In every step of pet and animal food production, from receipt of raw materials through packaging, keeping foreign matter from entering the process stream, and maintaining hygiene are critical objectives.
So is retaining product identity preservation, which adds value by ensuring a quality product free of adulteration. As such, many food processors are reconsidering the use of “open” conveying systems such as bucket elevators and flat-belt conveyors in favor of enclosed systems designed to prevent exposure to ambient conditions and possible contamination.
Since enactment in 2011 of the Food & Drug Administration’s Food Safety Modernization Act, which also applies to pet and animal feed, the importance of preventing product contamination has only increased, with stringent product track and trace mandates as well as demands for safety.
Additionally, as pet and animal food processors seek to increase production uptime and reduce laborious maintenance, the ease of cleaning equipment is a major concern.
Jim Moline, who owns Butler, Mo.-based pet food producer Moline Enterprises as well as Kansas City, Kan.-based animal feed processor International Commodity Services, said, “To create added value, our pet food and animal feed customers are trying to do [product] identity preservation. However, with traditional high-volume conveying systems, there is more potential for unintended cross-contamination.”
In pet and animal food production, line changeovers have become a focal issue relative to both cleanliness and changeover speed, as companies are increasingly running different product lines within a single shift or day. Despite these changeovers, processing plants are expected to maintain rigorous levels of sanitary, contamination-free operation.
“When switching between products, there is always going to be some residue. With traditional high-volume systems, that equates to a lot of labor and time to clean it out and prevent potential cross-contamination,” Moline said.
Also, important to animal and pet food processors’ bottom line is the capability of conveying equipment to reduce any potential product shrinkage or damage (such as to pellets or whole equipment to reduce any potential product shrinkage or damage (such as to pellets or whole flakes) in order to optimize profit and quality.
So, to ensure the safe, clean conveyance of even delicate materials with minimal product loss or degradation, a growing number of animal and pet food processors are turning to enclosed systems such as tubular drag conveyors. Such systems help prevent dust and fine granular product from escaping, which mitigates cross-contamination. The systems also significantly ease, or even automate, cleaning.
Traditionally, bucket elevators and flat-belt conveyors have commonly been used to transport food products. However, open systems like these have substantial drawbacks in terms of the potential for contamination and ease of cleaning.
Bucket elevators utilize a continuous line of buckets attached either to each other on a rubber belt or by pins to two endless chains running over tracks and driven by sprockets. Centrifugal force moves the food being conveyed out of the buckets into a discharge spout as the buckets pass. This type of conveyor handles food products gently but potentially exposes them to contamination from the surrounding environment.
Flat-belt conveyors have the same issue, so some are covered. Unfortunately, the covers can collect residue and must be removed and cleaned between runs — a tedious and time-consuming task.
A chief problem of any open conveyor is that it does not contain dust and fine particles, which can escape and lead to product loss. Even more significantly, it can pose a contamination danger or even a dust explosion hazard.
“High-speed open conveying equipment can create a lot of dust. If the product gets in the air, it can be a source of unwanted cross-contamination. Typically, you end up having to sweep it up and throw it away. However, feed dust also has the potential to cause a dust explosion if it isn’t controlled,” Moline said.
Additionally, open conveyors allow product (if hygroscopic) to absorb moisture. Given that many animal and pet food processing facilities are not climate controlled, such moisture absorption is a very real possibility, and it can cause the product to expand or clump, which can not only degrade quality but also make conveyor cleanup more difficult.
Unlike open systems, closed conveyor systems effectively seal off products from the outside environment and any potential contamination from it.
Although there are several types of closed systems, tubular drag cable conveyors are popular when conveying higher-value animal or pet food that is prone to breaking or product shrinkage.
These systems gently move product through a sealed tube using a coated, flexible, stainless-steel drag cable pulled through on a loop. Solid circular discs (flights) are attached to the cable, which drags the cable pulled through on a loop. Solid circular discs (flights) are attached to the cable, which pushes the product through the tube without the use of air. The coated cable is totally sealed to ensure that no debris accumulates within the strands of the cable.
The enclosed nature of tubular drag systems ensures that no dust escapes, as that could lead to an unsanitary and potentially dangerous coating of dust on the floor or process equipment. The result is a safer, cleaner, dust-free work environment and a reduced risk of dust explosions if the product is in powdered form.
Moline said he utilizes closed-system tubular cable conveyors in both his Moline Enterprises pet food plant and his International Commodity Services animal feed plant.
At the pet food plant, after raw ingredient processing, the tubular cable conveyors transport the pet food to the appropriate bins. At the animal feed plant, bulk product in a flowable granular or meal form from trucks and trains is mixed, converted, and conveyed to produce bagged or toted feed product for fish farming, young pigs or poultry, as well as dairy cows.
“Because the Cablevey tubular cable conveyor is enclosed, we minimize any potential cross-contamination via dust escaping, and we reduce product shrinkage. This enhances safety and profit,” Moline said.
Cablevey Conveyors is an Oskaloosa, Iowa-based premium, specialty material moving, mechanical conveyor company that has designed, engineered, and serviced enclosed cable and disc tube conveyors for almost 50 years and has a presence in more than 66 countries.
In the animal and pet food industry, the conveyors are utilized for product forms such as pellets, flakes, chunks, shavings, crumbles, granules, fluff, regrind, parts, prills, and powders. The systems can convey up to 2,000 cu. ft. per hour, with numerous layouts using multiple inlets and outlets. In the food industry, conveyors are widely used to transport nuts, cereal, snacks, beans, seeds, and coffee.
To avoid external contamination, processors also increasingly expect conveyor systems to be designed for easy cleaning. In this regard, bucket elevators are particularly difficult to clean in preparation for production line changeovers, as each bucket must be removed and cleaned inside and out to remove accumulated residue.
Every minute spent disassembling a conveyor system for cleaning consumes valuable production time, yet if not cleaned properly, the food product being conveyed must be discarded due to contamination, which equates to lost profit. Worse yet, pets or livestock could be harmed, resulting in costly recalls, brand and reputation damage, or even potential litigation and liability.
With closed conveyors, cleaning is also a mixed bag. Pneumatic conveyors are popular enclosed systems, but cleaning can still be relatively time-consuming. Because high-pressure air is used to convey the product, it can create excessive breakage as materials get battered through a course of vertical and horizontal tubing, turns, and sweeps.
“Pneumatic systems can be very dusty, hard to clean, and noisy as well,” Moline said.
To maintain cleanliness, tubular drag cable conveyor systems also offer more options for dry and wet tube conveyor cleaning. These include brush boxes, urethane wipers, air knives, inline sponges, inline bristle brushes, and multistep, essentially automated clean-in-place wet cleaning “With the closed-system tubular Cablevey Conveyors, we have found that doing a bit of a flush handles any potential cross-contamination issues,” Moline said.
Cleanliness is also a key consideration when selecting between cable and chain tubular drag conveyors, both of which come in contact with the food during operation. Tubular chain conveyors have more surface area and connection points where residue can accumulate compared to a coated cable, which has only 20% of the surface area.
“One of the main reasons I went with the tubular cable conveyor system is that it is so easy to clean and maintain as well as quiet,” Moline said. “Those factors go a long way toward keeping employees happy and productive.”
Tubular cable conveyor systems can also require less maintenance than chain-based systems. Heavy chain links tend to wear the sprockets and stretch the operating system used to drag the conveyors more quickly than smooth cable. Consequently, with chain-based systems, sprockets may need to be replaced more frequently, which involves added downtime and expense.