Engineering for Throughput
by Christopher Trunk, managing editor
Conveyor sortation and singulation are flying faster with new technology to meet today’s production demands.
“When thinking about sorters, you have to remember they are just one engineered component of a sortation system,” says Stephen Legg, director of marketing for FKI Logistex Automation Division (formerly Buschman and Mathews conveyor companies). “A sorter is like the second hand on a watch. It moves the most, but you need the other two hands to complete the job. That includes the induction, merge, singulation, sort and aftersort.”
Sortation conveyors use either tilt trays, tubes, pusher shoes, wheels or belts to sort cartons to various shipping lanes to fill customer orders or route goods by ZIP code, etc. Singulators take cartons that are dumped onto a conveyor and make them single file. Once in single file, metering belt conveyors can set a precise gap between packages using powered belts and photoeyes, as well as set the speed of a package to match that of the sortation system.
New technology for accomplishing sorts and singulation is increasing speed to new thresholds for faster production.
Engineering new technology
The Unisort XV from FKI Logistex Auto-mation Division is an all-electric, flat-slat sorter. It uses mechanical crossover switches for left and right diverts as well as electric switches, which replace bulkier pneumatic switches. This miniaturization allows the sorter to more densely pack sorting doors at just 4-foot centers rather than the typical 12-foot centers. This makes a big difference in system size and cost when, for example, you are a postal or parcel carrier with 150 sorting doors.
The newest shoe sorters can run up to 550 to 650 fpm. “At those fast speeds, the physics of how air currents affect small packages becomes important, as does changes to the geometry of conveyor diverts. It’s not difficult for light items to take flight at those speeds,” says Legg.
When you get into very high-speed distribution, more than 175 cartons/minute, you’re pushing that conveyor pretty hard, and products tend to creep up on one another, becoming side-by-sides.
To solve that problem a few years ago, the Buschman Company released the VHS Wedge product for high-speed lanes. The product is still offered and is installed at more sites now. It accumulates products and then releases them together in trains at very high speed. “With this technology, you can eliminate side-by-sides and increase speeds to above 220 cartons/minute,” reports Legg.
Crisplant has designed a number of AutoPack chutes. The principle behind the AutoPack chute is that product that has been discharged by the cross-belt or tilt-tray is automatically diverted into a shipping carton or container. The AutoPack design further reduces the labor required to process orders.
The Hytrol Conveyor Company offers the ProSort family of three sorters:
• ProSort 100, a small-item sliding shoe sorter. It handles 50-lb-and-under loads and items as small as a CD.
• ProSort 200, heavy-duty sliding shoe sorter used in warehouse and distribution centers. It handles more than 100-lb product at rates of 200 cartons/minute.
• ProSort SC. New for later this year, the ProSort SC is a pivot-wheel diverter that sorts from 100 to 120 items/minute. It is an economical sorter as compared to sliding shoe sorters. It lets you sort to one side or to both sides.
Hytrol also offers its Viper Sort machine to let retail distributors sort everything from lip gloss to baby formula for many stores orders. The machine sorts orders into pack lines.
Roach Manufacturing Corporation offers a SmartZone accumulation conveyor with photoeye technology. “The photoeyes allow the conveyor to be either a singulation or slug release machine,” says Charlie Parks, vice president of sales and engineering for Roach.
“Sortation is becoming more intelligent,” says Steve McElweenie, executive vice president of sales and marketing for Crisplant, a division of FKI Logistex. He says that sortation software is offering customers more information, including better reporting on individual inputs and workers doing induction or packing functions. “Buyers are concerned about shrinkage, and now we can scan a worker’s ID into a particular sortation chute and audit the flow of goods past that responsible worker,” McElweenie says.
Vision systems are the latest in singulation conveyor technology. The vision system takes a snapshot of a jumbled mass of parcels or cartons. With a PC controlling the power and speed of a conveyor section, either rollers, slats or belts are used in the singulator to untangle the packages.
Retrofitting versus new systems
Retrofitting is more prevalent in singulation than in sortation. “The reason why singulators are retrofitted into sortation systems is that side-by-side items are making their way onto tilt-tray sorters,” says Bryan Boyce, product manager for case conveyor products for Alvey Systems Inc. Another reason is to relieve the concentration of workers who are placing items onto an induction conveyor. Without a singulator, workers must always orient boxes precisely on conveyors the right way, with no boxes side-by-side. “Singulators take away the need for precise work from people more concerned about unloading a stack of boxes onto the conveyor,” says Boyce.
