Powdered milk formula for babies is a sensitive product that must be filled gently, safely, and accurately. There’s no room for error or inefficiency when it comes to size changeover, whether it’s the primary, secondary, or tertiary package that’s being changed.
One producer of powdered milk that installed a turnkey Rovema line—vertical form/fill/seal, cartoning, and case packing—relies on SIKO’s AP10 electronic position indicators with IO-Link interface for monitored and consistently reliable size changeovers. Up to 40 adjustment points may be necessary in order to adapt all functions to a new format in this turnkey system. Changeover that relies on purely mechanical position indicators is susceptible to errors and inaccuracies, which is why Rovema turned to an electronic solution. The first such solution implemented, however, required the addition of an integrated controller, which was more complicated to connect and also more expensive. That’s where the AP10 from SIKO came in. Featuring IO-Link interface, it cuts costs on the controller and makes it much easier to integrate the position indicators as IO-Link devices into the machine control system.
“IO-Link is a communication standard that is becoming increasingly widespread in the automation sector and is already being used more and more by us as an interface for sensors and actuators,” says Ingo Hamel, Head of Innovation R&D at Rovema. “It was therefore obvious to think about this for the size changeover and to involve SIKO, with whom we already have a longstanding constructive cooperation in the field of mechanical position indicators.”
According to Moritz Müller, Product Manager PositionLine at SIKO, the inquiry from Rovema came at a good time. “We too were already working with IO-Link and thus developed the AP10 with an IO-Link interface, which can be easily and safely integrated into machine control systems,” says Muller.
Infant formula in this particular customer installation is packaged in powder form in pack sizes ranging from 200 to 800 g. The powder is first filled into bags in parallel by two vf/f/s machines and then fed on two tracks to a horizontal cartoning machine. Here, one or two bags are placed in a folding carton and provided with a dosing spoon before the carton is closed. The cartons are then taken to a case packer and later to a palletizing system.
All 40 adjustment points along the line must always be adapted to a new package size when a size change is made. Most of the adjustment points are located in the cartoner and end-of-line packaging area, less so in the tubular bagging machine. When a new size is needed, the corresponding recipe is selected in the controller, whereby all electronic position indicators receive the new setpoints directly via the IO-Link interface and display them clearly on the backlit display. The LED displays immediately change to red in color since the current position has ceased to be correct. The operator then goes on to mechanically adjust all corresponding points to the new values. Once the actual position and the recommended setpoints match exactly, the LED display changes to green, thus indicating position reached. This is how the operator knows it’s okay to start running the new container size.
The advantages for the operator speak for themselves: no more paperwork and no more long lists of values to tick off and document. All values are already available electronically and are transmitted directly to the position indicators. Moreover, changeover is much faster as well as safer because the feedback of the LED lights is clear. The system can only be restarted if all the corresponding position indicators light up green.
One additional nuance in this installation is worth pointing out. The position indicators for the setpoints are given a specific tolerance range based on a nominal value. The operator has the possibility of making fine adjustment within this range and the position indicators will still light up green. If the operator picks a setting outside of this tolerance range, the display switches to red. Having this tolerance range can be advantageous in the event of packaging material inconsistencies in the carton area, for example. If the temperature of the hot-melt glue fluctuates or a corrugated case is slightly more creased, it may be useful to slightly adjust the guide rails or a contact pressure point. According to Hamel, the ability to make these fine adjustments is welcomed by the operators because they know the plant and product best: “The tolerance range allows the operators to make an independent assessment of the situation and gives them scope for action,” says Hamel. “This makes the process more efficient and helps the employee feel involved.”
IO-Link is a communications standard that is gaining ground internationally. Those who use IO-Link gain a number of advantages. As a standardized communications protocol that is subject to an international standard, IO-Link is manufacturer-independent. Accordingly, devices and masters can be developed as communication participants. Integration is possible via simple point-to-point connections at the lowest network level, and the wiring effort is extremely low compared to fieldbus interfaces. The AP10 displays are regarded as IO-Link devices, each of which is connected to an IO-Link master, which usually has eight ports. From the master, communication with the controller is via another high-performance protocol, in this case SERCOS III, though EtherNet/IP is also frequently used by Rovema. Müller explains the reasons for not using EtherNet/IP throughout for communication: “IO-Link is the much more cost-effective interface, which also makes significantly lower demands on the wiring and is thus also easily connected.”
Rovema’s Hamel confirms the easy integration: “We were very pleased that the first commissioning worked right away—without a lot of cabling work and with simple parameterization and integration into the control system.” According to Müller, there is also a simple diagnostic function. IO-Link quickly shows which device may have a fault or needs to be optimized. For this purpose, the position indicators can be exchanged during operation without having to open up an entire network ring. The affected device can be simply disconnected and replaced by a new one thanks to the star-shaped plug connection to the IO-Link master. The parameterization can then be loaded directly from the IO-Link master into the new (identical) device and thus accepted.
Electronic position indicators for monitored size changeover are optionally available for all Rovema machines and systems—which is very well accepted by customers. The customer of the packaging plant for infant formula had all 40 adjustment points equipped with AP10 displays because the benefits are so compelling: faster changeover times and much less documentation effort, because everything is electronically stored and retrievable. The most important advantage is the significantly increased process reliability due to the red/green LED system; incorrect settings can no longer occur. In fact about 50% of Rovema customers use this option for monitored size changeover in cartoning and case packaging technology.