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This paper aims to provide an overview of the recent findings of the mechanical properties of parts manufactured by fused deposition modeling (FDM). FDM has become a widely used technique for the manufacturing of thermoplastic parts. The mechanical performance of these parts under service conditions is difficult to predict due to the large number of process parameters involved. The review summarizes the current knowledge about the process-property relationships for FDM-based three-dimensional printing.

The review first discusses the effect of material selection, including pure thermoplastics and polymer-matrix composites. Second, process parameters such as nozzle temperature, raster orientation and infill ratio are discussed. Mechanisms that these parameters affect the specimen morphology are explained, and the effect of each parameter on the strength of printed parts are systematically presented.

Mechanical properties of FDM-produced parts strongly depend on process parameters and are usually lower than injection-molded counterparts. There is a need to understand the effect of each parameter and any synergistic effects involved better.

Through the optimization of process parameters, FDM has the potential to produce parts with strength values matching those produced by conventional methods. Further work in the field will make the FDM process more suitable for the manufacturing of load-bearing components.

This paper presents a critical assessment of the current knowledge about the mechanical properties of FDM-produced parts and suggests future research directions.

This paper aims to present a survey concerning the accuracy of thermoplastic polymeric parts fabricated by additive manufacturing (AM). Based on the scientific literature, the aim is to provide an updated map of trends and gaps in this relevant research field. Several technologies and investigation methods are examined, thus giving an overview and analysis of the growing body of research.

Permutations of keywords, which concern materials, technologies and the accuracy of thermoplastic polymeric parts fabricated by AM, are used for a systematic search in peer-review databases. The selected articles are screened and ranked to identify those that are more relevant. A bibliometric analysis is performed based on investigated materials and applied technologies of published papers. Finally, each paper is categorised and discussed by considering the implemented research methods.

The interest in the accuracy of additively manufactured thermoplastics is increasing. The principal sources of inaccuracies are those shrinkages occurring during part solidification. The analysis of the research methods shows a predominance of empirical approaches. Due to the experimental context, those achievements have consequently limited applicability. Analytical and numerical models, which generally require huge computational costs when applied to complex products, are also numerous and are investigated in detail. Several articles deal with artificial intelligence tools and are gaining more and more attention.

The cross-technology survey on the accuracy issue highlights the common critical aspects of thermoplastics transformed by AM. An updated map of the recent research literature is achieved. The analysis shows the advantages and limitations of different research methods in this field, providing an overview of research trends and gaps.

The present study aims to find out the best polymer/polymer pair in electrical insulating applications. Moreover, the effects of different polymer counterpart and applied load on the friction and wear behaviour of PA 46 + 30%GFR and unfilled PA 66 thermoplastic polymers are to be studied.

Friction and wear tests vs PA 46 + 30%GFR and PPS + 30%GFR polymer composites were carried out on a pin‐on‐disc arrangement and at a dry sliding conditions. Tribological tests were performed at room temperature under 20, 40 and 60 N loads and at 0.5 m/s sliding speed.

The results showed that, the coefficient of friction decreases with the increasing of load (up to 40 N) for PA 46 + 30%GFR composite and polyamide (PA) 66 polymer used in this study. However, above 40 N applied load the coefficient of friction increases. The specific wear rate for PA 46 + 30%GFR and PA 66 against PPS + 30%GFR polymer composite counterpart are about in the order of 10⁻¹³ m²/N while the specific wear rate for PA 46 + 30%GFR and PA 66 against PA 46 + 30%GFR polymer composite counterpart are in the order of 10⁻¹⁴ m²/N. For PA 46 + 30%GFR composite and unfilled PA 66 polymers tested the specific wear rate values increased with the increment of load. The highest specific wear rate is for unfilled PA 66 against PPS + 30%GFR with a value of 2.81 × 10⁻¹³ m²/N followed by PA 66 against PA 46 + 30%GFR with a value of 2.26 × 10⁻¹³ m²/N. The lowest wear rate is PA 46 + 30%GFR polymer composite against PA 46 + 30%GFR polymer composite counterpart with a value of 3.19 × 10⁻¹⁴ m²/N. The average specific wear rates for unfilled PA 66 against PA 46 + 30%GFR is 80 times higher than PA 46 + 30%GFR wear rate while specific wear rates for unfilled PA 66 against PPS + 30%GFR is 100 times higher than that of PA 46 + 30%GFR wear rate. From point view of tribological performance, PA 46 + 30%GFR is a more suitable engineering thermoplastic composite materials for electrical contact breaker applications.

In the present work, tribological tests were performed only at room temperature under three different loads and a sliding speed. This is the limitation of the work.

This work is easily used for industrial polyamides to check their tribological behaviours.

This is an original and experimental study and it will be useful both for academicians and for industrial sides.

