Frankfurt Airport plays a decisive role as an important hub in Europe: with a handling capacity of 20,000 tons per week, Lufthansa Cargo operates its largest logistics center in the world at Frankfurt Airport. This only works with a modern infrastructure. The cargo airline is investing around 600 million euros in construction and modernization measures in Cargo City North.
In the recently modernized RFS high-bay warehouse, two new Vollert stacker cranes store the special load carriers, so-called Unit Load Devices (ULD), from the freight machines on eight levels with a height of 30 m and a length of 100 m. Later, the containers and pallets are made available on call at the truck ramp. In the run-up to the project, Vollert's intralogistics specialists removed the outdated existing conveyor technology, upgraded the steel warehouse structure, renewed the entire cabling and fitted it with a modern control system. "We replaced the entire conveyor technology, IT systems and warehouse management with new technology. However, we continue to use the existing steel structure of the high-bay warehouse. To do this, we converted the storage bays from telescopic to roller transport and installed roller decks in all storage compartments. This enables us to achieve a higher storage capacity, shorter turnaround times and more efficient handling of truck transports," explains Lars Strobel, Head of Sales Intralogistics Systems at Vollert. With travel speeds of up to 2.5 m/s and a stroke of 1 m/s, the two stacker cranes each perform 16 double cycles per hour.
Deep storage compartments with roller conveyor transport
The single-aisle warehouse comprises a total of 510 compartments. These are arranged on both sides and can each hold up to two ULDs in a row - with a total weight of 14 tons. This is made possible by roller conveyors, which were integrated into the existing steel structure by Vollert. They transport the pallets or containers as a package into the storage compartment. They do not have their own drive or power supply. They are moved by friction wheel drives located on the stacker cranes, which drive the roller conveyors during storage and retrieval. Vollert's experts also used the installed stacker cranes as a platform for assembling the conveyor belts. Additional lifting systems were therefore not necessary. Lufthansa Cargo offers various unit load devices for a wide range of transported goods. For this reason, each piece of freight is weighed and measured by the Vollert control system during the infeed. Depending on the type and size, the warehouse offers space for up to 1,020 containers or pallets.
Retrofit for moving truck docks
In addition to the warehouse technology and control system, the loading and unloading zone on the road transport side was also completely modernized. For this purpose, two existing moving truck docks (MTD) - mobile lifting systems for loading the trucks - were completely dismantled, sandblasted, overhauled, repainted and equipped with new motors, bearings and control elements for retrofitting at Vollert in Weinsberg. With new power, they now move the ULDs delivered by the stacker cranes to the trucks again and lift them to the required loading height. Around 40 truck lanes are available for this. "One of the challenges of the overall system is the high availability required. Aircraft idle times are sometimes calculated every minute, which is why it is important to handle the aircraft quickly," explains Lars Strobel. "With the robust and redundant systems in the high-bay warehouse and at the moving truck docks, we achieve the required reliability and safety." For the installation, the Vollert team underwent all of the airport's required safety checks as well as special behavioral training for working on the airfield.
