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As the need to cut costs receives more and more emphasis, the requirements for longer fabric life and improved fabric performance have become crucial. On any section of the paper machine, use of the optimal clothing product can significantly impact a mill’s bottom line. Because of this, mills often turn to paper machine clothing suppliers for suggestions on addressing a variety of problems that impact profitability.
Clothing suppliers commonly help mills improve fabric life, but they are also a source of information for addressing other cost-related issues such as machine speed, sheet breaks, chemical consumption, steam consumption, and off-specification production.
In addition, using detailed analysis, these suppliers also offer equipment control suggestions that can help mills get the most mileage out of their clothing products. This article describes, in case study format, how paper machine clothing suppliers work with mills to address a variety of quality and cost issues.
FORMING
Single-Layer Fabric Offers Improved Runnability, Retention for Linerboard
Problem: A southern linerboard machine was experiencing increased wet-end break frequency, resulting in reduced productivity. The machine would perform fairly well following a fabric installation, but runnability would begin to deteriorate 30 to 40 days later, depending on the fabric being used. Single-layer fabrics were commonly used and the mill’s approved suppliers trialed low-density and extra strand, double-layer designs with only slight improvement.
Project: The mill consulted JWI Group, which chose to examine the linerboard machine in detail by conducting a thorough examination of all sections. This system audit did confirm that the wet end deserved a more critical review and a total engineered approach was undertaken. The engineered approach included a complete analysis of the furnish stream, primary and secondary headbox flow stability, whitewater system efficiency, and vacuum capability.
Concurrently, JWI Forming was developing an enhanced single-layer fabric design that utilizes a modified version of the extra-support strand concept. This five-shed configuration incorporates an alternating 4-1 and 3-2 paperside CD weave pattern in a high fill configuration, which provides good fiber support and drainage capability in a comparatively low caliper format. These characteristics are especially desirable for linerboard applications in general, so, after analysis of the machine and its problems, the JWI Maxum 46 fabric was chosen for the project.
Mill production personnel agreed with this design approach and a trial fabric was installed on the bottom/fourdrinier position along with the mill’s standard extra-strand double-layer on the top/Bel Bond position.
Results: Installation and startup were uneventful on 42 lb linerboard at 2,100 fpm. Several positive observations were immediately apparent:
• Sheet knock-off was excellent—almost a condition of sheet drop-off, but in the right location.
• Off couch draw was down 10 fpm, and the sheet was releasing very easily.
• The return run was clean, with virtually zero fiber carry-back.
• Desired sheet test properties were achieved easily.
All operating conditions were monitored closely over the next three weeks. Runnability was much improved—wet end breaks had been reduced by 75% and machine uptime was excellent. Retention had improved from 82% to 88%—drag loads had remained low, and the return run had stayed virtually fiber-free. These operating conditions prevailed throughout the fabric’s life, which went well past the previously critical time of 30 to 40 days.
Unfortunately, a front side deckle board bracket failure tore the fabric badly, necessitating its removal after 62 days. This was disappointing, since the fabric manufacturer had targeted an 80-day life for this trial.
Overall, the mill felt the new forming fabric performed extremely well with respect to papermaking and productivity. The second fabric is now in operation and results to date mirror the first trial.
PRESSING
Newsprint Machine Raises Efficiencies, Uses Less Steam with Open Structure Fabric
Problem: A North American newsprint machine was experiencing breaks and boilouts as its press fabric aged. The superintendent of this machine saw the potential of improved machine efficiencies and production rates through the use of a new press fabric design.
Project: To improve runnability and reduce downtime caused by breaks, the superintendent requested help from Albany International. The conventional method for optimizing sheet dewatering on newsprint machines requires a very compressible fabric that expresses large amounts of water at the nip exit. Although Albany recognized that compressible fabrics do help maintain maximum peak pressure in the nip, the supplier also noted that it is this very characteristic that contributes to the large swings in flow resistance and resulting water removal problems of holes, crushing, and breaks.
As machine speeds increase, flow resistance has become a very important factor in the application of press clothing. The machine still needs to handle the same amount of water, but it must do it in a shorter period of time. For the newsprint machine, an alternative to compressible press fabric was needed.
