In the world of conveyors, faster isn't always better. Manufacturers may tout the latest belt's blazing-fast travel speed. But in the real world, conveyor speed is about much more than feet per minute. Snaking through the innards of manufacturing and distribution, the conveyor functions much like the circulatory system's central artery, carrying cartons, totes and the like to the far corners of the DC. What matters is not so much how quickly it whips through the facility but how reliably it runs.
For a mechanism that's so critical to smooth DC operations, the conveyor has seen surprisingly few technological advances in the past three decades. "Simply put, conveyor technology has been static for 30 years," says Gregg VandenBosch, a product manager for Siemens. Though engineers have introduced increasingly powerful and sophisticated programmable logic controllers (PLCs) and other components through the years, he says, architecturally, innovation has been rare.
But that dry spell is over. In the past two or three years, manufacturers have rolled out dramatic improvements in conveyor design and technology. And based on their customers' requests, they've focused on making installation and maintenance simpler and quicker; making components more reliable; and engineering systems flexible enough to handle a variety of package sizes and weights.
Mixing it up
For conveyor manufacturers, that request for flexibility is something fairly new. "Recently, we've noted an increase in requests to handle a wider range of products, from Jiffy bags [padded mailers], to rugs, to oversized cartons, within the same system," says John Dillon, director of engineering for the Automotion Systems Group. That's prompted his company to look for new ways of combining its standard product lines and technology, he notes. In one case, Automotion rigged up an all-belt system with a high-speed slat sorter. "This multiple input all-belt system joined a low-speed 'inch and store' mode and a high-speed 'slug release' mode to maximize throughput. "The end result was that we were able to successfully mix those rugs, bags and oversized cartons all on the same system," he says.
Gordon Hellberg, vice president of conveyor manufacturer Ermanco, adds that many end users have changed their picking processes in the last few years, which has major implications for conveyor performance. "More and more, we're seeing cases with the empty box at the end of the line. The box has been sized to the order. Items for the order are picked directly into the box, which eventually moves to the end of the line for sealing and shipping. So conveyors have to handle a greater variety of containers, smaller on average than previously, and handle more of them."
Mike Johnson, senior vice president in the unit handling division of HK Systems, agrees. "One of the things we see changing is the size and complexity of orders. Most things in the past have been cases. Perhaps as a result of the growth in Internet commerce], instead of shipping solid cases, there are more and more 'eaches.' Package sizes vary and package sizes are getting smaller." He reports that one customer, a consumer products company, actually changed its system in mid-installation to add features that would make it easier to handle individual picks.
Boyce Bonham, manager of the technology center for Hytrol, adds that his company has also noticed that clients are handling a bigger variety of packages than in the past. For conveyor manufacturers, he says, that can pose design challenges. "If you're designing a system to handle a large variety of packages, you have to consider how to keep packages from going side to side and keep them single file," he explains. Bonham also notes that end users have reported that the packages they're handling are arriving in worse condition than in the past. Bonham doesn't know why package quality has deteriorated, although he speculates that perhaps lower-quality packaging materials are being used or that the items in question are imported products that have already undergone substantial handling. Whatever the cause, he notes, it creates an issue for the equipment that has to handle and sort the packages.
Plug and convey
Siemens' new C-L100 line of package conveyors is indicative of the direction in which conveyor design is heading. The line was designed, the company says, to reduce installation time, allow operational flexibility and monitor components in order to predict parts failure.
Fast installation is possible because the side channels are pre-wired at the factory with power and communications buses. Modules plug together quickly on site.
In addition, Siemens has standardized components, controls and software. The result, the company says, is reduced parts inventory, streamlined maintenance and reduced programming requirements.
To meet the demand for conveyors that can accommodate a greater variety of package sizes and weights, the C-L100 systems were designed to handle products weighing as little as 1/4 pound to as much as 100 pounds per zone in sizes ranging from 3 inches by 6 inches by 1/4 inch up to 53 inches long and 30 inches wide.
The system also meets emerging requirements for quieter systems by eliminating the use of pneumatics and entering a sleep mode when not in use.
They're even quick to assemble: VandenBosch, who is product manager for the C-L100 line, says that Siemens set out to modularize the three major installation phases—mechanical, electrical and communications. The result is a significant reduction in assembly time in the field.
Siemens isn't the only manufacturer to offer modular "plug and convey" systems. Late last year, FKI Logistex introduced a new flat-belt driven roller conveyor, called the Accutronic, with zone control modules and power connections integrated into the design.
Hytrol, too, is moving in that direction. "We're trying to make things more modular,more pluggable," says Bonham. Pre-wired products and decentralized drives, for instance, allow faster installation, require fewer technicians on site, and require less troubleshooting, he says. In addition, modular systems tend to work well in retrofits. Though equipment costs for modular, pre-wired systems may be higher than for unwired systems, the time and labor savings in the field can help offset that capital cost.
