Interested in linking to "The Smart, Modular and Automated Plant"?
You may use the Headline, Deck, Byline and URL of this article on your Web site. To link to this article, select and copy the HTML code below and paste it on your own Web site.
By Bob Sperber, Plant Operations Editor | 05/07/2010
Conveyors are no longer mere material handlers. Modular, flexible units wired for the computer age can connect to a plant's network, talk to machinery in front and in back of the conveyors, flip switches to turn themselves off and wake up when a signal comes down that dinner's coming -- and needs to be sent to the wrapper.
Both the mechanical and the electrical worlds collide in modern conveyors. They're no longer passive chunks of steel, but active participants in productivity, quality and compliance with management initiatives, standards and regulations.
Mechanically, conveyors are always getting better at shuttling around and manipulating products so Machine B can use Machine A's output. They're getting better at conserving floor space and energy, too. And when traditional conveyors won't work, robots are also coming of age as a significant product-handling solution. Controls become more miniaturized and capable, ushering-in "smart" conveyors for integrated automation.
The first step in any decision, of course, is to figure out what kind of machinery is needed to keep product flowing and organized at high speeds.
Some of the most challenging applications involve products whose sanitary guidelines prevent conveyors from direct product contact. That was the challenge a Wisconsin meat plant issued to Dorner Manufacturing (www.dornerconveyors.com), Hartland, Wis., when four lanes of unwrapped sausage in trays needed to be transferred into a single packaging machine's infeed conveyor.
Hytrol conveyors form a sortation and accumulation loop in a large meat processing facility.
"We used a system of servomotors, conveyors and other control system elements to gently accelerate and decelerate the trays to keep the line moving, without jarring product out of the tray," says Mike Hosch, director of product development. To keep high-speed plastic chain-belting running smoothly, nose-rollers were used. Nose rollers help reduce the gap at product transfer points, and are especially useful on curves, which helped to "transfer the product gently from one conveyor to the next without jostling the product," he adds.
Additionally, sensors, vision technology and stainless steel-enclosed servomotor and control equipment provided the tools to monitor the line and control speed, spacing and other parameters. "On this line, the conveyor looks like one, but actually it uses four individual belts on one conveyor, with each controlled by an independent servomotor control loop," Hosch says.
Elsewhere, processors have a hard time getting loose, processed products into the infeed line of equipment that will put them in trays, packages or lugs used for intermediate steps. Examples include frozen meat patties, breakfast foods and products in the sandwich category, including pocket-type products.
What looks like one conveyor is actually five. Successively faster conveyor modules from Kleenline divert and "chicane" a random product flow from processing into a higher-speed, singulated flow for packaging.
For example, it's a challenge to handle 900 pieces of a product coming off a spiral freezer belt, spread 10 or 20 pieces across. But by splitting that flow into five smaller conveyors running 180 pieces/min. gives a processor a chance. A series of smaller belts can split the flow into separate, successive conveyors that put the product into single-file for delivery to the packaging machine infeed. Such a "smart-belt distribution chicaning system" has been implemented by Kleenline (www.kleenline.com), Newburyport, Mass.
How smart are today's conveyors? Kleenline is now installing a system in a major processor's frozen meals plant that automatically changes configurations -- down to the servomotor-controlled rails that change their width based on product recipes stored in plant computers.
"You press a button for the meal you want to pack, and the rails across the plant -- it could be a mile's worth of conveyors elevated 25 ft. -- will all start changing," says Jim Laverdiere, CEO of Kleenline. Additionally, standard automation hardware and software monitors equipment to track a machine's hours of operation, scheduled maintenance needs and the full range of data needed for Optimal Equipment Effectiveness, continuous improvement, Lean Manufacturing and other programs.Rise of the robots
Once a stream is split into a manageable and organized flow, it can be handed-off to robots as well as conveyors feeding directly into wrappers, cartons or just bulk packs. Robots have proven reliable for decades, mainly in downstream material handling and palletizing applications. But "some processed foods are very difficult to handle with robots," continues Laverdiere. "It's all depends on the end-of-arm tooling."
Just like conveyors, robots are getting faster, smarter and more robust for upstream processes. One or more well-positioned small robots, for example, can transfer products from one conveyor to another when traditional conveyor transfers can't. This is sometimes the case for products or packages with odd shapes or loose components (meats and cheeses) that are likely to topple over in handling.
Laverdiere introduced robots into hard-to-convey applications roughly a decade ago when the parent of bakery cafe Panera Bread bought a machine to fill 300-400 2-oz. cups of cream cheese per minute -- but didn't have an efficient way to pack them into cases. A heavy manual labor operation wasn't an option, while conveyors alone wouldn't work because "They would shingle-up on one another and cause a lot of jamming," Laverdiere says.
The solution came with multiple conveyors that arranged the tubs into organized groups of 24 items. These organized groups fed a robot installed at the end of the line, which picked and packed a layer at a time into the case, adding a paperboard divider between them stabilize the contents.
