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ifm inductive sensors detect film orientation and monitor limit stops in a Tempo-Pack rotary wrapper. |
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Before goods leave the plant and hit the road, they have to be well packed. The most efficient method of shipping a large amount of boxes is to pack them on pallets using film. This protects the goods against the environment such as dust and moisture. In addition, the film keeps the boxes together and holds them firmly on the pallet.
Two techniques are widely used: shrink-wrapping and stretching. For shrink-wrapping, film is put over the boxes from the top and shrink-wrapped and sealed using heat. For the stretching method, pallets and boxes are wrapped using pre-stretched film.
The company Tempo-Pack manufactures and distributes turn-key packaging machines. A customer of these fully automated machines is the long-established company Rabenhorst, a manufacturer of high-quality fruit juices for over 100 years. Before the juice leaves the plant the pallets are packed in film by means of the stretching method.
The customer-specific boxes are produced in varying sizes. This results in stacks of boxes in different heights on the pallets. Regardless of the size differences, ifm inductive proximity sensors ensure reliable position detection and control throughout the packaging process.
The packaging process
The pallet moves into the rotary wrapper. From the top of the machine, a massive rotary device is lowered down with the roll of film. The device rotates around the boxes up to 60 rpm providing up to 12 layers of film protection. The thin film of only a few millimeters thick insures optimum packaging of the stack. ifm inductive sensors are placed on the wrapping ring to detect orientation and monitor the limit stops when lowering and raising the wrapper.
The film ensures that the boxes are also protected against dirt and moisture. A special control device places the film on the uppermost box and holds it in position during wrapping. This postioning is also monitored using ifm inductive sensors.
Robust and low cost
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For the entire process, more than 20 rectangular inductive sensors, type IM5115, are used on the rotary wrapper. "IM5115 is a reliable, robust and low-cost solution for position sensing," says Ralf Buttelmann, Managing Director of Tempo-Pack. Another advantage is the sensor’s two corner LEDs. The LEDs enable easy readout of readiness for operation and switching status from a wide viewing angle – even from a long distance and bright environment. The long sensing range of 20 mm provides sufficient protection. |
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To minimize wiring complexity in the plant, the fieldbus system AS-interface is used. To do so, ClassicLine modules are installed in the plant. They provide digital inputs and outputs and are the link between sensors and fieldbus. A AS-i two-wire flat cable transmits the sensor data to the controller. |
Type IMC5115 rectangular inductive proximity sensors
AS-i ClassicLine Modules
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