Printer Friendly

Sheeting technology keeps pace with fine papermaking.

Cut quality and output efficiency through enhanced automation are key concerns for papermakers investing in sheeting equipment, as tonnage continues to be the driving factor for most papermaking operations. Market forecasts indicate that papermaking capacity will increase by more than 6 million metric tons by 2007, with most of the focus on Western Europe and China. In addition, papermakers need more flexibility to deal with merchant customer demands in a market for commoditized fine paper products where customer service and response are becoming the true differentiators.

In addition to the increased running speeds of sheeting lines, a number of market issues have also driven technological development in sheeting. For example, print-on-demand requires paper-on-demand. The paper industry is seeing a gradual trend among its merchant customers to reduce inventory of standard and specialist sizes while working more closely with mills to produce smaller quantities of different formats of folio-size papers in response to customer requests.

Over the past 10 years, paper order sizes have dropped and variety has grown. Where in the past orders might have amounted to several hundred metric tons of a single paper grade, today's orders can be as limited as five or ten metric tons of different paper sizes, grades and wraps. The result is that a single sheeting device may frequently be called upon to produce five different sizes in a single day's output.

For today's fine papermaker, maximum format flexibility with minimum operator intervention is one of the keys to profitable production. Mills need to produce different formats without changing machines. In addition, pressure to reduce material waste has created the need for minimal damage to paper stock, even at ultra-high speeds. Developments in manufacturing have contributed to a typical reduction from 5% to 2% waste in recent years.

[ILLUSTRATION OMITTED]

The major investment criteria from most fine paper producers make five critical demands on the sheeting line:

* Flexible unwind to reduce reel change time

* High-performance slitting operation

* Automated changes of cut-off length, on the fly

* High-speed pallet change to limit machine downtime

* Ease of operation, maintenance, part replacement.

FLEXIBLE UNWIND OPERATION

The sheeting process starts with the positioning of the paper reel on the machine, to be unwound ready for slitting and cross-cutting. Optimum format flexibility in conversion relies on the ability to quickly load different reel sizes onto the sheeter and automate the unwind process.

One answer to this challenge is the development of folio sheeters that implement continuous operation with automatic reel feeding and residual reel disposal systems to minimize operator intervention. In these sheeters, electronic paper tension controls and automated paper web guiding and steering systems ensure that the paper is accurately positioned for the slitting and cross cutting processes. In typical plants, paper reels can now be changed on an hourly basis, with board changes occurring at almost double that frequency.

As the web of paper is fed into the slitting section, two issues impact the sheeting line's overall flexibility and production efficiency. First, it is crucial that the device can automate the position of the slitting unit to make size changes simple and foolproof for the machine operator. One system can vary slitting widths from 350mm upwards. Each knife has its own drive for positioning, ensuring that set-up times are kept to a minimum.

The second consideration is the effectiveness of dust removal at this stage, which has become more challenging with the exponential increase in production of coated versus uncoated stock. Indications are that in the next five years, growth rates for coated paper will be twice those of uncoated paper, with the impetus coming from Western Europe and China. This is a response to market demand from printers and their customers for a more luxurious sheet, with better aesthetic, technical and performance qualities on press.

One solution uses compressed air as opposed to vacuum extraction, emitting blasts of air at close to the speed of sound. This eliminates the need to apply abrasive action to the surface of the paper.

VARIABLE CUT-OFF LENGTH

Having tackled format flexibility upstream in the sheeting process through rapid automated reel changes and push-button variations in slitting width, sheeting equipment manufacturers have focused on introducing solutions that allow the mill to make frequent changes to cut-off length in the shortest possible time. Likewise, achieving maximum possible running speed at different cut-off lengths is always an issue.

This presents a manufacturing conundrum. Technically, the cut-off length permitted by the machine is limited by the circum-ference of the knife drum, which revolves parallel with the direction of the web, at the equivalent speed. A dual drum design performing a synchronous cross cutting operation is a common design feature for achieving the highest possible cutting quality.

An obvious solution would be a system that allows the operator to vary the movement of the knife drums to accommodate different cut-off lengths at highest possible web speeds. One difficulty would be overcoming the high inertia of a typical knife drum. The machine must be able to accelerate or decelerate the drum rotation responsively without necessarily increasing the horsepower of the motors--which would add to development, manufacturing and maintenance costs.

