Monitoring Manufacturing of Blister Machines Using Roughness Values

Product safety is vital in the production of pharmaceutical packaging and is subject to strict requirements. Uhlmann — specialists in the field of pharmaceutical packaging — uses the help of Alicona to confirm the quality of machine components, thereby acquiring knowledge on the reproducibility of manufacturing processes.

Quality Assurance in All Stages of Production

Pharmaceutical packaging should be optimally sealed to block foreign substances from entering and also it should adhere to all legal guidelines on traceability and counterfeit protection. With regards to the production of pharmaceutical packaging, focus is mainly given to the protection of high-quality ingredients and formulations while maintaining complete functionality.

Uhlmann Pac-Systeme GmbH & Co. KG, located in Germany, is one of the top suppliers of pharmaceutical packaging in the world. Uhlmann’s product series includes machines for all process steps, ranging from bottling lines and blister machines to cartoners and end-of-line packaging machines. This range is enhanced by extensive services for the whole life span of the systems.

3D pill measurement. Uhlmann use optical measurements to gain information on the slide characteristics of pills and capsules.

3D pill measurement. Uhlmann use optical measurements to gain information on the slide characteristics of pills and capsules.

New Knowledge on the Reproducibility of Manufacturing Processes

When producing unique pharmaceutical machines, the focus is to apply professional quality assurance processes at all production phases. A high-resolution measurement system, InfiniteFocus, is employed by Uhlmann to test the machine components and the packaging products they manufacture.

Alicona enables us to gain new knowledge on the reproducibility of our manufacturing processes. Besides this, the measurements also enable us to verify supplier specifications for purchased parts, predict the functional behavior of products and carry out cause analyses on the functionality of products.

Matthias Obert, Member of Quality Management Team, Uhlmann

Roughness Measurements to Monitor Manufacturing of Blister Machines

Obert uses the manufactured blister machines as an example to describe the process monitoring during serial production. “We use Alicona to carry out monitoring measurements in the manufacturing process and to verify the geometry and surface properties of individual components.” Blister machines are employed to manufacture blister packaging, more commonly called “blister packs”. These packs consist of pre-sorted medicine and are hygienically sealed using aluminum or plastic composite foils. Each individual drug unit has its own “cup”, from which the capsule or tablet can be popped out using your fingers.

Sa, Sz, Sk Roughness Parameters Verify Functionality

The process steps of a blister packaging machine predominantly involve the molding of the cup-shaped depressions into the base, which is composed of aluminum foil. The products — capsules or tablets — are subsequently placed in the cups. The next step involves feeding a cover film through the sealing station and positioning it over the base foil. The cover film is warmed up with the help of hot plates to allow it to mold to the base foil, thus covering the product in the cup-shaped depression.

Uhlmann employs the measuring system to determine material parameters (Sk, Spk) and surface parameters (Sa, Sz) to avoid adhering to the hot plates and to guarantee optimum heat distribution on the hot plates. “Surfaces with similar Sa values can have completely different structures. Often, one can only provide a sound statement about the functional behavior of the surface after evaluating the material ratio parameters,” said Obert.

Left: 3D measurement of the hot plate surface in true color. The hot plates warm up the cover film before sealing it onto the base foil. Alicona enables Uhlmann to determine extensive surface parameters (Sa, Sz) and material parameters (Sk, Spk). Right: 3D measurement of a blister sealing area in true color.

Left: 3D measurement of the hot plate surface in true color. The hot plates warm up the cover film before sealing it onto the base foil. Alicona enables Uhlmann to determine extensive surface parameters (Sa, Sz) and material parameters (Sk, Spk). Right: 3D measurement of a blister sealing area in true color.

“Dimensional Measurement Gives Essential Information!”

Sealing rollers composed of high-quality aluminum or tool-grade steel are used for bonding the film to the foil. The contact surfaces of the rollers have slanting surfaces and tips forming a pyramid-shaped corrugation. The distribution density of these “pyramids” decides how deep the tips penetrate in the foil composite and thereby offers a contact face adapted to the surface pressing demands.

Before we switched to the measuring technology of Alicona, we could not measure these corrugated geometries. The analysis of the pyramid stump dimensions, such as the angle, height, and distance to each other, gives us indispensable information.

Matthias Obert, Member of Quality Management Team, Uhlmann

Impact of Shape, Roughness and Color Information

After the sheet is hermetically sealed, each tablet is covered by two transverse sealing gutters and two longitudinal sealing gutters. The seal shape of the blisters is verified during the packaging process. Through color evaluation and shape measurement, Uhlmann can verify the homogeneity of the impression as well as gutter height and width.

Once the carrier foil and cover film are sealed, specific safety features such as batch number can be embossed permanently on the blister reel. With the help of die stamps, the serial numbers are punched in. Uhlmann employs InfiniteFocus to guarantee the correct letter height of the die stamp, measure the surface roughness, and carry out a visual inspection.

InfiniteFocus

Simple Handling and Extensive Applicability

Then, the cut regions of the punched blister packages are assessed.

About Alicona, we particularly appreciate the ease of use of the system and its extensive applicability. The color-coded height representation comes in very helpful to communicate surface properties easily and intelligibly to other interfaces in the company.

Matthias Obert, Member of Quality Management Team, Uhlmann

Why Tactile Measurement is No Longer Suitable

In addition, Uhlmann needs information on the slip properties of the capsules and tablets to assure the quality of the production process of the blister machines. In order to perform this, the surface roughness of the medicine must be known. Tactile measuring techniques are not appropriate for this application since the surface of the measuring object can change or get damaged if directly contacted with the medicine. Alicona helps determine surface characteristics of the tablets (for example, Sz and Sa) without contacting the surface.

This information has been sourced, reviewed and adapted from materials provided by Alicona Imaging GmbH.

For more information on this source, please visit Alicona Imaging GmbH.

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