Multi-stage optical inspection process reduces labor costs and delivers high quality end result.



No matter how you slice it, green beans mean business for Faribault Foods’ Mondovi, Wisconsin, plant. The facility processes nothing but green beans in season during an intense three-month period to supply all of its distribution centers around the country. During a typical season, the plant processes 30,000,000 pounds of green beans.

But mass quantity doesn’t mean minimized quality for Faribault’s customers. “We have a meticulous inspection process,” says Jim Kern, plant manager. “We grade by size because of customer demand. One wants a cut bean with a larger diameter and another wants a smaller size.”

Faribault Foods takes the usual cleaning steps when truckloads of green beans arrive at the plant. Before the raw product hits Key Technology’s optical sorters, the beans have been through dirt reels, air cleaners, washers, destoners, and cluster cutters. Then Key’s Tegra is put to work.

“We put the beans through a two-pass inspection process using the Tegra so none of our inspection equipment downstream is overloaded,” Kern says. “We get the foreign objects out with the first pass and the second pass is more for EVM (extraneous vegetable material) that’s green, like knuckles and ends that haven’t been cut off.”

After grading for size, larger beans are inspected on a smaller, two-camera Tegra as whole beans where about one third is selected for the French cut style. The balance goes through cutters, then to another Tegra for size grading and onto Optyx for grading by diameter.

The Optyx features the same camera, lighting, imaging, shape detection, and ejection technologies found in the Tegra, but is proportionately sized for lesser volumes in a self-contained one-meter (42-inch) cabinet. While the Tegra units are used downstream where the volume of whole beans is as high as 12 tons per hour, the Optyx units inspect four tons an hour each.

“Optyx fit the flow of our plant and our capacity,” notes Kern. “We didn’t really need a Tegra unit at this point in the process. The goal of putting in the Optyx wasn’t to increase capacity, it was to increase our product quality.”

Each Optyx is dedicated to sort a specific diameter size—one for small and one for larger sized beans. According to Kern, production efficiencies are enhanced since there is no need to change programs to target different sizes. “We try to let each machine do a specific thing instead of asking it to do everything. We have better luck doing it that way.”

The Optyx units have eliminated the need to manually inspect the cut beans after the Tegra checks for diameter specifications, reducing labor costs. Kern reports that between the manual inspection replaced by the Tegra and Optyx systems, Faribault has cut its seasonal staff from 145 to 105. All of these savings add up to an expected three-year payback for the two new Optyx units.