Tech Update: Conveying and Belting

May 1, 2010
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While conveyors may not be the highest-tech devices on the plant floor, current processor demands are bringing them up to speed.

The Advantage 120 is a 1.2-inch (30.5mm) pitch hybrid belt for straight runs or turn-curve and spiral applications with turn ratios from 1.4 to 2.8. The belt features an open area of up to 67% for airflow and sanitation. Source: Ashworth.


With the current financial environment and the need to produce safe food and beverage products, conveyor suppliers and belt makers are doing their best to satisfy a host of user demands that might be summed up as doing more, faster, better, cheaper and safer.

Dan DePiano, HK Systems distributor/integrator program director, lists processor requests:

• Clean design, minimizing crevices, openings, pockets and edges that can capture spillage or debris

• Reliability

• Maintenance-friendly design

• Competitive price

• Energy efficiency.

If these weren’t enough, Boyce Bonham, Hytrol systems development director, suggests additional wish list items from his customers. Processors want low-voltage, decentralized drive systems for carton and case handling because of the limited space they have in their facilities for these systems. His customers want to locate several conveyor lines both vertically and horizontally, and they need enough flexibility to negotiate curves with no minimum-length straight and curve combinations. Throw in no lubrication, no chain, no reducers and no regular maintenance requirements, too. Having a minimum of spare parts on hand and being able to hot-swap components to reduce downtime are also key issues for processors.

Conveyors should be seen and not heard, and when they don’t have anything to convey, they should not be running.

Many processors are trying to quiet down operations. Teri Johnson, Key Technology intercontinental sales manager, says she has had requests from some processors for conveyor drives not to exceed 80 dbA.

Two other needs, according to Clark Hicks, Heat and Control product handling systems sales manager, are gentle product handling and data acquisition systems that let operators know how well the equipment is performing. Should a repair be necessary, these systems can notify a technician, so they can be dispatched with the knowledge of what’s wrong and the right equipment to fix the problem.

Breaded chicken, fish, potato chips and other delicate foods can be moved gently with a horizontal motion conveyor. Source: Heat and Control

A closer look at motors/drives

For superior sanitation, Johnson says there is a strong preference for all-stainless-steel (SS) components, including motors and drives.

“To reduce energy use and operating costs, higher-efficiency motors are increasingly in demand,” she adds.

The use of energy-efficient, premium motors (defined in NEMA Standards Publication MG 1- 2006) is a good investment that can show a return in as little as six months, says Michael Weickert, Nercon director of engineering. Considering the payoff over the years when used in new equipment, premium-efficiency motors are a good investment.

Motors and gearing with paint-even epoxy paint-may be able to withstand washdowns, but when someone bangs into the device with something hard, there is always the possibility that a chip of paint will get into the food, adds Weickert. Paint chips aren’t detectable by metal detectors, and they can be missed in an X-ray inspection as well.

“The multiple-drive solutions that are available on the market demonstrate that processors continue to search for constant product improvement,” says Mike Peach, Habasit America director of business development. “No one product is right for every application, and each must be considered on its own merits,” he adds. Coating technologies are available today that eliminate the disadvantages of painted or aluminum gear-trains, yet provide the advantages of SS without the high cost or loss of efficiency, he adds.

While there is a trend toward gearmotor packages, which typically offer an initial cost savings and are easy to install, Weickert suggests taking a second look. In most cases, either the motor or the gearing fails, forcing the processor to replace the entire assembly rather than just the device that failed. Processors should determine cost-of-ownership based on mean-time between failures (MTBF), downtime, and cost to repair and replace.

Perhaps the ultimate integrated gear-train is the motorized pulley, or pulley motor, which combines a drum motor and gearing within and is mounted at one end of the conveyor. More than 2,800 of these SS drum motors supplied by Interroll are installed in 17 miles of conveying systems in Danish Crown’s pork slaughterhouse in Horsens, Jutland, Denmark. The drum motors realize about 47% lower primary energy consumption when compared to conventional counterparts and are rated IP66/67, so they can be pressure-cleaned. Danish Crown saves approximately 212,000 euros annually in primary energy costs and 70,000 euros in air conditioning costs due to less heat generation.

Which is right? It depends, says Mike Hosch, Dorner Manufacturing Corp. director of engineering. “Pulley motors have some advantages over reducers and gear motors. Even in the last few years, the market has seen the cost come down for pulley motors. Certainly in some hygienic applications, the internal pulley motors are more hygienic and carry a high sanitary certification,” he says. However, the lower base cost for a traditional reducer and gear motor is why the latter are a popular choice.

