Product Marketing Manager
VarioFlow, Bosch Rexroth Corp.
At one time conveyors were fabricated in permanent configurations. Structural members were usually welded from milled or stainless steel, or aluminum. Newer modular conveyors, however, use extruded aluminum framing that bolts together. These modular frames let manufacturers divide the components (drives, returns, straight and curved sections, supports) into modules that can be mixed and matched to meet changing needs. The concept is analogous to the curved and straight tracks of a model-train set.
Modular chain conveyors use plastic chain, which is also modular. The chain is usually made from links that mix and match to fit the application. For instance, a cleated link at every fifth link could move items along an incline as steep as 90°. In the future, cleated links at every tenth position, or perhaps a taller cleat, will better serve the purpose.
Conventional conveyors are satisfactory for a single application but they don’t easily accommodate field changes. It is not uncommon for the layout of a packaging line to change repeatedly until the moment it goes on line.
Modular conveyors give engineers an out when some detail is overlooked, like discovering a layout violates OSHA regulations because it’s 2 in. too close to the eyewash station. Or when the shifting of a primary machine suddenly makes a carefully laid out, welded conveyor unworkable.
Modular conveyors have been around since the early 1980s, and Robert Bosch GmbH was one of the first companies to experiment with extruded aluminum for the frame, thus pioneering the concept of flexible automation. Initially, these conveyors transported heavy-duty parts. But standard modules that combine to make custom configurations caught on quickly. Packaging applications were introduced in the early 1990s.
Modular conveyors continue to evolve, mostly by the addition of new modules or adaptations for specific applications. For example, food manufacturers prefer stainless- steel conveyors that open in the center for accessibility. Special chain links with soft flocking to protect cardboard packages from scratching are another innovation.
The use of modular conveyors in packaging lines is growing rapidly because the marketplace demands flexibility. Remember when mayonnaise only came in wide-mouth glass jars? Now you can buy mayonnaise in rectangular plastic containers that fit better in the refrigerator. The local supermarket testifies to the variety of packaging for foods, beverages, and cleaning supplies. Specialty packaging has become a major weapon in the battle for grocery dollars.
Every product reacts differently as it moves along a conveyor. Center of gravity, weight, friction, and a host of other factors mean the best approach for one item may not work for another. Reconfiguration of modular guide rails can prevent product tipping. But what’s making new conveyors better is the ability to bend tighter and tighter curves so accumulators and buffers take up less floor space. Many of today’s accumulating systems are simply tight-curve conveyors stacked one on top of the other.
In most packaging applications, adjustable guide rails are necessary for handling frequent adjustments. These guide-rail systems continue to offer more flexibility. And so-called T-slots in the extruded frame of modular conveyors let manufacturers add, remove, or customize packaging lines with side guides, sensors, and vision systems
Modern conveyors do more than move products from point A to point B. They form an important link in the packaging- line chain. Modular chain conveyors protect productivity, maximizing return on capital investment for the entire line. Using chains, curves, curve wheels, lateral guides, conveyor profiles, and variable speed drives, a well-designed conveyor can handle most applications without costly alterations. Modularity tackles challenges such as product tipping, product jamming, and the special handling needs of unusual or delicate packaging.
Modular chain conveyors relieve bottlenecks and other product- flow problems through line buffering and accumulators. They adapt to different speeds, infeed/ outfeed demands, production disturbances, labeler changeovers, and line stoppages.
Good conveyors also improve the operator’s experience by making processes accessible. No conveyor layout should ever impede operator movement around the labeler, checkweigher, case packer, palletizer, or other manually operated equipment. And a smart layout shrinks the footprint, thereby reducing operator movement and boosting productivity.
Preengineered components from turns and guide rails to motor and drive systems combine to form customized layouts. A stable chain that can handle tensile forces up to 1,250 N, at speeds up to 300 fpm, saves money by using fewer powered drives. Also, a tightly designed chain minimizes gaps between links, making it possible to convey small components.
Compared to steel, extruded-aluminum conveyor frame and plastic chains can adapt to new sizes and labels, while purpose- built, welded-steel designs are normally dedicated to a specific task. This distinction can be crucial in consumer products where package design is fundamental to function and brand differentiation.
Spiral buffers made from steel are difficult to weld, not easily expanded, and typically do not survive beyond their original deployment. Conversely, modular conveyors reconfigure for elevation changes, improved access, or changing infeed needs. Standard vertical curve modules, usually ranging from 5 to 90°, can combine with static friction or cleated chain for pitched conveyance without additional transfer points or secondary equipment. This means minimal additional investment, faster implementation, a smaller footprint, and less risk of damage.
Engineers should look for a range of tools to simplify conveyor design. The best conveyor suppliers offer a complete parts catalog, selection of components and configurations, macro components and functions, and 3D solid models to simplify the design process. Some companies even offer software that calculates driving power and chain tensile forces, thus ensuring proper component selection.
A recent PMMI-commissioned study examined the challenges in running multiple products and packaging formats on a single packaging line. It found that slow changeover time ranked highest among equipment-related factors that inhibit productivity. And 62% of companies in the study reported handling more products or size variations on their lines than they did the year before.
Flexibility means easy expansion and reconfiguration, including curves and inclines. Modular conveyors can run several SKUs on one line by simply adjusting mechanical side guides. Quick-adjust and positive-positioning elements incorporated into side-guide systems ensure both speed and repeatability of changeovers, including multiple label changeovers.
Finally, filling operations with downstream labeling typically have multiple label changeovers, even for the same product. RFID mandates can affect labeling standards. The labeling area, characterized by scaled, small-radius turns, can feature a buffering system that diverts material from the main line while the labeler is changed. The serpentine design of typical snaking conveyors takes up additional floor space, whereas modular chain conveyors can form upward-spiralling tiers.
Bosch Rexroth Corp., boschrexroth-us.com