Extensive material characterization for series production of 3D printer components

In the last decade, 3d printing technology has undergone rapid development. From the originaltechnology for the production of prototypes or special applications in medicine, racing oraerospace, to individual production and economically competitive series production. Additivemanufacturing opens up a variety of possibilities to manufacture even geometrically complexcomponents from metallic, ceramic or polymeric materials [1].The joint research project “Material and process optimization for series production of 3D printercomponents” aims to develop fundamentals for optimizing 3d printed polymeric components.Since components from 3d printing behave significantly differently than, for example, injectionmoulded parts, they also have to be designed and dimensioned differently. The differences can befound also in the material properties and in the processing-related material structure and surfacemorphology.Hence there is the necessity to characterize the resulting mechanical, morphological and chemicalproperties and the ageing behaviour of the versatile polymers (e.g. ABS, PA, PC, PLA, PP, TPU,… or fibre reinforced plastics) used for the different 3d printing processes (FDM, FFF, SLA,SLS,…) under different printing parameters. Therefor a special test specimen was designed(Figure 1). For the dimensioning of printed components, a detailed description of the materialproperties under application conditions must be provided. This requires knowledge of the materialstrength and the reduction of strength under mechanical stress. For a general description of thisbehavior, reduction factors have been determined to define the nominal design stress according tothe given load cases, e.g. static or dynamic mechanical loads, notching effects, elevated operationtemperature or aging / exposure.Surface morphology is monitored with large area and detailed Environmental Scanning ElectronMicroscopy (ESEM). Atomic Force Microscopy (AFM) can connect the surface structure with localmechanical properties. Computed tomography (CT) enables an insight into the component(defects and cavities). For a local detailed structure analysis the samples are cross-sectioned withmicrotomy techniques and then characterized with a multiscale approach of different microscopicmethods. From stitched Light Microscopy (LM) images in the mm range (Figure 2), via ScanningElectron in the μm range, up to interfaces investigated with Transmissions Electron Microscopy(TEM) in the nm range. Raman Integrated Scanning Microscopy (RISE) provides correlativeelemental and chemical information by combining EDXS and Raman spectroscopy (e.g. fibrereinforcement, distribution of additives, fillers and pigments) [2].