Special Supplement: Conveyor Systems Control Plant Flow

May 1, 2008
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If conveyors are an afterthought, plant efficiency is at risk.

At three ft. above floor level, the drive chains for this conveyor offer clear access for maintenance and washdown. Source: Bosch Rexroth.


The rotating proportional gate revolutionized conveying to multiple packagers. Source: Heat and Control.

Robert Louis Stevenson, the Scottish author, is said to have written these words: “To travel hopefully is a better thing than to arrive,” but in food plants, destinations usually take precedence over journeys. It’s natural: A $1 million cooking system or a $250,000 packaging machine or a huge spiral freezer tends to command attention. The conveying systems used to bring products-in-process to this kind of expensive, behemoth machinery seem puny and mundane by comparison.

But conveyors are the arteries of food plants, the avenues and boulevards that connect the vital functions. And just like human arteries, a clean, efficient conveying system establishes the overall health of the operation; a weak system puts the entire plant at risk.

“The bottom line is that conveyors are expensive,” says Paul Calabretta of Dairy Conveyor. “When they go down, the plant goes down. It’s not that the conveyor is an expensive piece of equipment; it’s that it can cost a plant a lot of money when a conveyor isn’t functioning, because nothing else is running either.”

“Without a conveyor, the product isn’t going anywhere,” adds Barry Voshell, director of marketing and business development for Cambridge International. “That said, conveyors do tend to be kind of an afterthought at a lot of plants. The bigger, more expensive pieces of equipment get most of the attention. But when your plant goes down because a 10-ft. section of conveyor isn’t running correctly, then all of a sudden the conveyor is the most important thing to the CEO.”

“What a lot of people don’t realize is that the output of the conveying system is the output of the plant,” comments Amy DeFayette, product manager at Bosch Rexroth. “Think of the conveyor as the critical link between operations and integrating it into the flow of the whole operation, not just as a link to bring product from point A to point B.”

Everyone needs conveyors, but no one knows how important they are until they break, says Marty Tabaka, director of sales for the Americas at Ashworth Brothers, a conveyor belt manufacturer. According to Tabaka, processors want more throughput, a system that is always clean and one that never breaks. “In other words,” he says, “the perfect piece of equipment.”

One common complaint about conveyor systems is that they are difficult to clean. “Poor conveyor design is the number one reason for poor belt sanitation-it can drive up cleaning costs and significantly increase the probability of food safety problems,” says Gary Larsen, food safety consultant at Intralox. “Taking control during the design process-before the installation of a new or retrofitted conveyor system-is the best approach to this problem. Taking into account the total cost of ownership, and purchasing a conveying system that will supply the biggest return in terms of cleanability and food safety, rather than focusing on the lowest up-front costs, is the solution to improving the bottom line.” 

Fortunately, equipment manufacturers today pay much closer attention to the total process, with an eye for making improvements in the area of hygienic conveyor design.  “In the past, poor conveyor design meant both hygiene and safety challenges for food processors. Closed construction left critical areas inaccessible for cleaning; open gaps presented finger traps,” Larsen continues. “Better options are now available to help food processors and packers exceed their hygiene and safety standards. The key is customization-offering complete solutions, rather than just conveyors or conveyor belts.”

Polyurethane belting resists cracks and abrasions, improving food safety by allowing complete coverage during washdown. Source: Mol Industries.

Thinking holistically

“Every plant wants to grow, no one wants to shrink their business,” emphasizes Dan Gulick, president of American Conveyor. “So how are you going to plan for the flexibility that growth requires? If you don’t think about that now, you’ll end up spending 20-30% more on conveying systems than you should.”

Conveyors do more than move product. They control flow and, when laid-out efficiently, can mitigate the effects of pinch-points and bottlenecks-particularly at weighing and blending points. “The performance of a conveying system is dependent on weighing and blending. Where do you weigh your product and where do you blend it? The answers to those questions will determine your approach to conveying,” says David Boger, product manager at Flexicon.

“More and more these days, processors are being asked to do more with less. That puts a lot of pressure on a conveying system, which a lot of plant managers think of only in terms of speed-faster and faster,” adds Rich Grantham, North American food segment manager at Forbo Siegling, a belt manufacturer. A properly engineered and laid out conveying system factors in food safety, maintenance, flow, accessibility and flexibility.