To remove clothing bottlenecks, Albany recommended a heavier, much more incompressible, open design that carried the water away from the nip to the uhle boxes. On the newer, cantilevered machines, this is easily achieved with a laminated fabric, but, in the instance of non-cantilevered machines such as this one, this stiffer design was unacceptable due to installation safety and difficulty. Because of these issues, Albany recommended the use of Seamtech seamed press clothing. The fabric features a very open structure with the least flow resistance possible while still maintaining stability. As an additional benefit, there is no need for fall prevention safety harnesses, since no one needs to climb inside the machine for installation.
Results: As a result of the new fabric, total combined water flows (uhle boxes and saveall) on the primary trial position—the suction pickup—were up substantially over the standard compressible endless clothing (Figure 1). Break frequency dropped significantly to the point of actually having to break the sheet solely for the purpose of doctor blade changes.
FIGURE 1: As a result of the seamed, open structure press fabric, total combined water flows on the newsprint machine’s primary trial position were up substantially over the standard compressible endless fabric.
When a gain like this is made in one press fabric, it is often at the expense of one of the other fabrics. However, as Figure 2 shows, the gain in combined pickup water flow has carried over completely into the dryers, allowing for the proportional savings in steam.
FIGURE 2: The gain in combined pickup water flow from the newsprint machine’s open structure press fabric carried over completely into the dryers, allowing for proportional savings in steam.
To calculate the theoretical steam savings, the assumption was made that the increase in press dewatering was free sheet moisture and not intrafiber water. At 19 gsm added water removal, using simple phase change energy requirements, the energy saved was calculated at approximately 900,000 BTU/ton.
The projected steam savings was only one of the benefits resulting from the added water removal. The most important improvements continue to be the increase in efficiencies and production rates.
Three-Dimensional Batt Fibers Eliminate Shedding, Enhance Fine Paper Printability
Problem: A fine paper mill in Arkansas was experiencing major problems with press fabric batt fiber shedding on one of its paper machines. This shedding resulted in printability problems and contamination of the machine’s press section.
Project: Based on the fabric supplier’s guarantee that its Hydrosmooth fabric with Triaxial batt fiber would not shed, the mill gave Cristini North America a trial opportunity. First, the supplier conducted an in-depth study of historical machine data and related press room difficulties. Numerous sheet samples—both printed and unprinted—were analyzed utilizing surface imaging capabilities unique to Cristini.
The press fabric supplier then performed a complete machine press section study, placing particular emphasis on both physical and chemical fabric conditioning. Subsequent to analysis of all collected data, Cristini recommended the incorporation of its proprietary Triaxial batt fiber into the trial felt.
Triaxial batt fiber is exclusively produced on Cristini’s Dynabelt equipment, which manufactures 100% machine direction batt. During the needling process, these “three-dimensional” fibers exhibit superior locking capabilities when compared with commonly-used two-dimensional-batt fibers. Additionally, these batt fibers have improved abrasion resistance properties—a feature that is extremely important with a problem like fiber shedding.
Results: Historically, problem felts start to “shed” within the first week of operation. This problem then rapidly becomes a major deterrent to machine efficiency and paper quality.
The Cristini Hydrosmooth fabric, incorporating Triaxial batt fiber, was installed on the second press where the most sever batt fiber shedding problems had been experienced. From that date until removal 40 days later, the new fabric did not shed whatsoever. This success led to repeat orders from the customer.
Linerboard Mill teams with Clothing, Equipment Suppliers to Improve Shoe Press Sleeve Life
Problem: In a mill producing linerboard, cross directional (CD) sleeve elongation on a shoe press was causing a reduction in overall sleeve life. The mill required an increase in the sleeve life to reduce its operating costs.
Project: To determine the root cause of the elongation and to improve both the product and the process to achieve longer sleeve life, the mill sought help from Ichikawa. During the process of gathering data, samples, and reviewing the mechanics of the shoe press and other shoe presses that were experiencing the same problem, the clothing supplier found it necessary to develop a procedure to trim the sleeve so that the mill could extend the product’s life.
Analysis showed the problem was most severe on Ichikawa’s flow-through sleeve quality and was not localized to one press but to all presses of this type. The supplier then took a proactive approach and started reviewing the base fabric design and working with the mill and the equipment vendor to reduce the CD stress on the sleeve, which was contributing to the elongation. This was a problem that had occurred on each of the new press installations.
The equipment vendor reviewed the hydraulic system and controls for CD tension on the sleeve with Ichikawa and the mill. The vendor immediately worked at developing a system that could reduce the tension in the cross direction on the sleeve.
