New floor on existing hall

The solution was to add a storey to an existing single-storey production hall: the finished goods warehouse located in the production area was to be dissolved and moved to the new floor. The new, heavy production systems could then be installed in the space that this freed up. In order to create the greatest possible storage capacity on the approximately 900 square meters of floor space on the new floor, the plan called for the installation of a mobile racking system. This storage system combines the high space and volume utilization of a block storage system with the directly accessible storage locations of a conventional pallet rack. In contrast to racking systems that are permanently bolted to the floor, mobile racking systems only require a single operation to reach all storage locations. This means that around twice as much can be stored in the same space. The aisle only opens between two rows of shelving when a storage bin needs to be accessed. This is made possible by electrically driven carriages on which the racks are mounted and which run on rails.

False ceiling with play

However, this solution posed a major challenge - for the statics of the new storey ceiling or suspended ceiling, but also for the mobile racking system. The ceiling had to be self-supporting so as not to hinder production on the first floor. A steel composite ceiling was therefore used, based on 25-metre-long steel beams. They were installed with pre-tensioning, which was calculated in such a way that the ceiling would only be level with the weight of the concreted ceiling, the shelving system and the stored goods. Without these loads, the steel girders would bulge up to 320 millimetres in the middle.

The combination of precise static calculation of the suspended ceiling by the structural engineer and the tailored design of the mobile racking system by Galler Lager- und Regaltechnik enabled Ernst Stadelmann to create 1,620 pallet spaces on the new floor and thus free up space for the production expansion on the first floor. The mobile racking system ensures the best possible use of space and also offers sufficient capacity for future growth. Thanks to the modifications to the mobile racking system, the system has been running smoothly since August 2020.

The challenge for mobile racking

This bulging is significantly reduced in the final stage. Nevertheless, a possible deformation of the false ceiling of +/-12 millimetres had to be taken into account when designing the mobile racking system. Mobile racking systems actually require a stable base plate with narrow rail tolerances.

This is because a deflection or bulge, as in the case of Stadelmann, means that the wheels of the transfer carriages are no longer exactly perpendicular to the rail and are also exposed to horizontal pressure. In addition, the transfer carriages also have to cope with any incline in the direction of travel, even when the racking system is fully loaded.

The existing conditions therefore required a special design for the mobile racking system. Ernst Stadelmann therefore commissioned Galler to implement the racking system: the Kulmbach-based company, which operates throughout Europe, not only supplies standard racking, but also develops customized storage solutions for pallets and industrial goods for each customer. For the mobile racking system for Stadelmann, this meant in particular adapting the trolleys: the new storage area was equipped with a total of twelve of them.

Each trolley is 18.7 meters long and carries a 6.1 meter high pallet rack. Together with the stored goods, the total weight of a single trolley is 17,500 kilograms. With more powerful drive motors, automatic brakes and reinforced drive wheels, the mobile racking system was tailored to the conditions of the flexible suspended ceiling.

Modified chassis

In order to ensure proper functioning even in the event of a possible deflection in the direction of the rails, Galler equipped the trolleys with oversized drives so that they can easily travel up a possible incline. In addition, automatic brakes ensure that the racks do not start rolling on their own on an incline.

Galler also took into account a possible inclination of the floor at a 90 degree angle to the track. The possible horizontal forces can lead to considerable wear on the running wheels of the chassis. Reinforced wheels were therefore installed, which are made of high-quality steel and can therefore also absorb the forces acting on their "flanks" without excessive wear.

An article from materialfluss 8-9/21.