Smart machines with advanced sensors that perform condition monitoring and allow remote diagnostics and repair are at the center of the brave new digital manufacturing world, but can “smart” be combined with “conveyor” without being labeled an oxymoron?
Conveyors have carried raw materials, work in progress and finished goods from point A to point B for decades, often running continuously until someone flips a switch to off. Proximity sensors that cut off power when nothing is on the belt represent a small step forward, but that hardly qualifies as machine smarts.
Certainly, controls technology comes into play in packaging, where individual items are grouped, collated and transferred. While these systems exhibit a high level of sophistication, they usually fall short of the self-diagnostics and two-way communications capabilities of equipment that leverages the potential of the Industrial Internet of Things.
Nonetheless, smart conveying is becoming a reality in what some refer to as intelligent track technology. Using servo motors and sensors that identify the exact location, position, direction and speed of individual items on the belt, intelligent track technology allows synchronization with fillers, checkweighers, robots and other machines in a production or packaging line. Instead of setting up those machines to conform to a run of products, they adapt to individual products.
“In food and beverage processing, this track technology promotes mass customization, all the way to a batch size of one,” maintains John Kowal, business development director at B&R Industrial Automation Corp. (www.br-automation.com), Roswell, Ga. “Applications can include individually customized meal kits, confectionary assortments, pizzas and rainbow packs, including customized messaging and portion sizing.”
The systems integrator cites the new “bottling on demand” system from Krones as an example of track technology. Bottling on demand provides individual bottles with the intelligence to control themselves as they move on a race track connected to a controller. Instead of filling each bottle with, for example, 12 oz. of juice, different sized bottles can be fed through the filler, which dispenses 8 oz., 16 oz. or whatever the specific bottle’s capacity is. Different caps can then be applied, and a direct printing system can apply as many as 12 different labels.
“Intelligent tracking technology is combining the functions of transport with production,” Kowal says. “Using independently controlled shuttles operating on tracks of various configurations, this technology is based on linear motors. To put it in traditional round motor terminology, the track is one big motor stator and the shuttle is essentially a motor rotor.”
That level of intelligence isn’t found in upstream processes, but smarter conveying is making inroads, even in bulk transport. An example is the torque limiters built into some of Dynamic Conveyor Corp.’s units. Those conveyors may transfer up to 30,000 lbs. of cashews or other commodities per hour, according to Paul Kuharevicz, sales project engineer at the Norton Shores, Mich., OEM (www.dynamicconveyor.com).
Infeed to those bulk conveyors varies, with motors prone to burnout when overloaded. “People are very conscious of mechanical breakdowns at the front end,” Kuharevicz notes. “If it goes down, the downstream machines are idled.”
To avoid that scenario, the torque limiter relays an alert to the central control point when the load approaches the motors’ limit. Ethernet or some other communications cable then sends a signal to lower the belt speed to reduce power draw.
Downtime prevention also is the objective with SmartArm shaker technology from Key Technology Inc. (www.key.net), Walla Walla, Wash. The condition monitoring tool measures and reports stroke and speed on the firm’s vibratory conveyors, collecting trending data and wirelessly reporting deviations from acceptable performance. “It’s a smart tool that provides feedback for uptime reliability, PM planning and proactive maintenance,” according to Mark Roedl, area sales manager at Key.
The SmartArm innovation is “under the radar,” a status that also applied until recently to Key’s specialized vibratory conveyor designed specifically for integration with metal detectors for bulk materials inspection immediately before packaging.
Modular plastic or fabric belting is necessary when conveying product through a metal detector, but those belts usually come with nooks where bacteria can grow. Plastic belts also have plastic pins and rods that can break off and go undetected, and fabric belts are prone to fraying.
Key’s solution is a vibratory conveyor with three sections: stainless steel for infeed and outfeed, and a middle section bolted to those sections and made of ultra high molecular weight (UHMW) polyethylene. Side guides are part of the mold and therefore part of the pan.
