Impact of vapor polishing on surface quality and mechanical properties of extruded ABS

Purpose - Additive manufacturing (AM) is readily capable of producing models and prototypes of complex geometry and is advancing in creating functional parts. However, AM processes typically underperform traditional manufacturing methods in mechanical properties, surface roughness and hermeticity. Solvent vapor treatments (vapor polishing) are commonly used to improve surface quality in thermoplastic parts, but the results are poorly characterized. Design/methodology/approach - This work quantifies the surface roughness change and also evaluates the effect on hermeticity and mechanical property impacts for "as-printed" and acetone vapor-polished ABS tensile specimens of 1-, 2-and 4-mm thicknesses produced by material extrusion (FDM). Findings - Vapor polishing proves to decrease the power spectral density for surface roughness features larger than 20 mu m by a factor of 10 x and shows significant improvement in hermeticity based on both perfluorocarbon gross leak and pressure leak tests. However, there is minimal impact on mechanical properties with the thin specimens showing a slight increase in elongation at break but decreased elastic modulus. A bi-exponential diffusion decay model for solvent evaporation suggest a thickness-independent and thickness-dependent time constant with the latter supporting a plasticizing effect on mechanical properties. Originality/value - The contributions of this work show vapor polishing can have a substantial impact on the performance for end-use application of ABS FDM components.