Storing and staging
There are plenty of equipment options when it comes to items and components that are smaller than a bread box.
By -- Modern Materials Handling, 10/1/2000
Where are my car keys? Who hasn't asked that question in the last few months? Weeks? Days?
Storing small items and then locating them again easily and swiftly can be a problem, as even the most organized individual would readily agree. We've all misplaced keys at some point.
Now take that personal hunt for car keys and extend it into the materials handling situations common in the industrial and commercial worlds.
What are some of the ways to store or stage and then find small parts, little pieces-anything, let's say, from a set of keys to a bread box sized component? Which methods will work best in your company's business?
From auto parts handling to washing machine manufacturing applications, there are many types of storage and staging systems and equipment from which to choose: Shelving. Storage cabinets. Modular drawers. Carton flow rack. Horizontal or vertical carousels. Vertical lift modules. Miniload automated storage and retrieval systems (AS/RSs). A-frame automated pickers. The tough part is determining which is best suited to your needs.
Selecting your system
Sizes (dimensions, volumes, shapes) and weights of items stored are prominent considerations when selecting any storage system, of course. The numbers of stockkeeping units (SKUs) categorized by size and weight will also affect your choice as will the total numbers of all items handled.
Another consideration, dictated in part by the kinds of items handled and in part by the kind of equipment doing the handling, is the container storing the items or pieces until they're picked. Keeping pieces in their original cartons or packs may work. Or those cartons might go into a bin, tote, wire basket, or other type of container. Or items may be removed from their original cartons and stored loose in the kind of container that best fits the selected system.
Other important considerations are item velocity through the facility and the rate of consumption of parts along an assembly line or in a work cell. In part, this where the concept of staging comes into the picture. What might be an appropriate equipment selection for stored parts that are accessed infrequently may not be as suitable for parts staged for short periods of time.
For instance, slow to medium movers might best be stored in a static system such as shelving. Very fast movers might require, at the least, a more mechanized system. Or with high demand for parts, an automated picking and delivery system, such as a carousel or a miniload AS/RS, may be necessary.
Organization, particularly when it comes to handling many small parts, is vital. Shelves or drawers, labeled as to their contents, may suffice. Bar coding the drawer, for example, and/or its contents improves upon the accuracy of storing and retrieving items over manual systems with items identified by name, part number, or stock keeping unit. Pick- or put-to-light systems further increase order filling accuracy.
System density and location within the plant or warehouse are other factors in the selection equation. Vertical storage systems with their small footprints will save on valuable floor space. Locating parts storage and handling systems on a mezzanine level frees up the main floor for other activities. But before you go up with parts storage, be sure you have an efficient and cost-justifiable means to get parts up to the mezzanine and back down again.
In manufacturing applications, meantime, parts storage may need to be right on an assembly line as a point-of-use system.
Here's another basic consideration: Will your system be man-to-part or part-to-man? Man-to-part methods send your operators off on a search to fill each order, much like the hunt for car keys. For slow movers, these methods may suffice. Light displays with part number and quantity shown will simplify the hunt. For very high throughputs, however, mechanized or automated part-to-man systems will tend to be more efficient and reduce labor costs. Wasted walk time is eliminated.
Finally, you need the system to be cost effective, not just from a labor perspective, but from the view of capital spending and return on investment (ROI) as well. Can you sell the project to top management? And be sure you've asked this question: Will you be in this business, with these small parts, long enough to get the desired ROI and productivity gains?
Equipment options
Here's a rundown by equipment type of your equipment options in small parts storage.
Shelving. Storing small items individually or in small packs of 6, 10, 12, 20, or whatever quantity, on shelving might solve your handling problem. Check the shelves' load bearing specs if stored parts are heavy ones. Shelving need not be static, moreover. Manually rotating shelves-operating like a "Lazy Susan" device, but with tiers of horizontal trays-can pack a lot into a small footprint.
Check, too, to see if conventional static, horizontal shelving is adjustable. This feature gives you flexibility if business changes. And you shouldn't have to pay that much more, if anything, for this flexibility. In addition, some shelving units can also be retrofitted with modular drawer units.
Storage cabinets, modular drawers. No doubt you're familiar with storage cabinets and modular drawers. A variety of standard and custom models are offered in each of these types of storage medium.
Storage cabinets provide more protection for items than do open shelving systems, while still offering high-density containment. Depending upon your requirements, the cabinets are available with certain value-added features. The cabinets, for example, can be secured with locks for expensive items. When used for storage of electronic components where static electricity is a concern, suppliers can provide cabinets with ESD (electrostatic discharge) protection so that the equipment safeguards individual parts from potential damage. Humidity can be controlled in cabinet systems, moreover.
Modular drawers, meantime, provide similar high-density storage as do cabinets. Modularity and adjustability are among their selling points. They also offer added security to stored items, through individual locks. Or they can be located in a secure area when they contain high-value tooling or similarly high-value items. Individual drawers can be compartmentalized, with partitions and dividers, further enhancing the organization of storage.
Carton flow rack. On assembly lines, workers may need boxes and modular drawers for their tools, of course. But for the consumable parts and components that will be used up as assembly progresses, carton flow racks offer one way to provide a continual supply of needed items. This kind of high-density storage system allows parts to index forward as items are pulled for use from the front of the flow rack; meantime, the rack can be replenished from the rear as quantities run low.