The purpose of this paper is to consider the static analysis of nanocomposite plates. Nanocomposites consist of a small amount of nanoscale reinforcements which can have an observable effect on the macroscale properties of the composites.

In the present study the reinforcements considered are non‐spherical, high aspect ratio fillers, in particular nanometer‐thin platelets (clays) and nanometer‐diameter cylinders (carbon nanotubes, CNTs). These plates are considered simply supported with a bi‐sinusoidal pressure applied at the top. These conditions allow the solving of the governing equations in a closed form. Four cases are investigated: a single layered plate with CNT reinforcements in elastomeric or thermoplastic polymers, a single layered plate with CNT reinforcements in a polymeric matrix embedding carbon fibers, a sandwich plate with external skins in aluminium alloy and an internal core in silicon foam filled with CNTs and a single layered plate with clay reinforcements in a polymeric matrix. A short review of the most important results in the literature is given to determine the elastic properties of the suggested nanocomposites which will be used in the proposed static analysis. The static response of the plates is obtained by using classical two‐dimensional models such as classical lamination theory (CLT) and first order shear deformation theory (FSDT), and an advanced mixed model based on the Carrera Unified Formulation (CUF) which makes use of a layer‐wise description for both displacement and transverse stress components.

The paper has two aims: to demonstrate that the use of classical theories, originally developed for traditional plates, is inappropriate to investigate the static response of nanocomposite plates and to quantify the beneficial effect of the nanoreinforcements in terms of static response (displacements and stresses).

In the literature these effects are usually given only in terms of elastic properties such as Young moduli, shear moduli and Poisson ratios, and not in terms of displacements and stresses.

The encapsulation of electronic assemblies within thermoplastic polymers is an attractive technology for the protection of circuitry used in harsh environments, such as those experienced in automotive applications. However, the relatively low‐thermal conductivity of the encapsulating polymer will introduce a thermally insulating barrier, which will impact on the dissipation of heat from the components and may result in the build‐up of stresses in the structure. This paper therefore seeks to present the results from computational models used to investigate the thermal and thermo‐mechanical issues arising during the operation of such electronic modules. In particular, a two‐shot overmoulded structure comprising an inner layer of water soluble and an outer layer of conventional engineering thermoplastics was investigated, due to this type of structure's potential to enable the easy separation of the electronics from the polymer at the end‐of‐life for recycling.

Representative finite element models of the overmoulded electronic structures were constructed and the effects of the polymer overmould were analysed through thermal and thermo‐mechanical simulations. Investigations were also carried out to explore the effect of materials properties on the overmoulded structure.

Models have shown that some power de‐rating of components is required to prevent temperatures exceeding those in unencapsulated circuits and have quantified the benefits of adding thermally conductive fillers to the polymer. Simulations have also clearly demonstrated the benefits of foamed polymers in reducing thermal stresses in the assemblies, despite their poorer thermal conductivity compared with solid polymers.

The paper illustrates the thermal issues affecting the overmoulded electronics and gives some guidelines for improving their performance.

To determine static friction coefficients between rapid tooled materials and thermoplastic materials to better understand ejection force requirements for the injection molding process using rapid‐tooled mold inserts.

Static coefficients of friction were determined for semi‐crystalline high‐density polyethylene (HDPE) and amorphous high‐impact polystyrene (HIPS) against two rapid tooling materials, sintered steel with bronze (LaserForm ST‐100) and stereolithography resin (SL5170), and against P‐20 mold steel. Friction tests, using the ASTM D 1894 standard, were run for all material pairs at room temperature, at typical part ejection temperatures, and at ejection temperatures preceded by processing temperatures. The tests at high temperature were designed to simulate injection molding process conditions.

The friction coefficients for HDPE were similar on P‐20 Steel, LaserForm ST‐100, and SL5170 Resin at all temperature conditions. The HIPS coefficients, however, varied significantly among tooling materials in heated tests. Both polymers showed highest coefficients on SL5170 Resin at all temperature conditions. Friction coefficients were especially high for HIPS on the SL5170 Resin tooling material.

Applications of these findings must consider that elevated temperature tests more closely simulated the injection‐molding environment, but did not exactly duplicate it.

The data obtained from these tests allow for more accurate determination of friction conditions and ejection forces, which can improve future design of injection molds using rapid tooling technologies.

This work provides previously unavailable friction data for two common thermoplastics against two rapid tooling materials and one steel tooling material, and under conditions that more closely simulate the injection‐molding environment.

The weakest point in additively manufactured polymer parts produced by material extrusion additive manufacturing (MEAM) is the interface between adjacent layers and deposition toolpaths or “roads”. This study aims to predict the mechanical strength of parts by utilizing a novel analytical approach. Strength predictions are made using the temperature history of these interfaces, polymer rheological data, and polymer weld theory.

