Machine Vision Helps BI Achieve Quality Control

Boehringer Ingelheim (BI), the world’s largest family-owned pharmaceutical company, produces around 120 million blister packs a year. The prescription-only drug products in BI’s blister packs are manufactured to reduce blood pressure, treat patients experiencing shortness of breath, and treat thrombosis.

These products get into patients’ hands via pharmaceutical wholesalers and pharmacies. In the past, the company relied on human inspections to ensure the printing quality on their blister packs, even though regular random sampling did not allow for meaningful conclusions about quality to be drawn. Under normal circumstances, the human eye can usually 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 churning out around 300,000 blister packs and 100,000 folding packs every day, employing a “human sensor” to inspect products randomly cannot meet the demand of perfect quality control. At this level of production, BI now relies on the vision technology to achieve its quality control objectives.

In BI’s production process, blister packs pass over a narrow belt at speeds impossible for the human eye to register any more than the outline of the individual objects. Today, the vision technology that BI deploys to inspect blister pack printing ensures 100% error-free quality. Absolute transparency in the production process has replaced the unreliable statistical projections made by humans.

On the manufacturing floor, four stations inspect the blister pack printing. Another unit is on station for inspecting folding medication packs. Boehringer Ingelheim’s objective is to assure every single product gets a quality inspection, operations enabled by Wesys-OCR vision software running on Cognex’s VisionPro platform.

In principle it appears perfectly simple: a camera identifies a series of letters and numbers, rejects defective objects and moves accepted objects though the production process. On a pharma production line, there are two factors that make this process challenging: the enormous speed at which the blister packs transit the line and the accuracy of inkjet printing. Inkjet printing is very flexible and practical, but it can generate inaccuracies when it is tasked to print consistently clear images on foils with irregular surfaces such as those found on blister packs. To the untrained eye, inkjet printing may appear perfectly legible, but does not necessarily satisfy a customer’s quality assurance standards. Small spots of ink not applied where they are supposed to be can be enough to cause a product to be rejected, an aspect of quality to which the pharmaceutical market in Asia is especially sensitive.

BI achieves perfect quality control by deploying a commercially available industrial camera in each of the four blister pack inspection units, supported by LED ring light, which detects the printed undersides of the foil in fractions of a second. The information is transferred to the vision software at lightning speed 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 intelligent vision software knows and recognizes all the relevant symbols and letters and, on the basis of previously taught parameters and tolerance limits, assesses the quality of the printing. The system’s OCR software is particularly characterized by its library of flexible, high-precision and easy-to-handle tools. It is possible to compile even complex product profiles which are accurate in every detail. It is particularly adept at reliable sample comparison — even reflections due to uneven surfaces and the changing foil colors of silver and white do not affect reliable inspection. The vision system reacts intelligently in these instances to fluctuations in print position and print quality.

Dirt, pressure and sharp edges are the greatest deterrents to detecting unacceptable print quality on folding packs. In instances where these factors are present, the vision system prevents defective folding packs from reaching customers. Via white LED surface illumination, six industrial cameras examine the corresponding six sides of each individual pack — up to 80 per minute. Dirt, pressure, and sharp edges generally do not impact blister pack quality control but there can be exceptions. On the rare occasions a blister pack is tarnished by dirt or damage, incorrectly glued tabs or print errors, the vision system ensures that the products are handled appropriately.

The system can be operated via touchscreen or keypad. Employees feeding the packs into the inspection process by hand determine the proper product format. They select specified data from a clear list and start the inspection process at the touch of a button. The interaction between humans and the technology occurs swiftly and simply and ensures consistent quality.