Starting point / Task definition

At CD Cartondruck AG, a leading manufacturer of exclusive packaging for cosmetics, the stacking of cartons on pallets used to be carried out by two employees in every shift. This strenuous work meant that up to 3,000 cartons with an average weight of 7 kg had to be handled in each shift.

In order to ease the load on the employees, the company was looking for an automated solution. The primary requirements specified by the user were short cycle times, flexibility and simple operator control.

Implementation / Solution

The strenuous physical work is now carried out by two KUKA KR 180 PA palletizing robots. Each robot loads pallets located on three roller conveyors. The KR 180 PAs insert cardboard slipsheets to help ensure maximum stability at all times. They load the pallets up to a height of 2.2 meters, which corresponds to five or six layers. As soon as one of the pallets is full, the robot controller generates a “finished” signal. The pallet then rolls forward to a transfer position, where it is picked up by a transverse shuttle and taken to a neighboring high-bay warehouse.

In order to facilitate operator control for 70 different sizes of cartons, which have to be palletized using some 15 different stacking patterns, the KUKA Control Panel has been provided with an extended user interface. This was done by superimposing a customer-specific user interface on top of the robot programming interface; this simplifies operator control of the system and provides assistance to employees in the event of a fault. The user can create the necessary stacking patterns with an absolute minimum of programming effort, and can then call them up later as required for the specific task. The reduction in programming work is largely due to the PalletTech application software, which makes it easier to calculate the ideal pallet structure, for example.

System components / Scope of supply

Two KUKA KR 180 PA palletizing robots
Two PC-based KR C2 robot controllers, including control panel with Windows interface
Two suction grippers
Infeed conveyor system from the automatic carton closing unit
Labeling
Outgoing conveyor system, including turntable and buffer segment in high-bay warehouse
Three empty pallet dispensers
Safeguards
System control using two Soft PLCs
Programming via the KUKA Control Panel without additional hardware
Data transfer via ASI bus for decentralized control architecture

Supplied by KUKA systems partner FPT Robotik GmbH & Co., Amtzell, Germany.


Results / Success

Flexibility

Because the size of the cartons to be handled changes at least twice per shift, Cartondruck decided in favor of the KR 180 PAs, and not the possible alternative, gantry robots, which would have been less flexible and also slower with regard to retooling. The flexibility of these palletizing robots is based on their suction cup gripper, which is designed for a payload of 25 kg and carton sizes with a surface area from 150 x 380 mm to 380 x 500 mm. Moreover, compared with mechanical grippers, the suction gripper reduces the risk of damage to the high-quality folding boxes.

Speed

Given that up to 600 cartons had to be palletized per hour, Cartondruck required a cycle time of twelve seconds per robot. Since each of the KR 180 PAs achieves up to 1800 palletizing cycles per hour, they have no trouble meeting this requirement.

Cost-effectiveness

The KR 180 PA “palletizing expert” is a four-axis robot with a passive fifth axis, whose application-specific, FEM-optimized kinematic system guarantees particularly efficient, and thus cost-effective, palletizing processes. Its arm is made of carbon fiber composite material (CRP), which thanks to its smaller mass moment of inertia, provides truly remarkable acceleration rates. Despite its lightweight construction, the arm demonstrates extremely high stiffness characteristics, allowing the KR 180 PA to stack loads weighing up to 180 kg to heights of up to 3000 mm. In any case, this automated solution is more economical, since compared to manual handling the robots operate with a minimized error rate in order-specific palletizing.