e-conveyors
It's not the same old distribution anymore at leading e-commerce facilities.
By David Maloney -- Modern Materials Handling, 1/1/2000
The age of e-commerce is here with a bang. Some might even say it has exploded. And with e-commerce comes distribution centers designed specifically to meet the demands of Internet order fulfillment. These facilities must complete orders quickly and ship as soon as possible, often that same day. Competition is fierce in this new world of e-commerce, and many will not survive.Those that do will probably credit their survival to a laser-like customer focus. Many may well credit a significant part of their success to a choice of materials handling systems, particularly conveyors and sorters that can handle the peculiar mix of products and quantities at the speeds characteristic of the e-commerce world.
To get a handle on exactly what these companies need, Modern Materials Handling spoke with several conveyor suppliers that have installed systems for these dot com distribution centers. We also spoke with three e-commerce companies, Amazon.com, Toysrus.com, and Priority Fulfillment Services, to find out how they approached selection of conveyors and sorters.
"Eaches" at Web speed
At this point, many of the items available through e-commerce are relatively small in size. For instance, there are a lot more books, pharmaceuticals, and apparel going through the e-commerce supply chain than sofas and riding lawn mowers.
In addition, most orders consist of a relatively small number of items. "Eaches" are the order of the day. As a result, conveyors in e-commerce distribution centers do not have to transport the same carton weights as do case and pallet conveyors in more conventional warehouses. They must, however, be able to convey totes, which are commonly used to hold items through processing.
What dot-coms lack in individual order size and weight, they more than make up for with order quantity. That places its own demands on both conveyors and sortation systems and their ability to manage the flow of a large total volume of small packages day after day.
Furthermore, flexibility is a must, as some e-tailers that may be in the book business today may find themselves distributing bar bells tomorrow. Successful dot-com companies must be able to adapt to such shifts in market strategies.
Through experience, traditional retailers have already discovered that existing DCs are not designed to efficiently fill their Internet orders. It simply does not work to use the same equipment for both business models. There is, however, a third model that many e-commerce companies might consider as a template for their new DCs-catalog companies.
Catalog companies are used to dealing in eaches and filling large volumes of orders with only a few items in each. In a way, they have given e-commerce a 20-year rehearsal at customer-direct distribution.
But whether a company follows a catalog model or not, it has three basic choices when it comes to its distribution strategy. It can: build a new facility for e-commerce orders; retrofit an existing distribution center; or contract with a third-party logistics provider (3PL) to do their order fulfillment for them.
Some of the toughest decisions must be made on little or no hard information. For instance, what will be the demand for their products via the web? How much volume should the facility be designed to handle? Making these types of judgements greatly affects the choice of materials handling systems.
Conveyor choices
Most conveyors used in e-commerce distribution today are traditional types-belt, roller, slider bed, and accumulating conveyors. All three are designed for high-speed conveying of product with a light-to-medium weight.
Roller conveyors consist of a series of rotating rollers, some of which are powered via shaft or small belts. As the rollers spin, they push product forward.
Belt conveyors transport goods on rotating belts and are often used to transport totes and cartons to a mezzanine, upper level workstation, or to a raised sortation system. The belts prevent slippage, especially as the cartons climb the incline.
Slider beds are made of any of several materials, including steel, aluminum, plastic, and vinyl. These usually are designed for small product on short runs. Since they cover the entire width of the conveyor, the bed prevents smaller items from slipping through the conveying surface as might occur with rollers.
Accumulating conveyors are used to combine product from several different sources while providing appropriate spacing between cartons or totes waiting for further handling.
Modular conveyors come in a variety of styles, including belt and roller models. They are designed as self-contained and powered sections that can be reconfigured as needs change. Modulars make sense for many e-tailers that often change product offerings or warehouse layouts by combining flexibility with a long-term investment.
All of these conveyor types can be configured to pass through picking zones that vary in type and size depending on the products being offered by the e-tailer. Hybrid solutions that combine several types of conveyors and sorters may achieve the best results.
Sorter choices
Extensive sortation is also required in most e-commerce facilities due to the volume of orders processed daily. In addition, automatic sortation helps the bottom line. Since most e-commerce companies rely on parcel delivery for the final leg to their customers, sortation increases loading dock flexibility to deliver items to designated dock doors for the carrier that offers the best shipping rate.
Small-to medium-size companies utilize pop-up wheel, pop-up belt, right angle transfers, push diverters, and sliding shoe sorters. These are often placed in picking zones as well as shipping areas where they divert product to desired carrier lanes or dock doors.
Pop-up wheel and pop-up belt do just as their names imply. As product approaches a divert point, the angled roller or belt rises from the main conveyor cavity to re-direct the item.
Push divertors and right angle transfers work in a similar manner. As product approaches a desired spur, a mechanical or pneumatically-controlled plate pushes the side of the box or tote to its new direction. Similarly, right angle transfers power-on as product rides over them, changing the item's direction by 90-degrees and diverting it onto a new conveyor.
Larger facilities typically have a greater need for high-speed, high-volume sortation. Tilt tray sorters, sliding shoe, and cross belt sortation systems are commonly used.
Sliding shoe sorters are among the most common systems, as they are affordable for a wide range of functions including diverting for pick zones, shipping, and order accumulation. These units have small knob-like shoe devices measuring approximately 6-inches in length. A series of these shoes slide in unison across the center of a moving conveyor, gently guiding product down spurs or chutes.