Why the sudden push for speedy installations? It seems that all too often, businesses spend months dithering about what kind of conveyor to install, only to pressure the manufacturer to get the job done quickly once the decision is made. "On the conveyor side, when you pull the trigger, you typically have a short lead time," says Gary Cash, vice president of product management and market for FKI Logistex's warehousing and distribution division. "What we're doing is trying to find ways to meet the needs for shorter schedules." Some of those schedules are short indeed. Cash reports that FKI Logistex provided the material handling systems for Dollar Tree Stores' new 1.2-million- square-foot DC in Joliet, Ill., in a whirlwind project that the company says took only 18 months from conception to completion.With deadlines like that, it's no surprise that conveyor companies are developing more integrated systems with the controls built in, which reduces the need for field testing.
Hellberg of Ermanco offers another explanation for the demand for factory pre-assembled systems. "Over the last couple of years, people have had to downsize, so they don't have the engineering [support] they used to have. We've become an extension of their engineering departments," he says. He adds that he's seen the downsizing both at the distributor level and among end users.
The demand for simple, predictable maintenance, too, has spurred some ingenious designs. For example, Joe O'Connor, Automotion's director of marketing, explains that his company has developed a pop-up wheel sorter with opposing bolts and flanges that allow workers to pull only those parts that need servicing through the side of the unit. Earlier-generation systems required technicians to drop the whole unit out from underneath.
Automotion also has developed software, which it calls the Computerized Maintenance Management System, that aids in both installation and maintenance. The complete bill of materials for a project is pre-loaded into the software. The software guides installation and maintenance teams. "It literally creates tasks for them," O'Connor says. "We've modified tasks and grouped them together and made them easier to do." The software also allows other equipment, such as lift trucks, to be added to the system, and it even stores information on maintenance personnel, such as schedules and particular skills.
HK Systems has approached the problem of simplifying maintenance by designing its conveyors so that potential problems will be confined to single components. "We try to do things so they won't take forever to fix," says Johnson. He cites a sliding shoe sorter that features a breakaway pin that snaps off in a product jam. "You're always going to get jams," he says. But a serious jam can cause slats in a sortation system to break. By using the breakaway pin, only the shoe itself has to be replaced—a five-minute task that's far easier than repairing the slats or a drive chain. "We try to make it so that if something does break, it's simpler to repair."
Hellberg believes that the time it takes to get a conveyor up and running again after a failure will become an important new measurement in DCs, in line with the traditional measure of mean time between failures. He says that repair time was an important consideration in the design of a narrow-belt accumulator Ermanco introduced in 2003.
Of course, it's important to remember that conveyors are usually purchased as part of a larger material handling system, which means that above all, they must be able to integrate with other parts of a system. Hellberg recalls discussing the issue of mixing brands with a distributor he was visiting not long ago. What he learned was that his client was not overly concerned with whose name was on each component as long as it all worked smoothly. "The end user doesn't care," he says, "as long as the system is providing the function."
You might think the world of conveyors, at least, would represent an island of sanity amid the chaos of the radio-frequency identification (RFID) revolution. But you'd be wrong. Conveyor manufacturers are getting caught up in the hubbub too.
For conveyor companies, the first inkling that they too were going to be drawn into the confusion came when requests to conduct RFID tests started trickling in. Mike Johnson, senior vice president in the unit handling systems division of HK Systems, reports that by now, his company has received numerous requests to conduct trials to determine how fast clients can run their conveyors without compromising RFID tag reading accuracy. That's more complicated than it might sound. Read rate is a function not just of conveyor speed but of the readers themselves, the tags and even product characteristics (metals and liquids are notorious for interfering with radio waves). As a result, there are usually a lot of variables to test.
Not surprisingly, testers have encountered plenty of hiccups. "We don't know of a great solution right now," Johnson says. "Although some are running at 600 feet per minute and running fine, some may have a label orientation issue. If the tag is facing away from the reader, there may be a problem. Metals and liquids are sometimes a problem."
But occasionally the tests turn out better than expected. Johnson tells of a test conducted for a battery manufacturer that assumed its metal-encased products would cause major read issues. To the testers' astonishment, they found that the dense products somehow enhanced the RFID readers' ability to capture information.
Beyond the customer testing, Johnson hopes to use RFID technology to streamline his own business someday. "We've taken a look at " [using] it [to track] equipment maintenance," he reports. He also envisions a day when HK will stick RFID tags on all outgoing shipments of conveyor and other equipment. "We'd like to have RFID tags on all the equipment going out," he says. "We could scan it going onto the truck, scan it when it's coming out." Johnson says he's eager for that day to arrive. One of the biggest headaches in any major conveyor installation is keeping track of an impossibly large number of components, he explains. "I'd love to get to the point where we would have a layout and know at any time where each component is."