As more logistics managers turn to automation to boost distribution center (DC) productivity, many are finding that the traditional solution isn't working according to plan. Automated warehouses typically have relied on two types of software in combination to oversee their operations—a warehouse management system (WMS) and a warehouse control system (WCS). But that hasn't always proved to be an efficient approach. "When companies have a ton of mechanization in the warehouse, the WMS has to integrate into a warehouse control system," says John Sidell, co-founder of the firm New Course LLC. "As a result, the utilization of automated material handling systems isn't as effective as expected."

To understand the problem, it helps to know a little about how the situation evolved. WMS solutions were originally developed to keep tabs on inventory and oversee activities like receiving, picking, and putaway. These solutions have proved highly effective in manual or semiautomated operations. But when DCs install automated material handling equipment—such as automated storage and retrieval systems, pick-to-light systems, and tilt tray sorters, to name a few—another "layer" of information technology is needed: a warehouse control system. The WCS essentially takes instructions from the WMS and then tells the equipment what to do. "The WMS is really about managing people," says Marc Wulfraat, president of MWVPL International Inc., "and the WCS is really about managing machines."

For many of the companies using a WMS in combination with a WCS, the problems begin when they attempt to sequence and optimize picking waves with their automated equipment. According to Sidell, warehouse management systems are sufficient for planning and executing manual pick waves. And in some cases, a WMS and WCS combined can handle the execution of pick waves with automated material handling equipment. But oftentimes, he says, the pick waves built by the WMS for execution by the WCS end up causing slack time in parts of the operation, resulting in reduced efficiency for the equipment and an overall slowdown in throughput.

As a result, Sidell says, companies are forced to heavily customize the WCS to build pick waves for automated equipment and then use the WMS only for processing manual pick orders. In fact, he told me that he knows of companies that have purchased a brand-name WMS package only to restrict its use to inbound shipments, directing activities like receiving, putaway, and storage. When these companies have orders to pick and ship, they turn off the WMS and then rely solely on the WCS to coordinate the equipment needed to move product out the door. "Many folks turn off the WMS on outbound and bolster the WCS to get the outbound efficiencies," says Sidell.

That's why some companies are turning to a recently developed application, the warehouse execution system (WES), that replaces both the WMS and WCS. This type of system is offered by Forte, Knighted/Intelligrated, and Reddwerks, among others.

A WES can both maintain the warehouse inventory records and drive the mechanization. Most importantly, WES packages typically have built-in intelligence that enables them to take orders and construct a work-path flow, coordinating warehouse labor and material handling equipment in real time to move products into and out of the facility. "It's really suited to heavily mechanized facilities that are pushing out huge volumes," Sidell says.

WES has attracted particular interest among retailers, many of whom are wrestling with the challenges of handling both direct-to-consumer fulfillment and store replenishment from a single DC. "The emergence of omnichannel retailing is putting even more pressure on the existing automated material handling equipment (AMHE) to function with higher levels of throughput and with a higher number of orders but lower order quantities," Sidell says. "Retailers are heavy users of AMHE, so this makes them a great fit for WES."