PSI - Issue 53

Francisco Matos et al. / Procedia Structural Integrity 53 (2024) 270–277

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Francisco Matos et al. / Structural Integrity Procedia 00 (2023) 000–000

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solidification direction. These results emphasise the e ff ectiveness of the LPBF process in producing components with mechanical characteristics similar (or even improved) to those manufactured through traditional methods.

Fig. 3: Optical micrograph showing the microstructure of 316L fabricated by LPBF.

3.2. Functionality assessment

The incorporation of brazed insert tips in the tool did not require additional machining step given the overall slot surface quality. The milling tool top surface (that contacts with the tool holder) was submitted to post-processing (machining and grinding) to remove support structures and to ensure its parallel alignment with the tool holder, thereby preventing any potential fluid leakage at the interface. In Figure 4 b) the additively manufactured milling tool body is presented, alongside with a picture of coolant channels, observed through a digital light microscope. In addition to visual inspection, destructive analyses of one part allowed to evaluate the internal channels, which revealed to be open and with the expected geometry. A sur face hardness of 210HV5 ± 11 was measured with a DuraScanG5 ZwickRoell hardness testing machine. External surface roughness, R a = 7.11 µ m and R z = 34.81 µ m , was measured with a portable Mitutoyo Surftest SJ-210R. The coolant channel internal roughness does not show abnormal roughness values and is comparable to the brazed tip slot roughness.

Fig. 4: (a) Cooling channel interior; (b) Additively manufactured milling tool body; (c) Tool body mounted on holder.