Yankee Operation and Energy Optimisation

Hot to obtain a satisfactory Yankee management strategy: the 4.0 fundamentals 


The role of advanced data management systems and big data analysis in the industry of tissue was the very subject of Ian Padley’s presentation at the latest Tissue World event in Milan, where he explained how ICT can positively impact the typical issues of Yankee management.

by Roberto Carminati

As a global provider of technology to the paper and tissue industry, Swiss-based BTG Eclèpens can display a wide range of solutions with which customers can also address the typical issues of Yankee safety. This is the reason why Ian Padley, marketing manager at the company’s tissue division, took part in the latest Tissue World event in Milan, during the Yankee operations and energy optimization technical session. Meaningfully, his speech was entitled Advanced Yankee data management for quality, productivity and asset protection. And how to build upon big data in order to implement a successful Yankee care program was one of the major points of interest in his overview. First of all, Padley, who was recruited by BTG in 2010 with the goal to assist the development of its tissue-oriented roadmap, focused on the importance that a Yankee has in a traditional tissue manufacturing process. Therefore he pointed out the «central» role these components play under a variety of points of view. «Yankee operations», as Ian Padley stated, «can determine your quality, productivity, and last but not least a manufacturer’s asset protection strategy. But we must also consider that the Yankee itself, and its overall performance, can be influenced by a number of factors». Among these elements, Padley included the effects of steam and doctoring, presses and hoods, chemicals and wet-ends. All of them should be taken into account carefully in order to design a most effective Yankee care policy, by exploiting the numerous resources of big data.

The importance of a reliable measurement system

According to the representative of BTG, three steps are needed to obtain a satisfactory Yankee management strategy. To implement a reliable smart vibration monitoring system is the first, allowing users to virtually open a window «onto the Yankee coating-blade interface». The following step is giving by the ability to identify and, again, measure precisely, the vibration initiator process inputs. Finally, the data gathered from these monitoring and measurement platform have to be managed and analysed with the aim to define «the best operation centrelines», as Padley observed, for the aforementioned aspects of quality, productivity and asset protection. The usage of FFT Process frequency mapping technologies offers customers the right tools to understand the way the critical blade-coating interface is performing, assuming that no control is possible without measuring, as Padley said. A comparison of the verified blade vibration trend with rolling or grade average levels and lifetime potential is then required, and motivated by the fact that «the vibrations caused by an excessive blade wear is», in Ian Padley’s view, «the first indicator of a non-optimized process». And this means that until this event is not corrected by an operator, «both quality and productivity will be compromised». A FFT dashboard proves most useful, with its real time and historical spectra features, so to describe the machine-specific critical frequencies.

History will teach us something

Also, the same FFT mapping tool can support users in correlating known process events to specific vibration frequencies. «For example», as Ian Padley explained, «hard edge coating is often expressed at lower frequencies. This frequency must be alarmed to alert the operator». In a complete big data management approach, the historical information collected give process engineers the possibility «to map past events» and therefore to build a model to «predict and mitigate further events», in Padley’s own words. The following steps deals with matching the vibration with other Yankee operation parameters, knowing that vibration is commonly considered as a valuable indicator of the coating quality. Thus, in case the coating is going too hard, for instance, other issues should possibly be analysed, such as steam pressure and fibre management, wet-end chemistry and hood drying, together with pressing, formation, doctoring and fines retention. The model that BTG has developed allowed its specialist to find out that «around 100 discreet process tags will have a direct or indirect influence on Yankee performance, as defined by vibration». The problem, at this stage, is «how to make sense of these 100 tags» and turn these data into business critical information.

Towards a multi-trend analysis

Given that the final goal is that to «centreline the operation and to define the optimum operating window for each tag», a reliable methodology should «identify the important process factors or variables; determine the best settings and ranges for all of the important variables and how these variables affect the process and the product». Finally, supervisors are requested «to ensure that these centre-lined settings are always used during production». Innovative and ICT based big data management systems can prove helpful in aggregating the data provided by a variety of sources, namely distributed control systems or DCS, Quality control systems (QCS); database and client database; manual entry and lab operations. The suggestion is to use multi-trend data tools able, for example, to identify the causal event by comparing the process vibration initiator and the vibration itself. A more detailed look could reveal that the recorded vibration «was driven by furnish issues, leading to a hard coating from refiner generated fines». Padley commented: «As the Yankee coating becomes progressively more polluted, we lose drying efficiency, due to less intimate sheet adhesion and more refined fibre; and begin to lose crepe ratio. Under these conditions, productivity is lost in terms of crepe ratio and quality is compromised, with coarse crepe and low stretch, and if not rectified, then there will be the serious possibility» of a major «Yankee damage». The case that BTG’s Ian Padley described only meant to be an example of how to deploy an efficient data collection and analysis strategy, illustrating «the way data management systems can support users» in spotting out causes and effects in Yankee management. But of course, Ian Padley’s suggestion is that to «develop a custom dashboard in a tissue manufacturer’s own data system in order to give a complete visualization of the issue back to the operators».