Glass Fiber Reinforced Plastics (GFRP) is finding increased applications in various fields of mechanical engineering, due to their good properties such as high strength, high stiffness and light weight. The application fields include automobile, biomechanics and aerospace industries. The good properties and potential applications necessitate machining of these composite materials. Though many investigators worked on machining of GFRP composites, the work on the effect of machining parameters on surface roughness parameters is minimum. In the present paper the influence of main cutting parameters and their interactions on surface roughness parameters (R_a, R_t, R_q, R_p and R_3z ) in turning of glass fibre reinforced  composite materials is investigated. The parameters considered for the investigation are: cutting speed and feed. Models were developed to correlate the machining parameters with surface roughness parameters. The adequacy of the models was checked by R-Sq values. The effect of parameters was evaluated by using main effect graphs and interaction graphs. The results indicates that the increase in feed mainly influence the surface roughness parameters in machining of GFRP composites.

Key words: Fibre-reinforced plastics, turning, surface roughness parameters, model.