January 2020

40 n PAPER January 2020 www.drivesncontrols.com Parchment-making machine is on a roll T he Finnish-headquartered Ahlstrom-Munksjö group specialises in producing fibre-based materials and ecological papers. he group employs 8,000 people and operates 45 production plants in 14 countries around the world. Its Ahlstrom Specialties plant, located in Saint-Séverin in France, specialises in producing parchment paper, and is a world leader in its field. Its customers are mainly in the food, electronics and aerospace industries. Demand for this type of paper is expanding rapidly, and the plant exports around the world. To keep pace with its order book, the plant has recently been expanded and now has four manufacturing lines. The company designs and manufactures its machines itself. “We take great care with the quality of our products and controlling our costs,” explains Gérard Giry, the site’s maintenance and engineering manager. “The manufacturing of high-quality, hi-tech paper requires us to guarantee high precision in the automation systems, on the scale of our machines, combined with great finesse.” Developing its machines in-house helps Ahlstrom Specialties to maintain control over its production facilities, and to manage its maintenance activities efficiently. It also helps to keep its manufacturing secrets under wraps. A typical machine is several metres wide, several metres high, and around 100m long. At one end is a spool unwinder from which emerges a 2–3m wide strip of paper, several tens of microns thick. The paper passes between hundreds of steel rollers, which help to keep it at the correct tension to avoid any tearing. As it zigzags through the machine, the paper strip covers a distance of more than 200m, moving at speeds of several metres per second. From the sheet being unwound at the start of the line, to being wound onto a drum at the other end, the paper passes through four production stations – coating, drying, finishing and winding. The final roll holds 35km of paper, and weighs around three tonnes. Perfect synchronisation of the rotation of the transverse rollers is essential. The slightest speed deviation of just one roller could cause the paper to tear, thus hitting production costs. Fine-scale control of parameters such as humidity level and porosity is vital to achieve reliable production. Just as important is to ensure that the motors and geared motors that drive the rollers operate identically. The machine’s dozens of rotation axes need to be controlled with the highest degree of synchronisation. Altogether, there are around 180 drive rollers on the line, all of which must operate reliably at the same speed to avoid stoppages. To ensure that this happens, Ahlstrom Specialties has chosen Compabloc 3000 geared motors from Nidec Leroy-Somer. The quiet-running motors offer a rated output torque of between 10Nm and 14.5kNm, a power output ranging from 0.06–110kW, reduction ratios of 1.16 to 252, and efficiencies of 95–98%. The motors are reversible. n A French plant that produces parchment paper has recently been expanded to keep pace with growing demand. Its 100m-long paper-making machines contain 180 steel rollers which must rotate at the same speed to avoid tearing the paper. This places heavy demands on the motors that drive them. The Ahlstrom Specialties parchment-producing machine is around 100m long and contains 180 steel rollers, which must all rotate at the same speed Part of the massive paper-making machine in a CAD rendering (left) and in reality (right)