Wörz, Andreas
Zu schichtabhängigen Struktur-Eigenschaftsbeziehungen von LS-Bauteilen
Andreas Wörz
Laser sintering with plastics is one of the leading additive manufacturing techniques for producing series components with high mechanical properties. Due to the high geometrical freedom and the layer-by-layer component generation, knowledge of the process-part interaction with reduced crosssections is increasingly required for component design. Laser sintering produces components layer-by-layer via alternating powder deposition and exposure using a CO2-laser. The resulting parts have pores inside and the melting behaviour depends on the process parameters. The component dimensions are influenced by shrinkage processes and geometric boundaries in the powder bed, which determines shape and dimensional accuracy. Adhering powder particles lead to a high surface roughness, which has a subordinate influence on the mechanics with increasing dimensions. This is mainly determined by type and speed of the mechanical loading, as well as by the component’s orientation during the manufacturing. As a result of a dimensional reduction, the significance of the individual influencing variables shift. The knowledge of which is absolutely necessary for the design. The goal of this thesis is to generate relations between structure-properties interactions with the influences of the process. The reduction of the cross-section induces a change in the thermal boundaries during processing, which is compensated with increasing number of layers. Increasing part thickness leads to a higher density and reduced ratio of unmelted particles, whereby there is no height dependency of the melting behaviour. Roughness of the components is independent of the number of layers, but its notching effect increases with reducing the cross-section resulting in reduced mechanical properties. By means of the presented investigations a minimum component dimension could be derived, which is necessary for a constant component behaviour. Furthermore, it was shown how this can be controlled by the process parameters and thus represents a considerable added value for using the geometric freedom for designing components for laser sintering.
Pages: 141
ISBN: –