FDM process parameters influence over the mechanical properties of polymer specimens: A review

Fused deposition modelling (FDM) is one of the fastest-growing additive manufacturing methods used in printing fibre-reinforced composites (FRC). The performances of the resulting printed parts are limited compared to those by other manufacturing methods due to their inherent defects. Hence, the effort to develop treatment methods to overcome these drawbacks has accelerated during the past few years. The main focus of this study is to review the impact of those defects on the mechanical performance of FRC and therefore to discuss the available treatment methods to eliminate or minimize them in order to enhance the functional properties of the printed parts. As FRC is a combination of polymer matrix material and continuous or short reinforcing fibres, this review will thoroughly discuss both thermoplastic polymers and FRCs printed via FDM technology, including the effect of printing parameters such as layer thickness, infill pattern, raster angle and fibre orientation. The most common defects on printed parts, in particular, the void formation, surface roughness and poor bonding between fibre and matrix, are explored. An inclusive discussion on the effectiveness of chemical, laser, heat and ultrasound treatments to minimize these drawbacks is provided by this review.

FDM-Based 3D Printing of Polymer and Associated Composite: A Review on Mechanical Properties, Defects and Treatments.

The rapid rise in the applications of carbon fibre reinforced polymer matrix composites (CFRPs) is creating a waste recycling challenge. The use of high-performance thermoset polymers as the matrix makes the recovery of the fibres and the resins extremely difficult. Implementation of a circular economy that can eliminate waste and re-use resources warrants the use of efficient processes to recycle end-of-life CFRP components and manufacturing wastes. To this end, herein we present a critical review of the current technologies for recovering carbon fibres and/or the polymers and re-manufacturing CFRPs. New research opportunities in developing new biodegradable thermosets and thermoplastic matrices are also outlined together with more radical recycling strategies for the future.

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Current status of carbon fibre and carbon fibre composites recycling

Fused deposition modeling (FDM) is an additive manufacturing (AM) process that is often used to fabricate geometrically complex shaped prototypes and parts. It is gaining popularity as it reduces cycle time for product development without the need for expensive tools. However, the commercialization of FDM technology in various industrial applications is currently limited due to several shortcomings, such as insufficient mechanical properties, poor surface quality, and low dimensional accuracy. The qualities of FDM-produced products are affected by various process parameters, for example, layer thickness, build orientation, raster width, or print speed. The setting of process parameters and their range depends on the section of FDM machines. Filament materials, nozzle dimensions, and the type of machine determine the range of various parameters. The optimum setting of parameters is deemed to improve the qualities of three-dimensional (3D) printed parts and may reduce post-production work. This paper intensively reviews state-of-the-art literature on the influence of parameters on part qualities and the existing work on process parameter optimization. Additionally, the shortcomings of existing works are identified, challenges and opportunities to work in this field are evaluated, and directions for future research in this field are suggested.

A Systematic Survey of FDM Process Parameter Optimization and Their Influence on Part Characteristics

The objective of this study was to compare the physical and mechanical performance of poly(lactic acid) (PLA), acrylonitrile butadiene styrene (ABS), and nylon 6 fabricated using fused deposition modeling (FDM) and conventional injection molding. It is found that different processing methods did not affect the viscosity of the samples, and the percentage difference for the density measurement is less than 4%. Water absorption of FDM samples is approximately 108% higher compared to those fabricated using the injection molding. The results also revealed that the FDM method did not strongly affect the degree of crystallinity of ABS, but it increased the degree of crystallinity of PLA and nylon 6. The tensile strength, Young's modulus, elongation at break, and impact strength of FDM samples were approximately 48%, 50%, 48%, and 78%, lower compared with the injection molded samples. The results presented can provide a guide to manufacturing the final products using FDM with the desired performance.

