Graphite/alloy bushings let telescopic coil grabs from Avon Engineering Ltd., Waterdown, Ont., operate lube-free in a harsh environment. The coil grabs transport hot steel coils from the mill to a quenching pond at California Steel Industries, Fontana.
Avon engineers typically spec aluminum bronze or 660 bronze for wear components, both of which need lubricating grease to work. But the application's unusually high operating speeds and ambient temperatures quickly degrade such lubricants. Moreover, the system is fully automated, so a failed bushing may go unnoticed, perhaps damaging equipment. For these reasons Avon chose Graphalloy bushings from Graphite Metallizing Corp., Yonkers, N.Y., (www.graphalloy.com).
Graphalloy is graphite impregnated with metal alloy. The graphite acts like a deck of cards with individual layers that easily slide off one another. This action makes the material self lubricating while the metal alloy adds durability. The bushings handle temperatures from cryogenic to 1,000°F in an oxidizing environment and can run without grease even when submerged in hostile liquids such as acids, alkalis, hydrocarbons, black liquor, and liquid gases. "The Graphalloy bushings have worked for 18 months at CSI with no noticeable wear," says Alan Robson, Avon Engineering project manager.