Averting a Sticky Situation at a Marshmallow Plant

Nov. 2, 2004
Many food ingredients, such as starch, flour and sugar, are not only explosive when combined with air, but dusty, sticky, messy and time consuming to clean from equipment and facilities. A pneumatic conveying system improved safety and increased production at a marshmallow manufacturer.

By Del Williams

When the Ghostbusters battled an angry 12-story walking marshmallow man in the classic 1984 movie, white goo covered half of New York City when they finally destroyed it with their backpack-mounted nuclear accelerators. In real marshmallow plants or other food manufacturing facilities, explosions and mess are no laughing matter.

For plant managers and others charged with streamlining production, sub-optimum conveying of powdery materials such as starch, flour and sugar in the manufacturing/packaging process can not only be dangerous, but also eat away at production efficiency through unnecessary downtime, cleaning, maintenance and product loss.

Some manufacturers, such as Elk Grove Village, Ill.-based Doumak Inc., one of the world's largest marshmallow producers, however, have found the secret to managing these problems using advanced, flexible pneumatic conveying systems instead of bucket elevators or other traditional equipment. Not only has the pneumatic conveying system at one plant made the facility safer by minimizing dust exposure, it has added about 8 hours a week to production by eliminating product/packaging bottlenecks, cleaning and maintenance; has reduced product loss; and improved product quality, among other benefits.

Mike Morgan, maintenance supervisor at Doumak's Bensenville, Ill. plant, has seen first hand the drawbacks of traditional conveying systems in production environments.

"There's a need for flexibility and integration that's often unmet by bucket elevators or similar conventional equipment,' says Morgan, a veteran of food industry production who has worked at a number of plants over the years. "In my experience, when a packaging machine malfunctions with a bucket elevator, production shuts down for at least 30 minutes. With 24/7 plant operation, we need constant throughput. On a production schedule that tight, any downtime immediately impacts revenue."


Essential to plant efficiency is the ability for conveying equipment used in production to properly coordinate with packaging equipment. Ultimately when a packaging machine goes off-line, product should be re-routable to operating machines; and the conveying equipment should adjust speed when packaging machines fill bags of different sizes. Traditional conveying equipment, however, such as bucket elevators, fail on these accounts.

With many moving parts, bucket elevators and their kin can be costly and time-consuming to maintain. During monthly preventive maintenance on bucket elevators, Morgan typically checked about 20 mechanically moving parts such as belts, motors, bearings and sprockets for wear and replacement. He estimates that dusty production environments could cut their lifespan by up to 50 percent.

Cleaning such equipment required production downtime as well. "Excess starch ended up in the bucket elevators, in bagged product, or on the floor," says Morgan. In addition to this, marshmallows regularly got pinched in bucket elevators that made the equipment sticky. "Twice a week, we shut down production to clean for several hours."

In the marshmallow making process, numerous pinch points of bucket elevators or conveyor belts can also compromise product quality. When an excessive amount of starch remains, product quality can diminish and production costs rise as materials go to waste. In addition to increasing production costs and adding to cleanup time, these and other open-air conveyors can contribute to respiratory hazards, necessitating that operators wear dust masks/respirators. They can even create an explosive hazard if dust or powders, such as starch, mix with air in certain combinations.

Maximizing Safety

To maximize safety, production efficiency and product quality at its Bensenville marshmallow plant, Doumak turned to Belleville, N.J.-based VAC-U-MAX, an expert in the design and manufacture of pneumatic systems and support equipment for conveying, batching and weighing dry materials.

After extensive testing to ensure required product quality, feed rates and other variables, VAC-U-MAX installed two pneumatic conveyor systems at the Bensenville plant that deliver finished marshmallows from processing to packaging, when each of six packaging machines signal for more product.

Instead of bucket elevators dumping marshmallows into packaging machines at an inflexible pace, vacuum receivers pneumatically convey the marshmallows through six FDA, USDA-approved hoses to the packaging machines on demand.

"With pneumatic conveying, if a packaging machine malfunctions, we can easily divert product to the other machines at the touch of a button," says Morgan. "And we have individual feed control, which allows the packaging machines run at maximum efficiency, no matter what size the product or bag. There's no overfeeding one machine and underfeeding another. The flexibility of pneumatic conveying adds about 8 hours a week to production, eliminating many of the production/packaging bottlenecks of bucket elevator systems."

Morgan added there's virtually no maintenance or cleaning necessary in the pneumatic conveying systems because they have few moving parts. "We just clean or swap out hoses, and check the motor and oil twice a year. That addsperhaps 30 hours a year of production, compared to doing monthly preventive maintenance on 20 or so moving parts for bucket-elevator type systems."


With the pneumatic conveying systems, vibratory pans shake loose excess starch from the marshmallows as they exit the cooling drums. The starch goes through filter separators and is recycled back to manufacturing for reuse. On the sides of each filter separator are explosion vents to safely redirect energy from any dust-triggered explosion, should one occur. Because the pneumatic conveying systems are enclosed, they keep loose starch from getting airborne and provide nearby workers with a cleaner, safer environment, so there's no need to wear or dispose of dust masks or respirators.

An added benefit of the systems is that they reclaim about 1,000 pounds of starch a day and reduce product loss by up to 2 percent, according to Morgan. "They put the starch back to good use."

Eliminating the many "pinch points" found in bucket elevators and other traditional equipment reduces excess starch in bagged marshmallows, which improves product quality. "Less physical contact means there's fewer places for sensitive product to get pinched or damaged," explains Morgan.

An additional benefit of the pneumatic conveying systems is they require 70 percent less factory floor space than their bucket elevator equivalents. The extra floor space allows Doumak to store raw materials next to the production line, saving travel time to restock at a central supply location.

"With pneumatic conveying systems, production is safer and up to 15 percent more efficient and product quality is better than with traditional equipment like bucket elevators," concludes Morgan. "That's important for those of us in the food or confection industries, where 24/7 plant operation is common and downtime must be kept to an absolute minimum."

VAC-U-MAX offers a wide range of standard pneumatic conveyor systems, weighing systems and accessories, plus semi-custom systems, as well as totally custom-engineered systems. For more information about VAC-U-MAX pneumatic material handling or industrial vacuum cleaning solutions, visit www.vac-u-max.com.

Del Williams is a technical writer based in Torrance, Calif.

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