Nina Deng, Frédéric Parent, Tony Manfred, Joe Aspler, Jean Hamel

FPInnovations-Paprican
570 Boul. St. Jean, Pointe Claire, Quebec, Canada H9R 3J9
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Abstract
Web breaks in pressrooms are affected not only by paper properties, but also by pressroom conditions. Recent research at Paprican has identified the key paper properties controlling web breaks. However, the impact of pressroom conditions has not been clarified. In this study, we used a synchronized pair of Laser Doppler sensors to measure high frequency draw variations of newsprint webs, and examined the relationship between draw variations and web breaks in five different newspaper pressrooms. The results show that the draw variation is related mainly to press configuration, operating conditions, and maintenance, while the contribution of the paper was found to be small. In certain cases, the draw variation can be very high (close to 1%) at press start-up and stop, as well as at pasting. We also found that severe out-of-roundness in newsprint rolls did have an impact on draw variations. Using frequency analysis, we showed that the sources of draw variations can be identified and linked to press variables. Finally, a correlation between pressroom draw variation and web break rate was found, with a higher draw variation causing a higher break rate. These results suggest that in addition to improving paper properties, it is important to minimize draw variation through better control of the press.

Keywords: Pressroom, runnability, tension variation, web break

Csaba Horvath⁽¹⁾, Zoltan Gaal⁽²⁾, Katalin Kerekes<sup>(3)

(1)</sup> Nyomda-Technika Kft.
H-4027 Debrecen, Boszormenyi ut 6, Hungary
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⁽²⁾ University of Pannonia, Department of Management
H-8200 Veszprem, Egyetem ut 10, Hungary

⁽³⁾ Alfoldi Nyomda Zrt.
H-4027 Debrecen, Boszormenyi ut 6, Hungary

Abstract
The authors outlined an extended model to examine the modern printing machines' unexpected breakdowns. They had been analisyng the different downtimemes for years. The results of the research helps to organize the pro-active maintenance at the graphic arts industry.

Keywords: Breakdown, operating of printing machines, predictive and pro-active maintenace

Anders Bjurstedt

Bjurstedt Management Consulting AB
Karlavägen 1, SE-114 24 Stockholm, Sweden
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Abstract
During the last decade, there have been many changes in the European media market. In particular, during the last 2-3 year, advertising money has been reallocated in many national markets from the traditional printed media to the web. This will also undoubtedly affect the publication printing markets, as has been pointed out by both Bjurstedt [2006] and Leckner [2007].

Although the manufacturing cost for the process has normally been the deciding parameter when choosing a printing process, the technical work-flow process is equally important. The latter factor has not previously been taken into account, but it was shown by Bjurstedt [2007] that it is a very important aspect when determining the minimum average print run (MAPR) of any printing process. 

The MAPR is dependent only on the turn-around time or cycle time for a set of printing forms, either offset plates or gravure cylinders, because no printer is willing to have idle press room units waiting for new cylinders or plates to be delivered. Modern CTP devices (Computer-To-Plate) have very short turn-around cycles for eight plates in relation to gravure cylinder processing (for the same number of processed pages), and this enables the user-printer to produce very short runs if the market so demands. This makes commercial web-offset almost independent of the plate-making process in this context.

This paper analyzes the various parameters in the gravure cylinder process and what can be done to significantly enhance the turn-around cycles. If the turn-around cycle and costs (calculated per m2) comparing a gravure cylinder and a web-offset plate would become very close, it would constitute a paradigm shift in the publication printing industry.

Keywords: Commercial web-offset, gravure cylinder engraving, offset plate-making, publication gravure, the minimum average print run (MAPR)