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Focus: Distribution/Materials Handling

Feature Article from Our Distribution and Materials Handling Subject Area - See All

From SCDigest's On-Target E-Magazine

- Sept. 17, 2013 -

Supply Chain News: DC Managers Want Task Interleaving - What it's All About?

Recent Study Says Logistics Pros See More Task Interleaving in their Futures - but It Is Harder to Achieve than Some Would Have You Believe


 SCDigest Editorial Staff

A recent survey on the future of warehousing and distribution found that among many other data points, logistics managers want to take greater advantage of "task interleaving." (See Where are Warehouses and Distribution Centers Headed? Warehousing 2018 Predictions.)

In that study from Motorola Solutions, 48% say they plan on increasing their use of so-called "task interleaving" in their DC operations over the next few years.

SCDigest Says:

When implemented effectively, task interleaving can reduce labor costs by as much as 20%, so the value is substantial.
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So what is task interleaving all about?

It is comparable in a sense to the concept of "continuous moves" in transportation. In a continuous move, a truckload carrier drops off one load, and then drives a short distance (or maybe none at all) to pick up another load for delivery somewhere else.

In extreme cases, a carrier might pick up yet another load (three total in the full route) to get the driver close to back home at the end of the third leg.

The obvious goals: reduce empty "deadhead" miles and improve asset utilization.

Task interleaving involves similar goals but in a DC setting, where the vehicle is a fork truck instead of a Class 8 over the road truck. The classic deadhead example in distribution is a receiving operation in which a driver takes a pallet load for putaway and then returns empty to the dock to grab another pallet.

But task interleaving is harder to achieve than many believe and than many Warehouse Management System (WMS) vendors promote. SCDigest will explore that in more detail in a follow-up article next week.

There are some relatively easy to achieve examples of task interleaving, the most common being combining cycle counts with almost any DC task. For example, DC workers could be asked to do a cycle count when they go to a location for any reason and the quantity of cases or "eaches" is say five or less (meaning it is easy to count that location).

But task interleaving can get harder from there to executive effectively. There is a simplicity in having a worker simply keep repeating a task rather than introducing additional, different types of tasks to their workloads.

(Distribution/Materials Handling Story Continues Below )


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At a high level, what tasks can be linked together are defined in the WMS task control area - but that itself can involve some complexity to configure correctly.

The chart below shows a non-interleaved example, where tasks such as putaways, replenishments, etc., are all performed by dedicated workers, resulting in a lot of deadheading.




In contrast, below is an example of a much more complex task interleave, as driven by the task management engine of a WMS.


In the second example shown below, an intelligent WMS (when optimally configured) can understand the total work pool that is available on the floor, and look for a complementary task that can be linked to the original task assigned to the operator. In this case, three types of tasks (putaway, replenishment and order pick) are combined in one "continuous move."

Sounds great in theory - but there are a number of practical challenges that combine to keep the amount of task interleaving in total much lower than many consultants and software vendors would have shippers believe.

When implemented effectively, task interleaving can reduce labor costs by as much as 20%, so the value is substantial.

What are your thoughts on task interleaving? Reality or myth? Where does it fit the best? Let us know your thoughts at the Feedback section below.

Recent Feedback

I agree with most of the article. In our operation we have found that we are much more efficient to keep order-fillers dedicated their entire shift.

Our Recieving and Replenishment people use some task interleaving.

All non-orderfilling personnel prioritize order-fillers needs to maximize efficiency in our operation.

We measure our overall efficiency by throughput per hour for all hours worked. This figure includes all warehouse personnel. The majority of other warehouses I have visited do not even measure their throughput. We are currently averaging 169 pieces per hour for every hour worked in our DC.

Bill Brauer
Warehouse Director
Caseys General Stores, Inc.
Dec, 26 2013