Optimization of drilling process parameters on customized alkali-silane treated pineapple fibre-epoxy composite using Taguchi-Grey relational approach

In this research, the role of surface-treated pineapple fibre on the machining behavior of epoxy composite is studied. The primary objective of this research was to identify the optimum process variable in the drilling process when machining an alkali-silane treated pineapple fibre-epoxy composite. The fibre was treated using NaOH for 2 h and subsequently treated with 3-Aminopropyltrimethoxysilane for 20 min. Followed by hand layup process 6 mm thick composites were made and cured at elevated temperature of 120 degrees C. The machining process was conducted on composite plates based on Taguchi L9 orthogonal array with the process inputs of drilling speed (rpm), feed rate (mm/min) and drill tool diameter (mm) also with the output responses of circularity difference (mm) and surface roughness (mu m). According to the results, the experimental pattern A3B3C2 (drilling speed of 1200 rpm, feed of 3 mm/min, drill too diameter of 6 mm) shows the highest GRG of 0.773 with a lowest circularity difference and surface roughness of 0.06 mm and 1 mu m. However, the optimized process variables after the grey relational approach were found to be A2B2C1 (drilling speed of 1000 rpm, feed of 2 mm/min, drill too diameter of 4 mm) with an improved GRG of 0.784. It is equal to the improvement of 1.423% with a lowest circularity difference of 0.0591 mm and surface roughness of 0.985 mu m. According to the results the drill tool diameter is found to be the most influencing process variable to produce high dimensionally stable drilled holes. Similarly, the drill tool diameter of 4 mm is most suitable to make flawless holes. These dimensionally stable composites with good machining quality can be used in automotives, aerospace, defense, marine and structural applications.