The world of warehouse execution systems—the warehouse management systems (WMS) and warehouse control systems (WCS) that manage processes, people and equipment—is changing. A WMS is still the norm for conventional warehouses and a WCS has become the standard for automated facilities.

For example, when American Eagle built a new 552,000 square foot distribution center in Ottawa, Kan., (a facility Modern featured in September 2007), the retailer installed a warehouse management system (Manhattan Associates, 770-955-7070, www.manh.com). Most warehouse management systems manage the picking, packing and shipping operations, but at American Eagle, the system directs receiving and putaway operations and keeps track of inventory. Order fulfillment is managed by another layer of software (Vargo Adaptive Software, 614-876-1163, www.vargocompanies.com) that determines which orders are going to be filled, who's going to fill them, and which station is going to pack them.

Likewise, Gardner Denver, a manufacturer of industrial blowers (a facility Modern featured in December 2007), relies on a warehouse management system (SAP, 800-872-1727, www.sap.com/usa/index.epx) to manage parts and components at its Sedalia, Mo., plant. But a warehouse control system (Innovative Automation, 858-452-2004, www.iasoftware.com) manages the picking, routing, packing and delivery of parts to the line as well as delivery to service parts customers.

But increasingly, end users are creating hybrid DCs and plants that incorporate automation and conventional operations to serve multiple customers and sales channels. In these facilities, voice recognition and pick-to-light may co-exist with bar code scanning. Also, carousels and automated storage and retrieval (AS/RS) systems share the floor with pallet and carton rack; and conveyors and sortation systems transport pieces and cartons while lift trucks move pallets. Those facilities are increasingly relying on the WCS as the engine for order fulfillment and synchronization.

“Historically, a WCS was responsible for the movement of goods by the equipment,” says Steve Banker, service director of supply chain management at ARC Advisory Group (781-471-1000, www.arcweb.com). “But today, there are optimization opportunities that aren't being filled by existing solutions. We're seeing the WCS push up into areas like inventory and order drop logic that you would usually associate with a WMS.”

Who can benefit from these kinds of solutions? “Complex distribution centers with high order volumes and automation,” says Banker.

So just what is a WCS in this new environment? “That has been a major discussion over the last two years, and there's no one agreed upon definition,” says Jeff Hanna, manager of control software development for Intelligrated (513-701-7300, www.intelligrated.com).

Some of the WCS duties remain unchanged. It still receives information from a WMS, sensors, scanners, photo eyes, PLCs and other data collection devices to synchronize the movement of goods on the equipment.

“You can think of a WCS as the orchestrator of automated warehouses,” says Mike Kotecki, senior vice president of HK Systems (800-457-9783, www.hksystems.com). “It has the core engine of a WMS to maximize and dispatch work and manage inventory, workflow and order processing. The difference is that a WCS dispatches that work to pieces of equipment, or people working with equipment.”

But it doesn't stop there.

In Hanna's definition, a WCS acts as the bridge, or translator, between a WMS or ERP system and the equipment, and puts those various pieces together to make things flow smoothly. “In particular, a WCS is going to be responsible for process automation or sequence control,” Hanna says. “To fill an order, an order has to be picked, it has to be packed, it has to be sealed, weight checked, labeled and delivered to the right door for the carrier. All of those steps have to be sequenced to complete the order.”

The new WCS has the logic to not only control the equipment, but to calculate the most efficient way to get those steps completed, and route an order from step to step. Finally, it feeds the real-time information it collects about the status and location of an order to another system of record.

“A WCS isn't responsible for productivity,” says Hanna. “But we can collect information about things like how many cartons are sorted to a particular packing station, and then feed that to a labor management module to track the productivity of that packer.”

As these systems evolve, they are becoming more sophisticated when it comes to balancing, and rebalancing, the workload. “The WCS has the intelligence to know the capabilities of the automated equipment,” says Rick Nichols, IT product manager for Dematic (877-725-7500, www.dematic.us). “It knows, for instance, how much product it can release through a merge area and how many packages per hour it can get through the sorter to each shipping lane. It can use that information to divide up the picking waves and distribute them into all of the areas in the distribution center to avoid bottlenecks.”

In addition, these systems are developing the capability to dynamically rebalance work. “If I get an expedited order, I could put it in a red tote so it's visible and manually move that order through the system,” says Tom Lehmkuhl, chief technology officer for Forte (800-796-5566, www.forte-industries.com). “But, if I have the right logic in a WCS, I can put the conveyor and sortation system in expedite mode and route the tote to where it's needed right now to get the order out.” Likewise, Lehmkuhl says, the WCS's coming to market have the ability to dynamically tell the warehouse to move people, equipment and other resources from one area in the warehouse to another if work requirements change during a shift.

Along with WMS and WCS, there is a third approach to order fulfillment emerging. While it doesn't have an acronym yet, it involves a layer of intelligence and optimization that sits on top of the other two systems and optimizes processes across the conventional and automated processes.

Some refer to it as waveless picking. Others call it demand-driven execution for a distribution operation. “In its simplest form, you're applying lean manufacturing principles to a distribution center,” explains Bob Carver, vice president for Vargo Adaptive Software. “The idea is to pull orders through a distribution center so that you're using your outbound resources at their highest efficiencies at all times, rather than the ebb and flow of activity you typically see in an order wave.”

In layman's terms, a warehouse can only operate as fast as the slowest process. There's no point in running a sorter at 60 cases per minute, for instance, if the packing stations can only handle 50 cases per minute. At American Eagle, the packing stations are the potential bottleneck. Instead of simply dropping a wave of orders to the floor, the system looks every 15 minutes at how work is progressing, then chooses orders to be filled based on the availability of inventory to complete an order, how long it will take for all of the pieces of an order to travel through the system at one time, and the workload at each packing station. “This way the packers are working at a constant pace through the day,” says Carver.

In some organizations, that same concept is being applied to sub-optimize targeted areas of automation, like a pod of carousels with a pick-to-light system in a pick module, adds Ed Romaine, vice president of marketing for FastPic Systems (908-537-7201, www.fastpicksystems.com). “A WMS or a WCS is a very large piece of software that can do a lot of things,” says Romaine. “But it can't be everything to everybody. When you're looking for a fast and flexible way to upgrade a zone or a few zones, this new layer of software comes into play.”

The system may rely on the WMS to manage inventory and send orders and rely on the WCS to route totes, cartons or inventory into and out of the zone. But the software provides the layer of intelligence to optimize what happens around fulfillment in that zone.

What all these approaches demonstrate is the growing sophistication of order fulfillment software, and the continued push to squeeze more productivity and efficiency out of the evolving DC. “At the end of the day, we're creating the architecture that will allow all of these things we are installing in today's sophisticated warehouse to communicate together,” says Forte's Lehmkuhl. “We can effectively get the throughput we need and dynamically adjust to what's happening in the DC to meet demand.”