Carousels.Industrial-grade versions of the horizontal carousels typically used at dry cleaning stores offer another means of storing small items. They mechanize and/or automate the materials handling task, operating in a part-to-man mode. Bins, baskets, totes, or other containers rotate horizontally bringing items to a station for picking from the system.
System density can be very high for efficient space utilization.
Equipped with computers and sophisticated software to track stored or staged items, horizontal carousels can provide high throughput and high picking accuracy. Pick-to-light displays add to accuracy.
Turn the horizontal carousel on end, in effect, and you have a vertical carousel; rotation of stored items occurs vertically, rather than horizontally. One advantage vertical units offer over horizontal models is a small footprint, which frees up floor space while increasing cube utilization.
Vertical lift storage modules, from the outside, look like vertical carousels, and feature the small footprint advantage over systems needing more floor space. Inside, however, the vertical lift storage modules differ from carousels. Trays or bins do not rotate; they're stationary. An inserter/extractor mechanism does the traveling from level to level to perform put away and picking activities.
Horizontal and vertical carousels along with the latter's "cousin," vertical lift storage modules, have many applications in warehousing and storage applications; sidebars to this story illustrate some possibilities. These systems can also provide a means to kit building and to parts supply to manufacturing operations.
Miniload AS/RS. Similar in some ways to the vertical lift storage module, the miniload AS/RS also takes advantage of vertical space but generally requires a much larger footprint. It holds items in totes or other kinds of containers on multiple levels of a system that has one or more aisles for access. Within these aisles, an S/R machine (sometimes called a crane) travels horizontally and vertically to put away or pick items. At the end of each aisle there are operator stations or pick up/putaway stations. Delivery/ takeaway conveyors often provide the interface with upstream and downstream operations.
Like the carousels and other more automated systems just described, the miniload can perform with high productivity in warehousing and manufacturing applications. One new system, handling three totes on each
S/R machine pass into the AS/RS, demonstrates this advantage.
A-frame automats.Far more common in Europe than in the U.S., A-frame "automats," or automatic orderpicking modules, offer one more handling option for small items.
In the typical A-frame unit, items are stored in sloped channels that form an A-frame over a central conveyor. When a small item is dispensed automatically, it falls down onto the takeaway belt. Channels are adjustable to fit the sizes of individual SKUs. Pharmaceuticals and health and beauty products are among the kinds of small items for which this technology has been used in distribution.
Whether it's health and beauty aids or auto parts, there are many options when it comes to storage and staging of small parts. The trick is to match the equipment to your specific needs.
Moving to a new warehouse, Schmersal LLC, a leading distributor of industrial safety products and switches, switched to a modular drawer storage system ( Lista, 800-722-3020, www.listaintl.com ) from industrial shelving.
"We did not want to settle into a new facility," says operations manager Bruce Eylmann, "only to find ourselves limited by the storage system. From past experience, we knew that industrial shelving would be inadequate; we decided to invest in a modular storage solution."
Schmersal packs a lot into just 3,000 sq. ft. of L-shaped storage space in its new facility. Five storage walls-each wall unit is comprised of modular drawers, adjustable shelves, and roll-out trays-take full advantage of vertical space and leave a small footprint.
"We saved 40% on warehouse space," says Eylmann. "We also are able to organize storage according to product family," he adds, "greatly enhancing inventory control and reducing order picking time." Space savings, moreover, "will accommodate 25% growth over the next several years."
At its new distribution center in the UK, a major British retailer stages small incoming items in a miniload automated storage and retrieval system (AS/RS). The four-aisle AS/RS ( Rapistan Systems, 877-725-7500, www.rapistan.com ) acts as a quick response buffer. It holds 72,000 totes staged in a double-deep configuration. The totes contain clothing, shoes, accessories, and household items coming from overseas suppliers; these items are not readily crossdocked. These goods are destined for distribution to the retailer's 120 stores.
Four AS/RS machines store or retrieve totes or combine these two functions on each pass through the system. The machines can handle three totes at a time, moreover, increasing system productivity. Throughput is high: Up to 450 totes per hour can be pulled out of the system and sent along to store distribution.
Overhead gripper devices on the machines' carriages grab and hold totes for transfers into and out of the system. Delivery/takeaway conveyors serve as the interfaces to other subsystems within this DC.
Keeping track of parts is a big job for Husky Injection Molding Systems. At its 80,000 sq. ft. distribution center near the Buffalo International Airport, Husky has some 22,000 different parts numbers and a total of 850,000 individual pieces in inventory.
A storage system ( Diamond Phoenix, 207-784-1381, www.diamondphoenix.com) is up to the task, however. It includes eight horizontal carousels and one vertical carousel (divided up into three individually manned pods) System software, pick-to-light displays, and bar coding of parts all help Husky's operators become more like bloodhounds in accurately and quickly tracking down the locations of needed items.
The productivity gains from this highly mechanized system are striking compared to an old manual system used for the previous 20 years. Customer response time rose 30% in just a few months after installation. The carousels also pick orders four times faster than before.
View All Blogs
