Editor’s note: This report was excerpted from the Autumn 2005 issue of Webline, the publication of PrintCity. For more information, visit www.printcity.org.

Over the past 25 years paper roll diameters have progressively increased in a series of steps from 39 inches to 43 inches to 45 inches and then 50 inches - which has been the norm for the last 15 years.

This trend has been driven by printers wishing to improve their efficiency through handling and splicing fewer rolls and has been accomplished by improvements in paper making, logistics and paster technologies.



(click to enlarge image)
The potential cost savings at the printing press are related to the number of operating hours and the number of webs. This chart depicts the savings per web that may be possible to offset the higher capital investment costs of paper handling equipment.
Source: PrintCity/Megtec

Commercial and newspaper printers have begun to ask what advantages and constraints are associated with now moving from 50-inch to 60-inch rolls.

To answer that, PrintCity’s Web Systems & Publishing Group investigated the impact of changing to larger-diameter paper rolls by drawing on the cross-industry expertise of its members and other specialists.

The review was produced by MAN Roland, Megtec Systems, UPM and Sappi Fine Paper Europe, with contributions from Eurographica, Sonoco-Alcore and Ifra.

While some publishers have already changed to 60-inch rolls, companies remain unsure about the impact of changing size. The PrintCity evaluation examined the complete value chain, from paper making, roll cores, transport, logistics at the print site and the paster, but does not make specific recommendations as to whether a printer should make the switch.

Further actions

PrintCity’s Web Systems project team identified a number of areas where the group will continue to work together to improve the viability and performance of using larger-diameter rolls, including:

*Developing a draft protocol on issues related to core specifications, testing, identification and labeling in order to propose that relevant international bodies amend and introduce more appropriate standards.

*Optimizing chuck and core interaction.

*Identifying best practices to improve performance throughout the production cycle.  

Impact of change

Principal advantages of moving to 60-inch rolls: Potentially lower operating costs from reduced paper waste, lower splice tape consumption, more efficient press time utilization and possibly reduced manning, due to:

*31 percent fewer rolls to handle, store and strip.

*31 percent fewer splices to prepare.

*31 percent fewer roll changes, associated waste and web break risk.

Principal constraints: Higher investment costs because all related equipment must be sized for the larger dimension and 44 percent greater roll weight:

*Paper mill trimming efficiency, handling, rewinding and wrapping lines may need to be substantially upgraded to allow widespread availability of larger roll sizes.

*Logistics required to handle and store rolls at paper mill, in transit and at printer.

*More robust pasters with larger dimensions and automated roll loading.

*In some cases, more expensive or larger cores will be required.



A pressroom worker stands between a conventional roll and a 60-inch version.
Photo: PrintCity/UPM

The economic viability of change will be different for commercial printers, wide web-width newspapers and single-width newspaper operations. In addition, each plant will have its own variables including operating hours, manning levels, number of pasters, run lengths, variety of paper types and local logistics.

Weight issues

The 60-inch roll increases the weight and size of a paper roll by 44 percent and all roll handling, cores and pasters must be sized and specified accordingly.

Roll core quality

The roll core is the essential link in the production chain at the paper mill (winding and rewinding) and the paster (acceleration, braking and unwinding). The challenge for cores and chucks for 60-inch rolls is that together they must handle the 44 percent increase in weight that doubles the inertia at an E-stop, and requires torque to be increased by 62 percent (in comparison to 50 inches).

The current 3-inch size core should be suitable for many 60-inch web offset rolls. However, higher grade, more expensive or larger diameter cores may be required in some wide web-width and weight combinations where the relationship between the core and the chucks becomes a critical issue. (Editor’s note: There is no clear industry consensus on this issue at this time.)

For this reason, paster manufacturers like MAN Roland and Megtec have made the decision to set performance limitations even where the risks to people and machines are minimal.

Large roll on a MAN Roland ColorMAN press.
Photo: PrintCity/MAN Roland

Very heavy rolls, currently defined as weighing more than 3.4 tons, will require 6-inch paperboard cores to ensure secure torque during E-stops. A benefit from larger cores is that they provide a better run and roundness with less residual paper layers on the core.

Very wide web widths (both 50-inch and 60-inch rolls), currently defined as being more than 79 inches wide with speeds of more than 36 feet per second, could, under some circumstances, suffer both a web break or a core break because an expiring roll on a 3-inch paperboard core can reach its resonance frequency just prior to splicing.

Although this risk is small, machine manufacturers are obliged to apply a principle of precaution by defining what cores can be used and providing safety protection around the paster.

Solutions include using a specified 3-inch paperboard core quality with a sufficient E-modulus/density ratio; or aluminum cores (currently a non-standard and very limited regional proposal); or 6-inch paperboard cores.

These limitations could change in the future because manufacturers are researching improved solutions that may include higher performance cores and different chuck designs.

Papermaking

The two key issues for papermakers are trimming efficiency and the core types required.

Paper suppliers will frequently need to make substantial investments to manufacture and handle the larger 60-inch rolls.

The consequences for the customer will initially be a more restricted choice of paper mills; higher minimum order quantity for 60-inch rolls; and perhaps higher price if the roll widths do not cut out efficiently from the parent roll. Therefore, cores may be more expensive.

Delivery logistics

Increased delivery costs might be incurred for some 60-inch roll weight/web width combinations if they use transport payload capacity less efficiently. In some cases, more transport will be needed to deliver a given tonnage of paper, probably leading to increased costs.

The current automatic roll loading/unloading systems are not adapted to the different loading patterns required for this size.

Logistics in printing plants

The increased roll size means less movement of rolls and more stable production conditions.

Currently installed equipment may not be able to handle the larger dimensions and weight of bigger rolls and, consequently, investment may be needed to safely increase capacity limits.

The principal impacts for different applications are:

*Commercial heatset: Handling of larger rolls will require higher capacity roll trucks and clamps, adapted paper store and driveway layout, and higher capacity automated roll loading at the paster.

*Single-width newspapers: The larger rolls will require higher capacity roll trucks and clamps (but not a significant cost) with an adapted paper store and driveway layout.

*Double- and triple-width newspapers: Large volume newspaper installations tend to use customized automated roll-handling and logistics systems. The impacts will be variable on different components of the system - some will be cost neutral, others will increase costs or in some cases reduce costs.

Pasters

Pasters for larger roll sizes need to be of a much more robust construction to handle the increased roll weight that doubles the inertia at an E-stop and requires torque to be increased by 62 percent. The higher inertia also requires more powerful acceleration motors. New chuck designs may be needed to handle the much higher torque from the rolls and in certain cases quick changeover chucks to handle 3- and 6-inch cores. These changes will lead to a higher investment cost. New paster designs for this size use a highly compact turret configuration to support the paster arms that allow 60-inch rolls to be handled in almost the same space occupied today by 50-inch models.

PrintCity is a strategic alliance of independent best-in-class companies in the graphic arts industry. It has more than 50 member companies present in more than 180 countries and with a combined turnover in excess of $36 billion and 160,000 employees. Members’ activities cover the three major market segments of publishing, packaging and commercial printing. Its head office is located in Augsburg, Germany.

Key contributors and sponsors companies:

MAN Roland, Megtec Systems, UPM and Sappi Fine Paper Europe. Other contributors: Eurographica, Sonoco-Alcore, Ifra.

©September 2005, PrintCity, Augsburg, Germany. All rights reserved.