Industrial robots are characterized by precision, short cycle times and high flexibility. The type KR 120 R2100 nano F exclusive offers a further advantage: it is specially designed for the extreme conditions in cleaning systems. Cleaning media, high humidity and chemical additives cannot harm it. "This robot was chosen because of its robustness and flexibility," says Robert Heimerl, responsible for sales and project management in the automation division at Schnupp Hydraulik, explaining the main reasons for integrating it into a washing cell at the BMW Group plant in Dingolfing. The robot feeds components from the roof bodies of various vehicle models to the nozzle units for cleaning forming media and dirt particles. Schnupp, based in Bogen in Lower Bavaria, specializes in plant and mechanical engineering and equips its customers from the processing industry and automotive manufacturers with complete solutions, for example in the areas of automation and hydraulics.

Cleaning in five steps

Heimerl and his team were entrusted with the automated linking of a production process. This involves bringing steel components of different sizes into the desired shape and finishing them. WK Systemtechnik was commissioned to design and implement the washing cell, which according to Heimerl is a new system. "The challenge during implementation was to integrate the washing cell into the robot interlinking system. Due to the space available, it was not possible to install a continuous cleaning system," says Herbert Winter, Managing Director of WK Systemtechnik, whose company from Spiegelau in Lower Bavaria specializes in industrial robot cleaning systems for the automated inline cleaning process.

In the first step, the KR Quantec nano F exclusive picks up the component from the inlet with a special multiple gripper. In step two, the cavity of the component is cleaned. To do this, the robot feeds it to the internal cleaning system with millimeter precision. After the first cleaning step, the component is moved on to the cleaning nozzles. There, the exterior is cleaned and then the interior of the component is neutralized by a DI rinse. In the final step, the robot, which holds the component in the specified position during the entire washing process, places it on the outfeed transport unit. Before it is moved out of the washing cell, it is also rinsed on the outside.

Demanding environment, short cycle times and different components

This environment is not normally suitable for industrial robots, as the robot is exposed to large quantities of water to which 3% of alkaline cleaning agents are added. In addition, temperatures of 60 °C and more prevail in the washing cell, which leads to considerable formation of water vapor. Special protective measures have been taken to ensure that the robot is not damaged by external influences: its mechanics are completely encapsulated and the interior is pressurized. The wiring harness is completely internal. In addition, the protective surface is resistant to alkalis, acids, heat and corrosion. The robot therefore meets the requirements of protection class IP69.

Other aspects that spoke in favor of the Kuka robot are its high flexibility and fast cycle times. This makes it possible to limit the duration of the entire washing process to 45 seconds and to process components of different sizes. "The required cycle times and the different geometries of the components were only possible thanks to this special robot design. Due to the small installation space, the freedom of movement of a conventional robot with a protective robot suit would not have been sufficient," says Winter.

Heimerl is also satisfied, as the customer's request for component handling under splash water was fulfilled. The system has proven its worth since it was commissioned in summer 2015. In the meantime, the next requests to automate further cleaning processes using a robot have already been received.