Achieving 100% error-free quality control

10 January 2012

Pharmaceutical company, Boehringer Ingelheim currently produces around 120 million blister packs of prescription-only drugs every year. Its products are designed to reduce blood pressure, treat patients experiencing shortness of breath, and treat thrombosis.

Traditionally, the company has relied on manual inspection to ensure the print quality on the blister packs. Under normal circumstances, the human eye is able to see printing on a blister pack or folding pack of medication easily. However, when faced with the task of inspecting printing quality on a production line that products around 300,000 blister packs and 100,000 folding packs every day, manual inspect is unable to meet the quality control demands. At this level of production, Boehringer Ingelheim relies on vision solutions supplied by Cognex and Weber Systemtechnik to achieve its quality control objectives.

In Boehringer Ingelheim’s production process, blister packs pass over a narrow belt at a speed making it is impossible for the human eye to see any more than the outline of the individual objects. The vision technology deployed to inspect blister pack printing here is said to ensure 100% error-free quality. Absolute transparency in the production process has replaced the unreliable projections made by humans.

On the manufacturing floor, four inspection stations inspect the printing of blister packs as well as a brand new unit for inspecting folding medication packs. At Boehringer Ingelheim every product gets a quality inspection. This has been made possible by Wesys-OCR vision software based on VisionPro from Cognex.

Quality under pressure
The principle is simple – a camera identifies a series of letters and numbers, rejects defective objects and moves accepted objects though the production process. The speed at which the blister packs move and the accuracy of inkjet printing make this a challenging task. Inkjet printing can be highly inaccurate when it is required to print consistent clear images on foils with irregular surfaces such as blister packs. Small spots of ink not applied where they are supposed to be can be enough to cause a product to be rejected, and the pharmaceutical market in Asia is especially quality-focused in this respect.

Boehringer Ingelheim achieves its high quality control levels by deploying a commercially-available industrial camera in each of the four blister pack inspection units, supported by LED ring light, that detects the printed undersides of the foil in fractions of a second. The information is transferred to the VisionPro-based Wesys-OCR vision software at high speeds so that it can perform a precise sample comparison. Depending on the product type, particular examination is made of varying details which are applied – including lot number and expiry date – in addition to looking at pre-printed information.

The vision software knows and recognises all the relevant symbols and letters and, on the basis of previously-taught parameters and tolerance limits, assesses the quality of a product. The VisionPro-based Wesys-OCR is particularly characterised by its library of flexible, high-precision tools. It is possible to compile complex product profiles that are accurate in every detail. Its particular strengths in the field of reliable sample comparison ensure that even reflections due to uneven surfaces and the changing foil colors of silver and white do not affect reliable inspection. VisionPro-based Wesys-OCR reacts intelligently in these instances to fluctuations in print position and print quality.

Handling additional challenges
The greatest enemies to detecting unacceptable print quality in the folding pack are dirt, pressure, and sharp edges. In instances where these factors are present, the system ensures that defective folding packs are prevented from reaching the customer. Supported by white LED surface illumination, six industrial cameras examine all the sides of each individual pack – at rates of up to 80 a minute. Dirt, pressure, and sharp edges do not generally affect quality control of blister packs but there are sometimes exceptions. In the event that any blister packs do contain slight dirt or damage, incorrectly glued tabs, and print errors, the system can ensure that the products are handled appropriately.
The system can be operated via touchscreen or keypad. The employee feeding the packs into the inspection process by hand determines the proper product format. The employee selects the specified data from a clear list and starts the inspection process at the touch of a button.

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