Three-dimensional (3D) printing of polylactic acid using the fused filament fabrication approach is a widely used additive manufacturing method in various fields, despite the historical issue of substantial surface roughness in fused filament fabrication products. Several strategies have been utilized to minimize the surface roughness of 3D-printed items. However, laser polishing is a novel technique for reducing surface roughness and improving other material qualities. In this study, polylactic acid was examined using the laser polishing method for surface roughness and mechanical properties, such as tensile and flexural strength and laser scan time. Several trials were conducted to determine how changing the laser’s characteristics may affect the materials’ surface quality and mechanical qualities. Before the final test, preliminary tests were performed to determine the lowest potential heat-affected zone. Laser polishing reduced surface roughness by more than 88.8% (from 7.8 µm to 0.87 µm). The tensile strength of the specimen increased by 14.03%, from 39.2 MPa to 44.7 MPa. Polylactic acid had a constant flexural strength of 70.1 MPa before and after polishing, and the laser scan time for samples was 19.4 s. Polished morphologies were studied to learn more about the microstructure. These findings show that laser polishing can improve and modify the surface properties of a fused filament fabrication product, which can benefit the industry and researchers.

The inflammation around poorly osseointegrated bioimplant is one of the root causes of its failure. Therefore, the biomedical industry constantly strives for new ways to develop bioactive surfaces in permanent implants to enhance the service life. In this regard, implant surface modification at micro/nanoscales is carried out to enrich substrate with higher engineering attributes and biocompatibility. Considering the complexities of post-processing of implants, this study evaluates the potentiality of an integrated process of implant machining and surface modification, namely, powder-mixed electric discharge machining (PMEDM). Ti6Al4V ELI implant material, as substrate, is machined under two distinct (Si, SiC) mixed additive conditions using a full factorial design of experiments. The surface quality, surface morphology, recast layer depth, surface chemistry, and work hardening have been holistically investigated. The bioactivity analysis of machined surfaces shows more porosity in the case of Si powder particles (200 to 400 nm) compared to SiC (100 to 250 nm). Furthermore, the study optimized the process parameters for minimum roughness and recast layer depth considering 5 g/L powder concentration, 5A pulse current, 50 µs pulse on time for Si, and 100 µs pulse on time for SiC. A comprehensive review of surface features based on process physical science is established, and nanoscale surface topography influencing protein absorption is analyzed.

Practitioners in the industry are developing predictive methods for assessing key parameters and responses of engineering materials. The aim of this research is to optimize the average surface roughness (R _a), flexural strength (FS), tensile strength (TS), print time (T), and print energy consumption (E) of 3D printed Nylon 6 (PA6). Quantitative parameters for infill density (ID), layer thickness (LT), and print speed (PS) were selected. Employing the central component design (CCD)-response surface methodology (RSM) for investigational design, statistical analysis, and multi-objective optimization, a total of 20 samples were produced and analyzed to develop prediction models. The implication of the selected parameters was confirmed through variance analysis (ANOVA), and the models were validated using confirmatory trial tests. It was found that LT was essential in achieving appropriate R _a and T values, while ID was a crucial factor in obtaining the necessary mechanical properties. RSM optimization led to an FS of 70.8 MPa, TS of 40.8 MPa, lowest T of 53 min, lowest possible R _a of 8.30 µm, and 0.203 kW·h “E” at ID = 84%, LT = 0.21 mm, and PS = 75 mm·s⁻¹. The study also revealed weak bond strength between layers and layers debonding after bending tests, as shown in SEM micrographs. The PA6 material exhibited flexibility during tensile testing, going into plasticity before breaking. The created numerically optimized model is anticipated to benefit manufacturers and practitioners in predicting the required surface quality for various factors before conducting experiments, ultimately improving 3D printing (3DP) processes and outcomes. Despite limitations such as limited parameter selection, small sample size, and material-specific focus, this research presents valuable insights for the 3DP industry.