Such a system has been developed. By making the knife drums out of special light-weight carbon fiber materials developed for other industries, the inherent inertia of the knife drums on the sheeting lines was substantially lowered, allowing them to be manipulated using lightweight mechanical components. The system incorporates a special servo drive system to control the variation of movement in the knife drums, resulting in a system that can deliver variable cutting lengths from 400 mm to 1600 mm at very high production speeds.

Development of the knife itself has also had to take account of market trends, such as the increased wear and tear caused by the rise in coated production. Because the coating agents have a negative impact on the typical lifespan of the cross-cutting knives, it has been essential for manufacturers to incorporate devices that reduce the time taken to change a knife.

HIGH-SPEED PALLET CHANGE

With the slitting and cross-cutting operations completed, the remainder of the sheeting line deals with the overlapping and stacking of the sheeted paper. The demand for non-stop operation has led to design advances such as a single-stacker "non-stop, no waste" pallet change system that does not even require the operator to slow the machine or reject sheets in order to change stacks. This improves efficiency and eliminates waste since the sheets produced during the slow-down would usually be discarded. With this combination of factors, a non-stop pallet changes system can improve efficiency by up to 40%. The logical next step in the drive to maximize production efficiency is to integrate the sheeting device with third-party wrapping equipment.

OPERATION AND MAINTENANCE

Since folio-sheeting devices were first developed, automation has reduced the number of operators for a typical sheeting line by half, giving mills enormous scope to re-deploy skilled personnel elsewhere in the production environment and facilitating integration with mill management information systems. Lower manning levels on sheeting lines, however, have increased the need for training and maintenance. One solution is to use sheeting lines equipped with a modem, allowing regular service and maintenance as well as remote diagnosis of problems. The manufacturer's technical staff can remotely intervene in the machine controls and can check or change programming parts. For regular maintenance, some machines also have a touchscreen machine operating system offering the operator an online spares catalogue and telephone support, minimizing the time it takes to deal with routine maintenance.

HIGH-TECH SOLUTIONS

Converting is often considered to be low-tech and mechanical. On the contrary, manufacturers are delivering high-end converting solutions designed to meet the requirements of the paper industry--increased output, quality, efficiency and capacity.

IN THIS ARTICLE, YOU WILL LEARN:

* The critical issues in mill sheeting operations

* How new technology is addressing these issues

ADDITIONAL RESOURCES:

* TAPPI Finishing and Converting Division. Go to www.tappi.org and click on "Divisions."

* E.C.H. Will web site: www.will.kpl.net

FRANK-UWE SCHULZ, E.C.H. WILL

ABOUT THE AUTHOR:

Frank-Uwe Schulz is General Manager for E.C.H. Will, a developer of cross-cutting technology for the production of cut-size and folio size papers. E.C.H. Will is a member of the Korber Paper-Link Group, Germany. Contact the author by email at folio-sheeting@will.kpl.net or by phone at +49 (40) 4 80 94-0.
COPYRIGHT 2004 Paper Industry Management Association
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 2004, Gale Group. All rights reserved. Gale Group is a Thomson Corporation Company.

Article Details
Printer friendly Cite/link Email Feedback
Title Annotation:Converting
Author:Schulz, Frank-Uwe
Publication:Solutions - for People, Processes and Paper
Date:Apr 1, 2004
Words:1395
Previous Article:Paper summit offers something for everyone.
Next Article:A maintenance weight loss program.


Related Articles
Breakthrough technology in papermaking: exciting breakthrough technologies offer papermakers huge benefits, but implementation time is critical.
A combined future: tracking the trends in machine clothing: machine clothing innovations will come party by combining sometimes disparate...
This affordable interactive training program builds technical and Practical knowledge of the Papermaking process from paper structure to dry end!
Papermaking.
Trends in papermaking: ideas from the experts.
Expert centers promote on-site teamwork--and results.
The basics: what you need to know about forming fabrics.
UPM Changshu: Finland on the Yangtze.

Terms of use | Copyright © 2018 Farlex, Inc. | Feedback | For webmasters