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Make the most of shutdowns with machine clothing checks: scheduled paper machine shutdowns offer an excellent opportunity to change out, inspect, clean, and optimize machine clothing.

Thomas Edison wrote that "opportunity is missed by most people because it is dressed in overalls and looks like work." At no time is that more true than during a paper machine's planned shutdown. Although a silent machine may be anathema to the corporate accountants, it is a positive boon for maintenance personnel willing to take advantage of the easier access a shutdown affords. Scheduled shutdowns offer an excellent opportunity to change out, inspect, clean, and optimize machine clothing in every position.

Most mills have designed customized maintenance routines for use during scheduled shutdowns; procedures may vary depending on the mill's needs, the length of the shutdown, and the availability of personnel. Solutions! asked clothing supplier" representatives to offer their suggestions For the "must-do" items during shutdown-related clothing checks. We have encapsulated their responses into the checklist on the next page.

When inspecting, cleaning, or repairing machine clothing, procedures differ depending on whether the clothing has been removed or remains on the machine. "If clothing is to be left on the machine, a very careful approach must be taken to any cleanup efforts," said Randy Kimpfbeck, papermaking services manager at Albany International Corp., Albany, New York, USA. "For instance, care must be taken not to wash rust and grease into the wire run when washing up. Many times mills do chemical cleaning around the machine and fail to adequately rinse the cleaning chemicals. This can result in the evaporation of water and high chemical concentrations, leading to later clothing issues."

Kimpfbeck recommends that, during all shutdowns, mill personnel should examine the general condition of clothing and associated equipment in sections. "The guideline on all pieces of clothing must be examined and documented," he said. "In addition to the guideline, each section has its own set of clothing and machine parameters to check while down. The shutdown is also the time to do shower maintenance, which should be an every shutdown occurrence." Me suggested that, before every shutdown, operators make a list of plugged nozzles on every shower on the machine so these nozzles can be changed quickly.

Steve Carmichael, sales/service engineer; Southeast for Weavexx, Wake Forest, North Carolina, noted that in the forming section, rolls are one of the key items to monitor.

"Check your vacuum rolls for plugging and wear, and other rolls for wear," he said. "Surface smoothness (RA) should also be monitored by mill or roll cover supplier When outage conditions allow, speed matching should be done to drive rolls without clothing."

GETTING DOWN TO WORK

To make the most of the shutdown's limited duration, mill personnel should be sure to have the proper inspection tools ready, and know how to use them.

"Typical tools used by clothing suppliers and the mill include optical magnification devices (with or without digital cameras), caliper gauges, a protractor, a ruler, a long measuring tape for sections, a permeability measuring gauge, fabric and felt mending or sewing kits, good flashlights, levels, and a sealing iron," noted Steve Carmichael, sales/service engineer at Weavexx, Wake Forest, North Carolina.

Voith Fabrics sales/service representative Mike Garrick also suggested a roll surface analyzer and noted that digital cameras are especially useful for comparing wear from shutdown to shutdown. "The most important tools to engage in this effort are the brain-power and experience of the supplier-operator team," added Garrick.

WHO IS ON THE TEAM?

The total number of operators that should be assigned to clothing duties during a shutdown win vary somewhat from mill to mill. "Typically, you have one or two operators that work primarily with the former and press after everything is down (excluding clothing installation)," said Carmichael. "They would work with their maintenance, roll, doctor, and clothing suppliers in inspection. One or two operators would also be responsible for the dryer sections."

According to Albany International's Kimpfbeck, machine tenders are best suited to handle inspections and work in the forming area; one individual dedicated to the tasks (other than cleanup) should be sufficient. In the press section, the same would apply for backtenders. "If time is an issue, the jobs could be split between two people," he said.

The dryer section requires more people, due to the number of positions involved to check, Kimpfbeck continued. "The number depends somewhat upon the number of sections, but a minimum of four people should be dedicated to checking on the condition of fabrics. The clean-up in all sections should be handled by as many people as possible, but adequate training must be done so everyone is aware of the types of materials used in clothing construction and their somewhat delicate nature when compared to the machine in general."

Machine clothing inspection areas can be broken into three sections: forming, pressing, and drying. To most effectively allocate resources, mills should perform as much inspection as possible before the shutdown, and coordinate the planned cleaning, repair, and inspection activities between each section. (The checklist on this and the next page has been organized into sections accordingly.)

