Assessment of the GFRP/Ti Hybrid Stack Drilling Under High-speed Cutting and Cooled-compressed Air

Multi-material joints are used in the manufacture and maintenance of aircraft using fiber-reinforced polymers and metallic alloys, and the drilling is a critical process for positioning rivet holes in fuselage assembly. Thus, the work aims to analyze the impact of cutting speed (40 and 220 m/min) and cooled-compressed air in the GFRP/Ti-6Al-4V hybrid stack drilling 0075sing an uncoated carbide drill. The analysis of variance (ANOVA) was used for evaluating the thrust force in drilling, the adjusted delamination factor in GFRP, the hole-wall roughness in Ti, and the roundness error in both plates. According to ANOVA (& alpha; & LE; 0.05), the thrust force significantly decreased for v(c) = 220 m/min and increased with cooled air for both materials. Delamination was also reduced for the higher cutting speed (significant for & alpha; & LE; 0.10). Despite not being significant, lower delamination was observed after cooled-compressed-air assisted drilling. A significant reduction of roundness error was identified in the GFRP using cooled air. Higher roundness error was observed in samples produced with v(c) = 220 m//min; however, this influence was not considered significant. The hole-wall roughness in the Ti plate was significantly influenced by v(c). A higher roughness value was observed after drilling with higher v(c). Despite the use of cooled air presenting no significant influence on the hole-wall roughness, the samples produced with this condition showed rougher surfaces. The analysis of the results indicates that combining high v(c) with cooled air allows higher productivity without increasing defects in the GFRP/Ti hybrid stack drilling.

Automated summary

This study analyzes the impact of cutting speed and cooled compressed air on the drilling process of GFRP/Ti-6Al-4V hybrid stack. The results show that increasing cutting speed and using cooled air can significantly reduce thrust force and delamination, and also influence hole-wall roughness and roundness error. It allows higher productivity without increasing defects in the GFRP/Ti hybrid stack drilling.