Warehousing 101: Why is Task Interleaving a Best Practice?

Task Interleaving

Task Interleaving is a Best Practice in Warehouses

One capability an advanced warehouse management system (WMS) has is task interleaving. A WMS assigns tasks to floor personnel whether they are the folks who work at the receiving dock, or those that take goods from the receiving dock and put them away, or order selectors, or the folks at the loading dock who are loading goods onto outbound trucks. Another category of work is cycle counting – going to a slot in the shelves where inventory is kept and making sure the product in the slot is what the system says it is, and that the number of items in the slot is also what the system says is there.

In more basic WMS solutions, these different types of tasks are independent of each other. In other words, the folks at the receiving dock are only focused on checking goods in until that work is finished, and they are assigned to something else. Similarly, the workers doing picking are only doing picking, and so forth.

One of the benefits of a WMS is that is saves money by optimizing how work is done. In other words, a given amount of work can be done using fewer people and less equipment.

The ability to create optimization savings is increased if work can be interleaved. Let me give an example. Say Jane drives a forklift truck and is focused on picking. Jane is told by the system to go to Aisle 1, slot A16, and pick up three pallets. She is then told to take those goods to shipping dock S14. After getting to the shipping dock and dropping her load, she is given a new picking task. Perhaps she must go to Aisle 2 and do some additional picks. There is a lot of minimally productive work involved in these long trips between Aisles 1 and 2 and shipping dock 14.

With task interleaving Jane can be more productive.  What if while Jane was in Aisle 1 the system noticed that slot A17, the slot right next to where she if picking up pallets, had not been cycle counted in some time? Jane could do that without having to do any travel. Then let’s say Jane drops her load and the system notices that there are pallets that need to be put-away in Aisle 2. Jane is already headed there.  Further, the receiving dock where these pallets are staged is not far from shipping dock she is currently located.  Jane can be far more efficient if she interleaves put-away with order selection.

Just because tasks can be interleaved does not mean they should be. There can be a need to get a wave of picks done before a truck arrives. High priority tasks – like making sure goods get loaded in a timely manner – should take priority over tasks like cycle counting, which can be done on a much more opportunistic basis.

A warehouse management system offers many ways in which labor can become more productive. Task interleaving is just one example.

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