Most of the early applications involved fresh, blanched or frozen fruits and vegetables. The specialty unit now is attracting processors of extruded meat and poultry products that are formed and frozen before undergoing metal detection prior to packaging. Key used to fabricate a vibratory conveyor with an all-plastic bed, but the combination of plastic and stainless steel is more economical, Roedl says.
The length and width of the unit is dictated by the product being inspected. The bed size is determined by the metal detector’s aperture. It can pass through openings from 150 to 380 mm high, or 6 to 15 inches.
“Once people understand you can use a vibratory shaker with a metal detector, they see the benefits,” says Roedl. “There are fewer parts to maintain, and it’s easier to clean and sanitize.”
Modular plastic belts typically are made of acetyl, a material that becomes brittle when exposed to certain chemicals, notably peracetic acid. Plastic fragments in poultry products were triggering recalls, causing belting manufacturers to look for alternative polymers.
“Belting companies came to us five or six years ago looking for a better alternative,” recalls Averie Palovcak, end-use application engineer – technical polymers with Arkema Inc. (www.arkema-americas.com), an advanced-materials company with offices in King of Prussia, Pa.
Arkema engineers settled on polyvinylidene difluoride (PVDF), a high-purity specialty plastic that is resistant to solvents, acids and other chemicals. The material also is compliant with FDA guidelines for direct contact with food, which eased NSF certification, Palovcak says.
It’s also three times as expensive as conventional polymers used for belting, she adds, but that hasn’t prevented many belting suppliers from using it in their molds. Typically, those suppliers identify the material as something other than PVDF.
Modular belts made from PVDF are heavier than conventional belts, but they can last up to 20 times longer, Palovcak says. In some applications, they are replacing stainless steel belts. The material is the “chemical sibling” of Teflon, though harder than that plastic. Poultry processors were the first end-users to use PVDF belts, and sausage manufacturers now are gravitating to it, she says.
Whether made of steel or plastic, open mesh belts present a cleaning challenge, particularly in dry environments like bakeries, snack food and confectionary manufacturing. Dry steam is one solution, and Goodway Technologies Corp. (www.goodway.com), a Stamford, Conn., supplier of industrial cleaning systems, recently brought a portable jet system that automates the process.
The mobile unit consists of a steam generator and an arm that extends across the belt. Nozzles in the arm move laterally, delivering dry steam with “explosive cleaning force” to the belt, according to Evan Reyes, national accounts manager. The nozzles are positioned within half an inch of the belt, with a steam temperature of about 180°F when it hits the belt. A touch-screen control retains 20 cleaning programs for belts in various areas of the facility.
Goodway’s portable cleaner is applied during production shutdowns. To prevent product carry-back during process runs and improve general housekeeping, Dynamic Conveyor developed a spring-loaded belt scraper for horizontal conveying.
Dynamic’s DynaClean conveyors for sanitary food transfer often are used for vertical transfer, in which case drive flights enable bulk product to defy gravity. “You can’t have a 3-in. drive flight with a belt scraper; we’d scrape that off,” notes Kuharevicz. For horizontal conveying, on the other hand, removing sticky product from the belt before it turns can reduce product loss and limit the area in which product is released.
Spring tensioning simplifies blade adjustments for optimum cleaning without damaging the belt. The scraper blade, with stainless steel and USDA-certified materials of construction, can be used with both solid surface and plastic link belts.
“One of the biggest challenges for conveyors is sticky products,” Kuharevicz points out, and the growing popularity of granola, gummies and other sticky products means more food processors are contending with release issues. Besides the belt scraper, Dynamic recently introduced belting with an embedded diamond top to minimize the likelihood product won’t release when needed.
As long as the product is large enough to bridge the one-eighth inch gap between the diamond studs, it should release, he adds. The embedded diamond belting is manufactured by Intralox.
Will conveyor belts ever issue alerts when too much product is sticking to them? Nobody’s asking for that capability, but as the gap between what’s possible and what’s feasible continues to narrow, smart conveyors and their components may one day deliver that capability.