Congestion should ease up this summer at Tween Brands' high-volume DC in Columbus, Ohio. But not for any of the reasons you might expect. The facility isn't gearing up for an expansion or anticipating a seasonal slowdown. Rather, it's installing a highspeed sortation system that will rev up throughput in the DC's receiving operations and free up some space.
Though it was built just five years ago, the DC is already feeling the squeeze. The facility supplies all of the stores in the Tween Brands network—Limited Too and Justice stores that sell clothing for girls ages 7 to 14. The retailer (formerly known as Too Inc.) has been engaged in an aggressive store opening campaign in recent years. At the time of its opening, the 365,000-square-foot DC served about 450 stores. Today, it supports more than 730 stores located across the United States and overseas.
To understand how the new sorter—a Dematic sliding-shoe system—will free up space, you have to know something about the facility's receiving process. Right now, when DC associates unload trailers, they first place cartons on the floor so they can scan them and re-label them if necessary. Once they're finished, they place the items onto pallets and introduce them into the receiving system. With the new sortation system in place, they'll be able to shift to a fluid unloading process that eliminates the need for a staging area. As trucks arrive, associates will unload merchandise directly onto the conveyor system, where the sorter will take over.
Along with freeing up space, the retailer expects the new sorter to speed up its receiving operations and take throughput to a whole new level. "In the time it takes a human being to read a label on a carton and determine where it needs to go, a high-speed sorter can have read and acted on hundreds of cases," says Matthew Dippold, the facility's manager of technical services. That's a big plus for a DC that handles 1.5 million units a week on average during normal periods, and 3.6 million units a week during peak season. The facility, which holds between 25,000 and 30,000 SKUs, based its expectations on its previous experience with sorters. It has one in its packing area and one in its shipping area, both of which were installed at the time of construction.
A welcome diversion
Originally used mainly by parcel carriers to sort packages by destination, sortation systems are fast becoming a fixture in retail distribution centers, where much of the activity is centered on breaking down incoming loads of merchandise and reassembling the items into new loads bound for individual stores. "Today, retail is a big driver for sortation systems because they're dealing with such a high volume of small parcels," says Tom Carbott, managing director of the conveyor product section of the Material Handling Industry of America (MHIA).
Sortation systems today come in a variety of types. Retail distribution centers—like the one run by Tween Brands—frequently choose the type known as the sliding-shoe sorter, which is designed to handle high volumes and can accommodate a variety of package sizes. Sliding-shoe models feature a series of linked slats with shoes on the side that move along with the slats. The shoes, which are capable of independent lateral movement, divert items, cartons, or totes down a conveyor chute.
Also popular these days are pop-up and push diverter sorters. Pop-up sorters typically feature wheels embedded below the conveyor's surface at the point where two or more lines meet. When a carton needs to be directed to another line, the embedded wheels pop up to nudge the carton to the right line. A push diverter, by contrast, uses an arm or pusher panel that swings or pushes out as a carton approaches to direct it to a different line or sorting bin.
If they're not handling fragile items, DCs sometimes install what are known as bomb-bay sorters, which open up like the bomb-bay door on an airplane's belly and drop the product directly into a tote or carton stationed beneath. Bomb-bay units are often used for relatively small products, notes Samuel Flanders, president of 2wmc.com, a warehouse-consulting firm in Durham, N.H.
Operations that are looking for speed often choose tilt-tray sorters. Items are placed onto trays that move along a circular path until they reach their destination. At that point, the tray tilts and the item slides off into an order container or sorting chute.
Regardless of type, today's sorters all move at a pretty fast clip. MHIA's Carbott reports that the average sorter moves at 400 feet per minute, while some models operate at speeds of up to 600 feet per minute.
When Bubba isn't enough
Though sortation systems are sometimes installed during the construction phase, many DCs start out with what consultant Paul Faber of Tompkins Associates calls "Bubba sorters," workers who sort the merchandise by hand.
But as throughput volume grows, they sometimes reach a point where they either have to expand or automate. That's when many turn to sortation systems. "I can handle the same volume at a higher speed with less square footage by having a good sortation system," says Tom Freese of Freese and Associates, a management consulting firm in Chagrin Falls, Ohio. "Sortation systems enable a distribution center to handle high activity without a build-up of employees or enlarging the warehouse's footprint."
Sortation systems come at a price, however. Equipment costs alone can run into the thousands of dollars. Models at the lower end of the price range, like narrow-belt sortation systems, cost around $100,000, according to Flanders. More sophisticated sortation systems, like tilt-tray or sliding-shoe sorters, can run upwards of $1,000,000 once all the design, installation, and software costs are factored in.
Equipment and installation costs vary according to the complexity of the sorting application. For example, if a company simply wants to sort products by the first three digits of the destination ZIP code, it can get by with a simple bar code and lower-end bar-code readers, says Freese. But if the company wants to sort by both shipment date and destination, it will require a longer, more complicated bar code, making it necessary to use top-of-the-line readers and printers.
Companies that ship thousands of orders per day may be able to use their sortation systems to reduce their transportation bills. Freese explains that sortation systems make it possible for companies to take advantage of "zone skipping" programs. For example, they could sort out items bound for the West Coast, load them into a truck, and move them via truckload service to a parcel carrier's hub on the West Coast for local delivery, thereby getting a break on parcel shipping costs.
Labor-saving devices
Whatever additional savings they may achieve, DCs that install sortation systems almost universally report a jump in productivity and labor utilization. That prospect led e-commerce specialist GSI Commerce to install a sophisticated sortation system in the 540,000-square-foot distribution center it's building in northern Kentucky.
Business has been growing at a 30-percent annual rate for the King of Prussia, Pa.-based company, which handles order fulfillment for more than 60 online retailers. As is common in the retail business, volume swells around the holidays. During the peak shipping season, the company processes more than 100,000 orders a day, reports Paul Chisholm, vice president and general manager of GSI's Louisville and Richwood, Ky., fulfillment centers. In the past, GSI has hired up 1,200 workers to handle the seasonal uptick. GSI hopes that with the sortation system in place, it will be able to avoid that expense in the future.
The new facility, slated to open this month, will actually contain two sortation systems working in tandem: a combination packing/shipping tilt-tray sorter from FKI Logistex and a sliding-shoe sorter from TGW-ERMANCO. Incoming items will first go through the tilt-tray sorter, which will direct them down the appropriate chute to a packing station, where a packer will deposit them in a box. From there, the unsealed boxes will travel by conveyor onto a mezzanine, where they'll enter the sliding-shoe sorter.
Acting on instructions from a warehouse control system, the second sorter will direct the carton down one of five lanes. If no special handling is required, the box will be sent to the first lane, where the packing slip will be created, void fill added, and a shipping label printed and applied. Orders that require gift wrapping will be sent to the second lane; fragile items will be diverted to the third lane; and items that must be shipped in plastic bags will be sent to the fourth lane. The fifth lane will be reserved for orders requiring problem resolution.
More demands, more sorters
Vendors say they're hearing a lot of stories like GSI's these days, which makes them bullish on their future. Sales of all types of sortation systems in the United States totaled about $750 million last year, according to Ken Ruehrdanz, a market development manager at Grand Rapids, Mich.-based Dematic Corp., which manufactures sorters. He predicts the market will soar as more and more DCs turn to sortation to boost productivity and meet growing demands from customers.
"I expect sortation requirements to increase in retail and wholesale distribution since the distribution requirements are becoming more complex," says Ruehrdanz. "There will continue to be more growth in the requirements to process smaller, split case orders more often. This equates to more sortation systems in the distribution center."
