Analysis of surface roughness and delamination factor applied to the drilling of hybrid polymeric composite materials by the Taguchi method

Abstract

This research studies the impact of drilling parameters, namely spindle speed (V), feed rate (f) and drill bit type (Diamond inlay drill bit DD and special carbide drill bit for Kevlar KD), on roughness (Ra) and delamination factors (Idf and Odf) generated when drilling composite materials. To design and evaluate the experiment, the orthogonal matrix L18 of Taguchi's method was used. An ANOVA analysis was performed to verify the statistical effect of the control variables in the experiment with a significance level of α = 0.05. Linear and quadratic regression equations were used to predict the values of the response variables at acceptable levels, with quadratic regression showing the best predictive result (R2 = 0.85). The analysis revealed that tool type was the most significant controlling factor affecting Ra and Odf, and feed rate had the greatest effect on Idf. The results indicated that the DD bit performed better than the KD bit for Ra. Increasing V reduced the surface quality of Ra, Idf and Odf. Conversely, increasing f increased Ra and Idf, but decreased Odf. Therefore, the use of a KD bit is more efficient when drilling this type of hybrid composite material. This assertion is further corroborated by SEM images that validate the extent of surface damage caused by the drilling process.