When Amcor (www.amcor.com) wanted to improve its quality assurance process on a line producing multiwall sacks for dry dairy products, it tasked iQVision (www.iqvision.com.au) to provide a vision-based inspection system.
In the manufacture of Amcor's multiwall bags, hot glue is first applied to their tops. These are then reheated and sealed by the company's customers during the filling process. To ensure the sacks seal properly, the glue must be applied in the same position, with strips all the same width and length. This prevents foreign material—including the reheating glue—from coming into contact with the bag's contents.
Although Amcor had deployed an existing vision system to handle the task, the company required greater precision to detect any excess hot melt at the top of the sack.
The system developed by iQVision uses a blue fluorescent illumination system to highlight the glue on the bags. According to iQVision's managing director Ken Razga, although the system works well, the tubes need to be replaced at regular intervals, so the company is now considering using LED-based lighting.
iQVision used a Cognex (www.cognex.com) In-Sight 5604 linescan camera to capture images of the bags. One-pixel-long slices along the length of the bag are then combined into a single image.
The result is a detailed image of each bag that can be used by the In-Sight software to check the exact amount of glue applied and its position on the bags as they pass the inspection station at an average rate of 160 bags/min.
The camera-based vision system is placed near the end of the production line, just before a reject station, where product that does not meet the quality assurance criteria is collected for disposal.
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