The trend continues to right-size the motor package for the application so power output and efficiencies are maximized.  According to Hosch, the implementation or use of brushless DC motors is on the rise, and this alternative offers some additional energy savings.

When processing dry powders and products in dusty environments, food manufacturers should specify explosion-proof drives, says Karl Seidel, Cablevey marketing manager.

Rather than use conventional drive trains and pulley-motor-driven belted conveyors, another option is the horizontal motion conveyor (HMC), as provided by Triple/S Dynamics and Heat and Control. Tim Talberg, Triple/S Dynamics sales engineer, says that HMCs eliminate the motor/gearbox/pulley/belt combination altogether and simply use a SS trough, which is decidedly easy to clean.

HMCs are known for gentle handling, and they have a drive system that slides the trough back and forth. Reliability is very important, says Hicks, and the use of long-life parts in the drive train makes it possible to offer Heat and Control’s FastBack HMC line with five-year warranties-thanks to the use of bearings rated at 80,000 hrs. MTBF.

Belting systems

The choice of belting is highly dependent on the application, whether it’s in processing, between processing and packaging or in palletizing. Types include modular plastic, urethane, wire mesh, vulcanized and several others. Typically, belts run on friction- or sprocketed-drive pulleys.

“Belt strength and performance are very important features that processors look at to choose a belt that fits their application,” says Jon Lasecki, Ashworth chief engineer. “Other issues processors should focus on when choosing belting include how the belt can reduce maintenance and how easy the belt is to clean,” he adds. Design advancements made to both stainless-steel and plastic belt lines not only increase strength and extend belt life but also increase system efficiency and reduce maintenance time and costs, Lasecki says.

According to Hosch, raw proteins have benefited from solid urethane belting. Over the past several years, the product breadth in this category has more than doubled. The technology is easy to clean and requires less labor, water, and energy to clean than other belting alternatives. It has been beneficial for RTE applications for the same reason.

Over the years, a need developed for a solid, homogeneous belt that wouldn’t slip and would be easy to clean. Mol Belting Systems, according to Quality Manager Andy Quist, developed a hybrid, adopting the monolithic belt style with no hinges or pins and driving it with a sprocket. This solution reduces maintenance headaches, makes it easy to clean and doesn’t slip, adds Quist.

For packaging applications, plastic chain suppliers continue to improve their designs for overall performance.  Plastic chain is often required to go up and down inclines and curve around obstacles within a facility. A variety of have been developed to meet these requirements, including product inserts, grip top, and cleats for inclines and declines, and robust designs for curved belts that facilitate speeds around curves up to 260 fpm, according to Hosch.

Some applications need tensioned belts and sprocket-driven belts.  Several hundred choices and combinations are available across the market today, and knowing what will work best is key in solving those tough applications, according to Hosch.

For some retort, baking, quick-freeze and other process applications, plastic, fabric, urethane and materials sensitive to extreme temperatures can’t be used. Wire-mesh belts allow products to be equally cooked or frozen from both sides without deteriorating. Early on, the chains were fairly heavy, and the mesh wasn’t very open, says Rick Milner, Wire Belt technical services representative.

“We’ve come up with a belt replacement for some of these heavy chain belts, which by their design prevent a lot of air flow through the belt,” says Milner. If the mesh is more open, cook or freeze time can be shortened, or less energy is needed to complete the process. Milner points to an application in Alabama, where replacing an old chain belt with a newer, more open belt in a nitrogen cooling tunnel reduced the cooling temperature from -180°F to -140°F, saving the processor a significant amount of nitrogen.

While hybrid plastic belts with SS rods may not withstand ovens at 300°F, some can operate at temperatures from -50° to 110°F, and they can be used in USDA raw protein applications. Because of their airflow, they can also be used in RTE/freezing applications, according to Lasecki.

Cleaner frames

There’s no question that today’s technology has sped up the time it takes to build a conveyor.

“Laser cut technology along with CNC bending allows for modular frame designs, minimizes the fitting time required compared to traditional structural steel frames, and provides a factory-polished appearance,” says Greg Jacob, Allpax Products general manager.

“An important frame design consideration is achieving the ideal balance between light-weighting (to minimize capital costs and reduce floor space) and maximizing equipment quality and dependability,” says Johnson. 3-D modeling allows better overall design, especially in regard to support frames and identifying issues prior to manufacturing. Stress analysis modeling tools assist in choosing the minimum material sizes required. Robotic welders create smooth, consistent weld joints with a minimum of added material. Cross members are tilted or round, reducing flat surface area, she adds.

