AUTOMATED ROLL WAREHOUSES WORLD PULP&PAPER 58 side of the storage, where any channel on different levels can be used as in- or out-take lines for the warehouse, as needed. This enables simplified layouts with less conveyors compared to using overhead crane concepts to move roll flows in and sort them out. At Stora Enso Imatra, the integration of this new central distribution buffer (requiring eight connection points in total) was far simpler and less space consuming with a TransRoll rack concept than any other alternative. Furthermore, any future expansion would be straightforward by simply adding length to the rack – achievable without disturbing the production process. Figure 2. The new TransRoll storage facility seen in “roof finishing” phase, November 2017. Lower right corner, 30 000 tons Automated Roll Warehouse. (photo: Stora Enso, Mikko Nikkinen) the deep channel technology that has been developed specifically for paper rolls has greatly expanded the rack storage concept’s capabilities order to keep the stacks stable (e.g. a 1.5m diameter equates to 15m high stacks); this doubles the piled roll stack heights compared to clamp truck operated warehouses. But the roll handling and sorting capabilities have been the bottleneck of the overhead crane concept. With vacuum grippers, a crane can handle only one roll at a time, and with mechanical grippers, the multi roll handling is very limited due to strict tolerance demands with roll diameter differences. Therefore, overhead crane concepts require quite extensive conveyor systems to serve the cranes, especially in cases where more than two cranes are needed due to the handling capacity requirements. This makes mill layout integration both difficult and expensive. Automated storage with rack concepts, widely used in other industries, were earlier considered unsuitable and expensive for paper mill usage due to the unusual pallet storage adaptations needed for paper rolls. But the deep channel technology that has been developed specifically for paper rolls has greatly expanded the rack storage concept’s capabilities. With deep channel technology, rolls are stored on horizontal roll stacks directly on the v-shaped supporting channels on both sides of the center aisle where the stacker cranes move. This kind of rack structure enables an unlimited number of connections from the long