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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

October 14, 2015

Logistics News: Understanding Sorting System Technology

Sorting Systems are Comprised of (3) Critical Subsystems

Holste Says:

...the best way to manage change is to deploy the most flexible and adaptable technologies available while striving for the highest level of productivity.
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Previous Columns by Cliff Holste

Sorting It Out: Shippers Looking To Increase System Capacity Are Surprised To Find It May Already Exist!

Sorting It Out: For Shippers - Benefits Of Real-Time Control In The DC Are Huge!

Sorting It Out: Shippers Looking to Improve Operations Choose Customer Centric Approach

Sorting It Out: Productivity is a Crucial Factor in Measuring Production Performance

Sorting It Out: Packaging Construction Impacts on Logistics Operations


Readers Note: The following article was originally published in April 2013. It was one of our most viewed articles. It contains important and relevant information for shippers who are considering deploying an automated sortation system to their order fulfillment operation.

Sortation is considered to be the heart of the order fulfillment process in companies where it is deployed. These shippers depend on their sorting systems to rapidly and accurately consolidate random flows of products into discrete orders for shipping so that they can expedite delivery and maintain a high level of customer service. They are capitalizing on a broad range of sortation technologies to meet their needs effectively and efficiently.

Essentially, there are two basic approaches to developing a sorting system solution. You can view sortation as a standalone operation sorting products or orders into consolidation lanes, or as an integrated component of an overall logistics solution. The latter is the most comprehensive because it takes into consideration all possible product mixes from all production areas. Typical, such systems consist of a mix of materials handling equipment and controls that are tied together through a Warehouse Management System (WMS).

Operational constraints requiring evaluation may include: product weight, case/package size, weight and handling characteristics, required throughput capacity (cases per minute), footprint and system configuration. Once business and physical requirements have been considered, the next step is to determine what level of sortation is needed.

Automation should be considered when two or more of the following requirements exist:


Throughput – 10,000 or more cases/units processed per eight hour day or work shift


Highest possible sorting accuracy rate (99% or greater)


Minimize product damage


Increase productivity (reduce incremental increases in headcount)


Optimize capacity of existing facility and processes


Improve working conditions and safety

Once it is determined that automated sorting is justified, there are (3) critical subsystems that comprise a properly deployed automated sorting system: Induction, Sortation, and Aftersort Conveyor.



The Induction Subsystem receives cases of product from upstream processing lines, merges and combines the cases into a single line, establishes the proper space/gap between cases, and feeds the cases onto the sorter at the maximum machine rate (referred to as the Demonstrable Rate expressed in cases per minute CPM). The following chart lists principle functions of the induction subsystem:



The Sortation Subsystem includes a broad range of technologies. The table below lists key characteristics for the types of sorters most often used:



The Aftersort Subsystem transports and stages/accumulates product from the sorter prior to packing, palletizing, or fluid loading onto shipping trailers. The following chart lists important considerations:



The above three subsystems are essential elements of the automated sorting system solution. Their proper design and application is critical to the performance of the overall material flow system. They should be located in an area within the facility that will not be considered for expansion anytime in the foreseeable future.

As an example: Locating the sorter over the shipping dock doors is definitely worth considering as this space is seldom used efficiently. In facilities that have a clear height of 25 feet or more, installing the induction and sortation subsystems on a floor supported mezzanine takes advantage of the buildings cubic space while creating unobstructed floor space underneath for staging, as well as the efficient movement of personnel and mobile equipment.

Of course, the software systems that integrate the sorting system into the DC’s business processes and physical flow patterns are the “brains” that drive the automation and provide the highest level of overall system performance, flexibility and adaptability.

Final Thoughts

Many logistics companies are concerned about unforeseen changes in their current business model and the effect those changes could have on system processes especially related to order fulfillment. Going forward, the best way to manage change is to deploy the most flexible and adaptable technologies available while striving for the highest level of productivity.

The next best opportunity to learn more about sorting equipment and system technology can be found at MODEX 2016 April 4 – 7, 2016 in Atlanta, GA. Check it out at:

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