No unplanned standstills, reduced wire wear, lower operating costs, higher operational reliability, and double the lifetime: These were the ambitious demands made by Rondo Ganahl AG based in Frastanz, Austria, on the new Voith Paper EvoRun C couch roll. Long-time operational results show that the design of blind-drilled rolls meets or even exceeds all expectations.

In spring 2007, the newly designed couch roll was put into field test operation on PM 2 in Frastanz. During the observation period until the end of 2009, there were no unplanned standstills caused by a failure or regrinding, thus meeting one of the major requirements - high operational reliability.

The feature of this roll is that the wire clothing has been replaced: EvoRun C runs with the BlackStone rubber cover instead. Voith says that the main benefit of this change is the considerably longer lifetime compared to earlier solutions with wire clothing. In Frastanz, service life increased from six to more than 24 months and the first regrinding of the BlackStone rubber cover was required only after over two years operation. Since lifetime was four times longer than usual, operating costs went down considerably for the paper mill. A service life of eight years is expected for the cover.

"Every six months, the wire clothing of the old couch roll had to be replaced with a new one. This has cost us a lot of time and money," reports Maik Willig, Frastanz mill manager. In addition, the new couch roll design has had a positive influence on top wire life.

After the successful start-up in Frastanz, a technology comparison before/after the rebuild was made. Most important, all technological parameters (such as SCT or breaking length) remained as good as they were. After hardly a year of operating experience, Rondo Ganahl was convinced and decided to order a second couch roll of the new design.

Rondo Ganahl AG is an Austrian family-owned enterprise, specialized in producing paper and packaging paper and corrugated board base papers, as well as collecting paper and packaging. Frastanz PM 2 produces about 110,000 tonnes/year in a 120-170 g/m² basis weight range at a wire width of 2,800 mm at a production speed of 800 m/min.

Voith Paper, www.voith.com

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