Alvey takes a section out of an infeed conveyor and installs a new singulator to improve performance of a sortation system so the wrong side-by-side items aren’t diverted to a customer’s order lane. “We typically install singulators on new systems to guarantee upfront design performance,” adds Boyce.
For Legg, most sortation business is in new systems, not retrofitting, and for good reason. “The sorter is like the spine of a system. To take it out and put in a new one requires shutting down the operation, and that’s a difficult proposition for customers,” says Legg. Typically, a new sorter is installed alongside an old one, or a second sorter is stacked on top of the first with new controls and aftersort lanes added.
But Legg warns about users with sorters that run now at 130 cartons/minute wanting to increase to 200 cartons/minute. There’s always a faster sorter that can be installed, but the whole sortation system may have to be reconfigured as well. “It means installing a new merge that can meet those rates and making significant retrofits to controls and speed changers. Given this, sometimes it is more expensive to upgrade the merge conveyor than the sorter itself,” observes Legg.
Sortation trends and applications
“A few years ago, the normal range for sorting product was at 60 to 120 fpm,” says Parks, “but now that range is from 120 to 200 cartons per minute, extending to conveyor speeds of 300 to 500 fpm.”
Add to that the complexity of more cases broken into smaller sizes and lighter-weight boxes, says Boyce. “There’s a great number of SKUs or carton sizes now, and a lot more shrinkwrapped containers. This all changes the way product must be handled,” says Boyce.
Parks says that the variety of product being conveyed and sorted includes large, 15-foot rolls of carpet and six-foot-long and 60-inch-wide rolls of fabric. “Any time you are conveying rolled goods,” says Parks, “you have to build in safety valves just to keep the product on top of the conveyor.” Roach specializes in engineering conveyor and sortation systems for awkward, difficult-to-handle items. Now Roach can handle from six to eight rolls of big carpet or fabric a minute. Other hard-to-handle items include tires and jig fixtures used to assemble products.
In the beverage industry, product is single-filed into carousels or other kinds of storage buffers to create “rainbow loads” or loads of mixed SKUs intended for one store order. Boyce says sorters are used to create these palletloads of mixed goods prior to shipment.
A major trend for sortation use is for zone skipping, when shipments are sorted into ZIP codes that match the areas served by various postal or common carrier hubs across the United States. “Users are looking to sorters to accomplish these zone skips with payback being less than a year on money saved through skipping,” says Legg. He says that in the past, it was typically tilt-tray or cross-belt sorters that handled zone skipping, but now the Automation Division’s Multisort XV shoe sorter can handle this task, too.
The drive for faster conveyor is also moving into conveyor manufacturing. The need to supply product within 24 hours of placing an order has driven some companies to high-tech, high-speed manufacturing techniques. Parks says, “We now use laser metal-cutting technology, a one-of-a-kind structural punching and cut-off machine that is designed for manufacturing conveyor,” says Parks, Roach has also installed an automatic fabrication system that punches, shears, sorts and retrieves components. This all supports his company’s program in which 35 percent of total shipments are made within 24 hours.
Don’ts for sortation and singulation
Sources have seen a lot of avoidable mistakes and offer this advice:
Steve McElweenie. Don’t short yourself on the time needed to properly engineer a sortation system. If you rush, all you get is a standard offering. Ask the customer to name 10 problems with the current operation and make sure you evaluate all 10 for major impact on the sortation system design.
Bryan Boyce. Don’t short yourself on testing. Set up a singulator and ask the vendor to run your product over it to ensure the product rotation is correct and that there are no hang-ups. It will also tell you what the throughput can be.
Boyce Bonham, manager of The Technology Center for Hytrol Conveyor Company. Don’t buy based solely on dollar cost for a system that meets today’s needs. Design your new sortation system for expected growth using variable speed drives that handle today’s and tomorrow’s needs. Variable speed drives also help handle peak and off-season throughput changes.
Stephen Legg. Don’t forget the aftersort. With packages coming off the sorter at high speed, do you want to maintain the package orientation, keep the label facing up or perform a secondary sort? Give a lot of study to the speed transition point for packages moving off the sorter into the accumulation zone.
Armed with this advice and new information on this technology, you’ll be able to make a better sort yourself between vendors offering these engineered systems. MHM
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