Blister packs not only enclose tablets and capsules in a practical form, but also protect them from moisture penetration. They are therefore indispensable in the pharmaceutical industry. Blister machines are used to produce this type of packaging, which must operate efficiently and with short throughput times. The prerequisite is a continuous sealing process for the packaging films. A research project at Bayer AG is taking a close look at this process. On board is measurement technology from Delphin Technology AG, which generates profitable analyses from data.
Blister packs use film materials to protect the respective item from environmental influences. They are mainly used for medical purposes, as they guarantee the highest standards of hygiene. However, they are also used in the food, electronics and toy industries. In Germany, medicines in tablet form are usually supplied in blister packs. The back wall of these blister packs is usually made of aluminum foil, and for non-medical products also of plastic foil or sturdy cardboard paper. Sealed airtight using a special process, dust particles and moisture have no chance.
At Bayer AG in Leverkusen, blister packaging is the order of the day. Day in, day out, countless tablets in various shapes are packed on different machines before they are sent to the end customer or to the retail trade. As routine as the process is, it also presents challenges. For example, when new film materials are used or new blisters have to be produced on the same machine. Despite their extensive know-how, machine operators still often fall back on their practical experience in operation, test various settings in the changeover process and arrive at the optimized process after a few trials. Even if different paths lead to the goal, valuable time is lost through manual adjustments.
Anna Márton, a student at TU Dortmund University, has taken on this task as part of her doctorate. The aim of her scientific work is to develop a process model for the blister process that provides precise information on the appropriate parameters and settings for machines and systems. This is because there is still no reference work available. The scientific work is being carried out in cooperation with the Invite research center for innovative production technologies (at Chempark Leverkusen). The focus is on the development of process and technology solutions for companies in the chemical, pharmaceutical and biotechnology industries.
ONLY IF THE TECHNICAL
CONNECTIONS WITHOUT EXCEPTION
ARE KNOWN, LET
OPTIMIZE PROCESSES
Together with Philipp Semla, project engineer at Bayer AG, Anna Márton examines the sealing process of the blister machine and scrutinizes weak points. State-of-the-art measurement technology and software from automation expert Delphin Technology, which is already well established at Bayer and has its technology in use in many areas, are used.
BLISTER PROCESS: THE PACKAGING PROCESS
FOR PHARMACEUTICAL PRODUCTS
Basically, a blister consists of a forming film, also known as a base film, as well as the top film and the product to be packaged, such as tablets or capsules. The bottom film is usually made of PVC, PP or aluminum. The top film is printed and is usually made of aluminum or plastic. Márton and Semla use a blister line from the company, which can now be used for research purposes, to simulate the blister process in practice.
The process: The tablets are transported into the machine via a hopper using a feed chute. At the same time, film is fed into the machine via rollers and thermoformed by a heater at three different temperatures. Compressed air ensures that the blister is formed into a round shape. This completes the shaping of the nap-shaped indentations in the bottom film.
In the next step, the tablets are filled into the nap-shaped cavities via a vibratory feeder and fed to the sealing station with the lidding film. The tablets must be positioned exactly in the blister and must not be at an angle or protrude from the top. To ensure this, a check is carried out using cameras integrated into the process. They can see exactly whether there really is a complete tablet in each shape. If this is not the case, the faulty blister is ejected.
The next step is the sealing process, which is the focus of Anna Márton's work. The top film is now heated via the sealing roller and sealed onto the bottom film, thus sealing the tablet airtightly in the nap-shaped cavity. The sealing roller is heated to approx. 220°C, while the counter roller is cooled to 18°C. "This is exactly where errors can occur, because depending on the material, minimal deviations in the process parameters are sufficient and the sealing seam is not 100%ig tight," explains Márton. This results in rejects, the machine comes to a standstill and has to be optimized manually in a rush. This costs time and money.
After the sealing process, the blister tape passes through the perforation station. Here, the perforation is made on the blister in such a way that consumers can separate the individual tablets without damaging the seal of the cavities containing the other tablets. At the next punching station, the blister is punched out of the blister strip and sent to the cartoner, which packs the blisters into folding cartons and prepares them for dispatch.
