20 HEIMBACH
Pulp Paper & Logistics
Photo 1: Measuring point five before the couch roll 3
of this article to the path from headbox to reel. The classic measuring points for ODIN analysis are numbered from one to six. Having discovered at position one that the fault was evident just prior to sheet reel-up, we can now move on to consider the remaining five positions. Measuring point two is located before the calender. If the ‘133.33 Hz fault’ were to disappear at this point we would know that: One or more of the calendar rolls are the cause of the barring, which we would then be able to verify by means of vibration measurement. However, since measuring shows the same fault at this point we proceed step by step. At point three measurements are carried out before the size press.
Everything is relevant The fourth measurement is taken between the press and dryer sections, though this is optional as it can sometimes be difficult to obtain access here. ODIN’s fifth measurement is at the end of the forming section, just prior to the
May/June 2018
suction couch roll. The sixth and last of these ‘classic’ measuring positions is located directly after the headbox. Everything must be looked at, and nothing must be missed; every single component with direct influence on the paper sheet must be considered as a causal factor – vacuum
pumps for example. In addition, water circulation, filler content, chemistry can have an effect – the list of possible sources of barring is long.
Beyond the machine In principle, everything concerned with air, stock and vacuum
systems requires special attention. Rolls are rarely identified as triggers, pumps much more frequently. In addition, the sizing process, screening system, suction boxes or any forming fabric vibrations come into possible consideration. It should also be admitted that clothing can also
Photo 2: Vertical screen with four-blade rotor
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