Effects of raster angle on tensile and surface roughness properties of various FDM filaments

Parts produced by FDM (fused deposition modelling) technique, where polymer filaments are used, are anisotropic and their properties vary depending on the printing parameters, one of which is raster angle. In this study, the effects of this parameter on the tensile and the surface roughness properties were investigated. It was determined that the ultimate tensile strength (UTS) decreased with increasing raster angle; hence, 0 degrees raster angle where tensile loading direction is parallel to the raster yielded the highest strength. Besides +/- 45 degrees raster angle resulted the most ductile behaviour with the highest fracture strains. Fracture occurred due to raster failure for 0 degrees raster angle but for 90 degrees raster angle, it was due to the failure of the interlayer raster bonds. In the case of +/- 45 degrees, both of the failure mechanisms were effective. Surface roughness values increased up to 7 mu m when measurement was perpendicular to the raster and dropped below 1 mu m when it was parallel to the raster.