From a sleeve design standpoint, the sleeve samples obtained from the mill showed that the crimp in the base fabric was being pulled out and the cross directional monofilaments were being stressed and elongated. The weave design of the double-layer base fabric of Ichikawa’s flow-through style sleeve could not stand up to the CD stress that was applied by the press’s CD tensioning system.
The clothing supplier’s design department then worked to develop a double-layer base fabric with a non-woven CD shoot stand in the woven base fabric that could withstand the CD force exerted on the sleeve. The supplier also upgraded the quality of the sleeve supplied to the mill to a Double-coat quality, which contains a triple-layer base fabric and an additional urethane layer for more stability.
Results: The equipment supplier changed the control strategy of the CD tensioning system, which reduced the CD tension on the sleeve by approximately 30%. This, coupled with the upgraded quality, increased the mill’s sleeve life by more than 2.5 times the original life, making the sleeve one of the most cost efficient pieces of clothing on the machine.
The new base fabric design for the flow-through style sleeve is now used on machines that have opted not to retrofit the process with the redesigned CD tensioning system. This has increased sleeve life by approximately 35%. However, the redesigned CD tensioning system is now standard on all new press installations.
Through communication and a team effort between the mill, the equipment supplier, and the clothing supplier, the mill’s goal of increasing sleeve life to reduce downtime and operating costs was met.
Coated Bleached Board Mill Achieves Better Smoothness with Flat Fiber Batt
Problem: A northeastern mill making coated bleached board was very concerned about off-specification product related to unacceptable board smoothness. This situation resulted in costly spoilage and required additional production time to meet the customer’s requirements.
Project: To address the problem and determine possible solutions, JWI Group was invited to join a product improvement team composed of papermakers, process engineers, and a coating specialist. The team’s challenge was to determine which process variables were limiting board smoothness. After considering many parts of the stock composition and machine conditions, several areas were identified as possibly affecting the board’s surface topography.
One area considered significant was the press section and, specifically, press felt design characteristics as well press felt age. Regression analysis of smoothness measurements for over a year was chronologically sorted, revealing a recurring trend—as the felts aged, board smoothness declined. This discovery led the team to focus on press felt design features that affect felt life.
The two primary components of the felt were examined—base structure and batt fiber—in context of their relationship to board smoothness. The press felt design had to provide superior pressure uniformity that would resist compacting more than conventional designs associated with the problem. Additionally, a coater streak problem related to felt hair shedding made resistance to wear an important design parameter for the press felts.
Regarding the base construction, the two competitive structures that were used had very different compositions. One was a light base containing multifilament yarns that had a very low void volume. The other was a heavy base with monofilament yarns and a high void volume. For the application, the product improvement team favored the direction of the second structure, but replaced a cabled monofilament with a single monofilament in JWI’s Gemini composite felt to improve compaction resistance and to maintain felt void volume later in life.
Next, the clothing supplier closely examined the batt and addressed the shedding issue while improving the contact area of the surface. The team chose JWI’s Equator batt design because the primary feature is a rectangular cross-section fiber instead of a round cross-section fiber used in conventional felts. When needled into the press felt, this flat fiber resulted in a very smooth and dense felt surface that maximized the contact between the sheet and the felt in the press nip.
Results: Results were evident as soon as the felts were installed. An immediate improvement was measured in both Parker Print Surface and Sheffield values. Parker Print results improved almost 5% and Sheffield numbers were over 14% better on the board surface that contacted the Equator/Gemini felt.
As the felt aged, the product improvement team tracked the performance to see if there would be any felt hair shedding that could cause coating disturbances on the sheet surface. The Equator batt appeared to shed less than conventional felts and held up better over the life of the felt. This is explained by the fact that the shape of the flat fiber allows for a fine surface to be made with stronger fibers. To get the same surface as Equator, much finer round cross-section fibers have to be used in conventional felts. The stronger flat fibers held up over the life of the felt and contributed to greater overall coating consistency on the machine.
The collaborative effort of key specialists and a program to optimize press felt design has resulted in a smoother, more consistent board. This allowed the mill to improve board quality and to lower production costs.
Improved Shower Techniques Result in Longer Fabric Life, Lower Costs
Problem: To stay competitive, a corrugated medium mill began looking for ways to lower fabric costs and improve productivity on its paper machine.
