The container glides into place virtually soundlessly, approaching its destination with even motion: the CleanDock. Elegance in stainless steel. Cleanly, confidently and reliably. Then it comes to a stop. The pneumatic gripping system of the active section advances from above, grips the container closure of the passive section and lifts it. Two to three air blasts indicate that the dosing element and target container are seamlessly joined. The flexible compensator of the passive section makes it possible to precisely tare the scale positioned under the container, independently of the product quantity it already holds. Then the filling of the bulk material begins. Once this process has ended, the active and passive sections detach from each other elegantly and cleanly and the container moves to the next filling station. What no one sees from the outside is that almost the entire filling process is controlled decentrally by the CleanDock itself.

A pioneering step
“Our systems transport and dispense all conceivable types of bulk materials,” says Frank Pahl, Head of Development at AZO GmbH + Co. KG in Osterburken. “They range from milk powder and ingredients for baby food to pharmaceuticals and detergents as well as different plastics and pigments, for example for wet paint production. We could report on the variety of implemented applications from our four areas of business Food, Vital, Chem and Poly for days.” With more than 1,000 employees worldwide, AZO has been making its technological mark in the area of bulk material handling for 70 years. One of the current pioneering innovations is the latest generation of the CleanDock. With this system, AZO is taking an important step towards fast commissioning, error reduction and increased safety in the filling of bulk materials together with its long-term partner and automation expert Festo. To do this, the CleanDock has been provided with the intelligence in the form of a decentralised controller, and thus autonomy in the process. While the process control system takes care of the big picture in terms of control technology, the modular electrical terminal CPX with integrated controller CEC and valve terminal MPA from Festo assumes the detailed processes of the docking and undocking procedures.

Safety has highest priority
“Bulk material handling is an art in itself that requires a lot of experience,” says Frank Pahl. “A handful of flour contains more particles than an entire truck full of gravel. The infamous angel hair can form when handling plastics, while higher degrees of grinding and finer powders with smaller particles in cosmetics and pharmaceuticals present us with new challenges every day. Bulk materials and bulk material technology are in motion. Our systems must handle these tasks without a problem – and they do. We are proud of that.” Two of the greatest challenges of the bulk materials industry are the prevention of cross-contamination and the unwanted release of dust. On the one hand, the objective is product purity and, on the other, employee protection. In the past few years, AZO has increasingly focused on the pharmaceutical and food industries in particular, but also the chemical industry. When handling bulk materials, dust from allergenic foods, for example, can lead to health problems for operating staff. In addition, explosion prevention and protection play a large role. The high number of different containers needed for transporting and handling raw materials, as well as the intermediate and finished products, don’t make things any easier for the designers of bulk material systems. This includes, amongst other things, FIBCs, drums, sacks and portable containers. As in other industry sectors, flexibility is becoming an increasingly important factor in bulk material handling.

No dust in the ambient air
“For the product to stay where it belongs, in target containers and the dosing device, both must be closed before docking takes place,” emphasises Pahl. This sounds simple, but isn’t. As is often the case, the devil lies in the details. “We definitely don’t want any of the product adhering to the inside of the dosing device’s downpipe to fall out before coupling and after decoupling and soil the floor or release dust into the ambient air.” AZO achieves this objective using the CleanDock. The dosing device and container remain hermetically sealed before and after filling. “While some double-cone systems available on the market do not consistently ensure freedom from carry-over effects, the CleanDock always guarantees this through the line contact of the components involved in the sealing process,” says Pahl. By using this technology in the CleanDock, AZO is very deliberately positioning itself between classic docking systems and the containment systems familiar from pharmaceuticals, such as split valves.

Decentralised control, reduced complexity
The passive section is docked to the active section using pneumatic linear actuators from Festo. They are also used for opening and closing the cone seal in the active section for filling the target container as well as locking and tightening the active and passive sections. A pneumatic knocker is used to loosen any bulk material residues stuck in the dosing device. The pneumatic actuators are controlled by the modular electrical terminal CPX with integrated controller CEC and valve terminal MPA. While in the predecessor version of the CleanDock the valve terminal CPV was centrally controlled by the process control system, the decentralised controller of the CPX-CEC now implements the control sequences directly on the dock. This especially reduces commissioning time. “Some bulk material plants store more than 80 raw materials in silos,” explains Frank Pahl. “The largest number of CleanDocks we have installed in a plant so far is around 60.” With so many filling stations, the programming and commissioning effort has been relatively high until now. The probability of errors also goes up as the number of units controlled via the process control system increases. “Controlling the CleanDock decentrally speeds up the commissioning of a plant and reduces the risk of errors,” says Pahl. “All the process control system does is give the command for docking and undocking. The CleanDock looks after all the detailed operations itself. Programmers no longer need to worry about these detailed processes on-site during commissioning.”

Modular, flexible, pioneering
The modular electrical terminal CPX from Festo with integrated controller CEC and valve terminal MPA provides a uniform interface for the decentralised intelligence and enables the complete control of machines or more complex subsystems. As an automation platform for electric and pneumatic components, it connects pneumatic and electric control chains to different automation systems and company-specific standards simply, quickly and flexibly. The entire system is programmed simply using CODESYS. Interfaces are reduced, engineering and handling processes are simplified and the reliability of machines and plants is increased.

Added to this is an essential aspect that is gaining significance worldwide for the future of plants: modularity. Automation functions are increasingly distributed across individual modules. The process management level merely sets the pace. The key to greater flexibility and simplified handling lies in the integrated, decentralised intelligence. While the process control system calls up a function, it doesn’t need to have a detailed knowledge of the stored process steps. This is taken care of by intelligent modules such as the CPX-CEC with valve terminal MPA at AZO.

Together towards a modular future
What AZO and Festo have already successfully implemented here corresponds with the objective currently being discussed in detail and worked out between NAMUR/ZVEI (Association of German Electrical and Electronic Manufacturers), machine builders and operators and research facilities for the automation of modular production plants. The decentralised and complete automation of the individual modules reduces complexity and shortens time-to-market for system operators.

Individual modules can also be produced for stock and adapted without a great deal of effort. Systems can be easily expanded with additional modules. In this way, system builders can react even more flexibly to the changing requirements of worldwide markets. As an automation expert, Festo is actively involved in the design of concepts and standards that drive and simplify the automation of modular plants now and in future.