Fame can be fleeting in the book publishing industry. A book that's a best-seller one week may be relegated to the half-price rack the next. That means that for book distributors, the pressure's on to whisk hot titles out to stores before they become paper weights.

To keep books flowing smoothly through its DCs, Simon & Schuster, one of the nation's largest book publishing houses, relies on a relatively unknown but powerful technology: a warehouse control system (WCS). Several years back, the publisher installed warehouse control systems from AL Systems at its two U.S. distribution centers to coordinate order fulfillment activities. The warehouse control systems are layered as "middleware" between the facilities' warehouse management systems and their material handling subsystems—conveyors, sorters, and the like. Essentially, the WCS serves as a "go between" or interface between the two, collecting information from the host system and then allocating work and providing specific instructions to the various pieces of material handling equipment.

Simon & Schuster is not alone in turning to a WCS to help run its operations. More and more companies are taking this route these days— usually, but not always, in conjunction with a WMS. (In some facilities, the WCS works directly with order- or inventory-management software.)

The appeal of warehouse control systems is not hard to understand. To begin with, they're affordable—warehouse control systems tend to be significantly less expensive than warehouse management systems. They're also quite versatile—warehouse control systems provide functionality that may not be available in standard warehouse management systems, or at least not without costly modifications. They're also easy to customize.

Compared to a WMS, a WCS is easier and cheaper to modify to meet a facility's individual needs. Also, for facilities with older warehouse management systems in place, a WCS can offer an economical means of upgrading. Oftentimes, a WCS can offer capabilities that older WMS systems lack, filling gaps and controlling processes that would otherwise require the user to upgrade—or even replace—its WMS.

Down to the nitty-gritty
In Simon & Schuster's case, the decision to install warehouse control systems was driven by a desire to gain greater control over its processes, in particular those processes associated with its extensive conveyor systems. "We have a lot of need for speed to the market and have to get our products there quickly," says Dave Schaeffer, the company's vice president of distribution and fulfillment.

The publisher uses the warehouse control systems in conjunction with warehouse management systems from Manhattan Associates at its distribution centers in Bristol, Pa., and Riverside, N.J. The two facilities, located about 11 miles apart, each measure about 600,000 square feet and hold different SKUs. Together, the two buildings provide distribution for all of North America and parts of Europe.

The WCS and WMS work together as part of an integrated system, says Schaeffer. "The warehouse control system controls the movement of cartons through the systems and onto the shipping docks. It works with the warehouse management system. But while the movement within the WMS is more product level, the actual real-time, minute-to-minute handling is done by the warehouse control system."

And that is precisely where warehouse control systems shine. Although warehouse management systems certainly have the capability to direct a number of warehouse processes, they typically perform most of their work at a higher level—for example, collecting orders, tracking and allocating inventory, and generating invoices. In contrast, the WCS is designed expressly to take care of the nitty-gritty operational details, telling the material handling subsystems not just what to do, but also how to do it (for example, directing a conveyor to send a case down a specific chute).

Ability to multi-task
In Simon & Schuster's Riverside facility, the WCS controls the movement of products over five miles of Hytrol conveyors, as well as a sliding-shoe shipping sorter and other subsorters. It also directs cartons through the facility's pick zones. The warehouse management system relays pick information to the warehouse control system, and the WCS then directs the actual picking activities, which for new titles usually involves picking full cases of books.

"The WMS and the WCS really work in partnership," says Schaeffer. "In our case, it really made sense to put more functionality into the WCS because of how the conveyors and the picking are integrated so closely together."

Schaeffer reports that directly linking the picking to the conveyor makes the conveyor more responsive to the picking process. "If there is a short on a pick," he says, "the conveyor can simply direct the carton to another lane before moving it on to shipping."

In addition to overseeing the picking of full cases of new titles, the WCS directs the split-case picking of older or "back list" titles—relaying picking instructions to workers via the company's Voxware voice system. Although the warehouse management system also has a module capable of directing the voice picking activities, Simon & Schuster chose to have the WCS manage its voice operations. Again, the advantage is that the WCS ties more closely into the related picking and material handling systems.

"The WCS has all of the components needed to direct voice," says Schaeffer. "The WCS can be molded easily and is just a better fit for the functionality." He adds that if Simon & Schuster someday decided to convert to, say, a pick-to-light system, it would be a simple matter to modify the WCS to handle that task.

In addition to picking, the WCS oversees quality control activities, which include check weighing (a process in which cartons are automatically weighed and their weight compared to the expected weight for the contents) and the selection of cartons for random inspection. It also handles all of the manifesting of orders.

As for Simon & Schuster's Bristol facility, the WCS there plays much the same role as its counterpart at Riverside. That is, it controls the movement of products through picking on the conveyors, full-case sortation, split-case sortation with weight verification, and the manifest stations. It also directs voice picking activities.

Ease of revision
All in all, Simon & Schuster believes the WCS is a good fit for its operations. For one thing, the WCS ensures that the operations and the associated equipment are tightly integrated, which allows both products and information to move swiftly and efficiently throughout the facilities. And when it comes time to make a change in any of the processes, the WCS can easily adapt.

"By its nature, the WCS is easy to upgrade," notes Schaeffer. "It is less complicated and is a more economical solution than upgrading a WMS."

And that's something you can make book on.