Komet, a packaging machine builder with experience in the meat packing industry, was challenged by its German clients to come up with a new sausage packing machine, one that would be faster than the previous model but still safe. The design it arrived at feeds plastic foil into the bottom of the machine via a roller. The foil is then transported via chain drive to a forming chamber where it is heated, and a special compressed air/forming procedure and the appropriate tool are used to form the foil into the desired tray shape for the product to be packaged.
At this point, workers insert grilled sausages by hand into the tray-shaped plastic film, six pieces per row and per pack, before the conveyor moves on and another tray emerges from the forming station. After this filling station comes the sealing station. Here a roller is used to introduce a top film. Then a vacuum pump extracts the air from the package and a blast of nitrogen is introduced to prevent the sausages from sticking together.
Finally, the top and bottom film layers are impulse sealed under pressure in the sealing chamber. The product packaging is now secure and durable. At the machine outfeed, longitudinal and transverse cutters separate the packaged product into individual trays, which are then fed into transport crates via conveyor.
According to Komet, part of the credit for Sprinter’s speed and success must go to a modern safety and control concept developed for Komet by safety equipment and control supplier Pilz GmbH & Co., Ostfildem, Germany. The system, called PNOZmulti, is designed to facilitate simpler and safer interaction between man and machine in this application. It has a modular structure and can be used flexibly to suit the application.
Instead of wiring, the user configures the needed functions using Pilz-supplied software and a configuration tool. This saves time, space and money as it drastically reduces wiring requirements. All the safety-related functions are located in one housing, making monitoring easier. By comparison, the safety devices on the predecessor machine were mainly based on individually wired switches and contactors. Large covers safeguarded wide-ranging potential danger zones such as the forming and sealing stations via switch contacts. The infeed area in between was narrow and only allowed a one-up arrangement.
On the Sprinter, the cover on the forming station is reduced to a minimum. Instead, an advanced security slide ensures that it is impossible to reach into either the forming or the sealing station from the filling station. If the slide switch is not closed, the safety system will prevent the bottom film from being formed and stop pressing and heat-sealing in the sealing station. Propulsion drives and valves are switched off; the central PMI (Pilz Machine Interface) operator terminal receives an error message, stating the cause and the source.
“With PNOZmulti, the machine has a flexible safety concept which is really easy to adapt to our requirements. Now the infeed area has a three-up arrangement, so assembly is quicker and easier, plus the machine is more productive“, says Harald Janke, technical manager at Komet.
