A novel 3D printing based fabrication process of Continuous Fiber Reinforced Thermoplastic Composites (CFRTPCs) was proposed. Continuous carbon fiber and PLA filament were utilized as reinforcing phase and matrix, respectively, and simultaneously fed into the fused deposition modeling (FDM) 3D printing process realizing the integrated preparation and forming of CFRTPCs. Interfaces and performance of printed composites were systematically studied by analyzing the influencing of process parameters on the temperature and pressure in the process. Forming mechanism of multiple interfaces was proposed and utilized to explain the correlations between process and performance. Fiber content of the printed specimens can be easily controlled by changing the process parameters. When the fiber content reached 27%, flexural strength of 335 MPa and modulus of 30 GPa were obtained for the printed composite specimens. Composite components were fabricated to demonstrate the process feasibility. Potential applications could be found in the field of aviation and aerospace.

Interface and performance of 3D printed continuous carbon fiber reinforced PLA composites

A process for forming a three-dimensional article in sequential layers in accordance with a digital model of the article. The process comprises the steps of defining a layer of a first liquid, applying a second liquid to the first liquid layer in a pattern corresponding to the digital model, and repeating these steps to form succesive layers. The first liquid comprises a first active component and the second liquid includes a second active component capable of reacting with the first reactive component so that the article is built up in layers.

Three-dimensional printing

Fused filament fabrication (FFF) is a 3D printing technique which allows layer-by-layer build-up of a part by the deposition of thermoplastic material through a nozzle. The technique allows for complex shapes to be made with a degree of design freedom unachievable with traditional manufacturing methods. However, the mechanical properties of the thermoplastic materials used are low compared to common engineering materials. In this work, composite 3D printing feedstocks for FFF are investigated, wherein carbon fibres are embedded into a thermoplastic matrix to increase strength and stiffness. First, the key processing parameters for FFF are reviewed, showing how fibres alter the printing dynamics by changing the viscosity and the thermal profile of the printed material. The state-of-the-art in composite 3D printing is presented, showing a distinction between short fibre feedstocks versus continuous fibre feedstocks. An experimental study was performed to benchmark these two methods. It is found that printing of continuous carbon fibres using the MarkOne printer gives significant increases in performance over unreinforced thermoplastics, with mechanical properties in the same order of magnitude of typical unidirectional epoxy matrix composites. The method, however, is limited in design freedom as the brittle continuous carbon fibres cannot be deposited freely through small steering radii and sharp angles. Filaments with embedded short carbon microfibres (∼100 μm) show better print capabilities and are suitable for use with standard printing methods, but only offer a slight increase in mechanical properties over the pure thermoplastic properties. It is hypothesized that increasing the fibre length in short fibre filament is expected to lead to increased mechanical properties, potentially approaching those of continuous fibre composites, whilst keeping the high degree of design freedom of the FFF process.

https://research-information.bris.ac.uk/files/159707908/1_s2.0_S2214860417305687_main.pdf

An investigation into 3D printing of fibre reinforced thermoplastic composites

Recent advancements in the Additive Manufacturing (AM) Fused Filament Fabrication (FFF) approach are described with focus on the application to tooling and molds for composite materials and structures. A detailed summary of mechanical properties of printed parts for different composite material systems is presented and discussed. These material systems are comprised of discontinuous fiber-reinforced polymers characterized by fiber orientation dominantly parallel to the direction of the extrudate. An overview of the FFF process and its physical phenomena is given including the flow and resulting fiber orientation, the bond formation between adjacent beads and the thermomechanical solidification behavior of the deposited material. Based on reviewed research in these different phenomena, future research needs are discussed and desirable objectives are formulated.

Fused filament fabrication of fiber-reinforced polymers: A review

Progress in additive manufacturing on new materials: A review

Influence of thermal processing conditions in 3D printing on the crystallinity and mechanical properties of PEEK material

Purpose




Continuous fiber reinforced thermoplastic composites (CFRTPCs) are becoming more significant in industrial applications but are limited by the high cost of molds, the manufacturing boundedness of complex constructions and the inability of special fiber alignment. The purpose of this paper is to put forward a novel three-dimensional (3D) printing process for CFRTPCs to realize the low-cost rapid fabrication of complicated composite components.




Design/methodology/approach




For this purpose, the mechanism of the proposed process, which consists of the thermoplastic polymer melting, the continuous fiber hot-dipping and the impregnated composites extruding, was investigated. A 3D printing equipment for CFRTPCs with a novel composite extrusion head was developed, and some composite samples have been fabricated for several mechanical tests. Moreover, the interface performance was clarified with scanning electron microscopy images.




