From sports shoes to car interiors: more and more people want customized products. Companies that respond to the increasing demand for greater product variety have a competitive advantage, but their prices often have to compete with those of rival products from highly efficient, automated and rigid production.

They are then faced with the choice between rigid production lines with high productivity or flexible production with low efficiency. Breaking this conflict of objectives and combining high flexibility with high productivity is the aim of the value stream kinematics research project.

This is a completely new approach to production. "Suitable production systems, which are characterized by a high degree of flexibility and a high degree of automation in equal measure, did not previously exist or only existed in rudimentary form. Our approach closes this gap," says Edgar Mühlbeier from the wbk Institute of Production Engineering at the Karlsruhe Institute of Technology (KIT). There, the mechanical engineer specializing in control technology is coordinating the development of this innovative production system. It combines the high productivity and precision of special machines with the flexibility of industrial robots.

"Value stream kinematics could revolutionize today's production landscape," says Professor Jürgen Fleischer, head of wbk and initiator of the innovative production approach. It could make large production halls superfluous and prevent long supply chains or production downtime due to supply bottlenecks. The current crisis caused by the pandemic has shown how quickly production lines can come to a standstill if supplies for production from abroad are not available in time. "If our flexible systems were in use, regional companies in the immediate vicinity could step in and produce the missing parts. The reduction in transport routes would also protect the environment and conserve resources," emphasizes Fleischer.

Structure enables frequent and flexible rearrangement

The system is made up of several standardized and freely configurable individual units (kinematics). They perform the usual handling tasks in robotics and are also able to dock various production tools in order to carry out processes such as assembly, additive manufacturing, cutting and joining processes as well as machining tasks and quality assurance fully automatically and within a multi-layered production flow. "This setup enables frequent and flexible rearrangement of the production system without the need to purchase costly additional systems," emphasizes Mühlbeier.

In order to solve these challenging tasks, the new system needs to be optimized in various ways compared to conventional vertical articulated robots, particularly in terms of its rigidity.

With the help of innovative gear technologies and software support, the researchers want to achieve path guidance during milling that is accurate to a few hundredths of a millimeter, for example. The individual work steps, such as the cutting speeds and the use of force, must be planned precisely. "The special feature of our production system is that the individual units can be linked in order to cooperate and thus replace today's specialized machines for certain tasks and processes," explains Mühlbeier. Once the task has been completed, they can be decoupled again and used separately. In this way, companies can reduce the number of - often very costly - production machines.

The flexible production system makes you independent of individual machines. For example, productivity increases can be achieved by coupling and decoupling as required.

© wbk, KIT

Fast assembly, shorter planning and commissioning times

The fast, simple and precise positioning of the flexible value stream kinematics in the room enables a grid that extends across the entire production area, "comparable to a Lego board on which the building blocks can be placed as required," says Mühlbeier. This allows the production system to be set up considerably faster. In order to significantly shorten the planning and commissioning time, an intuitive and easy-to-use engineering platform will also support engineers in medium-sized companies in a web-based and platform-independent manner: from designing a product in CAD to planning the number, arrangement and coupling of the kinematics to simulating and fine-tuning the production system.

The KIT scientists are driving their development forward together with industrial partners Siemens in the field of control technology and the machine tool manufacturer Grob as hardware developer and integrator. "Production technologies must meet the changing conditions of the market and the constantly increasing technological requirements. Our aim is to identify and develop innovative solutions for new processes and requirements," says Fleischer.