Project: To meet its cost and productivity requirements, the mill consulted with Scapa. The clothing supplier performed two total machine audits, as well as a number of follow-up service calls with service engineers. Working with mill process specialists and the mill’s chemical supplier, several recommendations made in the paper machine audits were implemented to improve press fabric life by using better showering techniques.
Recommendations included working with maintenance to attain proper shower assembly stroke and spray coverage, which included proper spray angle and correct nozzle sizing. Efforts with the mill engineering department increased spray water temperature to 130º F, which promoted better water migration within the felts.
Results: Results from the improved showering techniques provided a drier sheet entering the dryer section, which reduced steam load on the section. Press felt life has also increased in all positions. Total savings in steam will be in excess of $1.4 million/year. The cost of clothing in the press section has dropped from a composite of $4.92/ton of paper produced to $3.35/ton. This represents over $400,000 as an annual rate of savings.
SCA Machine Reduces Breaks, Chemical Costs with Two-Layer Laminated Wet Felt
Problem: The superintendent of a Midwestern paper machine producing 26 lb to 40 lb SCA grades was seeking to increase efficiency to make his machine more competitive. He recognized that the open draw to the first press was a limitation to the production efficiency improvement, so he sought the help of clothing suppliers.
The superintendent had interest in upgrading the first press fabric from single-layer to multi-layer construction. The multi-layer designs have better center-to-edge dimensional stability, higher base-to-batt ratio for easier cleaning, and increased mass for greater water handling capability.
Conversion to multi-layer construction had not previously been successful on this suction press position. The nip and framing were tight, making installation of multi-layer fabric very difficult due to felt stiffness. Since the SCA product is also sensitive to mark, a seamed felt was not an acceptable alternative. A pliable, endless multi-layer felt design was needed.
Project: Wangner Systems felt designers studied the application problem and a solution was proposed. The Geschmay FasFlex—a two-layer laminated wet felt—was recommended and accepted for evaluation by the mill. This design has the cross direction pliability of a single-layer wet felt design with the benefits associated with the multi-layer laminated construction.
Installation of the trial FasFlex felt was accomplished in the same time period required for the single-layer, and the paper machine was started back up on the same grade as before the shutdown.
Results: One immediate benefit from the two-layer laminated wet felt was that the draw between couch and first press was reduced by 20 fpm. This was the kind of performance the superintendent was looking for in a wet felt. Confirming his expectations with improved felt dewatering, not a single break occurred within the first 12 hours after startup.
The superintendent observed other benefits during the life of this trial felt. Felt cleaning had always been an issue for the single layer felts on this position, since the paper produced had a 10% to 15% filler load. Filler contamination had been a factor in wet felt performance, thus increased frequency of felt cleaning had been required. The two-layer felt ran more openly, therefore reducing the need for cleaning. Uhle box vacuum reflected the more open felt with observed reduction from 16 in. Hg to 10 in. Hg. A substantial reduction in chemical costs was realized with less frequent cleaning cycles, and cleaning chemical consumption was reduced by 25%.
On the production efficiency side, the single-layer felt had historically run saturated in the nip, and crushing and wrinkling had been a more common occurrence than desired. The resulting breaks adversely influenced runnability and productivity. These problems were addressed when the new two-layer laminated felt with increased dewatering capacity was introduced into the operation. Throughout the life of the felt, paper breaks were reduced from previous operating experience.
As a result of the successful application on the first machine, the superintendent ordered a FasFlex felt for another SCA machine at the same mill. This time, he requested that the new trial felt (also for a first press position) delivery be expedited, since the next scheduled outage was in only three weeks. Customer service, designers, and manufacturing personnel from Wangner Systems responded and delivered on time. The result of the wet felt trial on the second machine was a repeat of the initial success—a 20-fpm draw reduction and all the other associated benefits. The two machines are now operating with improved efficiency and savings on cleaning chemical costs.
Seamed Felt Offers Longevity of Endless Felt Along With Safety, Performance Gains
Problem: Approximately 1-1/2 years ago, a mill was experiencing peeling felt flaps, flap wear, and seam noise at the uhle box of its high-speed uncoated groundwood machine with a tri-nip press. As a result of wear problems, the mill was forced to remove the seamed felts prematurely due to marking on this critical machine, which operated at speeds of more than 4,000 fpm. The combined problems were reducing felt life from the expected 60 days to 40 to 45 days, compared with endless felts.