Prior to shutdown, the best approach is to identify areas of concern, suggested experts from AstenJohnson, Charleston, South Carolina, USA. They recommend reviewing past fabric analyses for areas of abnormal wear and observing machine equipment and forming fabrics for abnormal conditions.

When the shutdown work is complete, take the time to perform a "pre-startup check." AstenJohnson recommends that personnel make sure that there is proper clearance between fabric and apron; check edge deckle/fabric clearance; check the function of the guide mechanism; and ensure proper fabric tension. A good last step? "Hose any loose material from fabric surfaces prior to running the fabric," they say. Then enjoy the benefits of well-maintained machine clothing, and relax ... until the next shutdown. S!

IN THIS ARTICLE YOU WILL LEARN:

* Top items to include on your machine clothing outage checklist.

* The inspection tools necessary to check machine clothing during a shutdown

* What to look for during a shutdown inspection.

ADDITIONAL RESOURCES:

* "A combined future: tracking the trends in machine clothing," by Alan Rooks, Solutions!, January 2003, page 53

* For a complete listing of articles, technical papers, TAPPI Tips, and other information on this topic, search far "machine clothing" at www.tappi.org

FORMING SECTION

"First the fabric should be inspected closely while in crawl, to determine if any damage has taken place that requires repair. While the machine is down, the condition of the fabric should be assessed. Make a magnified image of the inside and sheet side of the fabric, using a digital camera; this can be used to determine if the wear on the fabric is sheet side or inside," said Randy Kimpfbeck, papermaking services manager, Albany International Corp. "If the forming fabric has been removed from the machine, this is the time to check and change equipment. While the machine is down and the fabric is off, is also the best time to change doctor blades."

CHECKLIST:

From Steve Carmichael, sales/service engineer, and Roy Jones, Manager--Forming Fabric Applications, Weavexx:

* Check for wear streaks (machine side and paper side).

* Check for ridges (inspect ridges on both machine and paper side to identify if ridges originate from wear streaks).

* Headbox deckle boards--wear, adjustment and lubrication ports if equipped.

* Is there proper slice-to-fabric clearance? Minimum 0.200 in., recommended 0.250-0.300 in. Check with feeler gauge.

* Ceramic blades/foils in former--wear, piano keying, cracking, alignment, unusual buildup.

* Poly blades in former--wear, alignment, and any unusual buildup.

* Vacuum boxes checked for plugging, deckle wear, end unusual wear.

* Suction boxes--what is condition of surface? Check levelness of all boxes.

* Lubrication, cleaning, and trimming shower nozzles--for plugging and nozzle integrity.

* Forming board, hydrofoils, vacufoils: Check for sharp edges. If blades are ceramic, diamond file-poly, use small hand plane.

* Doctor blades--check for wear and proper loading pressure and angle--unusual wear can be an indicator of uneven roll wear or carryover problems.

* Rolls--check vacuum rolls for plugging and wear, other rolls for wear. When outage conditions allow, speed matching should be done to drive rolls without clothing.

* Cleaning fabric--does it need cleaning? Will chemical affect fabric--do you need to rinse?

* Fabric condition--usually done by a clothing supplier. Magnified visual and edge caliper are typical. Seams can also be inspected.

From Mike Garrick, Paul Kelly, Jr. and Alvin Paul, sales/service representatives, Voith Fabrics:

For fabrics on machine, check:

* Caliper

* Dimensions

* Stability (skew)

* Tension

* Overall wear/edge ravel

* Stretch/guide mechanisms

* Shower function

If fabrics have been removed, check:

* Roll surfaces: wear, cracks, etc.

* Table elements: surface wear, chips, cracks, sharp edges.

* Clean fabric run thoroughly.

From Rod Backer, forming product manager; Jack Burgher, sales/service representative; Ron Christman, forming product manager; and Richard Watry, fanning product manager, AstenJohnson:

* Examine the fabric with a magnifying glass; include both papermaking and wear surfaces on both the front and back sides of the machine.

* Pinpoint areas of abnormal wear, determine cause and correct, if possible.

* Check fabric edge seal for integrity-raseal entire edge if necessary.

* Examine stationary former elements, including foils, suction boxes, etc.

* Remove any deposits on the outside edges of stationary equipment.

* Examine roils and doctors for non-uniform wear; non-uniform roll diameters will cause fabric distortion and uneven wear.

* Rolls should be free turning and doctor blade pressure set so as not to impede roll rotation.

* A well-planned roll grinding/covering swap-out program should be in place.

