For nearby residents of Sappi’s 300-year-old Alfeld Mill, this summer’s hoisting of a 138-ton machine glazed (MG) cylinder, 6.5 meters in diameter, by one of Europe’s largest cranes generated quite a bit of excitement. For mill director Stefan Karrer, it signaled the start of one of the most important stages of a meticulously planned € 61 million project to transform Alfeld’s Paper Machine 2 (PM2), one of five papermaking machines in the mill, into the world’s largest papermaking machine for one-side-coated speciality grades, running at 1.200 m/min.
The PM2 rebuild will reduce the coated wood-free production capacity at the mill by 150,000 tons annually, while speciality packaging paper production will increase by 135,000 tons annually.
The new cylinder is perfect for the production of Sappi’s new generation Fusion top liner for corrugated packaging. It enables a high bulk and better smoothness of the base paper whilst further enhancing the converting abilities for that grade. The MG cylinder will enhance grades with a very smooth top-side surface, high dimension stability, higher bulk, lower penetration of coating colour and high two-sidedness. The latter is in many cases a pre-condition for paper conversion.
Other improvements include better aesthetics in brightness, shade and opacity; enhanced printability with regard to uniformity, smoothness, evenness and ink lay-down; and increased runability thanks to added strength and dimensional stability.
Following the cylinder’s arrival, PM2 will be shut down at the beginning of September, ready for 39 days of frenetic round-the-clock activity to ensure that it will be up and running for a very tight October 12 deadline. Four days later, the first sheets of commercially saleable product will be produced.
The project involved Metso, which is undertaking the machine rebuild; ABB, the supplier of the driver; and GAW Technologies, the provider of the coating colour preparation and feeding systems.
The revamped machine will feature a new headbox with a dilution system, pre-dryer section in a single tier arrangement, and a 6.5 meter MG cylinder with a high temperature hood. The new configuration will re-use the after-dryer section and the hard nip calender while the existing film press will be fitted with new drying equipment.