Hole quality analysis and parameter optimization in drilling of novel h-BNNS reinforced Al-6082 nanocomposites fabricated using stir casting technique
Authors :- VK Pathak, P Saharan, P Kunal, MK Dikshit
Publication :- International Journal on Interactive Design and Manufacturing (Springer), 2025.
The present study aims to evaluate and analyze the hole quality during the drilling of a novel hexagonal boron nitride nanosheet (h-BNNS) reinforced Al-6082 nanocomposite. Hole quality was assessed in terms of top diameter (TD), bottom diameter (BD), and internal surface roughness (Ra). The nanocomposite was fabricated using the stir casting technique followed by ultrasonic sonication, reinforcing h-BNNS at three different weight percentages (0.3%, 0.5%, and 0.7%). Field Electron Scanning Electron Microscopy (FESEM) was used to examine the dispersion of h-BNNS within the Al-6082 matrix, where agglomeration was observed at 0.7 wt% reinforcement. Rotational speed, feed rate, and h-BNNS content were chosen as input parameters for the drilling experiments, which were designed using a Rotary Central Composite Design (RCCD). A total of 20 experiments were conducted, and TD, BD, and Ra were recorded as output responses. Analysis of Variance (ANOVA) confirmed that a full quadratic model sufficiently described the empirical relationship between input parameters and output responses. Results showed that TD initially decreased with increasing rotational speed and reinforcement content, followed by an increase beyond mid-level values. Feed rate had a minimal and almost linear effect on TD. In contrast, BD exhibited an opposite trend to TD for all three parameters, with the highest BD value (~ 5.015 mm) observed at the highest feed rate. Ra increased with rising rotational speed and also increased steadily with feed rate before slightly declining. The effect of reinforcement on Ra followed a similar trend to that of feed, but with a steeper rate of increase. Multi-objective Grasshopper Optimization Algorithm (MOGOA) was employed to determine the optimal input settings. The optimal parameter values (in coded form) were identified as a rotational speed of 4708 RS, a feed rate of 0.1 mm/rev, and a reinforcement content of 0.4 wt%, targeting a TD and BD of 5 mm while minimizing Ra.