Cognex OCR Technology meeting product regulations in toughest environments
Croatia-based INFO d.o.o. a distributor of Videojet (a leading manufacturer of industrial coding, printing and marking products) has developed a date printing and checking solution for a global building materials company. In addition to providing high quality products and reliable service to customers and communities throughout the world, INFO’s customer also needed to comply with new Croatian legal regulations calling for a printed production date on the side of each cement bag they produce in order to control quality and product counterfeiting. In order to comply, the company installed ink-jet printers on their packaging lines but this action alone did not solve the problem. The cement manufacturing line is a very rough production environment and date printing was not always successful and some bags went to the market without the required documentation. To tackle this problem, INFO deployed the robust Cognex In-Sight® 5000 vision system with its Optical Character Recognition (OCR) tool and this has proven to be the most suitable technology for the job.
The challenge: reliable work in very rough conditions
Factory floors where 25 and 50 kg bags of cement are produced are extremely challenging environments. When the bags are filled with cement they are dropped on to a conveyer and with a set of steel bars. Plates guide them in the right direction and position on the conveyer. Very often, the paper bags are accidentally torn apart and cement dust fills the environment. The second problem is that the bags are stained with cement from the outside. Very often the position of the bag on the conveyer is not perfect so the distance between the head of the ink-jet printer and the bag is not consistent. As a consequence, the difference in size, quality and position of the printed characters is significant. In addition, the lighting and contrast are very inconsistent - if the bag has a thin cement layer on the surface where the characters are printed, the contrast is very low and this creates a noisy background for the vision system.
The solution: In-Sight 5100 vision system
To solve this challenging application, Cognex Automation Solution Provider (ASP) Tipteh Zagreb d.o.o. conducted tests with different lighting and camera positions to achieve the best possible result.
At the conclusion of testing it was clear that the In-Sight 5100 vision system delivered the robustness, ruggedness, and software tool performance required to solve this application reliably in all physical conditions. Dust in the atmosphere had very little impact on the images acquired by the vision system because it features powerful lighting and good camera lens protection. Any challenges associated with the variable positions of the characters were handled by the pattern algorithm and the robust OCR tool. For inspection results monitoring, In-Sight is connected to the VisionView® 700 operator interface panel so that the operators can monitor the process. The In-Sight is also connected to the PLC over MODBUS TCP. In this network, In-Sight sends the decoded characters to the PLC and the PLC then compares them with characters in the database. The easy and smart integration of the In-Sight vision system with the equipment of different manufacturers (Unitronics PLC in this case) played an important role in solving this application and proved that In-Sight was the right choice for this application.