The division of labor between plastics processors and their customers is changing. Customers increasingly want complete, ready-to-install components rather than injection-molded parts, and this applies not only to the automotive industry, but also to other sectors such as the household appliance industry and mechanical engineering. For this reason, the assembly division at Weiss Kunststoffverarbeitung has grown steadily in recent years. As an engineering-oriented company, Weiss pursues the goal of utilizing the latest trends in this area as well.

The robot cell that is currently being put into operation at the Illertissen plant is a good example of this. A safety valve just 15 millimetres high is assembled in the cell, using filigree metal purchased parts such as springs, washers, valve tappets and balls in addition to injection-moulded parts. The company's assembly experts have put the principle of division of labor between humans and robots into practice. Dipl.-Ing. Robert Heller, whose responsibilities at Weiss include the design of production and automation technology: "The robot works very precisely and without fatigue, while the worker can make mistakes but is more flexible."

The cell is designed so that both "colleagues" can make the most of their respective strengths. In the first step, the worker standing in front of the cell assembles the central components in an assembly device. Then the robot inside the cell takes over. It inserts other small parts - a very small ball, for example. The worker then gives the signal to press the parts together, which is done pneumatically via a cylinder.

Now it's the robot's turn again. It removes the assembled valve from the fixture and places it in a test device, where it undergoes two pressure tests at 0.9 and two bar. After this one hundred percent test (in which the valve must remain closed during the 0.9 bar test and open when pressurized to two bar), a test stamp is applied using a marking system and the valve is ready for dispatch.

Weiss has put the principle of human-robot collaboration into practice here in a way that is as simple as it is elegant: Humans and robots each have access to the shared workspace. There is no safety fence or other spatial separation between worker and robot. Instead, the work area is protected on both sides by a pair of light barriers. Both pairs of light barriers are connected in terms of control technology and safety so that the robot does not reach into the shared work area when the operator is inserting or removing parts there. Conversely, the robot is stopped if it is currently active in the work area and the operator also reaches into it.

It goes without saying that the robot's control system is also integrated into this simple and practical safety concept. Robert Heller: "We used the robot manufacturer's 'Function Safety Unit' here, which has recently become available as an option: a plug-in card that can also be used to program safety areas, for example." pb