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Many Mills Now Make Most of Predictive and Preventive Maintenance

Founded in 1915 as the Technical Association of the Pulp and Paper Industry, TAPPI is today "the world's largest professional association serving the pulp/paper, nonwovens, converting, and packaging industries."  From 2001 to 2006, TAPPI published Solutions!, a slightly overenthusiastic-sounding monthly journal on all things pulp and paper.  Its August 202 issue included a five-page study "Benchmarking Maintenance Practices at North American Paper Mills," the joint effort of a team of seasoned maintenance professionals drawn from five different states.

The article is an eye-opening look at the state of maintenance at the turn of the 21st century, drawn from an industry-wide survey begun in 1997 of 571 U.S. and Canadian pulp and paper mills.  Of these, 141 (25 percent) took part.  Mills were of all types, and "ranged in tonnages from less than ten tonnes per year to one million tonnes per year, and from less than 100 employees to greater than 1,200 employees."

Annual maintenance budgets at 86 percent of these mills ran from $1 million to more than $25 million.  Much of that cost was labor, accounting for "30 to 40 percent of total maintenance budgets at more than two-thirds of...mills."  In fact, "Respondents reported that the number of maintenance employees equaled an average of about 20 percent of total mill employment," which actually was a drop of two to three percent since the mid-1980s.

"Since earlier paper industry surveys, mills have made substantial progress in the areas of preventive maintenance (PM) and predictive maintenance (PdM).  [Circa 1990], preventive maintenance was becoming was becoming a recognized best-practice, and predictive maintenance was seen by most as 'a nice theory.'  In fact, the earlier surveys did not even mention PdM.  However, with advances in sensor technologies and reduced costs of measuring and diagnostic equipment, PdM has become practical and cost-effective."

Mill budgets for PM and PdM soared accordingly.  Whereas "preventive maintenance had ranged from nine to 22 percent of the total maintenance budget" in the mid-1980s, "a few of the recently surveyed mills indicated budgets for both PM and PdM covered up to 100 percent of the total maintenance budget, with an average of nearly 40 percent."  Earlier surveys from 1993 to 2001 also showed the 85 to 90 percent of mills "rely on Computerized Maintenance Management Systems (CMMS) to track machine repair histories, schedule PM tasks, and provide a means of cost control."

"Most mills ranked quite high in their ability to control unscheduled downtime, with 72 percent...having less than five percent unscheduled downtime and 51 percent of the total reporting less than three percent.

Asked to rank 19 maintenance practices according to which gave the best value, vibration monitoring ranked far above the rest at 97 percent, followed by lube oil and wear analysis (64 percent), walk-down inspections (61 percent), alignment checks (54 percent), and temperature inspections (52 percent).

Even with near-unanimous agreement that vibration monitoring was valuable, actual practices varied wildly.  Ninety mills measured vibration at an average of 1,939 points in the paper machine area, but others monitored as few as ten points and others still up to 11,730 points.  Most mills did the monitoring on a monthly basis (54 mills) or a weekly basis (27 mills), but some monitored daily (17 mills), others annually (9 mills). And, 42 percent of mills reported that they outsourced the gathering of vibration data altogether.

Finally, mills were asked to report the effect of predictive and preventive maintenance on reducing unscheduled downtime to service mechanical and electrical problems.  Some 70 to 81 percent reported that PM and PdM "significantly" reduced downtime, 18 to 28 percent said that PM and PdM activities and programs had only a minimal effect, and only one to two percent felt they had no role whatsoever in reducing unscheduled downtime.

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