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CONTROL AND automation advances in the food industry have seemed a long time in coming to many observers, but come they have. Don't look to be dazzled by lots of gee-whiz gadgetry. The food industry is nothing if not practical. Keeping food safe and saving money remain top plant priorities. Productivity, efficiencies, security and safety still head the list of objectives.
Nevertheless, a handful of leading-edge technologies seem perfectly adept at just that. So things such as vision systems, robotics and sophisticated networking and communications are making inroads in food plants.
An Eye on Vision Systems
“As machine vision technology has become more rigorous it has become more successful in addressing applications in the food industry,” says Nello Zuech, a consultant to the vision industry and contributor to Machine Vision Online.
“While there are many applications of machine vision in the packaging side of the food industry [newer] applications include sorting and grading,” he continues. “With advances in color cameras and the underlying ability of microprocessors to handle the additional data derived from color-based processing, more applications are being addressed. In some cases multispectral processing is now possible at the speeds required to keep up with processing tons of a product per hour.”
Inspection is a key job for vision systems in the food industry. A Cognex vision system inspects bottle caps at Original Juice Co.
In addition to being reliable and repetitive, the vision system would need to inspect at speeds of up to 300 bottles per minute. The In-Sight 5100 from Cognex, Natick, Mass., incorporates a die-cast aluminum housing and sealed industrial M12 connectors to achieve an IP-67 rating for dust and wash-down protection on the factory floor. These environmental attributes would prove to be crucial in withstanding the wet, citric-acid environment of the inspection site.
The overall system consists of a touch-screen industrial PC incorporated into a stainless steel enclosure. The enclosure also houses the Ethernet hub, the digital power supply of the lights, a PLC and various power distribution components. After bottles have been filled and capped they travel down the conveyor line, where two cameras sequentially inspect the bottles.
The first camera looks directly at one side of the bottle and inspects the bottle cap at this side only. A red LED backlight provides the camera with a silhouette image of the bottle. Back lighting provides maximum contrast between the product outline and its background and is ideal for measuring external part edges. This results in images that work extremely well for the vision sensor's measurement and inspection tools.
When the bottle comes within the camera's field of view, a sensor is triggered and an image is taken. Cognex In-Sight vision software tools then analyze the image for defects and determine whether a bottle is flawed or not. In the event of a failure being detected, a fail signal is sent via one of the camera's outputs to the PLC. The PLC then triggers a reject mechanism, which removes the bottle from the line. After passing the first camera, the bottle will travel a little further before the second camera acquires another image of it, performing the same inspection on the other side of the bottle cap.
The poster child of advanced automation is the robot, the multi-functional, programmable machine that is almost synonymous with high-tech equipment. Robots have made slow entry into the food industry, primarily due to their high cost and an old reputation for being slow.
"We have worked hard to improve our product lines in sanitary food applications, says Rick Tallian, segment manager for ABB Inc., a manufacturer of industrial robots based in Auburn Hills, Mich.
Robots have a special talent for careful and accurate handling of delicate product. Dramatic improvements in system speed, coupled with continued refinement of their pick-and-place capabilities, have enabled them to find niches in several industry segments.
"Robots are very good in picking, packing and palletizing operations," says Ann Smith, spokesperson at ABB, noting the use of robots in snack handling, cookie assembly and icing, and portioned meat handling. Credit improvements in speed, sanitary design, software and affordability for the expanded applications. Processors also are becoming more confident in robot use.
Smith reports that one pretzel manufacturer uses a robotic system to handle pretzels individually. The system, featuring the high-speed IRB 340, performs up to 150 "picks" per minute. But the pretzel maker's real productivity increase comes in the dramatic decrease in damaged product. The robot's picking capability is quick and deft.
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