Evaluation of delamination in drilling of SiCp/sisal fiber reinforced epoxy composites by the analysis of acoustic emission and cutting force: Influence of tool condition

The presence of SiC particulate in the newly developed SiCp/sisal fiber/epoxy composites on drilling, influence the wear in the drill bit. This article presents the experimental investigations of the effect of tool condition on delamination during drilling of composite by the time, frequency domain, and discrete wavelet packet transformation (DWPT) of acoustic emission and cutting force measured in process. It may further be helpful for determining and assessing the root cause of the induced delamination damage. The drill bits are made of high-speed steel (HSS), the condition is categorized into three different types namely as received, cryogenically treated (-80 degrees C for 24 h), and cryogenically treated and tempered (-80 degrees C for 24 h and 200 degrees C for 2 h). Study of the frequency domain reveals that the dominant frequency of the acoustic emission (AE) signals falls between 100 and 300 kHz. The AE-specific energies of the decomposed signals are calculated based on DWPT analysis. It is noted from the AE specific energy that shearing occurs during drilling process. The cryogenically treated and tempered HSS drill contributes significantly to the reduction in delamination compared to other tools employed in this investigation.