Space case: Automated storage and retrieval system boosts inventory capacity and control

Thursday September 22, 2005
Written by Ed Romaine
Steady growth in its network systems and components business swelled Cabletron Systems inventory of manufacturing components and testing equipment from 850 SKUs to 6,500 SKUs. This growth threatened to push existing storage space to its limit, jeopardizing productivity and plant safety.

"I knew we were running out of room when I saw more and more bins being left in the aisles," says Ben Taylor, safety coordinator. "The aisles had become an extension of the storage area and this can cause problems. Not only will people waste time looking for what they need, there is a potentially serious safety hazard."

By implementing an automated storage and retrieval system made by Remstar International–vertical carousels and a Shuttle VLM system controlled by FastPic inventory management software–Taylor increased his storage capacity by 30 percent, reduced the area needed to store the SMT feeders by about a third, and reduced the storage area for IC Test Fixtures by about half. He has also absorbed continued growth in inventory.

Business is good

In less than 10 years, Rochester, N. H.-based Cabletron Systems grew from a startup supplier of network cables to a more than $1-billion leader in advanced networking systems and components. Many of the world's largest companies rely on Cabletron's systems to control data traffic in the networks they use to communicate within the company and with customers and suppliers.

Cabletron's product line now consists of hundreds of items and printed circuit boards are the primary component of most of them. Fueling Cabletron's ability to deliver quality products at competitive prices are efficiencies in its printed circuit board production operation, largely as a result of adopting a Surface Mount Technology (SMT) based automation strategy.

SMT enabled Cabletron to produce complex systems in high volumes. In the SMT manufacturing process, integrated circuits, resistors and other electronic components come to Cabletron packaged on tape which is rolled onto plastic reels, each about 13 inches in diameter. The reels are loaded onto surface mount feeders-each about 30 inches long-and these deliver components to assembly equipment for placement onto the circuit boards.

As the number and variety of circuit boards in production grew, so did the inventory of test equipment. Each family of circuit board produced requires a dedicated test fixture. Each fixture weighs up to 150 pounds, requires about the same storage area as an overhead storage compartment of an airplane, and can cost up to US$20,000. If one breaks, testing of that line may be interrupted until the item is repaired.

Other large items requiring storage and easy access are selective wave solder fixtures, plates about two-feet-square and a half-inch-thick, which guide the soldering process. All such fixtures plus product labels, metal faceplates and scores of other miscellaneous items had been stored either on overhead racks or conventional steel shelving, but that space was running out.

Evaluating automation alternatives

Taylor was already familiar with automated storage and retrieval systems, and knew of them as a way to convert unused overhead space into storage area. He saw them as a way to improve plant productivity and safety at the same time. With this in mind he began evaluating available systems, comparing them on the basis of cost, service and the applications knowledge of the sales personnel.

His first step was to control storage of the smaller items, the SMT components, labels, and mounting plates. This was accomplished with two vertical carousels. Each carousel is 16-feet high, just eight-feet wide and five-feet deep. Inside each carousel are component carriers, each of which can be configured with up to 30 storage compartments. Carriers hold items up to ten inches high.

To access items in the carousel, users enter an ID code into the control pad and mechanical drives deliver the carrier to them, swiftly and quietly. The items arrive at an ergonomically designed "Golden Zone," from which they are typically slid onto a cart and wheeled to the production site.

Items that are larger and less uniform in shape, such as the surface mount feeders and the IC test fixtures, are stored in a 19-foot high Shuttle Vertical Lift Module, which stretches from floor to ceiling. Shuttle VLMs are modular towers in which a mechanical lift transports metal trays to shelves enclosed within the walls of the structure. Each tray is six-feet wide and three-feet deep and the 19-foot high Shuttle VLM at Cabletron can be configured with up to 24 trays.

Surface mount feeders, IC test fixtures and other large items are stored in the six-by-three foot steel trays, which are delivered to and retrieved from the shelf by the mechanical lift. Workers request the item they need by entering its tray number into a control pad.

Shuttle VLMs differ from the vertical carousels, in the way that goods are assigned to storage areas. Where carousel compartments are typically assigned to particular part numbers, for example, storage trays in the Shuttle VLM are not. Instead the system uses photo eyes to size the item and find the optimal storage location for it. This provides a great deal of flexibility in size of items that can be stored and provides safe secure storage for fragile items such as the IC test fixtures.

By making it easy for people to put things away, Taylor has also met his intended accident prevention objectives. "There are three main areas: material handling, tripping and falling, and cumulative trauma disorders. With automated storage and retrieval systems, we improve safety in at least two of these areas," he says.

Automated storage and retrieval systems reduce material handling injuries by delivering items to the ergonomically positioned "Golden Zone." This eliminates need for workers to have to bend down to pick up heavy equipment or part bins, reducing risk of back and knee injuries. Automated storage and retrieval reduces trip and fall type injuries by eliminating clutter in the work area.

The automated systems also deliver inventory management benefits to Cabletron. All items in the carousels are stored by part number, which, in addition to simplifying access and retrieval of parts, provides an almost real-time count of inventory. All items in the Shuttle VLMs are also easily accounted for, with up to the minute inventory and usage reports ready for printing at any time.

Automated storage and retrieval also enables first in / first out (FIFO) utilization by making all items accessible at once, regardless of when they arrived. This ensures that an assembly process would always use the latest revision of any component.

To obtain additional inventory management benefits, Cabletron has installed Windows-based FastPic software. This will enable them to combine management of both the carousels and the Shuttle unit. It will also enable them to optimize storage area by recommending the most effective combinations of items to be stored in each system.

EDITOR'S NOTE: In 2001, Enterasys Networks and Cabletron Systems merged. Cabletron is now called Enterasys Networks.

Ed Romain is marketing director of Remstar International Inc.

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