Dynamic mechanical and drilling behavior of Alstonia macrophylla fiber-reinforced polypropylene (PP) composites

In this work, dynamic mechanical analysis (DMA) and drilling behaviour of the alkali treated Alstonia macrophylla (AS) fiber-reinforced polypropylene (PP) composites were investigated. These PP/AS composites were fabricated using compression moulding technique by their varying fiber volume fractions (0, 10, 20, 30, 40 and 50 Vol%). Study revealed that DMA properties of the PP/AS composites increased with increase in the fiber content and 40 Vol% fiber loaded composites exhibited better than its counterparts and neat PP. Drilling was performed on the PP/AS composite at a constant spindle speed (2500 RPM) in a vertical CNC machine using L9 orthogonal array of Taguchi design of experiment. Effect of parameters, viz. drill point angle (90°, 118°, and 130°), feed rate (20, 40, and 60 mm/min) on drillability of the PP/AS was explored in terms of thrust force, torque and delamination factor. Results showed that better quality of the hole was produced if the PP/AS composites were drilled at lower feed rate using drill bit of minimum drill point angle. Analysis of variance showed that drill point angle influenced quality of the drill hole than feed rate. Field emission scanning electron microscopy was used to capture the images of the drilled surface in order to understand the delamination mechanism of the PP/AS composite.