Post-treatment of ABS samples manufactured by FDM

Malagutti L., Ronconi G., Zanelli M., Mollica F., Mazzanti V.

Fused-filament fabrication is one of the most popular 3D printing techniques for thermoplastic materials because it is easy to use and is low-cost. On the other hand, it has the great limit of being suitable only for developing prototypes, because the printed object generally has low mechanical properties, and this prevents its use in structural applications. To solve this issue, the scientific literature has mainly focused on the optimization of the printing parameters and on performing some post-printing treatments, e.g., annealing, but despite some results being very promising, the topic has not yet been exhaustively investigated. In this paper, a post-printing treatment was studied that was based on two subsequent stages of remelting and compaction within a mold made of a granular material. The material chosen for this study was a green composite made of poly-(lactic acid) and poly-(hydroxyalkanoate) filled with wood fibers. The density, mechanical properties in terms of tension and microscopic observations were used to evaluate the treatment effectiveness. The main results were that voids were reduced, and the quality of the interlayer welding was increased, and this improved the mechanical properties, both in terms of stiffness and strength. In particular, the initial specimens displayed remarkable anisotropy, being stronger and stiffer in the longitudinal direction. After the post-processing treatment, despite the longitudinal properties having a very limited increase, the transversal properties increased significantly until they reached the longitudinal properties, thus leading to a more isotropic material.

Lluch-Cerezo J., Meseguer M.D., García-Manrique J.A., Benavente R.

Fused deposition modelling (FDM)-printed parts can be treated with various post-processes to improve their mechanical properties, dimensional accuracy and surface finish. Samples of polylactic acid (PLA) and acrylonitrile butadiene styrene (ABS) parts are treated with annealing to study a ceramic powder mould’s effectiveness in order to avoid dimensional part deformation. The variables chosen are annealing temperatures and the usage of a ceramic powder mould to avoid part deformations. A flexural strength test was carried out to evaluate the mould’s influence on the mechanical properties of the part. The effectiveness of the mould has been evaluated mainly attending to the length of the part, because this is the dimension most affected by deformation. A polynomial approximation to a deformation’s length and the effectiveness of the mould allows for their prediction. Results obtained show that effectiveness increases with the annealing temperature. Nevertheless, mould effectiveness decreases when parts are fabricated with PLA, because it is a semi-crystalline thermoplastic, and it suffers a lower shrinkage during thermal post-process than amorphous polymers such as ABS. Attending to the flexural strength test, mould has no significant influence on the mechanical properties of the treated parts in both materials studied.

Lluch-Cerezo J., Benavente R., Meseguer M.D., García-Manrique J.A.

The post-process thermal treatment of thermoplastics improves their mechanical properties, but causes deformations in parts, making them unusable. This work proposes a powder mould to prevent dimensional part deformation and studies the influence of line building direction in part deformations in a post-process thermal treatment of 3D printed polymers. Two sets of ABS (acrylonitrile butadiene styrene) test samples manufactured by fused deposition modelling (FDM) in six different raster directions have been treated and evaluated. One set has been packed with a ceramic powder mould during thermal treatment to evaluate deformations and mould effectiveness. Thermogravimetric tests have been carried out on ABS samples, concluding that the thermal treatment of the samples does not cause degradations in the polymeric material. An analysis of variance (ANOVA) was performed to study internal building geometry and mould influence on part deformation after the thermal treatment. It can be concluded that powder mould considerably reduces dimensional deformations during the thermal treatment process, with length being the most affected dimension for deformation. Attending to the length, mould effectiveness is greater than 80% in comparison to non-usage of moulding, reaching 90% when the building lines are in the same direction as the main part.

Vyavahare S., Teraiya S., Panghal D., Kumar S.

PurposeFused deposition modelling (FDM) is the most economical additive manufacturing technique. The purpose of this paper is to describe a detailed review of this technique. Total 211 research papers published during the past 26 years, that is, from the year 1994 to 2019 are critically reviewed. Based on the literature review, research gaps are identified and the scope for future work is discussed.Design/methodology/approachLiterature review in the domain of FDM is categorized into five sections – (i) process parameter optimization, (ii) environmental factors affecting the quality of printed parts, (iii) post-production finishing techniques to improve quality of parts, (iv) numerical simulation of process and (iv) recent advances in FDM. Summary of major research work in FDM is presented in tabular form.FindingsBased on literature review, research gaps are identified and scope of future work in FDM along with roadmap is discussed.Research limitations/implicationsIn the present paper, literature related to chemical, electric and magnetic properties of FDM parts made up of various filament feedstock materials is not reviewed.Originality/valueThis is a comprehensive literature review in the domain of FDM focused on identifying the direction for future work to enhance the acceptability of FDM printed parts in industries.

Potapov Andrey A., Volgin Vladimir M., Malakho Artem P., Gnidina Inna V.

The application of additive technologies to the manufacture of polymer and composite products is now actively expanding. The FDM printing process is popular because of its ability to adapt to specific tasks and to bring products with complex geometries into production quickly and at minimal cost, and is seen as a technology that can compete with injection molding. However, due to the nature of the process, FDM printed parts are significantly inferior in quality to injection molded parts. Much attention is now being paid to research into supplementary treatment methods to improve the properties of FDM printing parts. However, there is no complete and clear description of such methods, nor are there any recommendations on the choice of treatment methods aimed at improving the specific parts properties. The aim of this review is to analyse the research in the field of post-treatment of parts in order to systematise their advantages and limitations, which will allow a more reasoned choice of a post-treatment method to improve specific properties of FDM printing parts.The bibliography includes 120 references.