Control or Chaos?

July 23, 2008
Why you need an intelligent warehouse control system

Companies invest in material handling systems to gain efficiency and control over their warehouse operations -- yet in too many cases, they are back at the drawing board to modify their systems a short while later. Sometimes this is due to changes in the business environment, but more often it is due to equipment that is not delivering the performance that it should. At some point in the system's life, control has turned into chaos.

I saw an excellent example of this recently. Consider the case of pick modules feeding a multi-lane merge, which feeds into an accumulation line, followed by a singulator, gapper, scanner, and shipping sorter. The control system provided a nice panel view of the conveyor jams all along the accumulation conveyor. The client had a full-time person stationed upstream of the gapper to clear jams and make sure that packages could be scanned and diverted properly. This wasn't the case immediately following the system go-live; it had developed gradually over two year's time.

We discovered that a technician had "improved" the throughput of the merge without taking into account the subsequent increased demands on the accumulation line. Wear on the accumulation line created the conveyor jams. The control system was able to provide data on the number of jams; however, it wasn't able to turn that data into useful information. The problem would have been found earlier by the client if this system had been equipped with a warehouse control system (WCS) showing throughput in the various areas of operation. The WCS is the key to turning chaos into control.

Warehouse Control Systems Defined

A WCS is a software system that sits between the warehouse management system and the conveyor control PLC. Strictly speaking, it is middleware. Although middleware is supposed to be in decline in these days of Web 2.0 and .NET, the WCS market for it is expanding. The reason behind this is that good WCS systems provide timely information to operations management that is unavailable from a traditional hardware control system or even a typical implementation of a WMS.

The WCS market evolved over the last decade from two sources: pick-to-light software vendors and systems integration control vendors. Both of these vendor communities realized that modern WMSs were not being used to their fullest advantage to provide data about warehouse operations.

Operations managers needed a way to look at system performance in real time and adjust operations accordingly. In the case of Tier 1 WMSs, the information might be available, but it was not in real-time or not in a convenient form (i.e., green-screen versus web pages); and in the case of older or custom WMSs, the information was often not available at all.

Material handling controls vendors responded to this need by adding databases and web-based reporting tools to their product set. Pick-to-light vendors responded by looking beyond the pick function and adding features that would allow them to gather and report data from barcode scanners and other conveyor data-acquisition devices. The convergence of these two product sets has created the modern Warehouse Control System.

WCS Features and Best Practices

There are several features and best practices implemented by the leading WCS systems. They include:

  • Provide an intuitive, data-rich, unified user interface to all key warehouse systems using web-based reporting and graphical displays.
  • Give operations managers timely presentation of actionable information.
  • Provide an integrated database to store productivity, throughput, and alarm data in a way that may be queried by the user directly or via business-intelligence enterprise tools.
  • Send configurable critical-event notices, such as e-mail or Blackberry alerts, of critical shipping information or major system faults.
  • Act as a single focal point for communication with host systems (typically WMS) and other legacy applications.
  • Robust message-logging and delivery assurance for all computer communications between the warehouse equipment sub-systems.

These features and best practices are what set WCS software apart from traditional conveyor controls and WMS software. The WMS specializes in order processing, inventory and picking management. The MHE controls focus on the safe operation and maintenance of hardware. The WCS provides the essential view into operations. It helps operations managers make real-time decisions on allocation of work within their DC. In the event of system trouble, the message-logging features of WCS are essential to rapid troubleshooting.

Room for Growth

As stated earlier, the market for WCS software is growing. The Supply Chain Consortium provides metrics for estimating the maturity of the market. The Consortium data for 2004-2007 reported that 43% out of 180+ retail and retail-supplier companies had a WMS controlling an integrated material handling equipment system for picking and shipping. This is the target market for WCS systems -- companies with enough picking and shipping volume to implement an automated distribution system.

Of these respondents, slightly less than half reported that they received maintenance and problem alerts from their systems in a satisfactory manner. But only 36% reported that they were getting real-time throughput or productivity statistics from their equipment. The bottom line is that the maintenance manager is getting better and more timely data from MHE systems than the operations manager. In the sample surveyed, there is an opportunity to serve 64% of the market with a modern warehouse control system.

Case Study

Consider this example to demonstrate the applicability of WCS systems to real-world system problems. We had a client who was performing wave picking from multiple pick modules using a full-functioned WMS. Their wave-release practice evolved away from the original design case due to changes driven by new-product introductions. Because of deficiencies in the WMS wave-release information screen, waves had to be provisionally released to judge the pick-module labor required. The waves would then be released or cancelled based on picking progress in the previous waves.

The driver of pain in this case was the uncertainty in closing out pallets between waves. There were always some un-picked orders ("stragglers") that would hold up the ability to release the next wave. In this case, the WCS was able to develop an "aged pallet" screen from information contained in its database. This could also have been done as a custom mod to the WMS, but the time and expense would have been significantly higher. The result of using the WCS to identify open-order summaries for aged pallets resulted in pallets closing within the required timeframe, allowing smoother wave-release management and increased shipping volumes.


A WCS is the tool that turns data from the MHE and WMS into actionable information for operations management. The feature mix required of a WCS varies by company and will depend on particular MHE configuration and IT environment. Planning for a WCS as part of your next system expansion can unlock the performance data within your system and mean the difference between operational chaos and control.

Paul Faber is a Principal with Raleigh, N.C.-based Tompkins Associates, a supply-chain-solutions consulting firm. As the chief manager of equipment and systems implementation at Tompkins Emerging Technology Center, he possesses extensive experience in material handling solutions, systems integration, and installation. Faber has managed field integration and operations activities at material handling sites around the world.

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