Experimental investigation and optimization of process stability in drilling of Al 7075‑T651 using indexable insert drills

Akdulum A., Kayır Y.

JOURNAL OF THE BRAZILIAN SOCIETY OF MECHANICAL SCIENCES AND ENGINEERING, cilt.2023, sa.45, ss.1-20, 2023 (SCI-Expanded, Scopus)

Özet

The indexable insert drill, commonly known as the U drill, holds a significant market share of approximately 53% among

drilling tools. Therefore, investigation and improvement studies are carried out by both industry and academia. U drills are

usually produced in different length/diameter ratios and with two coolant holes. But in other cases, some manufacturers

design a third coolant hole in the chip evacuation channel, where the central insert of the U drills is located. It is thought

that the coolant holes and length/diameter ratios change the conditions of the drilling process. In this study, the impact of U

drills with various attributes was examined using thrust force, torque, spindle load, and audio signals. For this purpose, Al

7075-T651 aluminum alloy was drilled with 4 different U drills. The trials used three feed rates (0.06, 0.09, and 0.12 mm/rev)

and three cutting speeds (200, 250, and 300 m/min). Experimental results show that the length/diameter ratio of U drills has

the highest impact on thrust force (76.45%), spindle load (53.33%), and audio signal (87.53%). However, it was ineffective

for torque, according to the Anova analysis. Moreover, the U drill, which has an additional coolant hole, generates higher

thrust forces (39.89%) and audio signals (95.17%), lower spindle loads (41.28%), and lower torque (3.26%). Taguchi based

grey relational analysis that was used to optimize the test parameters provided an improvement of 26.06% according to the

gray relationship grade, which is the normal method used. To sum up, these findings may contribute to improving the design

and production of U drills to enhance their drilling performance.