AS/RS upgrade puts Big Blue in the black
A major overhaul of an automated storage and retrieval system at IBM's PC plant boosted throughput 50% and added 15 years to its life.
By David Maloney -- Modern Materials Handling, 4/1/1999
After more than 16 years of continuous service, the automated storage and retrieval system (AS/RS) at IBM's Charlotte, NC manufacturing facility was showing extensive wear and tear. Much of the existing control system was quickly becoming obsolete. Parts were either proprietary or very difficult to find. Plus, there were Y2K problems.IBM faced either the purchase of a new system or a total upgrade to their existing AS/RS, which serves as the primary warehousing system for raw materials used in production of PCs and point-of-sale terminals. Everything from boards and chassis to individual components are stored in the system. About one-fifth of the AS/RS capacity is also used for finished goods.
Safety was also an issue, as cracks had appeared in the rails used to guide the system's storage and retrieval machines (S/RMs). The fear of a potential accident was at the top of the list of concerns.
After investigating the alternatives, it was determined that a true systems upgrade would provide substantial savings- about one-tenth the estimated cost of a new system.
Since completing the upgrade (HK Systems, 800-457-9783), the AS/RS' operating costs have been greatly reduced. Productivity has also increased, storage density is higher, and better tracking systems have been implemented. The system can now handle 50% more throughput at 220 moves an hour, and up-time is now 98%.
Upgrading the system
Today, the AS/RS houses more than 28,000 stock keeping units (SKUs) in its ten, 80 ft high, 500 ft long aisles. An S/RM is dedicated to each aisle, handling both receiving and picking functions.
The entire AS/RS system is controlled by a series of PCs networked to an RS/6000 computer. The mainframe decides what products are needed for the day's manufacturing and builds a list of materials.
An S/RM is instructed to travel to an individual location where parts are stored. Photo eyes direct the S/RM to the exact location of the desired SKU and an extractor removes the load. The SR/M then delivers the part to a pick up/deposit station at the front of the aisle, placing the pallet on a slip sheet. A conveyor delivers the unit to the manufacturing workstation.
A major part of the upgrade was retrofitting the large double-masted S/RM units. The installation of new programmable logic controllers (PLCs), communication modems, photo eyes, and variable speed drives were also part of the retrofit. New controllers were additionally installed on both the conveyor that replenishes the front of the AS/RS and the separate conveyor that outputs to production.
In the past, both systems worked independently of each other and required separate control rooms. Now, as a result of the upgrade, both operate from the same PLCs, eliminating one control room, and the need for operators in two locations.
The new system software has not only benefited the control areas, but has greatly improved monitoring and reporting functions as well.
To get to the new, high level of performance was no easy task. As an essential component of the plant's production process, the AS/RS needed to continue to store and retrieve inventory throughout the entire retrofit process.
"It was challenging at best," says Navin Enand, IBM's project manager for the upgrade. "The system would run about 12 hours a day, and then the upgrade crew took over for the next 12 hours."
The crew had to meet a tight schedule in order to perform that day's installation work, do required testing and verification, and then be ready to switch it all back over for full production the next day.
The upgrade on the S/RM was performed aisle by aisle, with the first aisle taking seven days for its upgrade and three days each for the remaining nine aisles.
All 4,800 feet of floor rails that guide the S/RMs were also replaced with new thermite-welded, epoxy-grouted rails designed to prevent deterioration.
The original safety concerns have now vanished. Gone too are obsolete and proprietary parts, as all components are state of the art and Y2K compliant and readily available from a variety of suppliers.
Enand happily reports that there have been no major problems since cutover. "It just goes to show that if you do the job upfront, it makes it easier on the back end.''
IBM-Charlotte, NC
* AS/RS began operation in 1982
* Upgrade completed in 1998
* Building is 150 ft wide
* 28,000 SKUs
* 10 aisles, each 500 ft long
* Racks are 80 ft tall
* Stores 80% raw materials, 20% finished goods
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