Ingredient screening upgrade boosts pet food production.

Mobile 30-in. (762mm) diameter vibratory bag dump screener sifts dry ingredients prior to mixing them with meat protein. The waist-high unit minimizes physical effort in bag dumping, and includes a built-in dust collector. Source: Kason Corp.<br><br>

Established in 2005 by dog lovers John Phelps and Scott Morris, Freshpet produces refrigerated dog food products under two brand names for nationwide distribution through approximately 3,000 retailers. All of the products, marketed in supermarkets under the Freshpet Select brand and in specialty pet retailers under the Deli Fresh name, are made from fresh ingredients, including chicken, carrots, peas and rice, and contain no byproducts, fillers or preservatives.

Freshpet sifts and screens dry ingredients to maintain particle size uniformity and remove clumps and incidental foreign material prior to mixing the ingredients with meat protein. The company’s maintenance staff had designed and built a 20-in. x 20-in. sifting screen that could handle about 10 lbs. of ingredients at a time. An employee had to push the ingredients through the screen with a scraper. “Our guys went to a local box hardware store for the materials. It was real do-it-yourself affair,” says Michael Hieger, Freshpet’s general manager.

“It was a sturdy, little screen and kind of ingenious in its way, but we were having issues with small clumps in our dry ingredients. It would take us upwards of one hour to manually sift enough dry ingredients for one batch,” adds Hieger.

The company decided to upgrade the screening process for this and other reasons:

• It was forced to hire temporary help for screening when an employee could not be spared from another processing line.

• Dry ingredients are supplied in 50-lb. bags that are too heavy for some workers to lift and pour onto the screen.

• Ingredient uniformity was an issue. The manual process “did not produce the kind of uniformity we wanted in our dry ingredients,” explains Hieger. “The quality wasn’t there.”

Freshpet contacted Chris Dugan of Separator Technology (Browns Mills, NJ) for some recommendations, and purchased a Kason Corporation mobile, circular vibratory, bag-dump screener, which discharges into the feed hopper of a flexible screw conveyor. The screener is a Vibroscreen Flo Thru (low-profile) model with a single-deck, 30-in. diameter screen and built-in dust collector.

A worker now dumps a full bag of dry ingredients onto the screen that-at half the height of Freshpet’s homemade screener-reduces physical effort while the dust-containment system improves safety and plant hygiene. The screener employs two imbalanced-weight gyratory motors, mounted externally on opposite sides of the screener, to impart multi-plane inertial vibration that maximizes the rate at which particles pass through or across the screen surface.  Material clumps and foreign material discharge through an “overs” discharge spout at the screen’s periphery, while on-size particles (≤5.66mm) discharge by gravity at a rate of 50 lb./min. into a 6-ft. long, 6-in. dia. flexible screw conveyor inclined at 45°. Screened material is conveyed into mobile bins that are wheeled to the processing side of the plant for blending with proteins and cooking.

Mobility was important because the screening operation runs on an as-needed basis. Freshpet also wanted the option to use the space for additional purposes, and to empty the area for washdowns between shifts.

“What used to take us an hour now takes 10-15 minutes, and one person can easily lift 50-lb. bags to the height of the low-profile screener,” explains Hieger, adding, “The efficiency gained by the system is such that Freshpet’s production would have to increase a large amount before the screening operation once again bottlenecked production.”

For more information: Henry Alamzad, Kason Corporation, 973-467-8140,