innovations CASTING
the market for large-scale gears for its operation in Los Bronsis, Chile, only a handful of metalcasters were capable of producing the necessary compo- nents. Metso placed an order for a 44.3-ft. ring gear for use in a semi-au- togenous grinding (SAG) mill to crush rocks during the extraction process for gold and copper with Rexnord-Falk Mill Products, Milwaukee. Rexnord-Falk has produced more than 5,000 gears and pinions, with many gears stretching beyond 40 ft. in diameter. While unable to determine the world’s largest gear, Gear Technol- ogy Magazine has cited Rexnord-Falk as one of a half-dozen metalcasting facilities capable of producing such a component. For the Metso project, Rexnord-Falk engineers planned for the 8645 steel component to be cast
W Bigger is Better for Steel Gear Casting
hen global mining sup- plier Metso Corp., Helsinki, Finland, was in
in four sections, which then would be assembled using 3.5 x 22-in. studs to produce the massive ring gear. “To create each gear mold, cores
made of chemically bonded sand are assembled in one of our large pits,” said Paul Ostrenga, foundry opera- tions manager. “T e pit mold setups, which take up to a week to assemble, are poured using one of Rexnord- Falk’s specifi cally engineered materials providing customers with the necessary hardness and mechanical properties.” Each quarter section had a pour weight of 143,000 lbs. and cooled in the mold for two weeks before the casting was removed from the sand for further processing. T e four sections underwent upgrading opera- tions before a fi nal heat treatment. T e segments then were moved to Rexnord’s machine shop. “After each segment’s split joints
were machined and drilled to allow for the pieces to be assembled into a single large ring, the rough gear assembly was turned on a 50-ft. vertical boring mill
into a precision-turned blank,” said Ken Bannach, mill operator. “During this process, multiple rough cuts up to an inch deep are performed using large carbide inserts. T e fi nish machined blank with teeth cut on a MAAG gear shaper to an AGMA 10 rating was matched to a pair of carburized and ground mill pinions also manufactured at the same facility. Each of the four sections had a shipping weight of 68,000 lbs., and the fi nal machined weight of the entire gear was 189,385 lbs. T e result: Rexnord-Falk delivered
on of the world’s largest ring gears to Metso Corp. for use in its heavy min- ing operations. “T e process, from the initial draw-
ings through shipping of the fi nished gear, includes more than 100 highly skilled associates lending their ex- pertise,” said Robe rt Wiczynski, mill products engineer.
For more information, go to
www.rexnord.com.
The fi nal assembly of four separately cast sections measured 44.3 ft. in diameter and weighed nearly 190,000 lbs. 50 | METAL CASTING DESIGN & PURCHASING | Nov/Dec 2013
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