Conveying and Bulk Handling in Packaging

An Automated Solution to Reduce Labor, Waste and Costs

By Greg Slack, Vice President, Global Sales at Flexicon Corporation

Increasing the speed, accuracy and repeatability of bulk product packaging typically requires an efficient bulk material delivery system that conveys the material from blenders, screeners, bulk bags, silos or numerous other sources. Automated conveying systems can reduce labor and waste, while purchasing material in bulk bags can reduce costs.

In addition, properly configured bulk handling equipment can deliver ingredients dust-free in an enclosed system to downstream processing or packaging lines, preventing contamination of the product and plant environment.

Feed Packaging Lines

To meet demand, Globepak (PTY) Ltd., a producer of nutritional supplements, installed seven bulk bag discharger and flexible screw conveyor systems that transfer mixed ingredients from bulk bags to packaging machines under automated control for continuous filling and accurate package weights.

Bulk bags are loaded into the dischargers, which unload ingredients dust-free into covered hoppers that, in turn, charge the enclosed flexible screw conveyors feeding the surge hoppers of the packaging machines.  The “no touch” delivery of ingredients minimizes any opportunity for cross-contamination.

Low- and high-level sensors on each packaging machine’s surge hopper signal a programmable logic controller (PLC) when to start and stop the flexible screw conveyors, assuring non-stop operation.

Product changeovers are accomplished in under 20 minutes by using pressurized air or cleansing solutions to clean the hopper, conveyor tube and screw.

One of seven automated packaging lines for nutritional supplements seen from both ends. Image courtesy of Flexicon Corporation

Weigh Batch Automatically

To produce an agricultural seed lubricant, a business unit of Diamond Vogel installed a “gain-in-weight” batching system that conveys talc and graphite from bulk bag dischargers to a blender, or directly to packaging lines.

Load cells supporting the blender interface with the dischargers’ PLC to run and stop the conveyors in sequence. Once the weight gain of talc or graphite-talc mixture approaches the target weight, the conveyors slow to dribble speed, stopping immediately prior to reaching the target weight to account for material still in-flight, which results in accurate and repeatable batches.

At the end of the blending cycle, the talc or talc-graphite mixture gravity feeds into a surge hopper charging two flexible screw conveyors that transfer the powder to the packaging lines for jugs and boxes. Because the weigh-batching and blending cycles repeat back-to-back, the surge hopper is never empty, and operation is continuous.

Graphite and talc powders are transferred from twin cantilevered bulk bag dischargers through two flexible screw conveyors to the blender mounted on load cells, at rear. The batch discharges into an 80 cu ft (2265 l) surge hopper from which two smaller flexible screw conveyors supply two packaging lines. Image courtesy of Flexicon Corporation.

By contrast, Breedlove Foods employs a “loss-of-weight” batching system that feeds packaging machines with dehydrated potatoes, onions, carrots, rice, soy protein and lentils for humanitarian relief. The system sources ingredients from bulk bag unloaders, filter receivers, bag dump stations or other vessels or process equipment mounted on load cells, which transmit weight loss data to a controller that starts and stops each conveyor (or rotary airlock valve) to weigh each ingredient.

For example, load cells supporting each discharger transmit weight loss data to a PLC, which runs a conveyor at high speed as material is discharged into a designated mixer. The PLC steps down the conveyor feed rate to dribble as the target weight is approached, stopping the conveyor once the precise batch weight has been lost from the discharger.  Blended batches are discharged into a hopper that feeds the packaging machine.

Two flexible screw conveyors in an adjacent room move lentils from two bulk bag dischargers into the Packaging Room (shown) where a transition hopper charges four interconnected flexible screw conveyors that feed lentils to four mixers. Image courtesy of Flexicon Corporation.

Package Brittle Products

At Quality Pasta Company, pasta arrives in large corrugated “Gaylord” boxes that weight from 800 to 1300 lb (363 to 590 kg).  To convey these brittle ingredients to packaging machines, the company uses an open-chute box dumper and a series of tubular cable conveyors.

The open-chute box dumpers automatically raise and tilt the Gaylords, which discharge pasta into large hoppers. The material is then discharged onto a vibratory tray feeder that controls the rate at which it charges the inlet adapter of the tubular cable conveyor (TCC).

Tubular cable conveyor curves to vertical and discharges into the pasta cup packaging line. A clear section of vertical tubing permits visual monitoring of system performance and product quality during transport. Image courtesy of Flexicon Corporation.

Hopper level sensors signal a PLC to alert operators when hopper levels run low, calling for replacement of a Gaylord.

The TCC circuits run in an “S” shape starting horizontally, rising vertically and then continuing horizontally.

Discharged material flows through a metal detector and into the packaging machine hopper.  Because the TCC fully evacuates material, cleaning and product changeovers are accomplished in less than 20 minutes.

The company also uses a flexible screw conveyor to transport powdered cheese for packet packaging and inclusion in some product boxes.

Require Side-By-Side Laboratory Testing

Document the efficiency of your system prior to purchase by having your actual material test-run in a bulk handling laboratory equipped with multiple types of conveyors and upstream/downstream equipment. Variables in product characteristics (fragile, friable, sticky, moist), distance from storage of ingredients to packaging lines, and integration of new and existing equipment, will all factor into the design of a system that functions reliably, improves quality, boosts output and cuts cost.

About the Author

Greg Slack is Vice President, Global Sales for Flexicon Corporation (www.flexicon.com), at the world headquarters located in Bethlehem, Pennsylvania.  During his 17-year tenure at Flexicon, the author has previously held the positions of Sales Director, North & South America, Applications Engineering Manager and Regional Applications Engineer. Flexicon is a global leader in the design and manufacture of bulk handling equipment and custom-engineered and integrated plant-wide systems, with manufacturing facilities located on four continents. Flexicon manufactures a broad range of equipment including flexible screw conveyors, pneumatic conveying systems, bulk bag fillers, bulk bag dischargers, weigh batching systems, manual dumping stations, container dumpers, and tubular cable conveyors.