Search

Fused deposition modeling (FDM) technology decreases production time and cost in engineering industry, but with typical low surface quality. In this study, laser polishing was employed to improve surface quality of copper fiber/polylactide acid (Cu/PLA) composite parts fabricated by FDM. Surface roughness, surface morphology, dynamic mechanical analysis (DMA), and tensile properties were studied. The results showed that after laser polishing, the surface roughness was reduced by more than 91% (from 10.52 to 0.87 μm Sa) at the optimized parameters (the laser power of 5 W and the laser beam diameter of 200 μm). Laser polishing can effectively remove surface defects formed during FDM. DMA showed that the storage modulus, loss modulus, and glass transition temperature of Cu/PLA composites were significantly improved, because the Cu fibers and PLA matrix formed a strong interfacial adhesion after treatment. Moreover, the tensile strength and Young's modulus of the Cu/PLA composites sample also improved by laser polishing. The fracture morphologies were observed, and the possible strengthening mechanism was also discussed. [ABSTRACT FROM AUTHOR]

Owing to the layer-by-layer deposition characteristic of fused deposition modeling (FDM) process, parts produced via FDM have typical low surface quality and do not satisfy the requirements for end-use applications. Therefore, it is necessary to improve the surface quality of parts produced via FDM. In this study, laser polishing technology was employed to enhance the surface quality of aluminum fiber/polylactide acid (Al/PLA) composite parts produced via FDM. The surface roughness, surface morphology, dynamic mechanical properties, and tensile properties were investigated. With optimal polishing parameters, the laser polishing process removed the defects formed during the FDM process. The surface roughness was reduced from the initial value of 5.64 μm to 0.32 μm (Ra). The dynamic mechanical analysis (DMA) results showed that there was a remarkable improvement in the storage modulus (E ′), loss modulus (E "), and glass transition temperature of Al/PLA composite specimens after laser polishing. The re-melted and polished surface of the specimens also led to improvement in the tensile strength and Young's modulus. Lastly, the fracture morphologies were observed, and the possible strengthening mechanism was also discussed. These results indicate that laser polishing can be an efficient method for the surface polishing of FDM-printed parts. Unlabelled Image • Laser polished additive manufactured Al/PLA has higher surface quality and many defects are removed. • A maximum reduction in Al/PLA surface roughness of over 93% is achieved at optimized polishing settings. • Laser polishing effectively improves the dynamic mechanical properties and tensile properties of the FMD Al/PLA. • The strengthening mechanism induced by laser polishing is analyzed. [ABSTRACT FROM AUTHOR]

Although fused deposition modeling (FDM) has gradually become one of the popular additive manufacturing technologies in different industries, high surface roughness has always been an inevitable disadvantage of FDM parts. Laser polishing represents a recent and novel application of laser surface irradiation that can be used for precise, post-process smoothing of the rough surfaces commonly encountered on FDM parts. The influence of laser polishing on surface modification and mechanical properties of aluminum/Polylactic Acid (Al/PLA) composites has been investigated. Laser scanning speed was varied to evaluate its effect on the surface quality and mechanical properties of the experimental samples. The results indicated that laser polishing could enable reductions in surface roughness of over 86.6% (from 23.27 μm to 3.11 μm Sa). The tensile strength of specimen also increased from 41.01 MPa to 51.31 MPa with increasement of 25.1%. The dynamic mechanical analysis (DMA) results showed that there was a remarkable improvement in the storage modulus and glass transition temperature of Al/PLA composite specimens after laser polishing, which suggested that the laser polishing treatment could play a role in decreasing the porosity inside the FDM parts and improve interfacial adhesion between the PLA matrix and Al fibers. Moreover, the fracture morphologies were observed to investigate the possible strengthening mechanism. These results demonstrate how laser polishing can simultaneously smooth and modify the surface characteristics of a FDM part surface. Image 1 • Laser polished additive manufactured Al/PLA has higher surface quality and many defects are removed. • A maximum reduction in Al/PLA surface roughness is achieved at optimized polishing settings (laser scan speed of 100 mm/s). • Laser polishing effectively improves the dynamic mechanical properties and tensile properties of the FMD Al/PLA. • After laser polishing treated, Al/PLA composite specimens had a higher storage modulus and glass transition temperature. • The strengthening mechanism induced by laser polishing is analyzed. [ABSTRACT FROM AUTHOR]

While metal additive manufacturing has seen significant growth in recent years, the surfaces produced often need post-processing to improve surface finish, mitigate residual stresses, and remove surface-connected porosity. Laser polishing, by means of remelting a thin layer of the surface, is one post-processing method being investigated for surface finish improvements and other surface enhancements. In this work, the surface morphology and microstructure of laser powder bed fused (L-PBF) stainless-steel 316 L (316 L) before and after laser polishing are characterized by optical microscopy (OM), scanning electron microscopy (SEM), electron back-scatter diffraction (EBSD), and transmission electron microscopy (TEM). In addition, the cross-sectional microhardness of the samples is measured and reported. Additionally, the as-built and laser-polished sample's tensile properties are characterized using uniaxial tension tests. The results indicate that the surface roughness of as-built 316 L (Sa = 4.84 μm) can be substantially reduced through laser polishing (Sa = 0.65 μm). After laser polishing, the average grain diameter is reduced and the proportion of low angle grain boundaries (2°~5°) is increased in the L-PBF 316 L. The maximum sub-surface hardness reaches 262 HV, and both the tensile strength and ductility of 316 L are increased after laser polishing. This enhancement is attributed to thermal cycling stresses, grain refinement, the elimination of surface defects, and dislocation strengthening after laser polishing. [ABSTRACT FROM AUTHOR]