“Try to look at this holistically,” says Gulick. “How much does the product weigh? What’s going to happen to it on the conveyor-will it be cut or moved or seasoned or weighed? Do I really have to build curves into the conveyor to move product from this point to that point? What’s the most efficient flow design as well as the most flexible and accessible? Where are the inputs and outputs? Where are your control panels, your forklift lanes, your cleaning equipment?”

In a poorly designed conveyor layout, he adds, “the decisions were made from the standpoint of the machines. Not to disparage anyone, but machine suppliers don’t really know conveyors. Well-designed conveying systems always begin from the standpoint of flow and throughput.”

The logical approach

Just as technological development has improved a plant’s larger, shinier pieces of equipment, conveying systems have undergone a quiet revolution in recent years. Under pressure to improve the food-safety features of their equipment and at the same time enhance throughput and smooth plant flow, conveyor and belt manufacturers have created a new generation of conveying systems that in some ways make the flashy, expensive breaders, stuffers, blenders, ovens, freezers, baggers and packaging machines they connect with seem like the old-fashioned machinery rather than the other way around.

“We’ve seen big changes from a logic standpoint-we keep finding more and more applications in conveying systems for load cells, which can tighten flow and overall operation,” says Eric Doern, product line manager at PPM Technologies. “These cells allow for proportional flow, which really streamlines distribution inside the plant. The key thing is not to overwhelm the pinch-points in an operation. Scales and baggers are the traditional pinch-points where things can slow down. A good conveying system brings product to those pinch-points at an even and steady rate without creating a backup-proportioning flow backwards through the operation so that the flow runs the operation rather than the pinch-points.” That can be counter-intuitive for some operations, he notes, where increasing throughput is always the goal. “Slowing down to improve flow seems like taking a step backward,” he adds.

With proportional flow, says Doern, you’re not really slowing down; you’re allowing the system to judge how fast it needs to go for maximum efficiency. Speed and efficiency should not be confused, he points out. “It’s efficiency that you want. If you’ve got a super-fast system that really cranks stuff through, only to have it back up at the bagger or scale, your efficiency goes out the window, and it can wind up costing a lot of money.” 

Food and beverage plants spend a tremendous amount of money on packaging and packaging equipment. If processors want full utilization of that equipment, they need to create as much efficiency there as possible in terms of product flow and personnel, observes Blake Svejkovski, product manager at Heat and Control, which in 2000 introduced the proportional gate that revolutionized flow into the packaging area. “The traditional gate was a straight open-close system. The proportional gate measures outflow for efficiency,” he says, directing product to different packaging machines at the same time. In a snack-chip operation, what this means is that different seasonings can be applied at the same time, with the proportional gate controlling flow to different seasoning lines. “Typically for a snack-chip operation, they do a little bit of teriyaki, maybe a little bit of Cajun and tons of barbecue. With the old gate system, the plant would have to run either an entirely separate line for the non-barbecue product, producing in small batches, or wait until the main line was done with the barbecue to run the small-batch products after the seasonings in the seasoner had been changed. With the proportional gate, you can run the main processing continuously, and the gate will direct product in the right proportions to separate seasoners. 

Proportional flow offers other benefits, besides simultaneous processing: Processors don’t have to worry about shutting down a line and doing a complete washdown when switching from one kind of seasoning that may contain allergens to another that doesn’t. “Also, it means you can now do all your packaging in one central packaging hall, which is much more efficient,” Svejkovski adds. In the end, he observes, the new gate caused processors to think about the efficiency of conveying systems elsewhere in the plant, driving further development and innovation.

Blue is becoming the conveyor belting color of choice in some food operations to distinguish it from cutting boards and other non-moving surfaces. Source: Habasit America.

Touchy scenario

Belting, too, has improved from significant technological development. For decades, fabric belting, which is prone to fraying at the edges as well as stretching but is cheap to manufacture and replace, was the standard, but then plastic modular belting offered a no-stretch, no-fray alternative that also reduced weight, changing the way conveying systems could be structured and supported and thus reducing their in-plant footprint.

