A Systematic Survey of FDM Process Parameter Optimization and Their Influence on Part Characteristics <s> Part Geometry <s> In any rapid prototyping process, the layer by layer building process introduces an error in the amount of material used compared to the volume specified by the computer-aided design model. This affects the dimensional accuracy as well as the surface finish for different part build orientations. This paper describes a methodology for computing the volumetric error for any orientation of the parts built by the fused deposition modelling rapid prototyping system. The technique can be applied to determine the best orientation of the part, based on the minimum volumetric error. The technique is verified by comparing the results with the experimental measurements of the volumetric errors of the parts built at different orientations. <s> BIB001 </s> A Systematic Survey of FDM Process Parameter Optimization and Their Influence on Part Characteristics <s> Part Geometry <s> Purpose – The purpose of this paper is to investigate the mechanisms controlling the bond formation among extruded polymer filaments in the fused deposition modeling (FDM) process. The bonding phenomenon is thermally driven and ultimately determines the integrity and mechanical properties of the resultant prototypes.Design/methodology/approach – The bond quality was assessed through measuring and analyzing changes in the mesostructure and the degree of healing achieved at the interfaces between the adjoining polymer filaments. Experimental measurements of the temperature profiles were carried out for specimens produced under different processing conditions, and the effects on mesostructures and mechanical properties were observed. Parallel to the experimental work, predictions of the degree of bonding achieved during the filament deposition process were made based on the thermal analysis of extruded polymer filaments.Findings – Experimental results showed that the fabrication strategy, the envelope temper... <s> BIB002 </s> A Systematic Survey of FDM Process Parameter Optimization and Their Influence on Part Characteristics <s> Part Geometry <s> Fused deposition modelling (FDM) is one of rapid prototyping (RP) technologies which uses an additive fabrication approach. Each commercially available FDM model has different types of process parameters for different applications. Some of the desired parts require excellent surface finish as well as good tolerance. The most common parameters requiring setup are the raster angle, tool path, slice thickness, build orientation, and deposition speed. The purpose of this paper is to discuss the process parameters of FDM Prodigy Plus (Stratasys, Inc., Eden Prairie, MN, USA). Various selected parameters were tested and the optimum condition was proposed. The quality of the parts produced was accessed in terms of dimensional accuracy and surface finish. The optimum parameters obtained were then applied in the fabrication of the master pattern prior to silicone rubber moulding (SRM). These parameters would reduce the post processing time. The dimensional accuracy and surface roughness were analyzed using coordinate measuring machine (CMM) and surface roughness tester, respectively. Based on this study, the recommended parameters will improve the quality of the FDM parts produced in terms of dimensional accuracy and surface roughness for the application of SRM. <s> BIB003 </s> A Systematic Survey of FDM Process Parameter Optimization and Their Influence on Part Characteristics <s> Part Geometry <s> Abstract The paper presents a hybrid experimental/theoretical approach to study the effect of variation due to process parameter change on the dimensional and geometric accuracy of a part built through ‘fused deposition modeling’ process. A theoretical framework comprising of a primitive based fast geometric model and a comprehensive process parameter-geometric tolerance matrix is presented. This framework is tested with help of an experimental setup based on a geometric variation measurement model for major classes for Geometric Dimensioning & Tolerancing (GD&T) tolerances. Finally, a statistical approach based on Taguchi's design of experiment is utilized to study the effect of commonly used process parameters to establish indicative GD&T tolerance bands for the specific printer class as well as ranking of parameters. <s> BIB004 </s> A Systematic Survey of FDM Process Parameter Optimization and Their Influence on Part Characteristics <s> Part Geometry <s> The ability to form closed cavities inside the part printed is an important feature of Fused Filament Fabrication technology. A typical part consists of a dense shell bearing the primary load, filled with low-density plastic scaffold (infill). Such a constitution of the part provides in most cases appropriate strength and low weight. However, if the printed part shape includes horizontal (orthogonal to printer’s Z axis) flat surfaces other than its top and bottom surface, then the shell of the part becomes interrupted, which may lead to drastic drop in the ability of the part to withstand loads. In the current study, a representative sample of a part with interrupted shell and testing apparatus is developed. Influence of shell and base thicknesses, as well as influence of the infill density on the part strength, are studied. Different approaches to the sample shape modification were applied and tested. The part shape optimization made with respect to peculiarities of Fused Filament Fabrication technology resulted in increment of the force, required to fracture the part from 483 to 1096 N and in decreased part mass from 36.9 to 30.2 g. <s> BIB005 </s> A Systematic Survey of FDM Process Parameter Optimization and Their Influence on Part Characteristics <s> Part Geometry <s> This paper presents a numerical and experimental study of the compression uniaxial properties of PLA material manufactured with FDM based on product specifications. A first experimental test in accordance with the requirements and conditions established in the ISO 604 standard characterizes the mechanical and elastic properties of PLA manufactured with FDM technology and product requirements in a uniaxial compression stress field by testing six specimens. A second experimental test allows analyzing the structural behavior of the industrial