It used to be that automated storage and retrieval systems (AS/RS) pretty much did just that—stored and retrieved products. But with today's push for DC efficiency, automated storage and retrieval systems are fast becoming a strategic part of inventory control and order fulfillment. You might say that these systems have come of age.
Traditionally, AS/RS have been known for their matchless ability to save space by providing dense storage (they can store pallets several deep) and by using normally underutilized ceiling space. Unlike sprawling rack systems, AS/RS are built up vertically—some rise over 100 feet—making them ideal for facilities that have limited footprints. Then there's their versatility: AS/RS can be designed to handle both pallet-sized loads, which they store in high-rise racking systems, and cases and totes, which are placed into mini-load systems.
So how are today's systems different from those of a generation ago? The most noticeable difference lies in the sophistication of their controls, which have become faster and more precise. But more importantly, the systems have become integrated into the picking process itself. "You can use the power of an AS/RS to bring bins of products directly to the worker. It no longer is [just] a storage machine; [it's] now a picking machine," says Rob Schmit of SSI Schaefer. That delivery capability alone allows two or three people to pick more than 1,000 order lines per hour—a particular plus for operations whose orders consist largely of small parts.
Not only can an AS/RS speed up the picking process, it also can increase accuracy. Typically only one tote containing a single SKU is delivered at a time from storage to a picking station, which means workers would have to go out of their way to make an error. Another key inventory control advantage is that products can be dynamically assigned to storage locations based on factors like shortest travel distance, first-in/first-out, pick frequency and product weight. That "slotting" freedom allows the system to optimize its movements.
Today's systems also permit sequenced picking—selecting products in a certain order. Sequencing has a number of advantages. Facilities that perform value-added services, for instance, can pick products from storage in the order in which they'll need to be presented to the workstations where the services are carried out. Companies can also pick in a particular order to build delivery routes, so that the products arrive at shipping docks in the order they'll need to be loaded onto trucks. Similarly, products can be delivered from the AS/RS in a sequence that will make store putaway faster. That is, products for aisle one can be picked into one carton, aisle two into the next, etc.
Some pallet storage systems can also pick a layer of product at a time to build loads destined for a particular customer. Instead of extracting the entire pallet, the AS/RS has grippers that peel off only the top layer, which is then placed onto an order pallet. Additional layers of other SKUs are also added to this rainbow pallet, creating a pallet of mixed SKUs that can be shipped right to the end customer without the need to repalletize products elsewhere in the facility.
Similarly, grippers can eliminate the need to place every item into a tote or onto a pallet. "Carton grippers attached to the AS/RS load extractor mechanism allow direct storage and retrieval of cartons, thereby eliminating the need to repack merchandise into tote boxes," reports Ken Ruehrdanz of Siemens Logistics & Assembly Systems. The result of all these changes has been a shift in the way companies look at the AS/RS. "There are companies now using AS/RS ... as part of [their efforts to change] their distribution business from the front door to the back door," says John King of Daifuku America. "The technology is faster now and allows more applications that were not options 30 years ago," adds Daifuku's Steve Bell.
The Brrrrr factor
Beyond the inventory and picking efficiencies, today's AS/RS can help a company manage one of its bigger expenses—labor. To be precise, an AS/RS can save labor by reducing the operation's reliance on lift trucks and the operators who drive them. A typical crane may do the work of two lift trucks per shift. Lessening the reliance on humans also has some side benefits, such as a reduction in product damage and greater security.
AS/RS can also reduce the need for workers in freezers and other harsh environments. "People do not like to work in freezers and it's often difficult to find people willing to work in that environment," says Dan Labell of Westfalia Technologies. And even if companies can find workers willing to brave the cold, they're likely to pay the price in productivity. Human productivity in an uncomfortable environment like a freezer drops as much as 30 to 60 percent below standard, reports Mike Kotecki of HK Systems. It's far better to allow cranes to operate there and then bring the products out to the worker, who can sit in the relative comfort of the DC.
Automating freezer areas has advantages that go beyond the comfort factor, however. Since an AS/RS requires a relatively small footprint, it can save on energy costs. Some DCs have reported that cooling or providing humidity control for these dense storage areas costs about half as much as climatizing conventional storage systems.
Plenty of choices
Whatever the type of operation, when it comes to installing an AS/RS, today's buyer has a lot of choices in the level of automation. Some customers opt to automate fully, using automated cranes capable of maneuvering in tight quarters to move products in and out. Others take the semiautomatic route, selecting one of the hybrid systems that use aisle-changing cranes controlled by an operator. These systems offer the flexibility to expand as a company grows. "A system like this requires a long planning horizon of five to 10 years," explains Ken Matson of FKI Logistex. Matson advises clients to allow space for additional aisles and cranes that can be added later as demand increases.
Other hybrid solutions include automated forklifts that work in conventional aisles and racking. These don't require operators and basically function as a combination lift truck and automatic guided vehicle.
Not every new AS/RS project requires major construction. Some existing storage areas can be adapted into AS/RS systems, depending on space and aisle width. "Miniloads are quite easy to retrofit into existing systems," says John Ripple of viastore systems. He says that unit load machines that handle pallets are most efficient where there are high ceilings. For buildings with lower ceilings, it's usually better to simply add a rack-supported AS/RS area.
