Couplings streamline paper processing plant

Edited by the Engineeringtalk editorial team Oct 21, 2003

Frequent failures were costing a US paper plant huge sums in lost production - a problem that was solved by using a disc coupling that could accommodate misalignment.

Smooth, gleaming white rolls of paper stream out of one particular US Eastern Seaboard plant at a rate of almost 700kt annually.

Another 100kt of bleached market pulp for fine white paper is produced, destined for conversion into envelopes, computer paper and business forms for businesses across the nation to help them operate efficiently.

Yet inefficiency was plaguing the machinery that produces this essential commodity.

In this paper plant, the engineer was experiencing frequent, expensive failures in the dryer section of the paper machine.

Initially the company used gear couplings.

They later replaced them with disc couplings that failed after only 90 days of operation.

There failures caused production slowdowns, equipment inefficiencies and consequent economic loss due to excessive time spent on maintenance and repairs.

"Typically, the plant would utilise an entire 8h shift to replace this simple part", explains Len Andersen, the local Lovejoy sales representative, regarding the failure-prone gear couplings.

"Depending on the material the plant is producing, it can cost tens of thousands of dollars for this unexpected shutdown".

After a careful assessment of the situation, Andersen concluded that a small part can either cause a serious problem or offer an effective solution.

He found that the competitor's disc coupling was not rated for the amount of misalignment inherent in this type of installation, which caused the equipment failures.

That particular coupling design also was difficult to install and required a great deal of time for the plant staff to maintain.

The paper machine is comprised two main areas: the wet end and the drying end.

According to Andersen, there can be anywhere from 100 to 125 processing pumps supporting one paper machine, as well as conveyors and power systems, that all require some type of coupling.

The disc coupling causing trouble in the paper machine required a full 8h shift for repairs each time it failed.

Many paper mills don't have the personnel to maintain the couplings, adds Andersen.

Frequently, the management will contract with an outside company to perform routine lubrication services.

With over 100 pumps and other machines requiring lubrication, the costs add up rapidly for these contracting services.

One replacement option - a lubricated gear coupling - was ruled out because it would still require machine shutdown for routine maintenance.

The sheer weight of the coupling also increases the risk of premature breakdown and wear.

The best solution proved to be a Lovejoy/Jaure disc coupling.

This coupling offers superior tolerance of misalignment, eliminating both costly machinery breakdowns and the cost of high-precision alignment of heavy machinery.

Because the disc coupling has no moving parts and therefore no parts to wear out, there is no need for lubrication, saving time and money by eliminating downtime for maintenance.

Although one coupling replacement doesn't necessarily eliminate the need for an outside lubricating contractor, Andersen notes that several mills in his area are rapidly advancing towards a lubrication-free plant environment.

They are examining the existing couplings used in pumps and power generators and replacing them with Lovejoy parts, that require no lubrication.

In this case, the plant engineer decided to keep their current coupling but purchased the Lovejoy/Jaure disc coupling, intending to keep it in stock until their current part failed entirely.

This decision proved to be a wise course of action.

Delivery of the new part occurred just in time, as the current coupling did fail.

Instead of being shelved, the Lovejoy/Jaure disc coupling was installed immediately.

All this happened three years ago.

The Lovejoy/Jaure disc coupling has helped keep this paper plant successfully pumping out smooth rolls of paper for the past three years.

For a properly assessed engineering situation in which the parts are aligned to specification, the expected lifespan for this Lovejoy/Jaure disc coupling is 10 to 12 years.

The experience of this paper plant is yet another example of the value of turning to the expertise of the people and products at Lovejoy for long lasting results.