case, evaluating the compression stiffness, the compression yield stress, the field of displacements, and stress along its elastic area until reaching the compression yield stress and the ultimate yield stress data. To improve the structural analysis of the case study, a numerical validation was carried out using two analytical models. The first analytical model applies an interpolation procedure to the experimental results of the tested specimens in order to characterize the uniaxial tension-compression curve versus the nominal deformations by means of an 8-degree polynomial function. The second model defines the plastic material as elastic and isotropic with Young’s compression modulus constant and according to the guidelines established in ISO standard 604. The comparison between experimental tests and numerical simulation results for the study case verify that the new model that uses the proposed polynomial function is closer to the experimental solution with only an 0.36% error, in comparison with the model with Young’s compression modulus constant that reaches an error of 4.27%. The results of the structural analysis of the mechanical element indicate that the elastic region of the plastic material PLA manufactured with FDM can be modeled numerically as an isotropic material, using the elastic properties from the experimental results of the specimens tested according to ISO standard 604. In this way, it is possible to characterize the PLA FDM material as isotropic, obtaining as an advantage its easy definition in the numerical simulation software as it does not require the modification of the constitutive equations in the material database. SEM micrographs have indicated that the fracture of the failed test specimens is of the brittle type, mainly caused by the separation between the central plastic filament layers of the specimens. The results presented suggest that the use of FDM technology with PLA material is promising for the manufacture of low volume industrial components that are subject to compression efforts or for the manufacture of components by the user. <s> BIB006
The part characteristics of an FDM part deteriorate as the complexity of the part's geometry increases. For instance, the surface quality and dimensional accuracy of a flat-surfaced part are typically better than for a cylindrical or pyramid-shaped part. The staircase effect is a common problem in the FDM process. The support structures of an FDM printed part are typically required for overhanging parts, and the removal of these support structures may reduce part characteristics. The quality of an FDM part depends on process parameters, mechanical properties, and geometrical properties BIB004 . Bakar et al. BIB003 produced a test model with different shapes (slot, cube, ring cylinder). The authors showed that the impact of process parameters depended on part geometry. They concluded that the cylindrical shape had the maximum surface roughness and dimensional deviation when compared to the other shapes. It was also shown that the diameter size was important for part characteristics. The part with a smaller diameter had a higher surface roughness due to high thermal stress. Sun et al. BIB002 mentioned that print speed and the tool path selection also depended on part geometry. In addition, the bonding strength of layers and part characteristics were affected by extrusion temperature, build platform temperature, and cooling rate. Gajdos et al.  performed an experimental study to analyze the impact of printing conditions on the part structure. They showed that structural homogeneity was affected by the shape of a part. For their study, rectangular and circular cross-section parts were produced. Their results showed that extrusion temperature and build platform temperature were more significant for the structural homogeneity of a rectangular cross-section part. Masood et al. BIB001 analyzed the impact of build orientation on the volumetric error of a build part. Further, a mathematical model was developed to determine the optimum build orientation that minimized the volumetric error for different part geometries. It was shown that the optimum build orientation depended on part geometry. For uniformly shaped parts (cube or cylindrical parts), a horizontal or vertical build orientation is able to minimize volumetric errors. For non-uniformly shaped parts (pyramid parts), the selection of a build orientation that can minimize volumetric error depends on the overall part geometry's complexity. To analyze the impact of part geometry, Kuznetsov et al. BIB005 produced a part that consisted of two coaxial cylinders; one was larger, and the other was smaller in diameter size. Mechanical properties of the part were tested by applying a radial load to the small-diameter cylinder. The experimental study showed that the mechanical performance of a part can be improved in different ways such as by increasing part volume, introducing cavities, and converting an interrupted shell into a continuous shell. Carneiro et al.  produced five wing ribs with different configurations for an aircraft structure from PLA using an FDM process. The authors compared different wing ribs by determining strength, stiffness, and mass. According to their results, printing accuracy and surface finish affect the strength and part cross-section dimension. Mercado-Colmenero et al. BIB006 produced a real-world complex functional part (a machine for the olive harvesting process) using the FDM process with PLA as the filament material. It was shown that the FDM process is a promising technology for low-volume industrial complex component manufacturing. Short discussion and summary: To explore more on the capabilities of the FDM process and to expand the applications of the FDM process, it is necessary to produce functional parts for research purposes, in addition to testing samples according to international standards (e.g., ASTM). The part characteristics of a complex part can be improved by selecting proper geometrical configurations. The optimal process parameters related to geometrical configurations can be further determined to reduce printing errors and defects. Considering the complex part geometry and process parameters together for improving part characteristics is a research gap in the field of FDM part characteristic optimization.