Few things, if any, in the plant touch food products more than conveyor belts. This makes selection of a conveyor system one of the most important decisions a food processor can make. Modular plastic belting is simple in design and, with its sprocket-and-teeth drives, vastly improves tracking over the old fabric belts.

Since conveyor belting touches product at so many different points in a process, it’s a key element in a plant’s food-safety regimen. Indeed, food safety has forced processors to take a hard look at belting. As Barry Whitman, vice president of market development for Mol Manufacturing, asks: “What good does it do to have a cleanable machine if your conveyor belting can’t be as clean as the machine?”

Mol has developed new belting made from an extruded thermo-plastic polyurethane blend that not only is abrasion- and rip-resistant, as most modular belts are, but also provides the flexibility of the old fabric belts.  In addition, it has no cracks or crannies to harbor pathogens and allergens-it’s completely smooth and fully washable.

“A conveyor is only as clean as the belt is clean,” says Whitman, noting Mol’s plastic belting can take the hottest, harshest washdowns and at the same time move both frozen and hot product (though it cannot be run through a cooker). It’s lighter than other belting, too, though it’s not firm enough to be cut on. 

As in other equipment, antimicrobials are now being integrated into some conveyor belting, especially plastics and fabric. Habasit’s HabaGUARD, for example, is an FDA- and USDA-compliant antimicrobial manufactured into belting that prevents mold proliferation in addition to discoloration; it also offers surface degradation protection and remains effective after repeated cleanings and through normal wear and tear. (The belt manufacturer is careful to point out that HabaGUARD is not a replacement for good sanitation protocols.)

What about new nanoplastics? Intralox’s Gary Larsen thinks they have potential, but their development isn’t at a point of practicality yet in terms of new conveyor belting-and the food industry isn’t exactly clamoring for them. “Material research will continue to be a major push for the food processing industry.  To respond to the constantly evolving sanitation requirements of the food processing industry, it is important for conveyor belt manufacturers to always strive to determine which materials will best suit the needs of the industry,” he says. “While they do hold some promise, it is still very early to say whether nanoplastics will provide benefits to this market.”

Belting manufacturers approach new product development from three standpoints: food safety, ease of maintenance and versatility, says Barry Voshell of Cambridge International.  “The customer always wants more throughput but without risking the safety or integrity of their product. We’re working on developing wider belts in longer lengths that are positively driven to address throughput. Historically, the challenge has been that wider belts are typically friction-driven, not positively driven. You’re relying on the conveyor being 100% aligned all the time to prevent any tracking problems.”

In food plants, coatings such as flour, sugar and salt are often applied to products, increasing belt tension and wear due to abrasion. “Stronger belts that are easier to splice are very important to maintenance teams,” Voshell adds. Oils-coconut and palm oil, especially-can damage fabric belting.

For conveyor support structures, stainless steel continues to be the material of choice, even though its cost has increased significantly over the past couple of years, spiking in 2007 due to a nickel shortage but coming down a bit since then. “It was painful for everyone in the business,” comments Dan Gulick, president of American Conveyor. “But there’s still nothing out there that offers the versatility of stainless for the cost. Fiberglass breaks down, and cleaning solvents can destroy other materials over time.”

Rich Grantham at Forbo Siegling says that while conveyors may appear to be the prosaic pieces of equipment in a high-tech food plant, processors shouldn’t let appearance be deceiving. “Conveyors aren’t a commodity item anymore. There’s a lot of thought and R&D that goes into their design,” he points out.

For more information:
David Boger, Flexicon, 610-814-2400, dboger@flexicon.com
Paul Calabretta, Dairy Conveyor, 714-891- 0883, pcalabretta@dairyconveyor.com
Amy DeFayette, Bosch Rexroth, 269-697-5304, amy.defayette@us.bosch.com
Eric Doern, PPM Technologies, 503-538-3141, eric.doern@ppmtech.com
Steve Fesperman, Habasit America, 678-288-3540, steve.fesperman@us.habasit.com
Rich Grantham, Forbo Siegling, 704-948-0800, rich.grantham@forbo.com
Dan Gulick, American Conveyor, 718-386-0480, dgulick@americanconveyor.net
Gary Larsen, Intralox, 504-733-0463, gary.larsen@Intralox.com
Blake Svejkovski, Heat and Control, 972-488-2993, blakes@heatandcontrol.com
Marty Tabaka, Ashworth Brothers, 540-665-1350, mtabaka@ashworth.com
Barry Voshell, Cambridge International, 410-228-3007, bvoshell@cambridge-intl.com
Barry Whitman, Mol Manufacturing, 616-453-2484, whitman@molindustries.com

