YANKEE SURFACE MANAGEMENT Yankee Surface Management as an holistic concept will repay the tissue machine process engineer with improved quality, more production and enhanced asset protection hardest coating, and with wear rates of more than (sometimes much more than) 50 µm/100 km of machine travel, the steel cleaner soon has too great a sliding surface in localised spots for effective cleaning. The blade with the smallest sliding surface against the Yankee will of course do most of the cleaning work, thus with a high performance creper and steel cleaner, it is often the creper doing most of the work on the Yankee, compromising its lifetime and quality output. Good results have been obtained by using a high performance cleaning blade, with a design optimised for the cleaning position. In this case, the machine runs a 80° high performance crepe blade. On the left of Figure 7 is the FFT spectrum with the intermittent steel cleaner; the right shows a continuous ceramic cleaning blade. Over an extended period, overall vibration was reduced by 47% and the machine was able to break free of a two month regrind cycle. In a second case, after an extended trial, these benefits were confirmed for a modern high speed tissue machine using both state-of the art wet end fines control and high performance ceramic cleaning blades: • Consistent shut-to-shut Yankee surface roughness: no adhesive wear • 50% crepe blade vibration reduction • 30% longer crepe balde life (changed for quality) • Better bulk consistency • Fewer cleaning blade changes, a safety benefit CONCLUSION Attention to Yankee Surface Management as an holistic concept will repay the tissue machine process engineer with improved quality, more production and enhanced asset protection. The key steps are: • Implement an objective way to measure and track the organic Yankee surface condition, including classified visual observation, add-on measurement, vibration measurement and the more novel techniques as they come of age. • Understand and mitigate the wet end and natural coating influnces on the Yankee surface. • Implement active control measures to suit the circumstances: a. a wet end management system b. use of a high performance cleaning blade strategy Figure 7. Impact of high performance cleaning blade installation on crepe blade vibration REFERENCES 1. Paczkowski, M. “Material Interactions and the Effect of Doctor Blades on the Yankee Surface,” Tissue World 2009 Conference, Nice, France, March 23-26, 2009. 2. Archer, S., Furman, G. and Von Drasek, W. “Yankee Surface Chatter – Mechanics, Monitoring and Methods to Minimize Impact,” Tissue World, Nice, France, March 28-31, 2011. 3. Dreshfield, A. C. A Study of Transverse Moisture Distribution and Movement During Hot- Surface Drying of Paper. Ph.D. Thesis, The Institute of Paper Chemistry (1956). 4. Devilliers,J., Padley, I. “Fines measurement for tissue machines” Paper Technology, March 2014 WORLD PULP&PAPER 30