Good planning of vision inspection

Good planning also includes laboratory tests

Before deciding to purchase a solution for vision packaging control, it is wise to test the solution with the client’s own products. On request, Laetus can perform such sample tests, to build the best possible quality inspection solution from modular systems. Thanks to these tests, the pharmacist can also gain new knowledge about his process.

“The biggest challenges in package inspection are on the one hand, the belt speed, and on the other, the alignment of the object to be read in the case of rotating products,” explains Sadegh Deshmeh, Application Engineer Vision and Sample Tests at Laetus. “The evaluation units need reliable parameters and anchor points as a reference. This is difficult when the object is rotating, but not impossible.”

“What makes the work so exciting? No day is alike, each test job has its own peculiarities,” explains Deshmeh, “and thanks to the modular structure of our solutions, we can always select the right tools. Of course, the solution consists of a number of components, such as the right camera and appropriate lighting, which are combined to achieve the perfect inspection. It may also be the case that an external tool is used if it helps to achieve the objective.”

Laboratory vs. production

The environment created by the customer on site at the packaging line cannot be taken into consideration in the sample test. But from many years of experience in vision quality inspection, the testers know exactly what additional recommendations to make. For example, any disruptive light influence in the production hall can lead to incorrect results. The right light protection cover and corresponding filters therefore also form part of the optimum solution.

Deshmeh recalls a comprehensive test task, in which seven different aspects of syringes had to be checked. These ranged from checking the position of the plunger, to checking the presence of the syringe head and needles, right through to color inspection of label, finger flange and plunger as well as other points, such as the color mixture. All of these inspections can be performed with the vision quality control solution INSPECTwt.

The customer often wishes to carry out additional inspections at a later date, believing that simply because the test went smoothly with the initial requirements, the same will apply to the additional criteria. However, this isn’t always the case. Sometimes an additional camera or a sensor has to be installed which can become an issue with space limitations in many packaging lines. For this reason it is important to discuss any desired modification to ensure a reliable solution can be found.

It must also be taken into account that the tests must be carried out during standstill and for this reason, the speed of the belt must be factored into the vision inspection sequence. Here, various tried-and-tested formulas are available which almost exactly replicate live operation.

  • 1 Sample tests show feasibility

    3 Cost efficiency

  • 2 More targeted planning with pre-testing

Labels can prove tricky

The position inspection of labels on packaging is always challenging. An example from the cosmetics industry shows that sample tests are not directly transferable. One customer required various aspects to be checked in three branches. In two branches, the task at hand was vision inspection of labels on the front and rear side of bottles in two different sizes; in an additional branch, the sealing caps also had to be checked. The product colors were all different, which also influenced the result. The biggest challenge? Uneven edges on the labels. First, just presence and position of the labels was to be checked. This was possible without any problems, because – despite the unevenness – there were sufficient reference points and the bottles were transported on a belt. But then another request followed… identify damaged or incorrectly-applied labels. This could not be resolved satisfactorily due to the uneven edges. Later, in yet another branch, plain text and code inspections were also requested, which was once again viable without problems.

A similar request came from the personal healthcare sector. Here though, the request related to three different sizes of rotating objects, on which the position of the labels and a code were to be checked. Here, the task wasn’t easy to solve. It was possible to tackle the positioning, but given the very small font size and the poor print quality, the conditions for code reading had to be changed: Either a slower line speed, a second inspection station with a higher camera resolution or investment in a more powerful printer. In such a case, clarify with the customer as to where the priorities of the inspection lie and discuss potential alternatives.

Exciting cost efficiency

If the object to be inspected does not contrast much with the background, very high resolution cameras must be used, which is of course reflected in the costs. This is exactly why Deshmeh and his colleague Houshang Deris consider this point when establishing a sample test. Using a table to determine the optimal camera resolution, the sample testers select the appropriate camera. If reading difficulties arise, the resolution can be further increased. In this way, customers receive an individual offer for their request. “Sample tests are entirely practical, both for our customers and for us as a service provider. They provide planning security, especially when implementing in a packaging line and help to minimize costs,” explains Deris, and adds: “The varied tasks we are asked to perform constantly provide us with potential to improve our solutions.”

Sample tests for packaging vision quality inspections – a win-win situation.

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