**4. Conclusions**

The present work presents a comparative study of coating end-mills used to machine Inconel 718 alloy, known for its low machinability and excellent mechanical properties. These cause elevated levels of tool wear, even after only a few meters of cutting.

From the conducted and presented study, the following conclusions can be drawn:


• The obtained results, in terms of machined surface roughness, can be considered quite satisfactory, even when tool wear is quite high. However, the tools' coatings suffered a considerable amount of wear only after a few meters of cutting, not being recommended for longer operations that require many meters of cutting.

These results highlight the advantages of using TiAlN coatings to obtain a satisfactory surface roughness quality for finishing operations applied to Inconel 718. Furthermore, the inclusion of coating sublayers can bring many advantages regarding the wear behavior of the cutting tools, especially when machining a material such as Inconel 718, known for its low machinability and capability of inducing high levels of wear on cutting tools. These results can be used as a basis for future work, especially when aiming to optimize/improve the outcomes of finishing operations applied to Inconel 718, particularly for milling applications.

**Author Contributions:** Investigation, V.F.C.S. and F.J.G.S.; Conceptualization, F.J.G.S. and F.F.; Supervision, F.J.G.S., F.F. and R.C.M.S.-C.; Data collection, V.F.C.S., R.C.M.S.-C., F.F. and N.S.; Formal analysis, F.J.G.S., F.F., R.C.M.S.-C., N.S. and R.D.F.S.C.; Methodology, V.F.C.S., R.C.M.S.-C. and N.S.; Visualization, R.C.M.S.-C., R.D.F.S.C., F.F. and N.S.; Data curation: F.J.G.S., N.S. and R.D.F.S.C.; Writing—draft, V.F.C.S. and F.J.G.S.; Writing—reviewing, R.C.M.S.-C., R.D.F.S.C., F.F. and N.S.; Resources, V.F.C.S., F.J.G.S. and R.C.M.S.-C.; Main research, V.F.C.S. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Data Availability Statement:** Not applicable.

**Acknowledgments:** The authors would like to thank Rui Rocha from CEMUP for his crucial collaboration in taking SEM pictures and commenting on some phenomena. The authors would also like to thank CETRIB/INEGI/LAETA, namely Jorge Seabra and Carlos Fernandes, for their continuing support in experimental activities and work dissemination. Moreover, Luís Durão and Victor Moreira from Mechanical Technology Lab of ISEP are acknowledged for their commitment and support in all machining experiments.

**Conflicts of Interest:** The authors declare no conflict of interest.
