Optimizing PMC operations.
The blue shirt again, huh? Well, you can afford to make snap decisions about your clothing each day. That's not a luxury you have when choosing paper machine clothing. Paper machine clothing (PMC) is too expensive, too customized, and too important to your mill's performance to be chosen lightly. From trial (and error) through installation and maintenance, you will need expert advice on a string of critical decisions. Get it right, and enjoy huge returns in terms of sheet quality, increased machine efficiency, lower energy costs and other benefits.
To help readers optimize their PMC operations, Solutions! asked a few professionals for their best PMC "fashion tips." (By the way, don't worry, the blue shirt looks fine--really.)
CLOTHING TRIALS: PLAN THE WORK, WORK THE PLAN
Clothing trails offer a chance for mills and suppliers to work together on defined goals before making changes to a mill's PMC program. Since they represent a significant investment of resources on both sides, extensive planning and detailed measurements in several areas are crucial for best results, say experts.
"A PMC trial must address one or more key performance indicators (KPIs)," said Luc Farly, C.I. manager-forming, and Greg Leong, C.I. manager-pressing, for Weavexx, Wake Forest, North Carolina. "For example, some of the KPIs that our company addresses in our continuous improvement platform are: start-up time, off-couch consistency, retention and formation, sheet smoothness (Sheffield, Emveco, etc.), fiber usage, and energy consumption. At the outset of any trial, identify and quantify KPIs as a baseline for machine optimization. This baseline allows the mill and the supplier to work together to establish targets for KPI improvement, design effective trial clothing, and objectively evaluate the performance of the trial product. Also, plan for follow-up and review to ensure project results are sustainable and repeatable."
Measurement is essential, agreed Richard Delage, product business leader-press for AstenJohnson, Charleston, South Carolina, USA. "A trial run without a clear and measurable objective is doomed to fail," he said. "The most effective way for a mill to run trials of new machine clothing is to create a precise evaluation plan, and the backbone of the plan is the definition of a clear and measurable objective. Each trial should be designed to be a component of the mill's objectives and long-term goals."
As a first step, he recommended, the mill and supplier should document grade mix, furnish, operating conditions, machine and section configurations, vacuum capacity and any special considerations related to the specific application. "Before the trial is run, the current condition must be compared to the desired future condition. The objective of the trial is to bridge the gap. Whether the trial is related to an operating parameter or to an improvement in sheet properties, the objective should be quantified; a 'soft' objective definition can lead to confusion when trying to evaluate whether the trial was a success," said Delage.
Critical information gathering doesn't stop there, said Ken Walker, marketing manager, Albany International/Geschmay, headquartered in Albany, New York, USA. "The data collection continues with the monitoring of the trial and after to verify a definite change has taken place. Delivering value means more than just selling a trial fabric." Sales or service people should work with the mill to review the documented value received before the job is considered complete.
"The supplier must be able to assure the customer that the trial is going to bring tangible benefits to his operation. The burden of proof lies with the supplier," said David Buchanan, business development manager for Voith Paper Fabrics, Heidenheim, Germany.
"The days of feeling and emotion are long gone when evaluating machine clothing performance," he added. "The trial plan should include such things as abort criteria, inventory disposition, long-term plan for the position, quantifiable dollar savings or costs, cost of trial compared to standard clothing, and financial impact (plus or minus) if successful. A firm delivery and installation date should be agreed to at this time. Once the trial has been delivered a follow-up plan should be agreed on by both parties."
According to Buchanan, key questions to answer in the follow-up plan include:
* Who should be present during installation and startup?
* What type of coverage is necessary during the run?
* What type or types of data are pertinent to establish success or failure?
"The key to successful trialing of machine clothing is simple communication," Buchanan said.
Jim Taylor, executive vice president, sales and marketing for Cristini North America, Lachute, Quebec, pointed out that almost all aspects of papermaking are measurable when it comes to sheet properties, machine speeds, and absolute operating efficiencies. "Mills must be certain that all conditions during the trial are as close to the norm as possible. Often, trials of new machine clothing products are done when production demands are not at their peak, which may or may not be the ideal test," Taylor said.
Finally, "don't be the first but don't be afraid to take some risk," advised David Procter, PM2 production manager at the Stora Enso Port Hawkesbury Mill in Nova Scotia, Canada. "Be absolutely clear why you want to run a trial and set measurable and pertinent key performance indicators. Obtain a reference list from the proposed trial supplier and contact the best references directly to get the facts straight 'from the horse's mouth'. Be prepared for the trial to be a failure. If the trial is a failure learn from the mistakes and turn them into learning opportunities."
CONTROLLING COSTS RIGHT OUT OF THE BOX
The hard work is not over once the mill makes its decision to purchase new PMC. A well-planned approach to installation and maintenance will protect the mill's PMC investment and bring big returns, said our experts. Even developments in PMC packaging and delivery have made a difference for mills seeking to control costs and optimize performance.