Comparison of physical and mechanical properties of PLA, ABS and nylon 6 fabricated using fused deposition modeling and injection molding

A fused deposition modeling method was used in this research to investigate the possibility of improving the mechanical properties of poly(lactic acid) by changing the thermal conditions of the printing process. Sample models were prepared while varying a wide range of printing parameters, including bed temperature, melt temperature, and raster angle. Certain samples were also thermally treated by annealing. The prepared materials were subjected to a detailed thermomechanical analysis (differential scanning calorimetry, dynamic mechanical analysis, heat deflection temperature (HDT)), which allowed the formulation of several conclusions. For all prepared samples, the key changes in mechanical properties are related to the content of the poly(lactic acid) crystalline phase, which led to superior properties in annealed samples. The results also indicate the highly beneficial effect of increased bed temperature, where the best results were obtained for the samples printed at 105 °C. Compared to the reference ...

Improving the Impact Strength and Heat Resistance of 3D Printed Models: Structure, Property, and Processing Correlationships during Fused Deposition Modeling (FDM) of Poly(Lactic Acid).

The research presented in this article discusses the subject of poly(lactic acid) (PLA) modification via reactive mixing with the poly(butylene adipate-co-terephthalate) (PBAT) copolymer for 3D pri...

Development of Toughened Blends of Poly(lactic acid) and Poly(butylene adipate-co-terephthalate) for 3D Printing Applications: Compatibilization Methods and Material Performance Evaluation

Presented work discusses comparative studies of the use of a hybrid filler system on the properties of polypropylene and poly(lactic acid) composites. Wood flour have been added to improve the initially poor material performance of cork based composites. The hybrid cork/wood filler system used during this study was introduced to polymer system by two step extrusion/injection molding process in the amount of 10, 20 and 30 wt%. Samples were subjected to detailed thermo-mechanical and structural analysis. The investigated hybridization method was successfully implemented, leading to the enhancement of mechanical characteristics comparing to pure cork composites. Density analysis in combination with structural observations, confirmed significant changes in the morphology of cork, including the loss of the cellular structure, due to high shearing of the injection molding process. The favorable results of water absorbency tests indicate the potential use of cork filler to improve the dimensional stability of composites.

Cork-wood hybrid filler system for polypropylene and poly(lactic acid) based injection molded composites. Structure evaluation and mechanical performance

Polycarbonate biocomposites reinforced with a hybrid filler system of recycled carbon fiber and biocarbon: Preparation and thermomechanical characterization

The aim of this study was to determine thermal and mechanical properties and applicability of ground chestnut shell waste as a filler for poly(lactic acid) composites. The used amount of filler was ranging from 2.5 to 30 wt%. Spectroscopic analysis of composites and its ingredients was conducted by means of FT-IR method. The mechanical and thermal properties of the composites were determined in the course of static tensile test, Dynstat impact strength test, DMTA analysis, and DSC method. The fractured surface morphology of biocomposites was evaluated by SEM analysis. Incorporation of the filler influenced the overall mechanical properties of the composites characterized by high stiffness and lowered impact resistance. Fabricated composites with different amounts of non-reactive natural waste filler exhibited acceptable mechanical and thermal properties. Therefore, these composites can be used as eco-friendly, biodegradable materials for low-demanding applications.

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Jacek Andrzejewski

Papers

Improving the Impact Strength and Heat Resistance of 3D Printed Models: Structure, Property, and Processing Correlationships during Fused Deposition Modeling (FDM) of Poly(Lactic Acid).

Development of Toughened Blends of Poly(lactic acid) and Poly(butylene adipate-co-terephthalate) for 3D Printing Applications: Compatibilization Methods and Material Performance Evaluation

Cork-wood hybrid filler system for polypropylene and poly(lactic acid) based injection molded composites. Structure evaluation and mechanical performance

Polycarbonate biocomposites reinforced with a hybrid filler system of recycled carbon fiber and biocarbon: Preparation and thermomechanical characterization

Characterization of poly(lactic acid) biocomposites filled with chestnut shell waste