- February 01, 1995
Improving output while cutting labor costs was among the benefits received when a Wisconsin producer investigated the use of a waterjet-slitting system to ensure peak efficiency in the production of its tissue-paper products.
A Wisconsin converter of tissue products discovered waterjet slitting is providing numerous production benefits, including speed and tonnages increases with decreased labor costs.
The Consumer Products Div. of Pope & Talbot, Eau Claire, WI, converts a variety, of paper products, including facial tissue, towels, toilet tissue, napkins and disposable diapers.
The company wanted to streamline the process for producing tissue paper to ensure peak efficiency. After reviewing its manufacturing operations, Pope & Talbot determined it could eliminate the secondary winding that precedes converting by incorporating an ultra-high-pressure waterjet system.
Pope & Talbot previously used a T-24 winding machine to rewind tissue following the reeling process. The company encountered several problems with the rewinding process. The most serious problem was that rewinding reduced the running speed of its machinery. Additionally, rewinding required Pope & Talbot to increase the crepe specification for tissue paper because the process reduced crepe. The increase weakened the web, in turn, affecting quality.
Another problem centered around the use of knives to cut the overall web into smaller rolls. Located at the winder, the knives generated a significant amount of dust in the workplace. Though not a safety hazard, the dust had a negative effect on working conditions at the plant.
Seeking a solution to the problems, Pope & Talbot reviewed the success of its ultrahigh-pressure waterjet slitting system manufactured by Flow International Corp., Kent, WA. Pope & Talbot installed Flow equipment in 1986 to cut diapers at the Eau Claire plant. Benefits obtained from this machine led the company to examine other potential applications. After viewing a demonstration of waterjet machinery slitting tissue, Pope & Talbot purchased another Flow system for the Eau Claire facility.
Flow's slitting equipment uses water pressurized to 40,000 lb./sq. in. to slit the web. During operation, the ultra-high-pressure pump forces the water through a small diamond orifice .005 in. in diameter. A coherent, high-velocity waterjet system traveling at up to three times the speed of sound is formed. A catcher device collects the kerf material and spent water for easy disposal.
Flow's slitting system consists of an I-beam that spans the width of the paper web on the paper machine. Mounted trader the beam are multiple carriages, each equipped with two waterjet nozzles. The placement of two nozzles on each carriage ensures continuous operation with no interruptions for scheduled maintenance or emergency repairs. Carriages are configured across the beam in varying distances. Operators can easily adjust carriages on the beam to control the width of web cuts.
Pope & Talbot installed its Flow slitting system in January 1993 during a dryer grind. The installation took two days. Initial operations proceeded without disruption, and the firm has experienced no problems with the machinery.
Pope & Talbot has obtained numerous benefits from the slitter. It enabled the paper converter to increase the spool speed of its machines and reduce the crepe specification. Additionally, operators of the machinery can view the cutting process, enabling them to examine the tissue's straight, finished edge without visual obstructions.
Most importantly, Pope & Talbot has eliminated the secondary winding process, which has resulted in a substantial cost savings and productivity increase. Instead of transporting rolls to the winding machine, Pope & Talbot slits the paper directly at the reel with its Flow equipment. Machine speed was boosted by 40 fpm and tonnage was increased by 135 tons, for an annual costs savings of $17,575.
Elimination of the winding process allowed Pope & Talbot to reduce labor costs. This resulted in an annual savings of $178,875.
The Flow slitter decreased the amount of dust compared to the cutting knives previously used. Waterjets create little airborne dust during the cutting process. The waterjet stream travels at three times the speed of sound and creates a localized vacuum. As water mixes with air, the water carries the air downward. The result is that the vast majority of the kerf material is deposited directly into the catcher tanks.
Despite adding waterjet to the slitting process, Pope & Talbot hasn't experienced problems with wetting. "We haven't had any problems at all with wetting," Lee Skelley, maintenance manager at Pope & Talbot, said. The Flow slitter cuts with a .0005-in. jet stream moving at more than 2,000 ft./sec., causing little, if any, wetting of the paper.