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One of the machining failures in composite materials is delamination damage. In this paper, machining parameters and delamination damage caused by the drilling process on ramie woven reinforced composite material with an unsaturated polyester matrix were investigated. The ramie woven used is ramie yarn type 12S/3. The machining process used 1.5 kW pillar drills, with variations in the diameter of the brad and spur drill of 4 mm, 6 mm, 8 mm and 10 mm. This work focused on the influence of machining parameters like feeds rate and spindle speed. Holes quality was analysed in terms of thrust force and delamination failure. From the results of this study, the thrust force value obtained at the time of drilling is very closely related to the delamination damage that happens. Delamination damage occurs on both sides of the holes drill. [ABSTRACT FROM AUTHOR]

Natural fibres as reinforcement of composite have been applied during the last decade. One of natural fibre has been used as reinforcement is coir fibre. As reinforcement of composite, such fibre needs treatment to improve compatibility with its matrix with suitable treatment. In this paper, surface treatment of such fibre was conducted using sodium bicarbonate (NaHCO3) solution with various densities and soaking time differences. Mechanical and morphological properties of coir fibre were investigated. Coir fibres were soaked in the 8 wt.%, 10 wt.%, and 12 wt.% sodium bicarbonate solution for 24 hours and 120 hours. After treatment, coir fibres were characterized with tensile testing, scanning electron microscope (SEM), Fourier transform infrared (FTIR) and x-ray diffraction (XRD). The results suggested that mechanical properties of coir fibre after sodium bicarbonate solution changed for all densities and soaking time. The coir fibre treated in 12 wt.% sodium bicarbonate for soaking time 120 hours has highest tensile strength. The surface morphology of fibre was analyzed by using SEM. It showed micropores on the fibre surface which may influence the mechanical properties of coir fibre. [ABSTRACT FROM AUTHOR]