It is important to have as much flexibility as possible in complex plant systems, in spite of specific product characteristics, in order to be able to produce different variants of products, tubular bag and carton sizes. It is therefore essential that size changeovers for different packaging formats are smooth to ensure production processes are as efficient and reliable as possible.
Here, Rovema relies on Siko’s AP10 electronic position indicators with IO link interface for monitored and reliable size changeover, both for cartoning machines and for form-fill-seal machines. Up to 40 adjustment points may be necessary in order to adapt all functions to a product variant within turn-key system such as this, as designed by Rovema for packaging infant formula. Changeover that relies on purely mechanical position indicators is very susceptible to errors and inaccuracies. Similar competitor products were already being used before Rovema turned to Siko’s electronic solution, however, they required an additionally integrated controller. This was more complicated to connect and also the more expensive solution.
The AP10 from Siko with IO link interface saves the costs for the controller and makes it much easier to integrate the position indicators as IO link devices into the machine control system. Ingo Hamel, Head of Innovation R&D at Rovema, explains: “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. It was therefore obvious to think about this for the size changeover and to ask Siko. We already have a longstanding constructive cooperation in the field of mechanical position indicators.” Moritz Müller, Product Manager PositionLine at Siko, was pleased to act on the suggestion: “We were also 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.”
Infant formula is packaged in powder form in pack sizes ranging from 200 to 800 grams in the entire plant mentioned at the beginning. The powder is first filled into corresponding bags in parallel in two form fill and seal machines and then fed on two tracks to a horizontal cartoning machine. Here, one or two bags are placed in a folding box and provided with a dosing spoon before the box is closed. The ready-to-load boxes are then taken to the final packaging machine and packed into a transport carton. The last station is then the customer’s palletizing system.
All 40 adjustment points along the line must always be adapted to the new dimensions according to the respective packaging sizes. Most of the adjustment points are located in the cartoner and end-of-line packaging area, less so in the tubular bag 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 LEDs of the displays immediately switch to red, as the current position is now no longer correct. The operator then goes on to mechanically adjusts all corresponding points to the new values – another ergonomic advantage: The AP10 indicates the direction to the setpoint via the LEDs and the LCD with corresponding arrows, to make it very easy to visualize where the operator has to move to. If the position and setpoints then match exactly, the LED display changes to green: Position reached. This is how all the red position indicators are moved in order to finally be able to start the new product. The advantages for the operator speak for themselves: no more paperwork, 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.
In fact, in this case, 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 and the position indicators light up green. If the operator leaves the area, the display switches to red. This margin can be advantageous in the event of packaging material fluctuations in the carton area.
IO link is a communication standard that is gaining ground internationally. Those who use IO link for their automation benefit from many advantages. As a standardized communication 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 (EtherNet/IP is also frequently used by Rovema). Moritz Müller explains the reasons for not using EtherNet/IP throughout for communication, for example: “IO link is the much more cost-effective interface, which also makes significantly lower demands on the wiring and is thus also easily connected.”
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 Rovema benefits are obvious: 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.
By Michaela Wassenberg