Cantilever racking can be configured to suit all manner of locations. Uprights can be grouped in pairs or any combination to suit the products that need to be stored. Grouping uprights in sets, to suit a particular product, gives the most cost-effective approach.
However, this requires stocking levels to be predicted and controlled, so that the maximum stock level is not exceeded. Where stock levels are variable due to demand or supplier delivery patterns, a continuous run of frames is the best option. Stock can be placed in vacant areas and not limited to specifically designed locations. However, with the continuous approach, more frames are generally required.
Racking arm lengths are variable and can therefore be tailored to suit the products being stored. The number of arms per frame will depend on the size of products being stored and any height restrictions imposed by the building and handling equipment.
Frames can be configured as either single- or double-sided; since the worst loading conditions are when only one side is loaded, there are no savings to be made in column or base material and fabrication cost. Therefore, wherever possible, it’s always best to use double-sided frames, which are more balanced and far less expensive in terms of cost per item stocked.
The space between frames is determined by the length of products and their rigidity. For example, 100x100mm timber section, 3.6m long, would be ideally suited to 1.8m frame centres, while the same length component in a 25x50mm section will require additional support to prevent sagging.
Selection of the right vehicle to load and unload cantilever racking is essential. Standard front fork trucks require considerably more space to turn than a conventional sideloader or four-way truck.
The height of the truck platform must be taken into account when setting the first arm level, since sufficient clearance must be given to enable products to be placed/removed with the truck in close proximity to the frames.
Where aisles are narrow, rails attached to the base of the frame can be fitted to guide the truck down the aisle, ensuring optimum use of space and minimising racking damage – a common problem seen on sites is racking bases bent over, creating a severe safety issue.
Adequate support
Safety is paramount and cantilever racking should be designed to ensure adequate support to the load. Wise Handling adopts a safety factor of a minimum 2:1 calculation on a yield stress of 6 tonnes per square inch. Deflection of the racking under load is also of prime importance and must be considered.
Arm loadings are calculated on the assumption that the load is uniform along the arm. Therefore an arm with a safe working limit (SWL) of one tonne is not designed to take the full load at its tip. Similarly the distribution of the load at either side of the arm should be equal, otherwise severe overloading can occur.
Frequency of loading/offloading needs to be considered. Racking that is used frequently is more susceptible to fatigue of prime materials and welds than lesser used racks.
Operational personnel should be adequately trained so that they are familiar with the limitations of the racking in terms of correct loading, ensuring that the manufacturer’s SWL is not exceeded and the materials are correctly centred on the rack arms.
Staff should be encouraged to report any rack damage immediately, to enable a qualified person to establish if future use is safe. Severely damaged racking must be fully unloaded and quarantined until inspected and repaired.
Annual safety checks are essential and these can usually be arranged with the racking manufacturer or through a qualified inspector on a contract basis.