Findings




The results showed that the flexural strength and the tensile strength of these 10 Wt.% continuous carbon fiber (CCF)/acrylonitrile-butadiene-styrene (ABS) specimens were improved to 127 and 147 MPa, respectively, far greater than the one of ABS parts and close to the one of CCF/ABS (injection molding) with the same fiber content. Moreover, these test results also exposed the very low interlaminar shear strength (only 2.81 MPa) and the inferior interface performance. These results were explained by the weak meso/micro/nano scale interfaces in the 3D printed composite parts.




Originality/value




The 3D printing process for CFRTPCs with its controlled capabilities for the orientation and distribution of fiber has great potential for manufacturing of load-bearing composite parts in the industrial circle.

3D printing for continuous fiber reinforced thermoplastic composites: mechanism and performance

A micro-screw in-situ extrusion process was utilized to obtain high pressure for good impregnation and high fiber fraction of 3D printed continuous carbon fiber reinforced nylon (PA12) composites. Nylon pellets and different carbon fiber strand bundles (1 K and 3 K) were used as raw materials to print composites with different process parameters. Almost full impregnation for 1 K continuous carbon fiber (CCF) reinforced PA12 composites (1 K-CCF/PA12) with only 0.15% porosity and good impregnation for 3 K continuous carbon fiber reinforced PA12 composites (3 K-CCF/PA12) with 2.62% porosity achieved. Fiber volume fraction was dramatically improved from 31.9 vol% for 1 K-CCF/PA12 to 50.2 vol% for 3 K-CCF/PA12. Mechanical properties of different composites were measured systematically. Excellent longitudinal tensile strength and modulus of 735.7 MPa and 79.5 GPa, and simultaneously flexural strength and modulus of 772.6 MPa and 85.3 GPa for 3 K-CCF/PA12 were obtained. This novel 3D printing of continuous fiber reinforced composite process realized the integration of composites preparation and formation with enhanced impregnation, high fiber fraction and mechanical performance which could expand the applications of this technology to more and more industry fields.

High-pressure interfacial impregnation by micro-screw in-situ extrusion for 3D printed continuous carbon fiber reinforced nylon composites

The invention provides a continuous long-fiber reinforced-type composite material 3D printer and a printing method thereof. The 3D printer and the printing method are characterized in that the combination of the 3D printing technology and the composite material fiber placement technology achieves the 3D printing of a resin-based continuous long-fiber reinforced-type composite material, and the process does not need a die that is customized in advance and a pre-treated fiber pre-soaking belt, so that the cost is greatly decreased; meanwhile, the 3D printing method enables well and convenient control of the directions of the reinforced fibers in a manufactured part, and moreover, a composite material part with the customized mechanical property can be obtained easily, and the composite material part with a complex structure can be quickly manufactured; and compared with the original composite material fiber placement process, the printing method has the advantages that the application scope is wide, and the production efficiency is high.

Continuous long-fiber reinforced-type composite material 3D printer and printing method thereof

The invention discloses a multi-degree-of-freedom 3D printer of a fiber reinforced composite material and a printing method thereof. The 3D printing can be performed with any angle and any movement locus by making use of the flexibility of a manipulator; and a 3D printing head mounted on the multi-degree-of-freedom 3D printer can perform the 3D printing of a high-strength short fiber reinforced composite material, and can perform the splicing and the weaving of continuous resin-based long fiber to produce a structural body of a continuous fiber reinforced resin-based composite material. The multi-degree-of-freedom 3D printer can precisely control the orientation of reinforced fiber in a composite material part in the 3D printing process, and can realize the quick production of the composite material part with specific mechanical, electric and thermal performances and a complex structure. Meanwhile, a mold customized beforehand and a pretreated fiber prepreg tape are not needed in the process; and the multi-degree-of-freedom 3D printer is not only suitable for the production of large parts, but also suitable for the large-batch production of small parts, so that the production cost and the production period are largely reduced, and the wide application of the composite material parts is further promoted.

Cao Yi

Papers

Influence of thermal processing conditions in 3D printing on the crystallinity and mechanical properties of PEEK material

3D printing for continuous fiber reinforced thermoplastic composites: mechanism and performance

High-pressure interfacial impregnation by micro-screw in-situ extrusion for 3D printed continuous carbon fiber reinforced nylon composites

Continuous long-fiber reinforced-type composite material 3D printer and printing method thereof

Multi-degree-of-freedom 3D printer of fiber reinforced composite material and printing method thereof