WHEN THE SEALING PROCESS GETS STUCK
Sealing is a very sensitive process that must function reliably and flawlessly. "For example, the shaping of the blister walls can be faulty in that they are too thin, too thick or not fully formed. It can also happen that the specification of the film materials used does not match the actual material supplied, which means that the bottom and top films do not stick together," explains PhD student Márton. In order to take a closer look at the process, define possible sources of error and create a manual on what needs to be taken into account for which materials and forming tools, the appropriate measurement technology is now being used to enable precise process analysis.
A COMPETENT PARTNER Delphin Technology AG stands for pioneering measuring devices and software solutions for industrial measurement and testing technology: from measurement data acquisition and analysis to test stand automation and monitoring through to vibration measurement technology. The devices are used in electrical engineering, mechanical engineering and the chemical and pharmaceutical industries, among others.
ALL PARAMETERS AT A GLANCE
Measurement technology and software solutions from Delphin Technology form the core of the tests. Based in Bergisch Gladbach, the company specializes in both simple and complex tasks in the field of measurement and testing technology and knows how to solve individual problems automatically. For many years, the measurement technology
expert in the world of Bayer AG and quickly came up with the right concept. But first, let's take another look at the process. Two thermal imaging cameras are used to precisely analyze the sealing process - one is placed on the sealing roller, the second on the blister tape. Here, the sealed tape is examined immediately after sealing. The temperature and the temperature distribution at these two positions are analyzed. The system is also equipped with other sensors that record the coolant temperature, flow rate, sealing pressure, tension and current of the sealing roller, system temperature, room temperature, humidity and the web tension of the film.
COMPREHENSIVE MEASUREMENT ANALYSES
With the right measurement technology, the research team has many options at its disposal. These include analysis and monitoring functions, intelligent signal pre-processing with autonomous data storage and versatile fieldbus connections. Profisignal Go software the measurement data can be visualized as a diagram in just a few steps - both online and offline - and weak points can be made visible. In addition, Márton and Semla rely on data loggers that allow complex data acquisition. The device series Expert Logger proves to be particularly flexible in this respect, as up to 46 analog input channels can be processed independently with just one device, both at low and high sampling rates.
The required measurement technology is compactly positioned in the control cabinet and can be easily integrated into the existing infrastructure thanks to integrated interfaces
The measured values are precisely recorded, monitored, pre-processed and stored internally in the device memory. "The integrated interfaces, such as OPC UA, are a particular advantage of our measuring devices, allowing the customer to connect them optimally to the existing infrastructure," emphasizes Dietmar Scheider. And finally, the control cabinet could be realized with all the necessary equipment components and was even designed to be compact.
CONFIGURABLE ACCORDING TO REQUIREMENTS
"We chose Delphin Technology because we were able to obtain all the necessary measurement technology and software systems as well as flexible configurability from one manufacturer," summarizes Semla. "We were able to have the control cabinet configured as required for our needs. The connection technology was also so flexible that we could freely select our connections and plug connectors for the sensors without the need for new wiring.
Other advantages were the speed and dynamics of the devices, the convenient and intuitive operation of the software and the fact that we were able to teach the devices to function in no time at all without any major training. Thanks to the connection to OPC UA we were also able to read our machine data directly into the Delphin systems. Conversely, external data from infrared cameras or data listed in Excel files could be transferred to the Delphin measurement technology."
OUTLOOK:
INLINE PROCESS CONTROL
"We chose Delphin Technology because we were able to obtain all the necessary measurement technology and software systems as well as flexible configurability from one manufacturer," summarizes Semla. "We were able to have the control cabinet configured as required for our needs. The connection technology was also so flexible that
We were able to freely select our connections and plug connectors for the sensors without having to rewire them. Other advantages were the speed and dynamics of the devices, the convenient and intuitive operation of the software and the fact that we were able to teach the devices to function in no time at all without any major training. Thanks to the connection to OPC UA, we were also able to read our machine data directly into the Delphin systems. Conversely, external data from infrared cameras or data listed in Excel files could be transferred to the Delphin measurement technology."
Images: Decorative image DedMityay - stock.adobe.com,
other Nicole Steinicke
COMPANY
Delphin Technology AG
Lustheide 81 , 51427 Bergisch Gladbach
Phone 02204 / 97685-0
AUTHOR
Dipl.-Ing. (FH) Nicole Steinicke,
Editor-in-Chief Industrial Automation