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No Empty Lift Truck Forks in the Warehouse
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The installation of wireless networks has made the intake and release processes in warehouses much more efficient. Before, one lift-truck driver would be responsible for intake and another one for release, which meant that for much of the time the lift-trucks would be driving around empty. With the wireless network, drivers do not have to return to a fixed starting point to obtain the next order. Once they have finished one order, they can immediately request the next order on the RF-terminal. This makes it possible to perform an intake order directly after a release order.
Warehouses that optimize this process can reduce the time that lift trucks are empty by about 30%. The skill is to make smart combinations between the different orders, for instance by using the driving distance as an indicator: each lift-truck driver receives the order that is closest to him. Another strategy is based on priority: the next order always is the one that has the highest priority. Warehouse Management Systems (WMS) can assist with finding the best order combinations.
In many warehouses, lift truck drivers are not just responsible for intake and release orders but also for replenishment of picking locations. These replenishment orders should not be postponed for too long, because that would make it impossible for the order picker to finish his work.
In other warehouses, it is even more complex because intake and release orders are split up. That is for example the case in warehouses with narrow-aisle trucks. These trucks mostly put the pallets in a specific pick-and-drop location at the front of the rack and a lift truck will pick them up from there. These pick-and-drop locations should not be occupied for too long, because that would block the way for the narrow-aisle trucks.
In some situations, it may be advisable to include other preconditions when organizing the order assignment. For instance, to prevent drivers from getting in each other’s way, it might be smart to never send more then two lift trucks to the same aisle. Or the order assignment can be organized in such a way that drivers are not allowed to enter a particular zone. All these restrictions can be included with a WMS.
Different systems focus on different aspects of task management. Further, most systems also have a different way of calculating driving distances. Some systems only look at the order of storage locations, for instance by assigning a sequence number. Other systems assign an x, y or z coordinate to every location, which helps to calculate the actual driving time.
It is therefore important to carefully consider the balance between driving distance and priority. Many WMS suppliers have solved this problem by incorporating additional parameters when calculating these two factors.
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