* Showers: free of plugs, replace worn nozzles.

* Shower oscillators should be checked for correct function; check shower angle and distance from the fabric.

* Inspect former frame and headbox for rust and corrosion that can damage forming fabrics on the run; inspect for dried stock and remove.

PRESS SECTION

"The surface of all press fabrics should be inspected for loss of batt material and general surface condition. If seam fabrics are run, the seams should he spotted for inspection. This inspection should include flap wear, seam integrity, and condition of sewing at the ends of the seam," Kimpfbeck recommended. "A complete cleanup of the press section also must be done, but take care not to wash materials into the fabric that could either damage the fabric on startup or plug the fabric. When the fabrics are off, all rolls should be inspected for damage; inspect the suction rolls and the grooved rolls thoroughly for plugging. Quite often the grooved rolls are overlooked and can create problems that look as if they are fabric related."

CHECKLIST:

From Steve Carmichael, sales/service engineer, Weavexx:

* Uhle box strips/covers--ceramics for wear/buildup, cracking and piano keying, poly for wear and buildup. Both types have deckles that should he inspected far condition and positioning.

* Uhle box bodies--check for plugging.

* Rolls--check vacuum rolls for plugging and wear, other rolls for wear. Surface smoothness (RA) should also be monitored by mill or roll cover supplier. Nip impressions should be performed on a regular basis to assure uniform loading (twice per year, if no problems).

* Felt doctors--check for wear and positioning, inspect load/unload system if equipped.

* Roll doctor blades--check for wear and proper loading pressure and angle. Unusual wear can be an indicator or uneven roll wear or carryover problems.

* Lubrication and cleaning shower nozzles-for plugging and nozzle integrity.

* Shower oscillation systems--clean slides/bushings, filters if water driven.

* Does felt need cleaning? Will chemical affect felt--do you need to rinse?

* Guiding systems, palms, and roll movement devices--preventative maintenance is very important in preventing damaged clothing.

* Felt condition--usually done by a clothing supplier, visual, caliper, edge condition, and caliper check if desired.

From Mike Garrick, Paul Kelly, Jr. and Alvin Paul, sales/service representatives, Voith Fabrics:

For fabrics on machine, check:

* Caliper

* Dimensions

* Stability (skew)

* Overall wear/edge ravel

* Seam flap integrity

* Stretch/guide mechanisms

* Shower function

If fabrics have been removed, check:

* Roll surfaces: wear, cracks, etc.

* Uhle box covers: plugging, surface wear, chips, cracks, sharp edges.

* Clean fabric run thoroughly.

DRYING SECTION

"While shutting down, as many of the dryer fabric seams should be spotted for inspection as is possible. In the dryer section, the fabric edges should be checked for hydrolysis, edge seal should be checked to make certain it is intact, seams should be checked for open areas, the seam area should be checked for wear as well as the body of the fabric being checked for wear. If the fabrics are off the machine, blow boxes and any vacuum rolls should be checked for signs of filling and cleaned if needed," said Kimpfbeck.

CHECKLIST:

From Steve Carmichael, sales/service engineer, Weavexx:

* Guiding systems, palms, and roll movement devices--preventative maintenance is very important in preventing damaged clothing. The hot environment is hard on these systems,

* Roll condition surface smoothness, buildup and wear.

* Look for abrasion or plugged areas of fabric.

* Vacuum / blower rolls--check for plugging in hole openings.

* Blow box--check for cleanliness of blow slots and proper clearance between felt and box.

* Felt condition--usually done by a clothing supplier, visual, edge condition, seam condition, permeability, seam skew, and felt body integrity.

From Mike Garrick, Paul Kelly, Jr. and Alvin Paul sales/service representatives, Voith Fabrics:

For fabrics on machine, check:

* Dimensions

* Stability (skew)

* Tension

* Overall wear/edge ravel

* Hydrolyzed condition

* Seam condition

* Stretch/guide mechanisms

If fabrics have been removed, check:

* Roll surfaces: wear, cracks, etc.

* Dryer can condition: rust, pitting.

* Clean fabric run thoroughly.

Edited by JANICE BOTTIGLIERI, Senior Editor
COPYRIGHT 2003 Paper Industry Management Association
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 2003, Gale Group. All rights reserved. Gale Group is a Thomson Corporation Company.

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Title Annotation:Machine Clothing
Author:Bottiglieri, Janice
Publication:Solutions - for People, Processes and Paper
Date:Aug 1, 2003
Words:2206
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