160 Int. J. Machining and Machinability of Materials, Vol. 19, No. 2, 2017 Copyright © 2017 Inderscience Enterprises Ltd. Effect of banyan tree saw dust powder content on the mechanical properties and machining parameters on the machining behaviour of polypropylene composites Narayanappa Ramesha Government Tool Room Training Centre, Bangalore – 560010, India Email: samarthson@gmail.com Siddaramaiah Department of Polymer Science and Technology, Sri Jayachamarajendra College of Engineering, Mysore – 570006, India Email: siddaramaiah@gmail.com Sania Akhtar* Central Institute of Plastics Engineering and Technology, Mysore – 570016, India Email: saniazub@gmail.com *Corresponding author Abstract: Banyan tree saw dust (BSD) powder filled polypropylene (PP) green composites have been fabricated with varying amounts viz., 0, 20 and 40 wt% of BSD particulate filler by using a co-rotating twin screw extruder. The effect of BSD content on the mechanical properties has been studied. While drilling studies on glass fibre reinforced composites have been reported, not many studies have been reported on machining of natural fibre reinforced polymer composites. Hence, in the present study CNC milling and drilling behaviour of the PP/BSD green composites has been investigated. The surface roughness of the CNC milled and drilled composite specimens was measured to assess the effect of BSD content, cutting speed and feed rate on the machining behaviour of the green composites since machining often causes dimensional variations, burr formation, etc. Optical micrographs of the chips obtained during machining operations were examined and the milled surfaces studied under scanning electron microscope (SEM). Furthermore, the effects of addition of 4 wt% PP-g-MA (coupling agent) and 4% talc (mineral filler) on PP/BSD have also been evaluated. It was observed that unlike in metals, the surface roughness increases with increasing cutting speed in the PP-BSD composites. Keywords: polypropylene; banyan tree saw dust; green composites; mechanical performance; surface roughness; CNC milling; CNC drilling; wood plastic composites; WPC; machining.