OBRABOTKAMETALLOV Vol. 28 No. 2 2026 220 EQUIPMENT. INSTRUMENTS Investigation of the characteristics of chip formation and wear of working surfaces of milling inserts with CVD coating in high-speed α-Ti machining Petr Pivkin 1, a, Artem Babaev 2, b, *, Nikolai Savchenko 3, c, Viktor Kozlov 3, d, Artem Semenov 3, e, Vladimir Grechishnikov 1, f, Ludmila Uvarova 1, g Alexey Nadykto 1, h 1 Moscow State University of Technology “STANKIN”, 3a Vadkovski Lane, Moscow, 127055, Russian Federation 2 National Research Tomsk Polytechnic University, 30 Lenin Avenue, Tomsk, 634050, Russian Federation 3 National Research Tomsk State University, 36 Lenin Avenue, Tomsk, 634050, Russian Federation, 634050, Russian Federation a https://orcid.org/0000-0002-7547-4652, pmpivkin@gmail.com; b https://orcid.org/0000-0003-2334-1679, temkams@mail.ru; c https://orcid.org/0000-0001-8254-5853, savnick@ispms.ru; d https://orcid.org/0000-0001-9351-5713, kozlov-victor@bk.ru; e https://orcid.org/0000-0002-8663-4877, artems2102@yandex.ru; f https://orcid.org/0009-0001-5535-0724, grechishnikov1935@gmail.com; g https://orcid.org/0000-0003-1137-6436, l.uvarova@stankin.ru; h https://orcid.org/0000-0003-3652-7421, abnadykto@yandex.ru Obrabotka metallov - Metal Working and Material Science Journal homepage: http://journals.nstu.ru/obrabotka_metallov Obrabotka metallov (tekhnologiya, oborudovanie, instrumenty) = Metal Working and Material Science. 2026 vol. 28 no. 2 pp. 196–222 ISSN: 1994-6309 (print) / 2541-819X (online) DOI: 10.17212/1994-6309-2026-28.2-196-222 ART I CLE I NFO Article history: Received: 04 April 2026 Revised: 14 April 2026 Accepted: 30 April 2026 Available online: 15 June 2026 Keywords: Titanium alloy High-speed milling Chip Wear and tear Funding The research carried out with the fi - nancial support of the Russian Federation under project No. 22-79- 10353-П. Acknowledgements The authors express their gratitude to the Center for Collective Use of PhysicalChemical Mathematics (TPU). ABSTRACT Introduction. Due to the wide application of pure α-titanium in critical products, the intensifi cation of its machining by cutting is an urgent task. Existing studies focus mainly on alloyed alloys, while the features of high-speed dry milling of pure α-Ti are not well understood. The aim of this work was to investigate the infl uence of milling modes on the wear of a CVD-coating (Al2O3/TiCN+TiN) on carbide inserts, chip morphology and deformation processes in the surface layer of Ti Grade 2 alloy. Methodology. The experiments were carried out using parallel milling in the range of cutting speeds v = 100–300 m/min, feed rates f = 50–100 mm/min and depths of cut aр = 0.2–0.4 mm without coolant. The condition of the cutting edges and the morphology of the chips were investigated using SEM and EDX. X-ray diff raction analysis was used to assess deformation changes. The data were processed using correlation and regression analysis methods. Results and discussion. It has been found that with increasing cutting speed, adhesion processes and thermomechanical stresses are intensifi ed, leading to local scraping and delamination of the CVD coating on the rake surface. At a speed of 300 m/min, there is signifi cant material buildup, forming an unstable builtup edge. The study of the chips revealed a transition from continuous to elemental form. A strong negative correlation (r = −0.81) between the cutting speed and the height of protrusions (h3) on the chip was found, as well as a moderate positive infl uence of the depth of cut on the continuity coeffi cient (r = 0.55). The results obtained are relevant for the optimization of high-speed dry machining of pure titanium products used in cryogenic engineering and heat exchangers. Conclusions. The dominant wear mechanisms are adhesion and thermomechanical degradation of the coating. The critical mode leading to intensive buildup is a combination of v = 300 m/min, f = 100 mm/min, aр = 0.4 mm. To reduce wear, it is recommended to control heat dissipation by optimizing cutting speed and depth of cut. For citation: Pivkin P.M., Babaev A.S., Savchenko N.L., Kozlov V.N., Semenov A.R., Grechishinikov V.A., Uvarova L.A., Nadykto A.B. Investigation of the characteristics of chip formation and wear of working surfaces of milling inserts with CVD coating in high-speed α-Ti machining. Obrabotka metallov (tekhnologiya, oborudovanie, instrumenty) = Metal Working and Material Science, 2026, vol. 28, no. 2, pp. 196–222. DOI: 10.17212/1994-6309-2026-28.2-196-222. (In Russian). ______ * Corresponding author Babaev Artem S., Ph.D. (Engineering), Senior Researcher National Research Tomsk State University, 36 Lenin Avenue, 634050, Tomsk, Russian Federation Tel.: +7 952 805-09-26, e-mail: temkams@mail.ru
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