Smooth, gleaming rolls of fine white paper stream out of an Eastern-seaboard plant at a rate of almost 700,000 tons annually, plus another 100,000 tons of bleached market pulp -- all destined for conversion into the envelopes, computer paper, and business forms essential to American industry.
Yet in this particular plant, the machinery was plagued by inefficiency. Frequent, expensive failures were occurring, typically every 90-180 days, in the paper machine's dryer section. These failures in turn caused production slowdowns, equipment inefficiencies, and economic loss due to time diverted from production to maintenance and repairs. According to local Lovejoy representative Len Andersen, "Typically, the plant would utilize an entire 8-hour shift to replace a simple part. Depending on the material the plant is producing, it can cost them tens of thousands of dollars for this unexpected shutdown."
A close assessment of the situation revealed that a small part both caused the problem and presented the solution. Lovejoy representative Andersen noted that the disc coupling being used was not rated for the amount of misalignment needed to respond to the natural misalignment of the application, thus causing the equipment failures. In addition, that particular coupling design was difficult to install and time intensive for the plant staff to maintain. A Lovejoy/Jaure disc coupling proved to be the best solution.
A paper machine's two main sections are the wet area and the drying end. According to Andersen, one paper machine is supported by anywhere from 100-125 processing pumps, as well as conveyors and power systems, all requiring some type of coupling for smooth operation. Besides the downtime involved in repairing the disc coupling causing trouble in this situation, Andersen explained that many paper mills don't have the personnel to maintain the couplings and frequently, management will contract with an outside company to perform routine lubrication services. With upwards of 100 pumps and other machines requiring lubrication, costs add up rapidly.
One logical replacement option, a lubricated gear coupling, would still require machine shutdown for routine maintenance, and the sheer weight of the coupling increased its chances of premature breakdown and wear.
The Lovejoy/Jaure disc coupling selected by the paper mill in question offers superior misalignment capabilities, eliminating costly machinery breakdowns. Because it has no moving parts to wear out, the paper plant has no need to lubricate the part, eliminating downtime for maintenance. One coupling replacement doesn't necessarily eliminate the need for an outside lubricating contractor, however. Andersen notes that several mills in his area are rapidly advancing toward a lubrication-free plant environment, examining the current couplings utilized in pumps and power generators and replacing them with Lovejoy parts that require no lubrication.
The plant engineer decided to keep his current coupling, but purchased the Lovejoy/Jaure disc coupling to keep in stock until the current part failed entirely. Delivery of the new part came just in time, however, as the current coupling did indeed fail and the Lovejoy/Jaure, instead of being shelved, was installed immediately. This story has yet to reach its conclusion -- with the Lovejoy/Jaure disc coupling, the paper plant has been successfully pumping out smooth rolls of paper for the past three years. In a properly assessed engineering situation, where the parts are well aligned, the anticipated lifespan for this Lovejoy coupling is 10-12 years.
