What Works: Warehouse operations streamlined with wireless PCs

Aug. 24, 2007

The basic principles of Lean Manufacturing date back at least to the 18th century. In Poor Richard's Almanack, Benjamin Franklin wrote, “He that idly loses 5s. [shillings] worth of time, loses 5s., and might as prudently throw 5s. into the river. He that loses 5s not only loses that sum, but all the other advantages that might be made by turning it in dealing, which, by the time a young man becomes old, amounts to a comfortable bag of money.”

Consultant Michael Giuliano has advised automobile manufacturers and large consumer goods producers on applying Lean Manufacturing principles to warehouse logistical operations. “Many warehouse and distribution center operations continue to suffer from significant inefficiencies, as forklift operators waste time and resources hunting and digging, because they lack adequate information on the location of items and the optimal route for put-away, replenish and retrieval actions,” Giuliano says. “It is not unusual for our analysis to determine, for example, that 2.5 minutes are wasted during the average retrieval cycle, and that figure is multiplied by hundreds or thousands of cycles per week.”

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On the opposite end of the efficiency spectrum, new high-tech warehouses are designed from the bottom up to automate most or all operations. Elaborate cranes, conveyor belts and robotic systems are coordinated to perform put-away and retrieval operations with little or no human intervention. These operations are highly efficient, but the capital requirements make them cost-prohibitive for most types of warehouse operations.

A more practical and affordable solution for many warehouses is to empower operators by installing an onboard computer on each forklift, making the location of items and empty storage space immediately visible.

At the 900,000 sq. ft. distribution center for City Furniture, Tamarac, Fla., all 35 forklifts are equipped with GX-1200 fixed-mount rugged computers from Glacier Computer (www.glaciercomputer.com). “Our forklift operators perform at maximum efficiency, because they always have real-time access to the information they need,” says Chad Simpson, technical support supervisor, City Furniture. “An optimized step-by-step routing scheme is displayed on their screens to guide them to their destination.”

Rugged PCs with user-friendly touch-screen interfaces connect to a warehouse management system (WMS) via a wireless local area network. More sophisticated WMS systems can indicate not only the location to pick from, replenish from or to, and put-away to, but also the optimal sequence of these events.

The WMS is typically interfaced with an existing Enterprise Resource Planning (ERP) system or accounting package. This provides an integrated method of automatically tracking inventory, processing orders and handling returns. WMS is frequently implemented with automatic data collection using barcode scanners and the increasingly common radio-frequency identification (RFID) tags, now mandated by Wal-Mart and other retailers.

“Implementation of a WMS along with automated data collection will likely give you increases in accuracy, reduction in labor costs…and a greater ability to service the customer by reducing cycle times,” according to Dave Piasecki of Inventory Operations Consulting LLC, author of Inventory Accuracy: People, Processes, & Technology. For some warehouse operations, the more efficient processes and better utilization of storage space also will result in reduced inventory and increased storage capacity.

These benefits directly address the elimination of wastes at the core of Lean Manufacturing philosophy.

Equipping forklifts with computers integrated with a warehouse management system immediately reduces the waste involved in transportation, human motion and waiting.

Shorter, more direct routing reduces travel time and, therefore, the demand for forklifts and the associated labor, capital, maintenance and energy costs. Travel time is reduced because operators always know their precise destination. After a put-away, a warehouse management system can direct a forklift to do a pick at the closest available location in situations where like items may be stored in several areas.

Giving operators better information about item locations also reduces human motion: operators no longer need to get on and off the forklift to check three or four labels before finding the location of the intended item.

The Japanese industrial engineer, Shigeo Shingo, famously explained that a bolt with 15 threads on it cannot be tightened until the last turn, and therefore the other 14 turns are wasted. This observation led to the development of fasteners, tools and methods designed for one turn, one-motion installation.

Similarly, the forklift operator provides a necessary function only when they pick the correct item. Any searching activity leading up to the locating and retrieval of that item represents a waste of time and resources – waste that should be eliminated.

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