Vision system case study.
We were approached by a company who needed to make real-time measurements of holes that were being laser machined into packaging film. In order to measure the holes we mounted the vision system directly onto a web that moves at 350m / minute. The holes being measured varied in size between 30 – 120µm depending on how particular perforation jobs were set up. The vision system we installed checks that each hole is present and measures the whole to ensure that it is the correct size.
We achieved accurate measurement (in spite of the fluctuations in the speed of the web) by placing four lasers across the web, with a camera placed to correspond with each laser.
Key to the success of the project was the development of a proprietary algorithm which searches for the hole but disregards imaging locations with no hole features. This algorithm also provides the operator freedom to add or reduce web tension which also impacts the trigger location. An algorithm was also developed to find the holes in noisy images based upon the target hole size entered in to the laser system. This helps avoid detecting background noise as a hole feature.