December 1, 2010
by Shane Whitaker
Bakeries and snack manufacturing plants employ a wide variety of conveyance systems to move ingredients, doughs, formed products, finished baked foods and snacks, and packages through processing and packaging. Pneumatic, flexible screw, horizontal motion and roller conveyors can be applied in these facilities.
However, belt conveyors are the most common choice in today’s automated bakeries, and many different belts are available. Fabric, rubber, plastic, steel and wire mesh belts are all fairly common. Belt conveyors can run with low and high tension and feature positive or push drives. Decisions about which belt a bakery or snack manufacturer needs often depends upon the application.
No matter the style of conveyor belting, processors generally desire reliable conveyor belts that are easy to sanitize and reduce maintenance costs, according to Jon Lasecki, chief engineer, Ashworth Bros., Inc., Winchester, VA. The company’s latest conveyor belts include the Omni-Pro and Advantage lines. “Both of these belts were engineered to maximize throughput and minimize lifecycle costs,” he said. “These belts are used in coolers, proofers and freezers.
Baking and snack companies are looking for energy savings, said Rick Milner, technical services engineer, Wire Belt Co. of America, Londonderry, NH. “Everyone is going green — it’s all about what you can do to help the environment,” he noted.
To that end, Wire Belt manufactures light-duty stainless steel mesh belts that often require fractional horsepower motors. The snack industry traditionally has used balanced-weave belts that are much heavier, thus requiring larger motors, according to Mr. Milner. Also, a mesh belt allows for greater airflow, so less energy is needed to heat or cool products than on a balanced-weave belt.
Wire Belt’s newest offering is the patented CompactGrid, which was specifically designed for the snack industry, Mr. Milner said. It handles smaller, delicate products such as pita and potato chips, pretzels and cookies. CompactGrid can be used for frying, cooling, freezing, baking and many other applications.
CompactGrid also is designed for a glazer or icing line. “Glazes can be pasty, and with traditional balanced weave or flat wire belts, there is a lot of material on the belts where glaze can clog the mesh because of the thickness of the belt,” Mr. Milner added. “Because CompactGrid is so thin, glazes don’t have an opportunity to get clogged up in the mesh.”
The belts are 0.2 in. thick, yet they support product much like a solid surface belt. Processors also do not have to worry about a potato chip nosing itself down into the mesh because openings in the belt are 10 mm wide, he explained.
Additionally, CompactGrid is manufactured to allow processors to run it upside down, rather than have the smooth side up, to generate friction to hold products in place on an incline. Mr. Milner described how a snack manufacturer runs the belt upside down in a fryer to assist chips coming out of the trough at a slight incline. “Some standard belts wouldn’t let the product come up out of the fryer,” he said. “But by flipping the CompactGrid, it was a little more abrasive and helped to lift the chips from the fryer.”
Speaking of friction, Intralox, Harahan, LA, developed a new friction material for its plastic modular belts that is extremely robust and outlasts all others, according to Don Osborne, Intralox’s bakery team leader.
The friction material is co-moulded into modular plastic belts and helps to maintain the orientation of baked foods and pans on the conveyor belts. “When bread goes up an incline, it generally wants to slide backwards, but the friction material keeps it in a stable location because bakeries do not want two loaves touching one another as they go into a cooler,” he said. “The same thing happens with pans when going up inclines; the friction material holds them in position.”
Because pans are hot and can have oil on them, they are harsh on the friction material, but Intralox’s new solution is able to withstand this abuse much better, Mr. Osborne explained. “We are seeing a significant improvement in belt life,” he said.
Modular plastic belts come in a variety of surfaces to maintain product orientation as well as slick surfaces for product or pan accumulation, according to Mr. Osborne. Another sought-after trait is that they are easily repaired. “With a modular plastic belt, you just pull the rod out, put a piece of belt in and put the rod back in, and you are up and running very quickly,” he said.
The modular plastic belt’s positive drive sprockets maintain tracking, so bakers do not have to worry about the belts stretching and slipping. Mr. Osborne pointed out that unlike steel belts, plastic modular belting doesn’t wear out the bottom of pans. “It extends pan life, and that is part of the payback of converting to a modular plastic belt,” he added.
Intralox also offers heat-resistant belts. “We see them used a lot in oven discharge applications, where you wouldn’t think a plastic belt would work, but actually it works quite well,” Mr. Osborne said. These belts can receive pans or product from an oven intermittently at temperatures between 300 and 400°F.
Ashworth is the only belt manufacturer that provides either metal or plastic spiral belting, according to Mr. Lasecki. Since the company’s invention of the spiral conveyor more than 40 years ago, he said, a good portion of Ashworth’s business comes from bread bakeries needing spiral belting for proofers, coolers and freezers.
“Ashworth’s Advantage plastic spiral belt is designed to be very open, even when it collapses, so it cools products faster than any other plastic spiral belt,” he said.
The company incorporates stainless steel rods, rather than pliable plastic rods, to provide the strength needed to increase the open area of the plastic mesh. “In addition to increasing airflow efficiency, cleaning characteristics are also improved; in fact, Advantage belts are the only plastic spiral belts that are USDA-accepted, NSF-approved and BISSC-certified for cleanable performance,” Mr. Lasecki noted.
