Mechanical Properties of Laser Beam Melting Components Depending on Various Process Errors
Additive Manufacturing processes are constantly gaining more influence. The layer-wise creation of solid components by joining formless materials allows tool-free generation of parts with very complex geometries. Laser Beam Melting is one possible Additive Manufacturing process which allows the production of metal components with very good mechanical properties suitable for industrial applications. These are for example located in the field of medical technologies or aerospace. Despite this potential a breakthrough of the technology has not occurred yet. One of the main reasons for this issue is the lack of process stability and quality management. Due to the principle of this process, mechanical properties of the components are strongly depending on the process parameters being used for production. As a consequence incorrect parameters or process errors will influence part properties. For that reason possible process errors were identified and documented using high resolution imaging. In a next step tensile test specimens with pre-defined process errors were produced. The influence of these defects on mechanical properties were examined by determining the tensile strength and the elongation at break. The results from mechanical testing are validated with microscopy studies on error samples and tensile specimens. Finally this paper will give a summary of the impact of process errors on mechanical part quality. As an outlook the suitability of high resolution imaging for error detection is discussed. Based on these results a future contribution to quality management is aspired.
Robustness analysis of imaging system for inspection of laser beam melting systems
Laser Beam Melting (LBM) is an additive manufacturing process, which enables the layer-based production of complex parts from metal powder, i.e. “3D printing” with metal. In previous publications, we presented a high-resolution imaging system for inspection of LBM processes, which uses a high-resolution camera to acquire images of each powder layer and laser exposure result. The external camera position necessitates perspective correction, which is based on calibration markers which are “drawn” onto the powder by the LBM system's laser in the first layer. As movements of the powder deposition mechanism cause vibrations, the orientation of the camera may be changed, which would invalidate the calibration results and lead to imprecise measurements or segmentations. To evaluate the effect of these disturbances, we placed calibrations markers in multiple layers and determined the position offset using template matching. We analyze the relative marker drift in three LBM processes and determine the spatial acquisition error. The maximum distance is 4.91 pixels (156.1 μm on the part), while most detected markers deviate by less than 1.5 pixels (46 μm). Compared to the pixel size of 20 μm to 32μm, these deviations are significant and require a repeated calibration in higher layers for valid high-resolution image-based measurements.
What can students learn from studying medicine in literature?
To identify what students can learn from studying medicine and literature as part of a final‐year special study module in general practice.