Fused Deposition Modeling (FDM) is one of the efficient rapid prototyping (RP) technologies that forms 3D objects by adding material layer by layer from CAD generated solid models. However, the FDM built part is hardly anisotropic in nature due to layer-by-layer build mechanism. Literature suggests that mechanical property, especially tensile strength, of FDM built part is severely affected by process parameters. Among all the parameters, contour number happens to be an important parameter because it reduces stress concentration resulting in avoidance of premature breakdown. Therefore, in this work contour number along with five important process parameters such as layer thickness, raster width, part orientation, raster angle and air gap are considered and their effect on tensile strength of FDM built parts is studied. Experiments are conducted using Face Centred Central Composite Design (FCCCD) in order to reduce the experimental runs. An optimal parameter setting has been suggested for the maximisation of tensile strength of the FDM built parts.