Effects of nozzle-bed distance on the surface quality and mechanical properties of fused filament fabrication parts

Fused filament fabrication (FFF) is a widely studied additive manufacturing technology. However, the effect of initial nozzle-bed distance (NBD) is neglected in most of the studies. In this paper, the effects of the NBD on FFF process were investigated. The optimal NBD for fabrication of high quality FFF parts were evaluated based on the surface quality and mechanical properties of Acrylonitrile Butadiene Styrene (ABS) parts. With the NBD increases from 0.083 to 0.20 mm, the roughness of surface increases first and then lowered down, with best surface quality observed at NBD of 0.10 mm, which induces an average altitude intercept of approximately 102.0 mu m. More interestingly, the inter-layer adhesion decreases obviously with the NBD increasing. It was found that the NBD influences the voids formation in the first layer and hence the heat dissipation mechanism, which further influenced the interfacial bonding of the following layers. At higher NBD value, the heat dissipation mechanism also induces the decrease of part mechanical properties, such as tensile, compression and bending strength.