The stainless steel rods resolve other common problems inherent to plastic rod belts, he pointed out. For example, beam strength is increased, allowing the Advantage belt to support heavy loads without sagging, and fewer support rails are needed for wide belts, which reduces friction and saves energy, Mr. Lasecki added.
A relatively new style of modular plastic belting from Intralox is its Activated Roller Belt (ARB) technology, which features rollers placed in the belt at various angles from 0 to 90° to the direction of belt travel. Several different styles of rollers, which are positioned above and below the belt surface, are available, depending on the application. The rollers activate when they come in contact with a product and move it across the surface of the belt in the direction of the roller orientation. ARB conveyors change the direction, alignment and location of products on a belt without the use of rails or complicated mechanical controls.
“Historically, ARB has been used primarily in packaging, but we have recently done a lot of testing for both wear and sanitation when using this technology for direct food contact,” Mr. Osborne said. “We have proven that there is not excessive wear, and sanitation requirements are no more significant than what users traditionally experienced in those locations.”
Thus, it made sense to develop new applications for ARB technology, he stated, and one such new application is the use of these belts to lane sandwich thins. “This is a significant breakthrough because historically you had to have a lot of people there to get the buns into equal lanes,” Mr. Osborne noted. “Our laning technology is certainly revolutionary as opposed to evolutionary.
“Although this is a revolutionary concept, it is being accepted well in the marketplace,” Mr. Osborne continued.
Another popular feature from Intralox shown at the recent International Baking Industry Exposition in Las Vegas, NV, was the ability to make extended belt runs without transfers. With the use of its new intermediate Drive (i-Drive) technology, Intralox modular belts can “basically run forever without transfers,” Mr. Osborne said. “The applications where i-Drive can be highly successful are the transfers from the depanner to the cooler and the cooler to the wrapper,” he noted. “It eliminates cripples and bread tipping over at transfer points. It also eliminates a significant amount of sanding on bun lines.”
However, processors may not always be able to eliminate all transfer points. And in transfer applications, companies want sprocket-driven belts that can provide a very tight transfer so that products stay aligned and are not damaged when they move from one conveyor, or process, to the next, according to Mr. Lasecki.
For nimble maneuvering, Ashworth’s Cleatrac belt moves around the smallest nose bar diameters in the industry — as small as 0.2 in. — allowing it to accurately transfer small products and minimize product damage, he said.
To eliminate tracking issues with closed-surface flat belts, Intralox offers ThermoDrive technology. This smooth, flat conveying surface combines the reliability of positive drive with the cleanability of a solid plastic belting. ThermoDrive reduces sanitation times by at least 25% compared with other belt styles, according to Mr. Osborne. The belt has been extremely successful in snack operations, he said, and scoop flights can be added to the belts so that they can be used on inclined conveyors. The belts also are used for dough handling because processors can scrape the smooth monolithic surface to easily clean the belt surface.
Bakeries normally use metal belts where products come out of an oven directly onto the spiral belt at temperatures too high for a plastic surface, according to Mr. Lasecki. “Metal belts are usually more durable than plastic belts and have more mesh options that allow greater airflow and better product support,” he added.
Engineering and manufacturing advances to Ashworth’s Omni-Pro stainless steel belts improve their overall performance when compared with other metal grid belts, Mr. Lasecki stated. “Omni-Pro’s patented manufacturing process features zero-tension 360° buttonless welds that increase load-bearing capacity and are easier to clean versus traditional bridge welds,” he added. “Omni-Pro’s patented coining feature reduces run-in wear to increase belt life, and the patented ‘wear shield leg’ prevents welds from contacting spiral cage bars, enabling the belt to run smoother with less system wear.”
Oven belts for biscuit and cracker manufacturers need to evenly and efficiently retain heat because products are baked directly on the belt. The belt must also be able to effectively support the product and run extremely straight so that the belt does not get damaged. In the industrial bakery market, oven belts make up a large part of Ashworth’s business on the cookie, cracker and biscuit side, Mr. Lasecki noted.
The Ashworth CB5 Baking Band has been “the baking oven industry standard” since its introduction in 1963, he said. “The tight herringbone weave provides stable product support, even heating and allows cooking gases to be released uniformly, leaving a consistent and preferred pattern on the baked product,” Mr. Lasecki explained. “To ensure true tracking and long belt life, the Ashworth CB5 Baking Band is precision woven with the tightest industry tolerances and inspected with 22 different quality checkpoints.”
Berndorf Belt Technology, Elgin, IL, manufactures the CARBO 13 baking band for bakery ovens. Its steel goes through a complex heat treatment process to achieve the required tensile strength and surface for a bake oven belt. The Berndorf baking band runs in an endless condition between two drums, which allows dependable and safe tracking for trouble-free operation, according to the company.
Conveyor belts are the pavement of the bakeries’ highways, and manufacturers of these surfaces continue to develop new products that are easier to maintain and sanitize, reduce energy costs, and allow smoother operations in even in the tightest of bakeries and snack operations.