Project: Due to the significant advantages of the seamed felt product (safety, time, and performance improvements) compared with endless, the mill had refused to revert back to endless products. To address felt life issues and quality concerns, the mill asked Weavexx technical service, press felt design engineers, and product managers to address the problems so that the seamless felts for the tri-nip press could attain their normal life, which was the same as that for endless products.
Mill management and the clothing supplier’s technology group together agreed that broad changes should not be made to the felt all at once. Instead, for each successive trial, the changes were engineered one at a time in the seamed felt structure. This strategy allowed a targeted and focused change where improvements could be observed without jeopardizing the mill’s quality and production requirements.
Together, the mill and its clothing supplier established key performance indicators to monitor each felt’s performance after each successive installation. During installation and the scheduled outage, the clothing supplier team was in the mill to review the results from each felt and provide assistance to the crew as needed. Each incremental structural and process change to the felt on that position contributed to the documented continuous improvement in performance. In the end, the Weavexx Seamexx Extender seamed felt was applied.
Results: Today, the mill has not only met the normal endless felt life but has exceeded the endless felt normal life by 20% using Weavexx Seamexx Extender seamed felts. Wear/flap peeling and flap loss are no longer a problem for this mill. Also, machine efficiency has significantly increased without sacrificing the quality requirement.
Thorough Analysis Shows Press Felt Wear Due to Roll Speed Differences
Problem: Since startup of a linerboard machine in the mid-1990s, a mill had struggled with problems of severe roll cover and press felt wear problems in the second press position. The machine operated at speeds of up to 1,600 fpm and featured a doubled-felted long nip press (LNP) that operated at loads of more than 2,000 pli. Felt fiber shedding, with fiber loss to the woven base fabric, was chronic. Press felt life was only 30 to 35 days, and roll covers showed signs of corrugation within one month of installation.
Although felt installation was extremely difficult and time consuming, the customer was forced to run traditional endless felts because of seam failure (pulling apart) early in seamed felt life, which was due to the machine’s mechanical problems.
Project: To address the problems of short press felt and press roll cover life on the highly loaded second press position, the mill consulted with Weavexx and Stowe Woodward—both of which are a part of the BTR Siebe Paper Technology Group. Engineers from those companies suspected the problem was speed related, but proof was required.
The approach was to wait until the next shutdown, clean the rolls thoroughly, set “targets” on them by using a reflective material, and return after startup with a Uni-Lux strobe light to stroboscopically verify speeds. Because of the circumference of the 61.0-in. press rolls, the flash rate on the strobe light was very low at approximately 400 flashes/min. At this low flash rate, it was feared the margin for error might be too great, so another approach was taken to verify the results.
A felt-measuring wheel, with a roll circumference of exactly 12 in., was marked with the reflective materials. The felt wheel was placed on each press roll and the strobe light was used to stop the mark on the felt wheel. The wheel operated with a flash rate of approximately 1,300 flashes/min, which provided more accurate results. A 16 ft/min speed difference between the top and bottom rolls was identified, which was more than a 1.0% differential.
Results: As a result of the in-depth analysis, the mill was able to discover the root cause of the roll cover and press felt wear problems. The customer has contacted the original equipment manufacturer for the rolls to have the speed differential problem corrected immediately.
DRYING
Velcro Tape Allows Fast, Safe Fabric Installation At Northeastern Coated Paper Mill
Problem: While many factors are important in a manufacturing environment, two that are of primary concern are efficiency and safety. A Northeastern mill that produces coated paper switched to Asten’s MonoTier dryer fabric design to improve sheet handling. After numerous dryer fabric installations, the machine crews continued to encounter problems with joining the ends of the fabrics on the second and third top positions.
When installing a dryer fabric on these positions, the two fabric ends are brought together at a location where access to the seam is very difficult. To facilitate joining the fabric, the ends need to be held together so that the section can be jogged to put the seam in an accessible area. Previously, this was accomplished by using a Zip Tape. The Zip Tape was stapled to the fabric ends, and it provided a convenient means to handle the seaming difficulty.
Because of the smooth surface of the wide flat yarn used to make the MonoTier design, the tape could not be attached to the fabric in the usual manner without damaging its surface. The initial MonoTier dryer fabrics did not have any zipper assists and were extremely difficult to install and seam. The fabric installations took additional time, manpower, and hard work.
