The demand for customized products has been steadily increasing for years. This not only affects medical technology with the custom-fit and ergonomic production of implants or prostheses, but also leads to an increasing number of variants, for example in the automotive industry. The result is a decreasing number of units per component, which is why traditional series production methods such as injection molding are no longer economical. This is why new types of production processes are needed in order to manufacture even small quantities quickly and cost-effectively and thus be able to react very flexibly to product changes and individual adaptations.

Robot-based flexible manufacturing

A holistic approach developed at the Institute of Machine Tools and Production Engineering is the manufacturing concept of so-called incremental manufacturing, in which inexpensive metallic basic components are individualized using forming processes as well as additive and subtractive methods. The individual processing steps are carried out in a flexible sequence within a robot-based production cell to enable the fully automated production of individual products in variable quantities and at low unit costs. Intermediate measuring steps are used to detect and subsequently correct errors during the process.

A reliable connection between plastic (e.g. PP or ABS) and metal (such as aluminum or steel) is ensured by mechanically inserted interlocking structures in the metal surface, which are then filled by the plastic using a 3D printing process, creating a form-fit connection. Depending on the depth of the structures, which can be up to 3 mm, forces of up to 250 N per individual structure can be transferred. An in-house developed structuring tool (Fully automated Structuring Tool, FauST) is used to insert the structures.
This tool is used as an end effector on an industrial robot in order to be able to flexibly process free-form surfaces as well as planar surfaces.

As the highly productive 3D printing process does not ensure a sufficiently high surface quality, the product is subsequently finalized by milling. The chips produced during this process are extracted close to the cutting point with the help of an adaptive chip collection system so as not to interfere with the other processes in the machining cell. To avoid collisions with complex surface geometries, the position of the extraction hood adapts to the surface contour of the component to be machined depending on the planned path. The speed of the milling process is controlled on the basis of the spindle power, as different materials (such as plastics or metals) require different machining parameters.

Everything in one cell

Due to the use of robots for the manufacturing processes, the process chain presented is characterized by a high degree of flexibility and modularity. In addition to the integration of further handling tools, additional processes such as arc welding can be easily integrated into the machining cell. In addition to methods for planning, analysing and optimizing the process chain, algorithms for path planning are currently being developed and strategies for digitizing such a flexible system are being designed. Both product quality and the degree of automation are to be further increased through the cross-process use of data.

It can be assumed that the industrial application of the flexible process chain investigated will permanently change the production of individually manufactured components. In particular, the free scalability of the process chain in terms of quantities, component size and shape enables users to implement individualized production solutions for personalized products.