Article: Quality improvement in mechanical micro-drilling of titanium alloy under dry conditions Journal: International Journal of Machining and Machinability of Materials (IJMMM) 2021 Vol.23 No.5/6 pp.527 - 561 Abstract: Titanium alloy (Cp-Ti) grade-II is considered a hard-to-cut material due to low thermal conductivity, work hardening behaviour, and affinity with cutting tool materials. In this study, micro-holes are machined on titanium alloy (Cp-Ti) grade-II under dry conditions. Experiments are carried out by varying the machining parameters like cutting speed (5 m/min, 6.9 m/min, and 8.8 m/min), feed (5 µm/rev, 7.5 µm/rev, and 10 µm/rev), and drill diameter (Ø0.2 mm, Ø0.3 mm and Ø0.4 mm) at three levels based on full factorial design. The machined holes are characterised by responses like exit burr height, taper angle, and circularity, regression-based models are developed using response surface methodology. The optimal levels of machining parameters for multiple responses are ascertained. In the later part of the study, two methods providing a backup of aluminium and copper foil on the top and bottom surface of workpieces are experimentally evaluated. The copper foil backup method significantly reduced exit burr height and taper angle while improving circularity slightly. Whereas aluminium foil only reduced exit burr height. Finally, the effectiveness of backup methods is also analysed using recorded thrust force signals. Inderscience Publishers - linking academia, business and industry through research

Title: Quality improvement in mechanical micro-drilling of titanium alloy under dry conditions

Authors: P. Prashanth; Somashekhar S. Hiremath

Addresses: Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai-600036, Tamilnadu, India ' Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai-600036, Tamilnadu, India

Abstract: Titanium alloy (Cp-Ti) grade-II is considered a hard-to-cut material due to low thermal conductivity, work hardening behaviour, and affinity with cutting tool materials. In this study, micro-holes are machined on titanium alloy (Cp-Ti) grade-II under dry conditions. Experiments are carried out by varying the machining parameters like cutting speed (5 m/min, 6.9 m/min, and 8.8 m/min), feed (5 µm/rev, 7.5 µm/rev, and 10 µm/rev), and drill diameter (Ø0.2 mm, Ø0.3 mm and Ø0.4 mm) at three levels based on full factorial design. The machined holes are characterised by responses like exit burr height, taper angle, and circularity, regression-based models are developed using response surface methodology. The optimal levels of machining parameters for multiple responses are ascertained. In the later part of the study, two methods providing a backup of aluminium and copper foil on the top and bottom surface of workpieces are experimentally evaluated. The copper foil backup method significantly reduced exit burr height and taper angle while improving circularity slightly. Whereas aluminium foil only reduced exit burr height. Finally, the effectiveness of backup methods is also analysed using recorded thrust force signals.

Keywords: mechanical micro-drilling; exit burr height; taper angle; response surface methodology; RSM; exit thrust force; titanium alloy (Cp-Ti) grade-II.

DOI: 10.1504/IJMMM.2021.121165

International Journal of Machining and Machinability of Materials, 2021 Vol.23 No.5/6, pp.527 - 561

Received: 21 Nov 2020
Accepted: 05 Apr 2021
Published online: 28 Feb 2022 *

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Title: Quality improvement in mechanical micro-drilling of titanium alloy under dry conditions

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