Project: To solve the installation problems, Asten added Velcro tape secured with an adhesive. Individual Velcro strips were placed at one-foot intervals across the seam to hold the ends together. This did not work well because of the time mill personnel spent attaching each Velcro strip to the fabric. On the safety side, this was not a good alternative either. An operator had to climb into the machine frame and move across the fabric to attach each of the Velcro strips. This was a hot, difficult, and unsafe activity. Also, the procedure was inefficient because it did not join the ends of the fabric in a strong, uniform bond.
Machine crews from the mill came to Asten for another solution. They challenged the clothing supplier to modify the Velcro Zip Tape so that it was safer and more user-friendly. Joint meetings were held with the crews and Asten personnel to discuss the problem and to redesign the tape. The crews suggested that the supplier install a zipper on the Velcro and then attach the Velcro to the fabric with adhesive strips.
Asten’s new product development team at its dryer operation in Walterboro, S.C., experimented with several methods before finding one that would provide a workable solution. One slight problem prevented the crew’s method from working—the zipper was not aligned properly and it interfered with the seaming of the fabric. The team went back to work and offset the zipper from the seam.
Results: In May 1997, the redesigned Velcro Zip Tape was used for the first time at the mill. Mill personnel were able to install the fabric efficiently, safely, and in record time. Without entering the section, they were able to start the zipper on the front side of the machine and use a pole with a hook on the end to close the zipper from the back side. The fabric could then be tightened and run to the proper position for seaming.
Two additional MonoTier fabrics were installed during the same shutdown with favorable results. The clothing crews were pleased with the tape and insisted that every MonoTier fabric on the machine be installed with the same zipper assist. Last year, the Velcro Zip Tape became a standard Asten product.
Engineered Approach Yields Stable Fabric For Modified Unirun Configuration
Problem: Like many 1980s vintage paper machines, a fine paper machine converted its second dryer section from a conventional two-tier to a unirun configuration. However, operating personnel felt that the loss of drying—typical in uniruns—was unacceptable. Over several years, the mill developed a modified unirun for its first and second dryer sections. The modification allowed the sheet to be in contact with alternating bottom dryers, yet provided positive sheet support and control through the entire section.
While the modified unirun had many desirable papermaking attributes, dryer fabric life was disappointing. Although operating dryer fabric tensions were not abnormal, the fabric was subjected to unusual stresses through the paper run and dryer wraps often caused premature removal.
Before and during the modifications, JWI Group supplied a conventional design dryer fabric. This design has a long history of stability, strength, and performance on various paper machines and grades. However, it soon became apparent that fabric life, particularly in the second dryer section, had deteriorated. During the first year, the conventional design dryer fabrics averaged 65 days—with a low of five days to a high of 118 days.
Project: As a paper machine clothing business partner with the mill, JWI Group recognized the problem and initiated an analysis and evaluation of product application with the mill known as the engineered approach.
The first step was to evaluate fabric stability for this application. JWI used a series of proprietary physical tests that yielded a positive indication of the fabric stability. These results correlated to the dryer fabric’s stability on the paper machine and its ability to withstand the stresses inherent in papermaking.
Tests revealed a newly developed JWI series of dryer fabrics possessed a greater degree of stability in both the machine and cross-machine directions. The primary reason for this improved stability is the patented use of hollow CD yarns instead of solid or bundled ones. During manufacturing of JWI’s Unitier dryer fabric, the hollow yarns deform and rise to the sheet side, interlocking with the MD yarns. This fills the voids in the sheet side surface, adds dimensional stability, increases contact area, and improves wear resistance.
Of course, assessment of the dryer fabric seam strength was equally important. Tensile tests, which are destructive testing under controlled conditions, revealed that the Unitier Eliminator Spiral Seam placed in this new type of dryer fabric was especially suited for high-speed papermaking. In fact, this seam is 5% to 8% stronger than conventional designs. The combination of Unitier and the Unitier Eliminator Spiral Seam seemed to be a perfect application for this unusual dryer fabric application.
Results: The results have been impressive. Dryer fabric life on the second section of the machine averaged 75 days in 1996, and it improved to 112 days in 1997 and 137 days in 1998. This directly reduced the amount of paper machine clothing on this position by 40% in 1997 and another 33% in 1998. Also, at least one dryer fabric installation was eliminated each year.
In summary, a modification of the dryer section reduced dryer fabric life. Through analysis of operating conditions and the collaborative efforts of the mill’s operating personnel and the clothing supplier, a new dryer fabric design that substantially increased life and maintained good operation was implemented. Further analysis of fabrics removed from the position resulted in a slight modification and life increased dramatically again.
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