FPInnovations’ paper and consumer products group is leading research to quantify base tissue sheet variations and the presence of defects, then relate them to converting efficiency, with an eye to minimizing defects in the tissue making process.
Converting base tissue sheets has traditionally been the poor cousin of the big and expensive machines themselves, but as tissue makers increasingly seek out softer tissue products, the science of converting tissue efficiently is stepping into the forefront.
Base tissue converting is the process by which raw sheets of tissue are converted into consumer products like facial and bath tissue in a large converting line by embossing, cutting, gluing, and packaging. Tissue webs can break during converting due to the poor strength and variation of the tissue properties, especially when the products are softer and bulkier. Sheet breaks result in costly downtime.
Converting efficiency is the portion of tissue required for a converting line to run continuously. With the use of a Roll Testing Facility (RTF), manager, Frédéric Parent, and scientist, Nina Deng, are conducting studies to map out the cross-machine direction (CD) and machine direction (MD) of tissue property variations, which include strength, basis weight, bulk softness, and winding tensions. Converting efficiency is a key performance indicator and tissue makers that have higher converting efficiencies have lower costs and a competitive edge.
“Our results are encouraging and we’re getting closer to linking tissue converting efficiency to base sheet uniformity,” said Deng. “We need to do a lot more work to establish the correlation, but this is a step in the right direction, and our efforts will go a long way in optimizing the process of conversion for the tissue industry.”
The research team also applied a mathematical formula developed for printing and writing paper to quantify the variation of tissue strength (m factor) in machine direction. This can be used to fingerprint variations created in tissue making and benchmark the performance of different tissue machines. “Our members have already been using our findings to reduce variations on their tissue base sheet properties and are starting to see positive results,” said Deng. For more information, please contact Nina Deng.