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The growing demand for individualized products is becoming more and more significant and leads to a reduction in batch sizes. In particular, the production of multi-material components for lightweight design presents new challenges to the manufacturing process. This is evident when it comes to the production of individual parts, as today’s processes are characterized by high tool costs and manual operations. The described challenge can be overcome by a robot-based manufacturing cell allowing the use of a novel, modular process chain in which metal parts are mechanically pre-treated, subsequently completed by additive plastic application, and afterwards finalized in a machining step to achieve the required surface qualities and geometries. In order to realize the novel process chain, robot-based solutions for free-form metal sheet processing, increased interlayer bonding strength of plastic, and multi-material machining with integrated chip extraction have to be found. Therefore, this paper presents the first approach of a robot-guided surface structuring end-effector and a concept for a direct extraction hood, which is able to be adapted specifically to the movement of the robot and the part surface, so free-form surfaces can be machined. Based on this, first experimental studies for increasing the interlayer bonding strength of plastic were carried out using an extruder set up to applicate thermoplastics onto metal at high deposition rates. To define the positioning accuracy for a robot-guided structuring process, different point to point movements have been investigated.

Friction drilling is a widely used process to produce bushings in sheet materials, which are processed further by thread forming to create a connection port. Previous studies focused on the process parameters and did not pay detailed attention to the material flow of the bushing. In order to describe the material behaviour during a friction drilling process realistically, a detailed material characterisation was carried out. Temperature, strain rate, and rolling direction dependent tensile tests were performed. The results were used to parametrise the Johnson–Cook hardening and failure model. With the material data, numerical models of the friction drilling were created using the finite element method in 3D as well as 2D, and the finite volume method in 3D. Furthermore, friction drilling tests were carried out and analysed. The experimental results were compared with the numerical findings to evaluate which modelling method could describe the friction drilling process best. Highest imaging quality to reality was shown by the finite volume method in comparison to the experiments regarding the material flow and the geometry of the bushing.

The demand for customised products leads to an increasing diversity of variants and batch sizes in production. Therefore, established high volume production technologies have become less profitable. This loss results primarily from high product-specific investments in mould-based manufacturing systems such as injection moulding and sheet metal forming whose amortisation is challenged by smaller batch sizes. The increasing number of components in multi-material design, especially from metal and plastics, calls for flexible production technologies. This paper introduces a new robot-based process chain for metal-plastic parts to close the existing gap between manual production of small batches and mould-based high volume production. The idea is to combine surface treatments with additive and subtractive manufacturing processes in a single workspace implementing an incremental process chain to realise a scalable production system. This will increase the manufacturing flexibility for customised products and reduce the cost per unit. As a first step in the process chain, the surface of a pre-produced metal part is structured for mechanical interlocking and high strength joining. Subsequently, an additive process is used to directly apply a plastic section onto the pre-structured metal part, thus producing a hybrid component. Finally, the hybrid component is machined to add individual holes or pockets and to finish the surface of the additively manufactured area. This paper presents a scalable process chain for metal-plastic components as well as concepts for its technological implementation. Furthermore, first experimental results from the fabrication of a metal-plastic part using additive and conventional processes are presented.