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Cliff Holste is Supply Chain Digest's Material Handling Editor. With more than 30 years experience in designing and implementing material handling and order picking systems in distribution, Holste has worked with dozens of large and smaller companies to improve distribution performance

Logistics News

By Cliff Holste

September 28, 2011

Logistics News: Quick & Easy Ways To Boost DC Productivity Just In Time For The Busiest Season Of The Year!

If You Already Own The WMS Software, Why Not Use It?

There is not much time left before shipping volume begins its traditional build-up towards the end of year holiday season. All approved 2011 productivity improvements are probably implemented by now. However, there may still be time to deploy WMS supported, productivity boosting, functionality that is generally included with the out-of-the-box software, but, for reasons that may have initially made sense, were not fully deployed.


The following WMS functions are not new. They have been imbedded in most WMS packages since the early days when WMS was the big new thing. While it may not be entirely clear why this functionality was not fully deployed at system startup, it could be that DC managers had their hands full understanding and getting comfortable with all the new technology while deploying the highest priority functions. Today, after decades of successful WMS deployments, putting the following additional functionality into practice, perhaps with a little help from the vendor, should be relatively easy to do. 

Taking Full Advantage of WMS Interleaving Functionality

On the receiving and shipping docks of most busy DCs it’s not unusual to see lift trucks racing about minus a load. Chances are the operator has just completed a delivery task and is returning to pick-up another load. This practice is referred to as dead-heading and over time represents a significant loss of productivity. While all dead-heading cannot be eliminated, it can be greatly reduced by allowing the WMS to optimize lift truck operations, for example:

  • Pick up a specific pallet load at a designated location on the receiving dock and put it away in a pre-assigned reserve storage or active location.
  • Retrieve a pallet load from reserve storage (aisle or pallet slot) and deliver it to a specific pick slot location or shipping dock staging location.
  • Pick up stack of empty pallets and deliver to storage/dispensing location near receiving dock.

Holste Says:

If you haven't done so already, now is a good time to have your existing WMS evaluated to make sure you are utilizing all of the available built-in and appropriate functionality.
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In the above example, the lift truck is being fully utilized while completing a series of moves that efficiently brings it back to its initial starting location. All of the moves are directed by the WMS based on priority protocols using software interleaving functionality, RF scanning, and on-board communication technology. This method insures that all available lift trucks are working on the highest priority tasks.

Another opportunity for WMS directed interleaving can be found in Serial Zone Picking, which is also known as Pick-&-Pass:

      • Pick-&-Pass is a popular discrete order, split-case picking method where cartons and/or tote boxes containing picked product are conveyed from one pick zone to the next. The productivity challenge is to maintain a level workload in each zone. If there is no queue of work coming into the zone, then the picker is idle. If there is a surge of work, congestion can occur. Either way, throughput slows down. Worse yet, when left unchecked, either condition can potentially starve downstream operations.

In this type of picking operation it is common to have a high occurrence of single line orders or orders that can be completed in a single pick zone (typical of Internet orders). These orders can be held back in the WMS and used to fill lulls in the flow of multi-zone orders. This will increase productivity by reducing congestion caused by a surge in single line orders, while interleaving work into otherwise idle zones.

  • In another Pick-&-Pass example - as pickers move along the face of the flow rack or dawn an aisle of bin shelving, their productivity 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.

Most WMS packages can easily provide the above interleaving capabilities, especially when picking is directed by RF or Voice Directed technologies.


Boost Shipping Productivity By Eliminating Congestion And Smoothing Out Flow

Automated sorting systems often represent the most critical constraint for even the most technically advanced operations. However, there may be a number of opportunities to squeeze a little more capacity from them:

  • Test different wave picking strategies like limiting the pickers to no more than two active pick waves at a time. This will increase system throughput by reducing congestion on the sorter caused by a high amount of re-circulated cases.
  • Review critical path conveyor speeds, including the sorter itself, to determine if they can and should be increased.
  • Bypass the sorting system for single-line orders and those that may be completed with a sub-set of popular products.
  • At the central merge, invest in up-to-date merge control logic that can reduce the gap distance between cases to just a few inches. This will increase the sorting systems throughput capacity.
  • Maintain a steady workflow through notorious bottlenecks areas such as; Pick & Pass, WIP, Weighing & Manifesting, by adjusting labor in upstream processes.


Final Thoughts

If you haven’t done so already, now is a good time to have your existing WMS evaluated to make sure you are utilizing all of the available built-in and appropriate functionality.

While adoption of any of the above suggested interleaving productivity enhancement will involve some planning and changes to well established practices, activating this functionality within an existing WMS should be relatively easy and quick with little or no disruption to on-going operations.

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