"Clothing suppliers today have a variety of products and treatments that are specifically designed to ease installation and maintenance without sacrificing productivity or quality," said Farly and Leong of Weavexx. "Beyond clothing design, clothing packaging can greatly impact installation time and cost. Clothing suppliers have spent a great deal of effort and expense developing special installation tools and accessories such as seaming lights, seaming tools, leaders, handles, zipper assists, seam protectors, and stabilizer bars. Also, suppliers will work with mills to develop special rolling or folding procedures, sometimes using specific cores or ropes, so that the clothing comes out of the box or tube in the correct configuration to go directly on the machine. Finally, special labeling can be included on the packaging or the clothing itself to reduce confusion and greatly simplify installation."
Papermakers can also play a major role in reducing cost of installation, says Voith Paper Fabric's David Buchanan. He suggests that mills:
* Prepare operational instructions for installation for each section and position
* Work with suppliers to improve packaging
* Purchase and maintain installation aids such as winches and clamps
* Ensure a clean, well-lit, and accessible area for installing clothing
* Maintain installation areas such as catwalks in the dryer and press sections
* Plan the location of clothing inventory and staging areas to reduce downtime for a clothing change
"The most cost effective way to reduce clothing installation cost is to ensure that a machine is never idled solely as a result of a necessary clothing change," added AstenJohnson's Daniel Hedou, strategic account leader. "The cost of clothing changes is significantly reduced if production losses are not added to the equation. To ensure that clothing changes occur in a predictable fashion, great care must be taken to plan such changes in accordance with the useful life of clothing in question. Returned fabric analyses are the best predictive tool in this regard. To ensure that clothing change time does not become a bottleneck, even on planned shuts, mills have performed efficiency studies and found safe and innovative rigs to assist with endless fabric installation." Hedou noted that these rigs should be prepared in advance, to minimize handling during costly down time.
"The increased use of 'pin seamed' press felts has certainly reduced the cost of installing felts, especially on certain cylinder board and kraft paper machines," noted Jim Taylor of Cristini North America. "Recently, this technology has been used successfully on Yankee pickup felts on high speed tissue machines."
Buchanan agreed "Seam press fabrics represent almost 56% of all press fabrics used in the United States," he noted. "The advent of seamed press fabrics obviously reduced the cost of installation by greatly reducing downtime. There are not many applications that seamed press fabrics can or do not run on today."
Walker of Albany International/Geschmay called seamed press fabrics "another great example of how papermakers and fabric producers have worked together to reduce cost. Also, seamed press fabrics help improve the machine crew safety while reducing installation downtime. This one product has allowed mills to produce more paper and board in a safer environment."
Once the fabric choice has been made, diligent maintenance is the mill's best route to controlling cost and optimizing performance. "Maintaining clothing is critical to efficient machine performance," said Farly and Leong of Weavexx. "TAPPI offers guidelines that cover many of the cleaning and conditioning elements with which most machines are equipped. These standards cover shower and vacuum systems. Showers systems include high pressure, lubricating, chemical, flooded nip showers, etc. Vacuum guidelines cover pump sizing, flow, pressure, and more. Beyond the TAPPI standards, the best suppliers can offer further assistance in engineering systems, as well as through regular inspections during service calls." Also, contaminant resistant materials and treatments for forming fabrics and dryer fabrics can extend the time between cleaning; when chemical cleaning is required, chemical resistant treatments are available for press felts that decrease their susceptibility to chemical damage, thereby increasing their useful life.
"The main difference between good efficiencies and great efficiencies can be tied back to maintenance and its positive or negative effect on the machine clothing," noted Buchanan. He suggested that:
* Rolls need to be changed, ground, and recovered to ensure the clothing is not being adversely affected by contact with these roll surfaces.
* Crowns and loads need to be verified and maintained.
* Shower nozzles need to be changed on a routine basis; the shower angle to the fabric and the shower pressures can have an impact on the cost of maintaining clothing.
* All covers on vacuum units need to be repaired or replaced on a regular basis to ensure good clothing performance.
* Steam showers or boxes need to be checked for pressure and uniformity on a regular basis.
* Chemical cleaning showers should be routinely checked and maintained to ensure no negative impact of clothing.
According to Walker, "Papermakers understand that the acquisition price of each piece of paper machine clothing is not the actual cost of ownership. The value of ownership relates to how much quality, salable paper each square foot of machine clothing produces.
"Over the past several years papermakers--with the assistance of clothing suppliers, chemical suppliers and machine builders--have been able to produce more tons of paper with fewer dollars spent on machine clothing. In addition to proper fabric design and application, total cost of ownership can be further reduced through proper fabric cleaning and conditioning."
Is all the work of trialing, installing, and maintaining your mill's PMC investments really worth it? Absolutely, said our panel of experts, who shared "tales from the front" describing PMC projects that offered real returns.
