Boehringer Ingelheim switches to 100% testing of capsules

Published: 20-Aug-2010

Uses digital camera from Allied Vision Technologies

German pharmaceutical manufacturer Boehringer Ingelheim has developed an optical testing system in-house for its capsule filling line at Ingelheim that uses a camera supplied by Allied Vision Technologies.

At this plant, the company produces, among other items, inhaled medicines for respiratory diseases. The active ingredient is loaded in micronised powder form into pharmaceutical hard gelatine capsules. Patients then load these capsules into special inhalers.

Each capsule contains 5.5mg of powder, which is dispensed by filling machines into the capsules in a weakly compacted cylinder. The precise and rapid dosing of such a small amount of powder is a masterstroke of Boehringer engineering. Nevertheless, there is a residual risk that the amount deposited into individual capsules might deviate from the intended value.

Such risk is unacceptable to Boehringer and the company has developed the 100% optical system under the direction of senior scientist Peter Stöckel.

Boehringer placed the optical system in the assembly process after filling and before sealing the capsules. After filling, the content of each still-open capsule is imaged from above. The filling machine’s clock pulse triggers a digital camera and its dedicated LED flash unit via the camera’s external trigger input. The half-capsule is then illuminated from below using a high-intensity LED. Since the camera cannot be housed over the capsules that are travelling past, it captures their contents via a tilted mirror on the side. The camera in use is a Marlin F-046B from Allied Vision Technologies.

This camera, through its FireWire connection, transmits the image data to an industrial PC. There, applications software analyses the images. Boehringer programmed the software, based on NI LabVIEW 7.1 by National Instruments.

After the capsule has been localised within the image, the imaging software first tests whether it contains any powder. If so, it then analyses the silhouette of the powder cylinder to derive the volumes and amounts of the active ingredient. If a capsule is identified as defective an SPS-controlled air jet removes it.

‘At an output of 80,000 capsules per hour, one capsule leaves the filling machine every 45m/s – put another way, the capsules move at a speed of 1.5m/s,’ said Stöckel. This means the camera must capture 22 capsules per second. To avoid motion blurring, the exposure time cannot exceed 80μs.

‘We’re very satisfied with the Allied Vision Technologies camera. In continuous operation, it gives us sharp images that are indispensible for reliable evaluation,’ he added.

The imaging system has now been installed on several machines in series production.

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