Refurbishment of calender rollers for sustained efficiency increases in the battery industry
The manufacturing of electrodes within the battery industry places incredibly high demands on the quality of the rollers in use. This is due to the direct influence the rollers have on the quality of electrode coating and consequently the performance and service life of battery cells. Refurbishment services addressing the reconditioning and reuse of calender rollers, gains significant importance in the context of quality assurance, cost efficiency and sustainability.
To achieve the required performance in electrode production, high requirements are placed on the calender rollers in terms of concentricity, cylindrical shape and surface quality. Precision is one of the central keywords at Matthews Engineering.
“In roller production and refurbishment, we rely on future-oriented machinery and the in-depth expertise of our experienced team. Precision external cylindrical grinding and finishing are carried out with tolerances in the thousandths range,” Stefan Heßeling, Senior Sales Manager Rollers at Matthews Engineering, explains.
Calender rollers made by Matthews Engineering are used in industrial battery electrode production based on wet chemical coating. In this process, a chemical slurry is applied to the respective substrate film made from aluminum or copper, and after drying, the electrode is compressed to its final density and thickness by means of calendering. Matthews Engineering has developed an innovative technology where the calender rollers are used for the production of dry battery electrodes, or DBE for short. This technology differs from conventional methods as it allows for powder-to-film and lamination onto a current collector foil with maximum accuracy in a limited number of production steps. In both systems, the rollers need to cope with the demanding temperatures and loads in the roller gap.
Under such demands and stresses, even highest-quality rollers are still subject to continuous wear and tear as well as the risk of damage which could negatively affect machine efficiency and the quality of electrode coating. In the worst case leading to unforeseen machine downtime. Monitoring and the implementation of a systematic refurbishment program help to minimize production shortfalls and to secure a constant high quality and efficiency in production. This ultimately has an enormous effect on the final product, more specifically the performance and service life of battery cells.
Successful refurbishment in practice
What is the best approach when suspecting that the status of the calender rollers is having a negative effect on production results and the quality of electrode coatings? The first step is a thorough check to determine the degree of wear, to detect any damages and to set the specific requirements for reconditioning. High-precision measurement technologies are used to collect substantive data, from which appropriate conclusions can be drawn. Depending on the initial condition and the results of the inspection, a surface treatment is carried out by which abrasions and irregularities on the roller surface are removed by grinding and polishing. Precision grinding is also feasible as a so-called hot grinding. The roller is heated to its subsequent operating temperature and machined in its heated state. This ensures an optimal situation in the roller gap at operating temperature.
In the case that damages of any kind have been detected and cannot be removed by precision grinding only, the calender roller can be recoated. This is then followed by precision grinding to ultimately achieve the original condition of the roller. In some cases, the realization of alternative coatings can even result in an optimized roller as compared to the previous coating concept. If required, attachments such as bearing units are disassembled and cleaned thoroughly and assembled by specialized staff after the refurbishment process. The customer receives the calender roller “ready for installation”. Calender rollers that are tempered by liquid media can be cleaned on the inside if necessary, to restore an even heating and temperature distribution. The final step is a comprehensive quality control and the preparation of detailed documentation. This ensures that the processed rollers fulfill the high standards and specifications required for electrode production. All measures are aimed at maintaining and optimizing the durability and performance of the rollers, thus extending their service life.
Significant advantages through consistent refurbishment of calender rollers
“By implementing a systematic refurbishment program, production costs in many cases were significantly reduced, while at the same time the service life of the calender rollers could be increased. For our customers, this means enormous benefits in terms of cost efficiency, product quality and the achievement of sustainability targets,” emphasizes Alwin Göring, Senior Vice President Rollers & Technical Applications, Matthews Engineering.
Compared to the replacement of a roller or a complete set of rollers, refurbishment offers a cost-effective alternative – and thanks to their reuse and extension of service life, this proceeding makes a decisive contribution to further reducing the ecological footprint of the battery industry. The focus is on increased production output while reducing costs at the same time. This customized refurbishment ensures a consistently high quality of electrode production. Reduced downtimes and optimized energy consumption also contribute to lower operating costs and higher process efficiency. Maintenance on a regular basis and early detection of damages minimize production risks and protects the staff.
Refurbishment for the future
Matthews Engineering offers comprehensive refurbishment services at the Precision Center in Vreden, Germany, which is currently being expanded, and at the North American location in San Antonio, Texas (USA). Each is equipped with advanced machinery for precision grinding and the necessary final finishing of the rollers. Besides precision, the focus is on innovation and continuous development. Owing to rapid progress in battery technology, the refurbishment techniques must be continuously adapted.
“In the future, innovations in the field of materials science and automation could improve existing processes and further increase the importance of refurbishment in the industry,” states Stefan Heßeling. “This is how the industry successfully can meet the challenges of the future.”
Matthews Engineering is already developing intelligent solutions for tracking and for the provision of detailed analysis containing all data in relation to the roller which is relevant for production quality assurance. This includes operational performance, temperature and vibrations. The goal is to enable predictive maintenance so operating times can be optimized even further.
To learn more about the potential of calender rollers, how to improve their efficiency and reliability, and to position one’s own business ideally for the future, Matthews Engineering offers targeted workshops on Calender Rollers and Refurbishment to customers from the battery industry. The workshops can take place either at the customer’s premises or at the Vreden and San Antonio sites. They provide practical examples tailored to the customer’s specific questions and the focus is on how a sustainable increase in efficiency can be achieved by the means of refurbishment.
This article was published in PRO Flexconvert. Magazine for Converting Professionals, issue 4, 2024.
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