By A PPI Special report
BRUSSELS,
Nov. 12, 2009
(RISI) -
Wausau Paper is the result of the 1977 merger between Wausau Paper Mills Company and Mosinee Paper Corporation. The merger brought together two companies with rich traditions in the paper industry that dated back to 1819 and 1910 respectively.
Headquartered in Wausau, WI, the company is a premier producer of laser printer paper, resume and stationery paper, masking tape, medical bandages, microwave popcorn packages, specialty papers and paper towels used in public restrooms.
Its products are manufactured in multiple locations across the United States. Specialty products are manufactured in; Mosinee, WI; Jay, ME; and Rhinelander, WI. Printing and writing papers are manufactured in; Brokaw, WI; Brainerd, MN; and Appleton WI. Towel and tissue products are manufactured in: Middleton, OH; and Harrodsburg, KY.
Acquired though a series of acquisitions, the Rhinelander paper mill is a leading supplier of fine technical speciality papers. With a 165,000-tons/yr capacity, the mill manufactures highly diverse technical specialty papers with unique performance characteristics, including pressure-sensitive release liner, food service and packaging papers, masking tape base papers, and a broad range of commercial and industrial papers.
Over the years, the Rhinelander mill has been improved and modernized a number of times. The most recent was a major, multi-million dollar upgrade of the equipment used for paper liner manufacture, which was completed in 2000.
The Rhinelander mill has installed numerous types of rotating process equipment as part of various upgrades and improvements. Most of this equipment came equipped from the OEMs with methods to seal the bearings that were common at the time of its design and manufacture and have since become outdated.
These old technology methods have proven to be ineffective in protecting bearings and contributed to an unacceptable Mean Time Between Failure (MTBF). These methods included the likes of contact seals, fibrous packing, flingers, lip seals, simple labyrinth seals and other devices.
In 1987, Rhinelander Paper began to install Inpro/Seal bearing isolators on thick stock pumps and then expanded to use them on other pumps, pulper drives and gear boxes. In 2003 it implemented a comprehensive program of retrofitting all pumps with Inpro/Seal bearing isolators. This program has proven to be so successful that bearing related pump failures are a fraction of what they were and improvements in pump reliability were dramatic.
The Rhinelander problem
The Rhinelander paper machines came equipped from the manufacturer with simple labyrinth seals that used a flinger that was supposed to work with the labyrinth and protect the roll bearings.
As with other bearing protection methods that do not provide a long lasting solution, the open labyrinth affected the reliability of the machine. Heat, humidity, paper stock, water and other contaminants were allowed to enter the bearing housing, causing the roll bearings to fail. The end result was a high rate of bearing failure on its paper machine rolls.
The mill tried other methods, including contact seals, but these methods did not last either. Most lacked the ability to meet the size, speed, and alignment and operating conditions of the paper machine rolls, nor did they eliminate the root cause of the problem.
The root cause of equipment breakdown is not the fault of the actual equipment. In the case of the Rhinelander mill, the root cause of the equipment breakdown was contamination entering the bearing environment which caused the paper machine roll bearings to fail.
Contaminated, poorly protected bearings that used outdated sealing methods were what failed, not the equipment.
Contact seals, lip seals and operate on a contact basis are subject to excess wear and fail to protect bearings. Seal faces can wear out in as little as 1,000 hours.
Lip seals, once the seal of choice, have fallen out of favor as more and more end users discover they carry a 100% failure rate. At Rhinelander, when lip seals were used, service life was so short, that it was unable to make improvements to plant MTBF. In addition, lubricant is free to exit the bearing enclosure and as the equipment cycles, moisture in the environment is drawn into the enclosure where it condenses and contaminates the lubricant.
Due to the success Rhinelander was having protecting the bearings on its other rotating equipment, in 1993 it began installing bearing isolators on paper machine rolls (PM 7 wire rolls).
Failure is not an option
According to Rhinelander's maintenance superintendent Chris Weiler, "With today's focus on profitability, the driving force of our maintenance department is to maximize production, increase operating efficiencies, reduce maintenance repairs costs, and most importantly increase equipment reliability.
"Several years ago we learned that if we keep repeating what we have done in the past, we will continue to obtain the same results. It is no longer acceptable to consider any bearing loss normal, and continue on as we have in the past. As a result, we established a reliability program that encourages our maintenance people to recognize opportunities to improve equipment reliability."
Weiler continues, "Using root cause failure analysis, we can identify where a newer technology, such as the Inpro/Seal PMR bearing isolator can eliminate a cause of equipment failure. We knew that the leading cause of paper machine breakdown tied into contamination entering the bearing housing. We also knew that bearing failure was the root cause of the problem. That being said, we are now able to apply the PMR as Best Available Technology (BAT) and make upgrades as necessary. After, all the bearing protection technology we had been using dated back at least 75 years."
Weiler concludes, "As our pump sealing up-grade program had proven successful in eliminating the root cause of our pump failures, it made sense to investigate the benefits of a similar program and initiate an Inpro/Seal program for our paper machine rolls. As with the pumps, our goal was to achieve high reliability and reduced repair and downtime costs."
