The IKV investigates novel slicing, process, and system strategies in the field of additive manufacturing. The focus lies on non-planar slicing methods for load-path-optimized components, adaptive process chains for injection-molding-like, locally graded fiber architectures, and pressure-advance algorithms for stabilizing material deposition in large-scale SEAM systems. The results will be presented at the 33rd International Colloquium on Plastics Engineering.
New manufacturing strategies for the 3D printing of technical components
Aachen, December 2025 – 3D printing of technical components is moving from prototype production to end use when software, process control and plant engineering are systematically combined. For screw extrusion additive manufacturing (SEAM) in particular, this means that path planning must go far beyond the simple ‘processing’ of part geometry. Instead material flow, thermal history and the resulting component properties must also be managed and coordinated. Rather than in planar layers, the strand must be deposited in three-dimensional, load- and process-oriented paths while optimising surface quality, interlayer strength and resource efficiency.
At the same time, the SEAM-specific constraints – continuous mass throughput, limited retraction and lagging melt buffers – must be taken into account in both path planning and machine control. The decisive factor is the interaction of process-oriented paths that minimise the demand for support structures and infill material and reduce dispersion through a stable material flow. If both conditions are fulfilled, the additively generated morphology translates into functional component properties.
The Institute for Plastics Processing (IKV) in Industry and Craft at RWTH Aachen University is investigating novel slicing, process and system strategies in the field of additive manufacturing. The focus is on non-planar slicing methods for load path-optimised components, adaptive process chains for injection moulding-analogous, locally graded fibre architectures, and discharge-stabilising pressure advance algorithms for large-volume SEAM systems. The aim is to show how functionally optimised path planning can be automatically derived from simulation and measurement data and how a robust transfer between materials and systems can be achieved.
Furthermore, the project is investigating how to achieve real-time quality assurance and how to integrate the information into digital development and production systems. The results will be presented at the 33rd International Colloquium Plastics Technology in Session 15, New manufacturing strategies for the 3D printing of technical components. The approach aims at a consistent process architecture in which CAD/CAE-coupled path planning and SEAM-adapted strategies form a continuous line from design to series production. In this way, SEAM can become a robust manufacturing technology for demanding technical components through suitable slicing.
Advanced slicing for scalable material extrusion
In advanced slicing, the limitations of planar layers are overcome by adapting the path planning of filament deposition three-dimensionally to the component geometry, surface contours, and expected load paths (Figure 1). Non-planar paths reduce staircase effects, enable variable layer heights close to the contour, and make targeted use of the anisotropic mechanical properties of the component instead of working against them. For SEAM, this means above all that strategies must be designed for a continuous material flow. Continuous perimeters reduce start/stop transitions. A flow-guided speed mode links the path speed to the extrusion capability. Inclined slicing makes overhangs and closed deck surfaces accessible and saves support and infill structures. The combination of geometry and process knowledge is crucial here. Where does the main load path lie? Which path orientation supports local stiffness? What thermal history allows sufficient welding between the layers within a reasonable construction time? At the same time, the interfaces to the simulation are important in order to include load cases or fibre orientations (for fibre-reinforced materials as target variables in path generation, for example Slicing thus becomes an integral part of product and process design in material extrusion.
© IKVAdaptive production of locally graded fibre architectures
Locally graded fibre architectures enable targeted variation of stiffness, strength, and load transfer within a component, smooth transitions, and help to avoid failure-critical discontinuities (Figure 2). Injection moulding processes quickly reach their limits when implementing such fibre architectures. Although a characteristic fibre architecture is formed, the fibre volume content remains largely constant across the component, so that defined gradations can only be achieved with great effort. Additive manufacturing, on the other hand, offers the possibility of varying the fibre architecture locally.
An intrinsic approach to manufacturing graded components combines both processes. First, additively manufactured test specimens are produced in such a way that their fibre architecture is as close as possible to an injection-moulded structure. They are then consolidated above their melting point in external, variothermal moulds to eliminate pores and reproduce a morphology with injection-moulded-like crystallinity and pvT history.
Right from the start, four criteria are taken into account in the additive phase: material (fibre type and matrix system), fibre orientation, fibre volume content, and fibre length. Fibre type and matrix system define the processing and property-related boundary conditions for the intended fibre architecture. The locally adjustable fibre volume content is controlled by combining two melt flows or using a twin screw extruder and is introduced into the component with precise positioning by synchronising it with the robot’s movement. The fibre orientation is replicated similar to injection moulding and introduced layer by layer using suitable slicing strategies and non-planar path planning, in order to achieve targeted alignment along the intended load paths. The adjustment of the fibre length is facilitated by a correspondingly designed extruder and process control, so that mechanically effective length distributions can be achieved with minimal fibre damage.
© IKVA customised slicing technique translates simulated fibre architectures into real tool paths: curved layers follow the contour, inner and outer layers are assigned different path logics, and the inertia of the mixing system is taken into account in the dosing process to ensure that the right material ends up in the right place. In variothermal transformation, pressure, temperature, and cooling rates are controlled in such a way that porosity is minimised and welding between layers is maximised. Subsequent characterisation is performed with regard to material, geometry, morphology, and process and includes fibre orientation, fibre length distribution, fibre volume fraction, and porosity as well as—in the case of semi-crystalline systems—the degree and distribution of crystallinity.
Process stability in large-volume SEAM through dynamic compensation
Process stability is a key quality feature in large-volume screw extrusion. Due to the large melt buffers and the viscoelastic material behaviour of the polymer melt, the volume flow reacts sluggishly to speed changes. This can lead to under- and over-extrusion, geometric deviations, and surface artefacts.
A practical solution consists of software compensation at the G-code level: movement sections are pre-processed, transitions at acceleration/deceleration phases are smoothed with additional segments, and corner areas are softened in terms of material application. This is based on an empirical characterisation of the system-typical deceleration which is incorporated as a parameter in the post-processing logic, enabling the extrusion dynamics to be anticipated. The appeal of this approach lies in the fact that no major changes to the hardware or firmware are required and its transferability to existing systems.
Lightweight construction an FRP at the 33rd International Colloquium Plastics Technology
The topics of lightweight construction and FRPP will be addressed in
- Session 3: Plastics as a key to scaling the hydrogen economy
- Session 6: Mechanical recycling of CFRP: Vitrimers as enablers
- Session 10: Artificial intelligence in product development and simulation
- Session 15: New manufacturing strategies for the 3D printing of technical components
At ‘IKV 360° – Research Live’, IKV scientists bring the topic to life at various stations in the IKV technical centre.