Robot cleaning of components after machining

Dieter Abler: "Our customer reported that he was cleaning his components in an immersion system, but was no longer achieving the desired cleanliness. We then analyzed his situation and presented him with a system concept with a robot. He liked the flexibility of the system."

Stefan Pollinger: "The customer machines steel and aluminum parts. He wanted a system in which he could clean both materials well - which is relatively unusual and technically demanding. On top of that, the customer expected a high degree of flexibility: the system was to be designed in such a way that many different components could be cleaned - without major conversions. Initially, he gave us three component types, but the customer wanted to be able to expand this range at any time. Another challenge was the variance of the parts in terms of size and weight: the steel parts currently to be cleaned weigh around 7 kg, while the aluminum parts are somewhat heavier at up to 10 kg. The largest part is around 800 mm long and 600 mm wide."

Stefan Pollinger: "With such requirements, we quickly realized that we had to develop a completely individual system. It was obvious that a robot cell was best suited to the desired flexibility."

Dieter Abler: "However, the customer has very little space in his production hall. However, a robot cell requires a certain amount of floor space - the robot needs room to move in the wet cell in order to grip the various parts and feed them to the individual cleaning elements."

Stefan Pollinger: "We suggested to the customer that the component be placed on a product carrier and guided past the robot. The robot was not supposed to pick up the component and feed it to a fixed cleaning tool, but rather clean the component with the cleaning tool."

Dieter Abler: "We have already implemented the basic concept several times and it fitted the customer's requirements perfectly: We need less space for the system because handling in the cell is simpler and therefore saves space. This solution is much more cost-effective: if the robot grips the component, a new gripper has to be designed for each new part. This is no longer necessary, because in our concept the robot grips the cleaning tool. If a new component is added, we only have to adapt the product carrier. This is much cheaper. The set-up times in operation are shorter because the entire handling is less complicated."

Stefan Pollinger: "What was new was that we gave the robots additional flexibility by integrating the tool changing system. This allows our customer to use up to five cleaning tools."

Dieter Abler: "The components enter the system on a product carrier specially designed for the parts. The parts are rinsed in a first chamber. For this pre-cleaning, a cleaning fluid is used that is individually tailored to the soiling. It comes from the so-called "first tank", is fed back into the tank after use and pumped through a filter system for reuse. The parts are then transported to the robot station. A first robot cleans one side of the components with its cleaning tool. The product carrier then moves on to the second robot, which cleans the opposite side of the component. Cleaning fluid from a second tank is used here. Thanks to filtration, this liquid can also be used for many thousands of parts. After cleaning by the robots, a final rinse is carried out with water from a third tank. Finally, the components are pre-dried with hot air. They are rotated and swiveled with the product carrier on the transport system so that the air reaches all areas. The last step is vacuum drying. In a vacuum, even low air temperatures are sufficient to dry the parts completely and thus meet the highest standards of dryness. The parts are loaded and destacked manually. The product carriers are located on a rolling conveyor system."

Stefan Pollinger: "The robots can theoretically use up to five different tools. However, this is currently not necessary. In this system, the first robot therefore works with a single, permanently fixed tool, (1). The second robot always accesses two different tools during a cycle, (1) and (2).

Tool 1: A total of 100 liters of cleaning fluid per minute at 100 bar hits the component from a flat jet nozzle and a solid jet nozzle. This is ideal for cleaning surfaces, undercuts, blind holes or drill holes.

Tool 2: This tool has five flat jet nozzles spraying in different directions, which can clean large surfaces, side areas and larger cavities. It also cleans with 100 bar water pressure.

As long as the tools are not in use, they are stored in a protected, largely dry area. This protects the tools from dirt. Customers can even order special storage stations for this purpose on request."

Stefan Pollinger: "We needed a tool changer for the robots, including a so-called water transfer module. Something that works reliably in a wet cell. So I asked various suppliers, including Stäubli, a specialist in changing systems and plug-in connections with fluid feed-through. And lo and behold - Stäubli had a solution that we could build on. There was no standard product in this form - but the basic version combined with the technical expertise of the Stäubli contacts got us there."