In the case of Rhinelander Paper, Chuck Medinger is the regional manager and has been with Inpro/Seal for more than 38 years, much of that time calling on some 40 paper mills in his territory, including Rhinelander. Chuck Kimball heads MRO Tech, a well-established distributorship that has been handling Inpro/Seal products for more than 30 years. Both have been working with the people at Rhinelander for more than 30 years.
The upgrade program
According to Bill Gray, reliability specialist, "In 2003, we got together with Medinger and Kimball to pursue a reliability program that would upgrade our paper machine roll bearings to be the most modern and tested sealing product available. This would involve using the Best Available Technology (BAT) in bearing protection."
Gray adds, "We were concerned that to be successful in paper roll applications, bearing seals must able to over come a host of potential problems, including: the ability to accommodate spherical roller bearings; misalignment; roll handling; excessive greasing; chemical clean-up; and a severely wet, humid and hot operating environment."
Using years of experience in sealing the bearings on roll housings (including steel mill rolls), Inpro/Seal had developed its "PMR" (paper machine roll) Bearing Isolator. With a few modifications, the PMR could address all of the tough parameters found in protecting paper machine roll housings.
With the successful Inpro/Seal pump reliability program as a model, it developed a retrofit program for paper machine rolls and implemented the program in 2003.
The solution to the problem lay with the Inpro/Seal PMR Bearing Isolator. The PMR was developed following numerous end user requests for a bearing isolator that would increase reliability and extend the service life of paper machines.
A very important feature of the PMR design is the ability to meet the size, speed, alignment and operating conditions of wet and dry ends of paper machine rolls.
On the wet end rolls (breast, table, press, wire return), water, pulp and paper stock are prevented from entering and contaminating the bearing housing. On the dry end rolls (calender, coating, queen, suction, starch, drum, end), leakage from oil-lubricated bearings that can ruin product is eliminated.
Over-greasing, common in this type of application, is virtually eliminated by an inherent design feature that accommodates excess greasing and prevents contaminants from entering the bearing housing. In addition, as paper passes through the machine it is not degraded, because it works without contact, there is no friction, wear or heat while operating.
According to Kimball, "Installation of bearing isolators on paper machines is not as cut and dried as it is on pumps and motors. With the need for a rugged installation, most of the seals were modified with addition of a flange mount. Some required a modification to the bearing cover. These modifications were easily made in our fully equipped repair/rebuild shop."
Kimball continues, "Medinger and I were on site, helping size seals and provide any necessary training. In order to keep the Rhinelander mill downtime to a minimum, in some cases, Inpro/Seal headquarters was able to provide same day design service for fast approvals and same day shipping for next day delivery. The first installations were on wire rolls that operated in the most hostile of environments. As the program advances, other rolls will be retrofitted with the PMR bearing isolator."
According to Medinger and Kimball who helped order, design and install the equipment, "With a paper machine roll (PMR) bearing isolator installed on the wet and dry ends, it is literally impossible to contaminate paper machine roll bearings. The PMR was designed to vastly improve the paper machine roll bearings and enhance the means for proper lubrication."
According to Gray and the people that run the maintenance department at Rhinelander, "With the PMR bearing isolator on our paper machines, we have yet to have a bearing related breakdown. By retrofitting the roll bearing housings on our paper machines, we have at a minimum, doubled the service life of paper machine rolls."
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The Inpro/Seal Company is the originator and leading manufacturer of bearing isolators. Its Rock Island, IL, facility, the largest of its kind, includes: engineering, research, development, testing and manufacturing. David C. Orlowski, inventor of the bearing isolator is also the founder and CEO of the company.
Bearing isolators are used to protect motor and pump bearings, machine tool spindles, turbines, fans, gearboxes, paper machine rolls and many other types of rotating equipment. About 10 years ago, Inpro/Seal developed a specific design for use on paper machine rolls. Its bearing isolator is a non-contact, non-wearing, permanent bearing protection device. It has a rotor and a stator, and the two are unitized, so that they don’t separate from one another while in use. Typically, the rotor turns with a rotating shaft, while the stator is pressed into a bearing housing. The two components interact to keep contamination out of the bearing enclosure and the lubricant in.
More than four million Inpro/Seal branded bearing isolator designs are in operation in process plants around the globe, where end users continue to report significantly reduced operating costs with increased productivity and reliability. Protected bearings typically run 150,000 hours (17+ years) or more, eliminating the need for continual maintenance and repair. Documented cases show that a plant can easily double the mean-time-between failure (MTBF) and reduce maintenance costs by at least half, with users reporting an extremely high ROI. Inpro/Seal provides customer support on multiple levels backed by strategically placed regional managers and distributors. An Inpro/Seal regional manager knows tribology, rotating equipment, bearing protection and sealing technologies.
Direct employees manage an assigned territory where they supervise: their own distributor network; end user contact; pricing; training and implement corporate policy. A typical Inpro/Seal distributor is also specially trained in the same areas. The difference is they are independent business people with their own employees, and in the case of Kimball, operate their own repair facilities.
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