14 INDUSTRY NEWS VALMET
Pulp Paper & LogisticsPulp Paper & Logistics
Next-generation press felt for demanding machine conditions
Many performance benefits for printing paper machines are claimed for SprintMaster felts from Valmet, says Marjaana Lehtinen
up, lifetime, and energy consumption are available to paper makers with the application of Valmet’s new SprintMaster press felt. Designed for high-speed
S
printing and packaging paper machines, SprintMaster press felt has a structure that provides
avings potential allied to improvements in runnability, dry content, start-
a good start-up and high nip dewatering similar to that of nonwoven or hybrid felts, but without the need for any special chemical start-up treatment. It also features strength and stability as good as conventional woven laminated felts. Coming in a variety of base
weights, the felt can be used in all positions. The best results have been achieved on high- speed printing paper machines
in PU positions where the usage of nonwoven or hybrid felts is often limited due to the risk of felt plugging and/or edge-related problems or low cross machine directional (CMD) stability of the felt. “The felts have been tested,
proven and chosen as standard products on many demanding SC, newsprint and fine paper machines. The first trials on packaging machines have been
successful too,” says Leena Silakoski, product manager for press felts at Valmet.
Optimized nip dewatering By optimizing and maximizing nip dewatering, it is possible to reach high dryness and a good felt cleaning effect in the nip. In a conventional press section, the draw level has been reduced through increased dewatering in the first nips. This allows higher
Figure 1: When the base has an open structure, the Z direction dewatering speed is low and the felt carries water to the Uhle boxes. This also means lower hydraulic pressure due to lower saturation and flow resistance. Rewetting after the felt/sheet separation point is also higher
Figure 2: With a denser base, the Z direction dewatering speed increases due to the higher hydraulic pressure and 100 per cent saturated felt. The higher dewatering speed through the felt also improves press suction roll performance and decreases rewetting at the separation point
May/June 2015
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