PSI - Issue 77

Y. Bakir et al. / Procedia Structural Integrity 77 (2026) 639–648

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Y.Bakir et al./ Structural Integrity Procedia 00 (2026) 000–000

On the other hand, this difference was only visible near the edge of the parts. Melting tracks formed demonstrate some other differences as well. The gaps between the melting tracks seem to have differed and also the connection of melting tracks with the edge of the parts were also different. The gaps between the conjoined tracks seem to be wider, due to shrinkage.

Figure 7 A) ending of melting tracks formed by default process, B) end of melting tracks formed by while enabling idle time between exposure of hatching lines[4].

3.2. Evaluation of Monitoring Data In situ process monitoring, for this work, is carried out by using a thermal camera as explained. Thermal camera obtains data by recording the radiation emitted from melting pool. Data is expressed by unit of Grey Value(GV) and it indicates the data as brightness of a pixel. The amount of radiation that is emitted depends on multiple factors. Some of the main factors are such as exposure strategies and conduction rate of the heat applied by the laser beam. Data from each pixel refers to a certain location on building platform. Depending on the size of the area that is exposed for every layer, the number of pixels that records data changes. The graphs given in this work demonstrate the mean GV curves of each layer. The parts with rectangular prism shape, have the same cross-section through all building height. And the resulting graph does not demonstrate any increasing or decreasing fashion across building height. This indicates that ratio of heat applied to the conduction rate did not change significantly during the print.

Figure 8 Mean GV curves along building height that are generated by data according to printing of rectangular prism shaped parts.

There is a visible drop in the average GV when the idle time is introduced. Generally, the Heat Affected Zone(HAZ) of subsequent hatching lines overlap. Heat is applied in the same amount and by the same spatial strategy while idle time could be decreasing the average temperatures reached at HAZ.