"The right paper machine clothing technology applied to the right machine can yield enormous returns for paper machine operating teams," said marketing manager Jeff Landry of AstenJohnson. "We have examples of our InTegra[R] triple layer forming fabric improving formation (better sheet quality) or reducing retention aid dosage (decreasing cost and improving formation) or improving life (reducing clothing cost and possibly reducing shutdown time). The return of these benefits exceeds the slight initial cost of the triple layer technology."
Taylor agreed that three could be a "magic number" for forming fabrics. "The use of 'true' three weft system triple layer forming fabrics has drastically improved sheet properties on most white grades, and certain brown grades, and resulted in increased speeds and productivity," he said. "This has been well documented in mills in North America. Benefits reported by users of Cristini's patented TrioTwin triple layer fabric include improved opacity, reduced two sidedness, less retention aid usage, improved first pass retention, reduced drag load (leading to lower energy costs) and more."
Weavexx's Farly and Leong had stories to tell as well. "There are many examples of significant gains reached via the application of upgraded clothing. For example, in the forming section, a Northeastern gap former was able to reduce brightening chemical usage, saving $6 million annually by replacing double layers fabrics with Huytexx designs. Other twin wire applications saw improved off-couch consistency by up to 2% via the application of the thinner caliper Synergie design. On a Midwestern fourdrinier, the Avantexx2, the first plain weave top double layer, has provided a 15.7% draw reduction. All these designs have plain weave surfaces that provide improved surface topography, which has led to improved smoothness and printability."
The proper press fabrics, in particular, can make a significant impact, said AstenJohnson's Landry. "The objective in the press section is to apply pressure uniformly to the paper web to improve water removal and to 'protect' the sheet topography. In one instance we were able to increase the speed of a corrugating medium machine by nearly 80 fpm for a potential profit contribution to the mill of more than $1.5 million annually," he said. "Building a press fabric with the very finest material can positively affect the smoothness of the sheet. In one case a freesheet maker was struggling with a two-sidedness issue that was eliminated with a super-fine multi-axial AXiom[TM] press fabric. In another case, a freesheet maker had to increase the loading of the calender stack to maintain the required smoothness of the sheet, losing the sheet caliper in doing so. To overcome the caliper issue, the only avenue left was to increase the basis weight of the sheet--a VERY expensive solution. By building a flat batt cap (Equator[TM]) on a multi-axial base, mill personnel were able to relax the loading of the stack, enabling them to reduce the basis weight of the sheet and saving them a minimum of $1 million a year."
Successful press clothing trials led to big savings for a U.S. tissue mill, noted Walker. "Recently the mill trailed several Geschmay HydroDuct press fabrics; the trials proved the paper machine could operate at higher efficiencies, with 20 percent less shower water and with several percentage point improvements in moisture profiles. These trials translate into reduced energy costs and new production records, creating over a million dollars a year in new value," he said.
A western U.S. tissue manufacturer working with Weavexx found increased press felt life and increased productivity, said Farly and Leong. "Through the application of the Millennium tissue felt with exclusive chemical resistance characteristics, the mill was able to realize a 40% increase in felt life with improved break-in and decreased energy consumption. The savings from the reduction in felt changes and the associated downtime alone totaled $200,000."
Dryer fabrics offer another chance for papermakers to maximize results, said AstenJohnson's Jim Heaton, product manager-dryer. "The main way dryer fabrics affect machine efficiency is related to sheet control at higher speeds. Sheet flutter and resultant sheet wrinkles and breaks can limit speed or reduce efficiency. To reduce sheet flutter, it is important that the air carried by the dryer fabric be reduced as much as possible. This is accomplished by supplying a fabric design that provides a smooth aerodynamic surface. The MonoTier[R] Series of dryer fabrics has been proven to have exceptionally low air carrying characteristics in wind tunnel tests as compared to conventional dryer fabric designs. These results have been verified on paper machines using vane anemometer instrumentation and by visual reduction in sheet flutter.
"In a nut shell, we can significantly influence a papermakers's bottom line with the proper selection of paper machine clothing (both construction and application)," Landry said. "It's a very small investment with a very high return."
IN THIS ARTICLE, YOU WILL LEARN:
* How to get the most from clothing trials.
* Maintenance techniques to maximize your PMC investment.
* Real mill results from improved PMC programs.
* Paper Machine Clothing Performance Analysis: Technical Information Paper (TIP) 0404-26. To access this TIP, go to www.tappi.org and type Product Code 0108040426 into the search box.
* "The Basics: What you need to know about forming fabrics," Richard Reese, Solutions! August 2005, Product Code 05AUGSO33.
* "Machine clothing: How do the best mills operate?," J. Bottiglieri, Solutions! January 2004, product code 04JANSO70.
EDITED BY JAN BOTTIGLIERI, SENIOR EDITOR
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|Title Annotation:||MACHINE CLOTHING|
|Publication:||Solutions - for People, Processes and Paper|
|Article Type:||Cover Story|
|Date:||Oct 1, 2005|
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