Design for growth

Well laid-out conveying systems share several common design features, say conveying experts. They’re efficient and streamlined, without complicated extra channels, diversions and offshoots. They’re accessible for ease of maintenance and repair. They’re appropriate, with the right belting for the right product. And they’re designed with growth and flexibility in mind. “On Day One, the system might look good, but as a plant grows, the conveyors suddenly are going all over the place,” says Steve Fesperman, director of marketing for Habasit America’s plastics division. “The best systems don’t lose their efficiency as the plant grows.”



When planning a new conveying system, experts advise the following:

  • Involve representatives from prospective conveyor suppliers from the very beginning, and keep lines of communication open. “Also make sure the supplier has a strong applications and engineering department,” comments David Boger of Flexicon, “because every project is different.”

  •   “Look at the system as a whole, not as individual components,” states Bosch Rexroth’s Amy DeFayette. “What makes a good conveyor system is system integration.” 

  •   “The single most important information that is required from a customer is complete product details,” adds Kevin Mauger, a system integrator with NCC Automated Systems. “This includes photographs and samples of all products that are going to be conveyed. A product matrix table with product description (name or SKU), length, width, height, rate, weight and orientation is required. Another key factor is to identify is the level of control integration throughout the system. Is there a separate controls system provider, or will the conveyor integrator supply its own control system? Has the plant standardized on a specific control platform and devices? How will the material handling system need to interface with the master control system and other equipment in the system? This information should all be provided during the solicitation process.”

  •   Identify and start from the plant’s main operations-frying, cooking, freezing, bagging, etc.

  •   Know the exact location of all equipment that will be connected by the conveyors. “Don’t rely on architectural drawings, they are sometimes insufficient for equipment placement,” says Paul Calabretta at Dairy Conveyor. “Do the measurements on-site, down to the quarter inch. You have to know these measurements precisely.” If it’s a new plant, plan where the major pieces of equipment will be located, but leave the final exact location to the conveyor supplier.

  •   Minimize curves and drives (on a conveyor that moves containers, a drive is necessary every 35 ft.), and maximize space for operators and maintenance personnel.

  •   Keep the number of transfers-product moving from one conveyor to another-to a minimum. “Transfers cause product damage and create cleaning issues,” says Fesperman.

  •   According to Bosch Rexroth, well-designed conveyor systems have their drive chains accessible at floor level. But overhead space can be useful, too, and it’s often very accessible from overhead walkways and gangways.

  •   Allow for electrical switches, door swings, forklift lanes and personnel ingress and egress.

  •   Make sure the belting is appropriate for the job. Some belts can withstand cutting and abrasions; others can’t. Some belting can endure the frigid temperatures inside a spiral freezer and can also carry hot product; few belts can withstand oven temperatures. Some belts are much easier to wash down than others. Some belting systems are abraded by salts and sugars.

  •   Keep at least one extra drive motor on hand for emergency maintenance, and several extra links of chain.

  •   Visit test facilities of prospective conveyor suppliers. “Be an educated consumer. Don’t make a decision without 100% of the information,” stresses Flexicon’s David Boger. “Inexperience gets you in trouble.”

    The biggest mistake general managers make is underestimating the total cost of a conveyor system, notes Calabretta. “They focus on the cost of the conveyors, but that’s not the half of it. For example, the electrical cost is typically a five-figure number-at least. If building the system is going to involve concrete work, that’s very expensive.” Construction modifications are expensive, which is why it’s important to involve conveyor experts from the start.

    “Most processors underestimate a conveying system’s cost by 20%,” Calabretta concludes, “and that’s always from not looking at all the requirements of the system from the start.”
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