Graphite Alloy solves bearing failure problem at G-P pulp mill.

Switching to a new graphite alloy material solved a bearing failure problem in a hot-lime conveyor at Georgia-Pacific's Cedar Springs, GA, pulp mill. In this challenging application, the drag chain conveyor moves hot lime at 2100[degrees]F from the No. 2 lime kiln to a storage tank. The bearings on the original conveyors failed at frequent intervals, requiring considerable maintenance that resulted in downtime. The problem was solved by installing a new conveyor from Vulcan Engineering Co., of Helena, AL. The conveyor uses a proprietary alloy drag chain that is supported on the return by chain rollers with pillow blocks incorporating the graphite alloy bushings. The new bushings have eliminated the need for unscheduled maintenance, reducing downtime of the rotary kiln.

Pillow blocks featuring GRAPHALLOY[R] bearings were selected to support the return chain rollers in place of the roller bearings that had been used in the past. Graphite Metallizing, Yonkers, NY, produces GRAPHALLOY, a graphite-metal alloy, high-temperature bearing material. GRAPHALLOY combines the properties of graphite and metal. The graphite structure can be compared to a deck of cards with individual layers that are able to easily slide off the deck. This phenomenon gives the material a self-lubricating ability, and external lubricants are not necessary. GRAPHALLOY is graphite filled with a metal impregnant to enhance the chemical, mechanical, and tribological properties of the material. The material works at the high temperatures of the lime kiln without the problems caused when oil-based lubricants burn off or plastics fail.