The approach is validated using experimental data for two common 3D-printed polymers: polycarbonate (PC) and acrylonitrile butadiene styrene (ABS). Interface temperature history data are collected in situ using infrared imaging. Rheological data of the polycarbonate and acrylonitrile butadiene styrene used to fabricate the fused filament fabrication parts in this study have been determined experimentally.

The strength of the interfaces has been predicted, to within 10% of experimental strength, using polymer weld theory from the literature adapted to the specific properties of the polycarbonate and acrylonitrile butadiene styrene feedstock used in this study.

This paper introduces a novel approach for predicting the strength of parts produced by MEAM based on the strength of interfaces using polymer weld theory, polymer rheology, temperature history of the interface and the forces applied to the interface. Unlike methods that require experimental strength data as a prediction input, the proposed approach is material and build orientation agnostic once fundamental parameters related to material composition have been determined.

The purpose of this study is to test a flexible polymer with different characteristics compared to other classical polymers mostly used in the additive manufacturing process, and to improve its mechanical properties and microstructure, by modifying different printing parameters, to make it more suitable for various industrial applications.

Seven parameters were tested, namely, nozzle temperature, bed temperature, layer thickness, printing speed, flow rate, printing time gap between two successive printed layers and raster orientation. Rheological characterizations were conducted to evaluate the influence of nozzle temperature on the melt viscosity of thermoplastic polyurethane (TPU). The effect of thermal printing parameters on the crystallinity behavior was explored. Tomographic characterizations were realized to measure the porosity and evaluate the internal structure quality of printed specimens.

Increases of the nozzle temperature, bed temperature, layer thickness and flow rate had a positive influence on the tensile strength properties of TPU with a reduction of porosity. Higher printing speeds created defects and negatively influenced the strength properties of TPU. An increase in the printing time gap between layers led to poor interlayer adhesion and decreased the tensile strength. Specimens with layers all oriented parallel to the loading direction exhibited superior mechanical properties compared to other raster orientations.

Thermoplastic elastomers are a unique class of polymers characterized by the combined thermal, chemical and mechanical properties of their elastomer and thermoplastic parts. TPU elastomer, as one of the elastomer families, has found an important position in the bioengineering and three-dimensional printing industry. This study reports a comprehensive study of the impact of additive manufacturing parameters on the properties of TPU.

The thermoplastic polymers do not decompose easily due to the presence of long-chain stable polymeric structure, and thus, causes serious effects on the environment. Recycling of these polymer wastes becomes the only solution to minimize their adverse effects on the environment. The purpose of this study was to explore the feasibility of using recycled thermoplastic material as filament for fused deposition modeling technique.

In this study, the researchers fabricated fused filaments (in-house) for fused deposition modeling (FDM) technique of additive manufacturing from secondary recycled acrylonitrile butadiene styrene (ABS) by using a twin-screw extruder. After measuring the melt flow index of the secondary recycled ABS, the twin-screw extrusion parameters (rpm/speed of the screw, extrusion temperature and load) were varied to predict their influence on the various properties (rheological/mechanical/thermal) of the fabricated filaments. Experimental work was executed as per Taguchi’s L9 orthogonal array.

Thermal analysis performed to estimate the heat carrying capacity of recycled ABS highlighted that the heat capacity of ABS increases significantly from 0.28 J/g to 3.94 J/g during the heating cycle. The maximum value of peak strength and percentage break elongation for the fused filaments was investigated at 12.5 kg load, 2,250 C extrusion temperature and 70 rpm speed.

The filaments fabricated by recycling the polymeric waste has been successfully used in the FDM machine for the preparation of the three-dimensional printed tensile specimen.

Additive manufacturing (AM) of thermoplastic polymers for powder bed fusion processes typically requires each layer to be fused before the next can be deposited. The purpose of this paper is to present a volumetric AM method in the form of deeply penetrating radio frequency (RF) radiation to improve the speed of the process and the mechanical properties of the polymer parts.

The focus of this study was to demonstrate the volumetric fusion of composite mixtures containing polyamide (nylon) 12 and graphite powders using RF radiation as the sole energy source to establish the feasibility of a volumetric AM process for thermoplastic polymers. Impedance spectroscopy was used to measure the dielectric properties of the mixtures as a function of increasing graphite content and identify the percolation limit. The mixtures were then tested in a parallel plate electrode chamber connected to an RF generator to measure the heating effectiveness of different graphite concentrations. During the experiments, the surface temperature of the doped mixtures was monitored.

Nylon 12 mixtures containing between 10% and 60% graphite by weight were created, and the loss tangent reached a maximum of 35%. Selective RF heating was shown through the formation of fused composite parts within the powder beds.

The feasibility of a novel volumetric AM process for thermoplastic polymers was demonstrated in this study, in which RF radiation was used to achieve fusion in graphite-doped nylon powders.