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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

Feb. 22, 2012

 
Logistics News: Does "Count-Back" Make Sense for Case Pick-to Belt Applications and Downstream Sortation?


Food Industry Practice to Reduce Case Pick Errors Might Work for Other Sectors - and Reduce Challenges Related to Batch Pick Accuracy?

 

Cliff Holste, Materials Handling Editor


Does a technique originally developed to reduce inventory discrepancies between 3PLs and leading food manufacturers make sense to at least partially combat a long-standing problem in mechanized case pick-to-belt applications tied to downstream automated sortation?

SCDigest Says:

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In automated sortation systems, errors of under- or over-picking are almost always identified by the system itself, but the costs related to each error remain high.
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That technique is called "count-back," and it involves the immediate cycle count of full case pick slot in pallet flow racking after each and every case pick to ensure the correct number of cartons were picked. It started at a food company (believed to be Kraft) which outsourced distribution center management to 3PLs, but which had constant issues with inventory discrepancies with those 3PLs. Many of those issues were later traced to case pick errors, usually on manual case lines in pick-to-pallet mode.

The company then modified their WMS software so that at the end of each case pick, the picker is prompted to enter the number of layers still on the pallet and the number of loose cases. The WMS would maintain a profile of each SKU's pallet configuration, andthus be able to total up how many cases are left n the location. If it doesn't match what the WMS thinks it should be, the picker rechecks the number of cases that were picked, and corrects the error. If he or she has picked the right number of cases, the previous picker's pallet would be checked.

The count-back application is able to deal with situatons where the pick empties a current pallet and continues on with a fresh one.

While the practice of doing a cycle count after each pick seems like a waste of time to some, in reality the count back process takes just a few seconds. It must have shown its value to the food industry, as companies such as Conagra, Hershey and others besides Kraft have adopted the process, startng in the late 1990s, and continuing to this day. This migration was often faciilitated as managers moved from one CPG company to another and recommended the practice.

That said, count-back has stayed almost exclusively within that food manufacturing sector.

“The use of the count-back program is just one component of being able to prove perfect order picking and the highest degree of inventory accuracy,” Ken Miesemer, former Director of Distribution and International Logistics at Hershey Foods, past president of WERC, and now a consultant at St. Onge, told SCDigest in 2008. “At Hershey, we combined the count-back process with an RF generated “pick with pride” label. That was then combined with a load manifest to prove that you loaded the pallet and where it was on the trailer. The manifest would give the pallet ID, who picked it, who loaded it, where on truck it was placed, and what were the contents. With that foundation, you can start to address the customer ship-to locations that are robbing you blind with reported shortages.”

Always implemented as a custom enhancement for many years, today a few WMS providers offer count-back as a standard feature.

Certainly, companies with case pick accuracies issues outside of those in the food industy might want to consider the count-back to address their challenges in manual pick processes. But is the technique perhaps a solution to pick accuracy problems that are associated with more automated systems?

 

A Solution for Case Pick Errors in Automated Systems?

Probably the most common form of distribution center automation involves a sortation system downstream from full case pick areas. Generally, much of the ROI for these systems comes from leveraging the sorter to enable batch picking of cartons during some period of time, such as a pick wave, versus traditional discrete order picking, where each order is picked individually. In batch picking, all the orders for a time period/wave are consolidated, so that a picker only needs to stop once at a location for each wave, picking all the cases needed for that wave at one time.

This selection actvity is often performed in special "pick module" areas, where the picked cases are put onto a belt that leads to the sorter, though cases can usually get into the system from some other locations as well. For example, some SKUs may kept only in reserve storage locations, picked to pallet using order picker trucks, then placed on a section of conveyor leading to the sorter. But the pick modules is where the brunt of the work is usually performed.

 

(Distribution/Materials Handling Story Continues Below )

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This provides significant efficiency through the reduction of travel time versus discrete order picking, in which numerous pickers all travel to the same SKUs/locations for different orders.

The downstream sorter then separates those batch picks back into discrete orders, consolidating them with other cases as required, such as any coming from piece picking areas or value-added service areas. The sorter delivers those cases for pallet building and truck loading down divert lanes.

 

 

The batch picking process, however, can result in significant cases quantities per wave, especially (though not always) for fast moving SKUs. Dozens or even a hundred or more cases might be required in a single pick (though as quantities go up, some WMS systems are smart enough to call for a full pallet of the SKU to be brought from reserve and then have cases placed on a pick belt).

In manual systems, case picking errors lead to costs, either from shipping extra cases to customers (rarely reported by them), short shipping (which is almost always caught and leads to deductions and chargebacks), or having the error caught in a DC audit process before the order is shipped, which is better than having a shipping error but must be dealt with manually.

In automated sortation systems, errors of under- or over-picking are almost always identified by the system itself, but the costs related to each error remain high. If cases are under-picked, that wave or those pallets cannot be "closed" awaiting the missing carton(s). This can lead to system inefficiency and poor sorter utilization, and a costly process of working through the WMS to have to missing cartons picked and brought to pallet build areas.

Over-picks are recognized by the Warehouse Control System (WCS) and sent to the "reject line," where they are usually mixed up with cartons for which the bar code couldn't be read on the sortation system. Re-processing the cartons on the reject line is time consuming and thus costly.

And as may be clear, cartons thought to be missing could in fact be in the reject lane, compounding the time and cost of resolving the errors.

So, case pick accuracy would seem highly important in such automated system. Unfortunately, in trying to ensure that accuracy there are usually trade-offs between accuracy goals and productivity reality.

In part 2 of this article, we'll look at what the choices and trade-offs are, and consider whether count-back, which is rarely used in these automated system scenarios, ought to be one of the solutions considered, as well as some newer technology choices available.

Are you familar with Count-Back? Any opinions pro or con? Do you have or see issues with case pick accuracy with pick-to-bel applicatons and batch picking? Let us know your thoughts at the Feedback button below.


Recent Feedback

Many 3PLs also use count-back. The key is not to slow the pickers down. Determining Ti-Hi-Loose in a hard to see slot is often time consumming and frustrating to a picker and cannot be used in a caseflow slot. Using RF devices, or even better RF Voice units, alternative methods are to have the picker confirm the quantity picked (lappet and case slots), confirm quantity remaining (case slots), or only confirm zero when the pick slot is empty.


David Price
Partner
freewmsconsulting.com
Mar, 09 2012
 
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