Damage-free hole making using microwave drilling in flax/PP composite

Abstract

ABSTRACT The current study focused on the examination of hole quality in microwave drilling of microwave cured natural flax and polypropylene composites. The effect of two input parameters, i.e. microwave power and feed rate of the concentrator were investigated to evaluate HAZ, circularity error, and overcut of the hole. Stereomicroscopic images were used for examination of the response parameters. The full factorial design of the experiments was carried out with two factors and four levels. It was found that flax/PP composite drilled at 180 W of microwave power and 130 mm/min of feed rate resulted in a minimum overcut and circularity error of 9 µm and 138.5 µm, respectively. Also, 360 W of microwave power and 130 mm/min of feed rate showed a reduced HAZ of 67.5 mm2. There was no fiber delamination observed during hole formation. Regression analysis was done in order to establish a relationship among responses and process parameters. Additionally, an ANOVA was undertaken to determine the significance of the model. Over 95% of the correlation between the experimental data and the projected model outcomes was observed. Combined interaction of both the input parameters was shown through surface and contour plots.