In the frame design, hygienic goals remain the same as mechanical: simple, visible, accessible, minimal horizontal surfaces, open and easy to clean, says Hosch.

“If you can incorporate these principles into the frame design, product accumulation and addressing the frame for sanitation will be a success,” he adds. Also, operator safety should be considered, which means sprockets and other moving parts should not be exposed, and safety guards need to be designed with hygiene in mind.

HMCs are relatively easy to clean since they consist of SS troughs. Tubular conveyors, by their nature, are enclosed and keep product from being exposed to the environment. Tubular-drag conveyors, says Seidel, are also gentle product handlers, and they’re well suited to handling frozen foods, especially when product changes are made since cleanout time is short.

For CIP operations, incremental improvement should be the goal, says Peach. A CIP system will improve the consistency of a manual cleaning operation; however, some manual cleaning may still be required depending on the environment, access and the product conveyed.

According to Quist, a lot of belts have to be removed from the conveyor and soaked in dip tanks. Nobody wants to do a clean-out-of-place operation today. With a seamless belt, a set of spray nozzles can easily clean the belt. In addition, Quist says belts can be lifted in place with a cantilever to clean the underside when necessary.

Each CIP system needs to be designed for each application and belt used on the conveyor, says Hosch. For a raw protein application, good hygienic design principles will include the judicious placement of valves, spray nozzles and spray bars. The objective is to remove particulate or product accumulation from the conveyor belt, so that when the belt returns to the infeed of raw product, it has a clean, debris-free surface. One spray bar can be located within the frame of the conveyor and one on the outfeed end. The two spray bars work in combination to effectively remove material from the belting material.

Conveying information

Automated food processing and packaging lines have been increasing over the last several years, improving throughput and the flexibility to support frequent changeovers. As a result, conveyors have become smarter, says Hosch.

Conveyors now have PLCs for brains, which control their speed and tie into video inspection systems to check for presence, absence or the color of food products on the conveyor. PLCs can act as the host for a number of conveyors, checkweighers, inspection systems, industrial sensors, variable frequency drives (VFDs) and actuators to reject or redirect products from one conveyor to another-a veritable distributed control system (DCS).

Weickert says a DCS reduces wiring and wiring mistakes and makes the commissioning of a system much easier because it can be simulated and tested before installation. Processors can actually get a look at how their conveyor control system will run before it’s installed.

Controlling conveyors helps maximize product quality, yield and line efficiencies, says Johnson. Controls are much smaller, enabling integration of more functions in a smaller footprint. Today, Ethernet and wireless systems are extending the usefulness of controls, connecting remote line locations to plant networks.

“In retorting applications, tracking the products through the conveyor system to ensure that the raw products are being processed prior to being sent to end-of-line packaging is a vital component of plant food safety,” says Jacob. Complex product tracking systems are now being integrated into the conveyor logic. Additionally, the price difference between a VFD and a traditional motor starter has prompted processors to spend a little more to gain the intelligence and speed flexibility of VFD technology, according to Jacob.

Information gleaned at the conveyor level is no longer stagnating in a plant floor computer. Weickert notes that more often than not, processors are connecting these plant-level data and manufacturing execution systems to the company ERP system, enabling the exchange of communication between the two and allowing planning that wasn’t possible in the past. That connection will become even tighter as the data assists in real-time production planning.


For more information:
Dan DePiano, HK Systems, 859-334-2767, dan.depiano@hksystems.com
Boyce Bonham, Hytrol, 870-974-5652, bbonham@hytrol.com
Teri Johnson, Key Technology, 509-394-3358, tjohnson@key.net
Clark Hicks, Heat and Control, 469-464-2700, clarkh@heatandcontrol.com
Michael Weickert, Nercon, 920-233-3268, mweickert@nercon.com
Mike Peach, Habasit Amereica, 800-458-6431, mike.peach@us.habasit.com
Mike Hosch, Dorner Mfg. Corp, 800-397-8664, mike.hosch@dorner.com
Tim Talberg, Triple/S Dynamics, 800-527-2116, ttalberg@sssdynamics.com
Andy Quist, Mol Belting Systems, 616-453-2484, aquist@molbelting.com
Rick Milner, Wire Belt, 603-644-2500, rmilner@wirebelt.com
Karl Seidel, Cablevey, 641-673-8451, karl.seidel@cablevey.com
Greg Jacob, Allpax Products, 985-893-9277, info@allpax.com
Jon Lasecki, Ashworth, 800-682-4594, ashworth@ashworth.com

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