For 50 years, Bausch+Ströbel in Germany has been developing packaging and production systems for the pharmaceutical industries. The company’s goal is to offer the best technical and economical solutions for the challenges of modern industry. Its new ESA1025 labelling machine shows how this is achieved with PC-based control from Beckhoff as the central motion controller.
High-quality liquid and powdered pharmaceuticals are filled into syringes, vials, cartridges and ampoules. The process starts with cleaning and sterilising the objects and extends to labelling and syringe assembly.
Modular label dispenser with servo drive technology
Self-adhesive labels on a roll are used for labelling vials and similar pharmaceutical containers. To ensure these can be applied quickly, accurately and reliably, the ESA1025 labelling machine is equipped with a new modular label dispenser. The benefits include precise and gentle labelling, fast, tool-free changeover to other object and label sizes, and increased print quality through servo drive technology from Beckhoff. The system is also extremely compact, as the entire electrical system and control components have been integrated into the machine to save space. The high requirements for control can be seen in the complexity of the process flow.
Object transport in the system: The vials are brought in via an infeed screw, which is engaged and disengaged on the main star while the system is running. The main star can have different star pitches (ratios) depending on the object size, which is relevant when coupling with the inlet screw and the electronic cam switch. The outfeed wheels are mechanically coupled to the main star and have no drive of their own.
Accumulation: This is operated at a constant speed derived from the label dispenser. Good synchronisation is required to avoid wrinkling.
Labelling: The label dispenser is operated in a cycle, and the gearless label web feed is restarted at full speed every 75 ms. The label web feed is stopped by a sensor, which detects the gap between the individual labels. A special logic ensures that correct positioning takes place even in the absence of labels (missing triggers). The servo drive of the label tape feed generates different, highly accurate trigger signals that are required to control the vision and printing systems.
Gerald Kreft, a programmer in the software development department at Bausch+Ströbel, explains further special features that are important for transporting pharmaceutical containers. The labelling machine can process fragile objects with very thin walls, such as vials. It is also essential to ensure that the labelled object shows no signs of cosmetic damage. This is why the through transport has to be as stress-free as possible.
Today substrates are made of plastic with the thinnest possible walls; but these are more prone to stretching than their paper counterparts. This makes high-speed processing much more difficult. With the new label dispenser, however, the printing can be decoupled from the labelling process via a separate servo drive, which allows fast and accurate positioning of the printing, even with plastic substrates.
Benefits of central control architecture
In the previous model of the ESA1025, the servomotors for the label dispenser and for the through transport were each controlled via separate servo drives. “Separate controls meant having to establish, manage and maintain several communication paths,” says Kreft. “By merging all servo axes into a central TwinCAT controller, and achieving a higher degree of standardisation, we are able to achieve a lower overall cost. In addition, PC-based control from Beckhoff makes optimum use of the limited installation space due to the integrated control cabinet.”
The super-fast label dispenser is capable of handling up to 48 000 units per hour. The actual maximum output that can be achieved depends on the material being processed, such as the vial size and label length; however, the new dispenser makes it possible to cut reduce dependence on the label material. The consolidation of all servo drives in a central motion controller achieves this. Another advantage is the modular design. This means that the labelling system can easily be used on other types of machines.
The core of the centralised motion control system is the Beckhoff CX2062 Embedded PC with eight-core processor and TwinCAT software, and also the AX8000 multi-axis servo system. The latter features a modular design consisting of an AX8620 power supply module and three AX8206 dual-axis modules, which control the OCT servomotors in the AM8000 series. The range of PC-based control systems used is rounded out by various EtherCAT terminals and the operating unit, consisting of a CP3918 multi-touch control panel and the C6930 control cabinet industrial PC connected via the CP-Link 4 single-cable solution.
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