"I didn't find out until afterward, but Panera had called several robotic case-packing companies around the country, and none of them had a cost-effective solution for the project," says Laverdiere, "because it was a very customized project for this application."
Many food processors are skeptical that robots are too expensive and difficult to maintain, and they require staff with specialized knowledge to maintain them. "I can't say some of that's not true," Laverdiere says. "[But] one robot can do the work of several people. When you start to look at the numbers, all of a sudden, robots don't look that expensive in terms of getting a return on your investment."
When plants find themselves growing but don't have the capital for physical expansion projects, robots are an option. The question is: What is the optimal configuration with minimal floor space that produces the speed and throughput you need?
The answer is different for everyone, says Sal Spada, research director covering production machinery at consultancy ARC Advisory Group (www.arcweb.com), Dedham, Mass. But with floor space at a premium in many plants, robots can add flexibility and accomplish tasks that would otherwise require conveyors with impossibly tight-radius turns.
"Instead of using long conveyors that shuttle products around in different directions, a robot can 'decide' how to move things from one location to the next," Spada says. "We see this in the food & beverage market, especially on packaging lines." He notes that many plants that are increasing throughput but cannot yet budget a major capital project to expand might find robots a viable alternative for keeping or adding a packaging operation.
The rise of "smart conveyors" equipped with sensors, vision, motion and other control technologies is a direct response to plants' need for speed, quality, safety, energy savings and data to drive improvements such as business analytics. Smaller, more flexible conveyors are teaming with equally compact control systems. Compact, efficient motors and gearboxes are replacing large energy hogs, and conveyor modules are moving toward control cabinets with self-contained AC drive and embedded programmable controllers.
Although automation can be costly, the cost often can be justified by the elimination of product gaps, pile-ups and downtime. Longer-term, onboard controllers can share data, reduce energy and improve productivity in much the same way as any piece of computer-controlled equipment. Energy savings is a major driver of payback calculations that carries both short- and long-term savings along with a "green" corporate patina.
"A lot of older conveyors are running all the time, whether they have material on them or not," Spada says. Today's smart technology lets equipment stop running based on various types of sensors to fit the application, just as warehouse lighting systems turn themselves off to save energy. And when a "wake-up" signal arrives that product is coming, the conveyor can automatically start-up again. Likewise, it can signal downstream equipment that product is on the way. "That is a big energy saver in some large conveyance operations," Spada says.
When noise is a health hazard, ultra-quiet and highly precise roller conveyors that put individual servomotor controls in each roller are an option. Circuit board manufacturers and other light, hybrid, manual-and-automated assembly operations were early adopters of these conveyors, which also are offered by food equipment suppliers. Another safety factor are the guards that prevent workers from getting hurt, from gates that require manual lockout/tag-out before a worker can go near a conveyor or robot to sensor-activated systems that shut down machinery when human activity is detected.
Low-tech upgrades still important
Often, benefits designed for one aspect of an upgrade -- sanitation, maintenance, quality, productivity -- yield improvements in other areas. For example, lift-up conveyor sections speed cleaning as well as enhance productivity, and quick-connect hardware enhances food safety, eases maintenance and speeds changeovers.
The alignment key Dorner Manufacturing uses to eliminate set-screws helps reduce the "inherent biohazard risks" of bolts, connectors and set-screws that can collect and harbor contaminants, says Hosch. For the same reason, he says, smooth, continuous welding is critical to sanitation and therefore preferable to skip-welded connections on equipment.
The combination of many small, related improvements can produce significant, cumulative savings and benefits. "We get calls from customers all the time who are looking for simple solutions," says Rick Milner, technical services engineer with Wire Belt & Co. (www.wirebelt.com), Londonderry, N.H. "They're not looking for something to help them fly to the moon."
In addition to its U.S. belt manufacturing, Milner's division, together with international sister divisions, offers small, specialty conveyor systems. It's a relatively low-tech affair, typically with no need for sensors, servomotors or programmable controllers. The typical unit includes a motor geared from 6-36 ft. per minute. "We've never been asked to do more, except for our shuttle conveyors, which use a pneumatic stroke and need some controls," Milner says.
Food processors, automation contractors and larger machinery-makers, however, often will integrate their conveyors to track run rates, temperature ranges and data on the plant floor -- using whichever automation hardware and software the end-user requires. Other than the shuttle conveyors with their pneumatic controls, Wire Belt's conveyors limit controls to a motor and gearbox.
Some innovations come not with technology but with new sources for replacement parts or customer service enhancements. For example, patent expiration on Frigoscandia (www.jbtfoodtech.com) spiral freezer parts led Ashworth Bros. (www.ashworth.com), Winchester, Va., to offer drop-in replacement belts. In addition to its metal belts, the company appears to be unique in offering what appears to be the only USDA-accepted plastic belting, good for applications down to -50 degrees Fahrenheit. The plastic mesh is said to be more open and accessible than standard metal and therefore easier to clean.
Other low-tech but effective innovations include the spool-like "Rack-n-Roll" crating, in which the self-stacking belting is delivered. Users can minimize damage while more effectively unfurling it for easy installation and maintenance.