Although height is a big advantage, that doesn't mean that areas with lower ceilings can't be adapted for use by a smaller system or a hybrid solution. "We prefer a ceiling height of at least 30 feet, but we have worked with less," says Terry Krantz of Witron. "Many people think [their sites] are too small to look at automation, but things are changing. There are some very interesting solutions out there that are smaller, modular and expandable and can work for many companies."
keeping their cool
Ohio isn't exactly Death Valley, but for JTM Foods, which operates a frozen foods storage facility in Harrison, heat gain is still a huge concern. "Freezers are extremely expensive to build and expensive to operate," says Joe Maas, vice president of operations for the company, which supplies meat and other items to schools, restaurants, institutions and grocery retailers. "A great deal of heat gain in a freezer is through the roof."
To keep the lid on energy costs and provide a more comfortable work environment, JTM opted for high-density storage, which minimizes both the footprint and the roof area. Last year, the company installed an automated storage and retrieval system from Siemens Logistics & Assembly Systems to handle pallet loads of products. The high-density storage system occupies a footprint of only 20,000 square feet, which is half of the amount of space required for a conventional freezer.
JTM's AS/RS consists of one aisle and one crane that serves 9,200 pallet locations in the 82-foot high racking. Pallets are packed tightly into the system, with pallets eight deep on one side and four deep on the other. Maas calculates that a conventional warehouse holding the same amount of inventory would require a footprint four times larger than the footprint of the AS/RS.
Maas notes that the AS/RS has saved energy in other ways as well. A lot of energy tends to be wasted at door positions, he says. The typical 8- by 12-foot door opening needed to allow lift trucks to enter the freezer allows a lot of cold air to escape and lets in a lot of moisture. The new AS/RS, by contrast, only needs an opening large enough to allow pallets to enter and exit. Its door measures a mere 5 by 7 feet. Maas also notes that although his engineers originally projected that 103 tons of refrigerant would be needed to maintain a temperature of -10 degrees F, only 64 tons are needed. Similarly, the freezer coils only have to be defrosted once a month, or about one-twelfth as often as expected.
The AS/RS has also eliminated the need for workers to enter the freezer's storage area. "The conditions they have to work in have improved dramatically," notes Maas, adding that worker turnover has dropped and productivity has improved. Better still, since installing the AS/RS system, JTM has experienced less forklift damage, less rack damage and fewer product losses.
easy pickings
As order picking environments go, Future Electronics' new DC in Memphis represents something of a challenge. The company carries 67,000 active SKUs at the site—microchips, resistors, capacitors, etc. And they aren't just your run-of-the-mill components: Many of them are small, delicate pieces that must be protected in storage, secured within the company's supply chain, and picked according to exact customer specifications.
Yet company execs insist that picking at the center presents no problems. Order pickers at the Memphis site actually have it easier than most order pickers, they say, because machines do some of the work for them. In July, Future installed Witron's Ergonomic Order Picking System, which combines the storage functions of an AS/RS with picking stations where workers quickly and accurately assemble customer orders.
The system actually includes two separate units, one that handles full pallets and one that contains totes filled with small parts. The pallet system contains 4,200 locations within three 600-foot long, 50-foot high aisles. Automatic cranes pull pallets and deliver them to picking stations where items are selected for orders. Many of the pallets have shelving built onto them, so they act as portable storage shelves that move products directly to the pickers' positions.
The tote system contains 360,000 storage locations where 23 cranes pull products in sequenced order as directed by the unit's picking software, which is tied to the warehouse management system (also supplied by Witron). The pulled totes pass through a small sorter that feeds 23 picking stations, where workers pick from product totes into order cartons.
"Pickers cannot pick from the wrong tote. They only get one tote at a time and cannot make a mistake," reports Bernard Betts, vice president of worldwide distribution operations for Future. "Everything is sequenced, so it makes it really easy for the picker."
The system, which has only been in place since July, is already paying huge dividends in addition to the very high rates of accuracy. It is 71 percent more productive than the radio-frequencybased system used in the previous facility, while requiring only about one-third of the labor. Orders can be processed faster and with greater flexibility.
"It's been a charm," says Betts. "You expect with a startup to have problems with equipment and software, but we have not had any. The systems have been fantastic."
it's not rocket science
It's probably only fitting that an airline facing a space crunch would look upward for a solution. And so it was that Jet Blue, which faced a serious capacity shortage in the DC where it stores repair parts, decided to take the high road when it came to storage systems.
This past summer, the company installed an AS/RS in its repair-parts facility, which is located at the company's JFK hub in New York City. "Our objective in installing the system was to maximize cube space," says Terry Inglis, Jet Blue's director of materiel. "Based on our growth, we would have needed 55,000 feet of warehouse [floor] space to match what we have in the AS/RS, which occupies a tenth of the space."
The AS/RS supplied by Murata Machinery USA has been in operation since June. The one-aisle system runs the full length of the repair hangar, which can hold three A-320 aircraft. Dual cranes operate in the aisle to assure that processing can continue if one crane is taken down for maintenance. The cranes shuttle parts as needed from storage locations, where items Sure they provide dense storage and fast retrieval, are held in 4,500 trays measuring 44 inches long by 22 inches wide of varying heights.
Many of the parts are extremely fragile. The AS/RS assures that these are handled with care to prevent damage and to ensure picking accuracy. And because many of the avionics used in repairs are also sensitive to temperature and humidity, the AS/RS is climate controlled. The center's small footprint also means the cost of climatizing is a fraction of what it would be in a conventional warehouse.
The AS/RS stores and retrieves not only items needed to service aircraft in the JFK hangar, but also parts needed anywhere Jet Blue has a plane needing repairs. Picking is organized to select parts by the city where the planes are located and by when they will need the parts. The system can even accommodate requests to expedite orders of critical parts needed to get grounded aircraft back into service. "If we have a plane on the ground," says Inglis, "we can have the system bypass the other orders and push them aside to address parts needed for that repair."