Tilt tray sorters consist of a series of trays that rapidly loop past accumulation chutes. Products ride directly on top of the trays, which physically tilt to slide items off into the proper destination chutes.
Crossbelt sorters have a similar design to tilt trays but use short belts set perpendicular to the sortation system's accumulation chutes. As an item approaches its destination, the belts power on, gently rolling the item into the chute.
Advice from the experts
Fortunately, there are already some experts out there on the selection of conveyors and sortation systems for e-commerce DCs. Three notable ones are Toysrus.com, Amazon.com , and Priority Fulfillment Services. Each represents a different model of e-tailing-a traditional retailer, an Internet-only operation, and a third-party provider, respectively.
Toysrus.com. "No other toy e-commerce business has the network of stores we have," says Gregg Treadway, vice president of Logistics for Toysrus.com. "There is tremendous trust and value in our name."
Because of this, Toys R Us had a lower risk in starting e-commerce operations as compared to many start-ups. They view it as simply another method for reaching their customers. They can also draw on the experience and buying power of 700+ stores.
Instead of building from scratch, Toysrus.com's strategy was to buy an existing catalog-fulfillment center that had experience in processing direct-to-consumer orders. This gave the company a huge advantage in entering the recent holiday season.
The facility uses a variety of conveyors and sorting equipment. All of them are able to convey a standard tote that holds items throughout the fulfillment process. The system is also designed to be flexible, as it conveys everything from hockey sticks to Furbies.
The heart of the order processing area is a unique cross-belt sorter. It is a two-level design, the only one its kind in the nation. It was chosen because of its speed, ability to carry a wide range of products, and it saves space within the facility. The sorter features 360 chutes where products can divert to 180 packing stations. Treadway says the volume it can sort is comparable to three tilt tray sorters.
The facility also has carton erectors that speed the packing process. A tilt tray sorter is used on the outbound side as a shipping sorter. 150,000 cartons a day are sorted on the 313 trays.
"The system brings us the right item at the right place and the right time," says Treadway.
For a complete look at the Toysrus. com facility, see next month's MMH.
Amazon.com. This is probably the best recognized and the most successful of the e-commerce start-ups. They cut their teeth on books and music distribution, but have since added videos, consumer electronics, tools, software, and an auction service.
With such a variety of products, Amazon.com built its seven U.S. distribution facilities to be able to efficiently handle their current merchandise as well as next year's additions-whatever they may be. All of their systems must be able to handle huge volumes and small packages.
"The systems we select have flexibility, agility, and can process freight at the rate we require," says Chris Arnold, Amazon's director of logistics. "We look for systems that can handle any kind of product."
Amazon.com distribution centers have several types of conveyors, including gravity and roller. Sorters in their facilities include crossbelt and tilt tray systems.
Priority Fulfillment Services. Here is one of the leading 3PL suppliers to the e-commerce world. PFS built its distribution center in Memphis (see July 1999 MMH ) based on overnight parcel service via Fed Ex.
Their conveyors and sorters were selected to handle a wide range of products, as they distribute everything from office supplies to garden equipment for their clients. They use a combination of belt, line shaft, and roller conveyors. There are a number of transfer points within the system. For these, PFS uses pop-up roller and pop-up belt diverters.
"No one type of equipment can do all jobs," says David Mitchell, general manager. "We take the best of breeds to fit the application."
Mitchell says the PFS conveyor system was designed to serve pick and pack operations. Conveyors travel to several zones where product is picked from storage systems based on product and picking frequency. These include flow rack, static shelves, and carousels. Products are packed at the picking stations and sent on to the conveyor which either takes the carton to shipping or sends it to another zone for additional picking.
PFS has been very successful, as the company expanded recently by acquiring an abandoned Starter athletic wear distribution center in Memphis. Starter had delivered to retail stores previously, so some of the conveyors had to be re-routed to accommodate the pick and pack operations. The warehouse management system also needed to be replaced.
Mitchell stresses that you must design to fit the work of the facility.
"You don't build a Yugo to do the work of a Porsche," he says.
Profiles of 3 e-commerce operations
SMALL
Less than 10,000 units/day
Under $500,000 materials handling system cost
Picking-paper directed
Pick directly to conveyor belt
Pick into totes
Hand picking or simple pick to light from flow rack or shelving
Simple accumulation
Pop up wheel or belt divertors
MEDIUM
Up to 100,000 units/day
Under $2,000,000 system cost
Low level WMS
Pick and pass
Small batch picking
Simple Pick to light or voice-directed
Carousels, flow rack, and shelving
Sliding shoe sorter
LARGE
Up to 250,000 units/day
$2,000,000-plus system cost
Large WMS
More automation-hybrid systems
Radio frequency picking by waves
Wave picking
Higher speed conveyors
Increased versatility
Wide range of storage methods
Greater accumulation
Tilt-tray and cross-belt sortation
e-considerations
- More individual cartons, 1-6 items in each
- Speed is a must
- Systems must be flexible to ship a wide range of products
- Right-sizing systems to reflect actual volume is crucial
- Rate shopping can save on shipping
- Hybrid materials handling systems often work best
- Customer acquisition costs are higher than traditional retailers
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