making vehicles lighter to achieve fuel efficiency requirements and therefore castings need to be lighter and thinner. Ductile iron castings can be produced with thinner walls to reduce weight whereas gray iron can leak if the walls are too thin. “You don’t want water jackets leaking in engine blocks,” Wood said. Wood noted that more design engineers are realizing ductile iron parts can replace weldments and forgings. “For example, where manufacturers may take some parts and weld them together, they can do that instead as an as-cast casting out of ductile iron.” Sandvik Coromant’s Cole said the market for drills to machine ductile cast CUTTING TOOL ENGINEERING Magazine is protected under U.S. and international copyright laws. Before reproducing anything from this Web site, call the Copyright Clearance Center Inc. at (978) 750-8400.
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