Apr 15, 2014
In the new 360°Rolls approach, roll maintenance takes into account the entire roll environment. The papermaking process performs in the best possible way if all factors related to rolls perform well and seamlessly together.
By questioning their current operating models, paper mills greatly increase the chances of success in the search for lower costs, better availability, and higher efficiency. Valmet’s new 360°Rolls approach enables papermakers to achieve better results with a 360° view of rolls and the roll environment. Rather than concentrating on single products, the focus is firmly on the whole process, including production and maintenance.
Rolls account for as much as 60% of the value of a paper machine, which means their optimal performance is crucial. Roll changes lead to a lot of downtime, especially if those roll changes are unexpected. Roll performance has an impact on, for example, sheet release, paper profiles, paper quality, and dewatering, and all are directly connected with the results achieved. In addition, rolls can also limit the production efficiency of the machine.
360°Rolls – Valmet’s new approach to roll maintenance – addresses the mill's main business drivers. It means deep understanding of the customer’s production and maintenance processes and how different factors, such as fabrics, roll covers, and doctor blades, have an effect. The papermaking process functions at its best only when all factors related to rolls perform well and seamlessly together.
Cooperation between the papermaker and Valmet in roll-related issues is the foundation of 360°Rolls. The joint goal is to lower roll life cycle costs and increase the cost efficiency of the paper machine. Cooperation also provides the mill with access to the latest results in energy efficiency, safety, end product quality, and materials technology through Valmet’s continuous R&D process.
The benefit of the new approach is the added value that comes from better paper machine efficiency through increased roll reliability, control changes, better doctoring or energy savings, among others.
It is now harder than ever to achieve revenues from papermaking; and as already stated, rolls play a major role in this. By improving roll availability, unexpected downtime can be avoided. Further, by extending roll lifetime and avoiding possible failures, production line efficiency can be improved. Good roll performance also improves paper quality and increases the amount of saleable tonnes.
Traditionally, mills have invested in their own roll maintenance tools, staff, and roll workshops. However, considering how to use assets in the most efficient way and how much should be tied into rolls can pay off. It should also be remembered that maintaining and developing the capabilities of staff is not free either.
Every mill wants to minimize risks, including maintenance-related risks. One way to do it is to ensure maintenance efficiency. Risks increase when the skills and experience of staff disappear as specialists retire or resources are otherwise cut. Maintenance planning and implementation as well as foreseeing necessary investments call for experience and special know-how. Risks are also presented by the availability or quality of spare parts. Problems can also arise when the maintenance history of rolls is unknown.
By taking the right measures at the right time it is possible to save costs. This real life example shows the impact of proactive maintenance on couch roll lifetime.
Roll life cycle costs are made up of upkeep, service, and repairs. Under- or overservicing increases costs, not the other way around. However, the highest costs arise from disturbances that lead to shutdowns. One way to lower life cycle costs is to use resources efficiently.
The new 360°Rolls thinking is about optimizing, sharing work, and allocating resources correctly. If a mill has its own strong resources, Valmet’s role is to provide only maintenance support and expertise. However, if there are no such resources, Valmet can be more actively involved in the mill’s daily operations. It is not a question of outsourcing maintenance but about using resources more efficiently.
It should be stressed that nothing changes in the new 360°Rolls approach unless a mill wants change. For example, if the staff have always changed roll sealings during scheduled maintenance shutdowns, they will continue to do it in the future. However, if needed, Valmet will provide them with better instructions and perhaps some additional training. Special attention is paid to documentation since maintenance history data can be useful in developing roll maintenance.
Operators observe roll performance and document its impact on the process. All additional information makes it possible to better understand what kinds of disturbances occur on the machine and for what reasons rolls come out of the machine. Based on this information, measures can be taken to extend roll lifetime and thus increase the operational hours of the machine.
Roll maintenance generates costs regardless of who is responsible for it. The benefit to the paper mill lies in the added value that comes from better paper machine efficiency through increased roll reliability, control changes, better doctoring or energy savings, among others. Learning new things, in turn, adds to the staff’s motivation, their willingness to develop themselves, and their ability to observe roll performance better. This all leads to more efficient operations, eliminates online risks, and reveals improvement needs.
Valmet's committed specialists in a global network of over 20 roll service centers are easy to reach and eager to help. By working together, the right solution for each customer’s specific needs will be found. Entering cooperation is easy and flexible; no major background work or investments are needed.
The 360°Rolls approach has been successfully applied to production equipment maintenance at several paper mills around the world – with good results.