Carton Flow 101

Carton flow is typically defined as shelving that uses gravity to move product dynamically through a racking system in order to facilitate the order selection process. Carton flow systems are loaded in the rear of the rack. As each item is picked from the front, the next product slides forward to the point of pick. Instead of lining the same product up at the front of the rack horizontally, carton flow allows one to use the depth of the rack for product storage, increase throughput as well as the number of product facings on a pick line. Carton flow rack is used in order to increase efficiencies and productivity compared to your standard static racking system.

In today’s manufacturing and distribution facilities, the most common types of carton flow you will encounter are roller lanes, wheel beds, and wheel rails- each with their own distinct advantages. They will commonly be mounted within pallet rack structures or customized flow rack structures.




In the early 1950’s, New Jersey based grocer Grand Union developed the first carton flow for use within their stores and warehouses. Grand Union would later go on to market their carton flow product, dubbed Quik-Pik, to other grocery operations. Their original concept, consisting of Nylon strips mounted on metal rails, was replicated by competitors, who over the years slowly introduced different conveying technologies into the mix. As the plastic molding industry matured, the Nylon strips gave way to molded plastic wheel lanes, which became the standard for many years. Carton flow solutions eventually moved out of the grocery stores and into distribution facilities where the technology allowed for increased SKUs on the pick line, maximized picks per line feet, and dramatically increased pick rates.


Years after Grand Union’s original patent, UNEX filed one of its own in 1973- a patent on an aluminum full-width roller carton flow solution. The industry, previously dominated by wheel rail solutions, transformed again. In the mid-1990’s, UNEX reinvented carton flow with its patented Span-Track. This solution eliminated the need for carton flow shelving, providing the first flow lanes designed to retrofit into any existing pallet rack structure.


Order picking is a core function of distribution operations. Parts picking plays a major role in manufacturing operations. Because of the importance of these processes, many operations live and die by the productivity and efficiency of their picking operations. Without optimization, your typical picking process can suffer from several common ailments:

  • Pickers are travelling significant distances between picks, burning valuable time and energy.
  • The amount of SKUs or parts required by the facility consume valuable floor space and increase the “sprawl” of their storage areas.
  • Items are difficult to reach due to being stored too high, too low, or deep within the rack.
  • Parts are not presented to the pickers in a way that makes them easy to pick accurately.
  • Products and parts are replenished and picked in the same place, causing traffic jams in picking areas.
  • Time-sensitive SKUs are stored first in last out, increasing the risk of the product or part expiring or not being picked in the proper .

These are just some of the issues common in a poorly optimized picking operation, but each point of pain can result in significant profit loss for the facilities in which they occur.


Implementing carton flow systems in these environments can significantly improve efficiency and productivity, and provide answers to the common problems of a picking operation.

  • Carton flow can significantly condense storage space and utilize more of the cube, dramatically reducing the amount of space and time traversed between picks.
  • The space consolidation benefits of carton flow allow facilities to reduce the sprawl of storage areas and free up space for more value-added operations.
  • Carton flow systems can keep items at the point of pick, ensuring pickers do not have to bend and reach into a rack to retrieve the required item or part.
  • Knuckled systems and angled trays allow pickers to easily spot and grab individual items from master cases for ergonomic, accurate picks.
  • Products are picked from the front of the rack and replenished from the back, reducing traffic in picking aisles and keeping pickers safe from hazardous interactions with forklifts, tuggers, and other vehicles common to distribution and manufacturing facilities.
  • The first product put to a carton flow system is the first product picked, allowing for first in first out storage that ensures time-sensitive SKUs and parts are sequenced properly.


Using carton flow to implement dynamic storage systems can dramatically transform storage areas. The difference from static storage systems, as illustrated in this graphic, is stark:



Carton flow solutions can reduce travel time on the pick line by 80% by increasing storage density. Keeping items and parts close together and easily accessible can boost productivity of picking operations by more than 40%. Carton flow solutions can also increase throughput of products by 150% when compared to picking from static pallet positions, keeping products moving through the facility faster and reducing the time between opening an order and completion. In some cases, carton flow solutions can even reduce the workforce required by picking operations by as much as 33%. These improvements add up to serious savings. Be it within distribution, manufacturing, retail, or logistics operations, carton flow provides more product throughput in less space, and maximize the efficiencies of order picking operations.

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UNEX Manufacturing, Inc.
691 New Hampshire Avenue
Lakewood, NJ 08701

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