I was sitting in the dentist's chair not long ago. It leaves one with a lot of time to think - because it's really hard to talk with all of that stuff in your mouth. Although my appointment was for an hour and a half, I was getting attention from my dentist only a fraction of that time. It occurred to me that I was not the only person with a 7:30 appointment that morning. And yet, I felt comfortable that he was taking good care of me.

He’s been my dentists for over 20 years now, and as always doing a masterful job of interleaving tasks, although I doubt he would be familiar with that term. That is, he was serving me and perhaps several other patients at the same time. He was making excellent use of what would otherwise have been idle time - waiting for anesthetic to take effect, impressions to harden and who knows what else.

I started thinking about how often are we able to plan our own operations to use idle time more productively? In an office environment, I believe it’s referred to as multi-tasking or maybe time management. In the DC it’s called interleaving and it’s a very good idea.

Three Quick & Easy Ways To Do Interleaving In The DC

1) One of the most common applications of interleaving encounter in the DC is combining the retrieval of a pallet with a pallet put-away task, eliminating the empty travel back to the dock.

This works, of course, only if the shipping and receiving docks are relatively close to one another. Meanwhile, a full-function warehouse management system (WMS) can direct the putaway to a location near the pick, or find a pallet to be retrieved close to the one just stored.

2) Serial zone picking is a popular discrete order picking method. Order cartons or totes are conveyed from one zone to the next. One of the difficult tasks in this method is keeping a level workload in each zone. If there is no queue of work coming into the zone, then the picker is idle. On the other hand, if there is a large queue to provide continuous work, then orders move more slowly from one zone to another, potentially starving the downstream zones.

This method presents an interleaving opportunity in operations where there are many single line orders, or orders that can be completed in a single zone. These orders can be held back and used to fill lulls in the flow of multi-zone orders. However, priority should be given to processing the orders that need to move on to another zone. When there are no orders entering the zone, single line/zone orders can be interleaved into the normal waiting time.

3) In another picking method, pickers move along the face of a flow rack or down an aisle of bin shelving. Their efficiency can be improved considerably by reversing the sequence of locations for the next order to be picked so that the return trip is used productively (similar to #1 above for pallets). Most WMS packages can do this with little trouble, especially when picking is directed by wireless terminals.

Final Thoughts

Check your own operations, and even your office for interleaving opportunities. They are practically free!

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