Hole-quality evaluation in drilling fiber-reinforced composites

This paper presents a novel approach for a complex evaluation of the quality of drilled holes in fiber-reinforced composite materials. The proposed methodology is based on non-destructive quantification of visible defects based on the numerical analysis of drilled hole images. Automatic contour definition and profile formation for the uncut fibers and delamination were implemented via modularized algorithms. Four criteria for the evaluation of the defect height and width distribution were developed and combined into an overall quality parameter, Q. The methodology was validated experimentally by drilling carbon-fiber-reinforced polymer (CFRP) samples with a cemented carbide drill bit. The results showed a linear relation between the hole quality Q, the drilled hole number, and tool wear.