Equipment & Systems
Calender upgrade lets Holmen produce new paper grades
Voith has upgraded and successfully commissioned a paper machine at Holmen Paper in Braviken, Sweden, allowing the papermaker to produce various paper grades ranging from newsprint to sophisticated SC papers, including the recently developed Holmen UNIQ SC paper.
By Cindy Macdonald
This paper grade in the basis weight range 43 – 50 g/m2 is suitable for magazines, catalogs and advertising supplements.
As part of the three-week upgrade to PM 53, Voith replaced the former EcoSoft calenders with a Janus MK 2 calender. The special design of this calender, featuring a 45° incline of the roll stack, meant that the existing Nipco rolls could be reused while achieving a 40 per cent higher line load. The MasterReel reel winder was relocated for reasons of space and fitted with a LunaReel rubber roll cover, a minor adjustment that was necessary to be able to produce the higher-quality paper grades.
The special machine concept of the Janus MK 2 calenders allowed the upgrade to be carried out quickly and efficiently. There was no need for major structural work in the building, as the new calender could be placed on the existing paper machine foundations thanks to the 45° incline of the roll stack, putting it on the same level as the paper machine. The inclined stack configuration also provides further benefits, says Voith, such as reduced susceptibility to vibrations, shorter roll change times and very good access.
Holmen production manager Jenny Melander says the paper was of a very good quality directly after startup. The rebuild allows Holmen Paper to enhance its flexibility, because PM 53 can switch the calender between single, double or multi-nip operating modes at any time without interrupting production, enabling it to produce paper qualities ranging from matt to glossy and from low to high density.
Holmen Paper is part of the Swedish Holmen Group and a major manufacturer of graphic papers.
Voith Paper produces equipment to optimize the paper manufacturing process, focusing on developing products to reduce the use of energy, water, and fibers.