Investigating the thermo-mechanical response and bush formation during friction drilling of LPBF AlSi10Mg alloy

This study investigates the thermo-mechanical response of laser powder bed fused (LPBF) AlSi10Mg alloy during friction drilling and its influence on bushing formation. Experiments were conducted under dry drilling conditions by varying the rotational speed (2000 to 5000 rev/min) and feed rate (100 to 250 mm/min). Results provide valuable insights into combined effects of process parameters and LPBF-induced microstructure on friction drilling performance of AlSi10Mg alloy. The ultrafine cellular microstructure of LPBF AlSi10Mg significantly increased its hardness and flow stress, thereby strongly influencing the friction drilling behavior. Compared with conventional cast aluminum alloys, LPBF AlSi10Mg generated substantially higher temperatures, thrust forces, and torque owing to its greater mechanical strength, higher microhardness, enhanced frictional interaction, and microstructural heterogeneity. Whereas the bushing produced in the LPBF alloy was smaller than those formed in their cast counterparts. Both thrust force and torque decreased with increasing rotational speed, whereas higher feed rates resulted in higher force and torque values. The maximum temperature of 396 °C was recorded at a rotational speed of 5000 rev/min and a feed rate of 100 mm/min. A rise in rotational speed led to higher temperatures because of increased frictional heat generation at tool–workpiece interface, while it decreased with increasing feed rate owing to the reduced tool–workpiece interaction time. Larger and more uniform bushings were obtained at a rotational speed of 5000 rev/min combined with lower feed rate of 100 mm/min. Analysis of variance (ANOVA) revealed that rotational speed was the most influential parameter affecting thrust force, torque, and temperature, followed by feed rate.