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Motion System Design

Color sorting quick facts

Sensing color: Many products (from automotive parts to food packaging) either have color requirements or are color-coded. Industrial color sensors are used to inspect these items for quality, key features, and hue and intensity. Usually either color cameras or photonic spectrometers are used, but a newer option to speed inspection is true-color photoelectric sensors. These have 60-µsec response times. Some designed for web processing can even detect marks on spooled product as small as 1/16 by ¼-in., depending on opacity and winder velocity.

Primary function: Most color sensors on production lines either verify pigment or send signals to controls that trigger mechanical removal or redirection of mismatched product.

Redirection: Several systems remove, mark, and track flagged parts on assembly lines and machines: Simple air cylinders and electric actuators push product off of conveyors; mechanical gates open and close to redirect product to alternate lines for elimination or repair; inkjet printers mark and identify product for later removal when mechanical constraints at the inspection location prevent immediate redirection. Other times, product to be rerouted is punched with a hole or marked with chalk.

These handy tips were provided by Tim Kelley of Tri-Tronics Co., Tampa, Fla. For more information, call (800) 237-0946 or visit

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