Optimization of Additive Manufacturing for Layer Sticking and Dimensional Accuracy

Author(s):  
Syed Faiz Ali ◽  
Fasih Munir Malik ◽  
Emin Faruk Kececi ◽  
Burak Bal

When the 3D printing process is considered, there are also other parameters, such as nozzle size, flow rate of material, print-speed, print-bed temperature, cooling rate, and pattern of printing. There are also dependencies that will be addressed in between these parameters; for example, if the printing temperature is increased, it is not clear if the viscosity of the material will increase or decrease. This chapter aims to explain the effect of printing temperature on layer sticking while dimensional accuracy is achieved. Theoretical modelling and experimental testing will be performed to prove the relationship. This type of formulation can be later adapted into a slicer program, so that the program automatically selects some of the printing parameters to achieve desired dimensional accuracy and layer sticking.

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 774 ◽  
Author(s):  
Damir Godec ◽  
Santiago Cano ◽  
Clemens Holzer ◽  
Joamin Gonzalez-Gutierrez

Fused filament fabrication (FFF) combined with debinding and sintering could be an economical process for three-dimensional (3D) printing of metal parts. In this paper, compounding, filament making, and FFF processing of feedstock material with 55% vol. of 17-4PH stainless steel powder in a multicomponent binder system are presented. The experimental part of the paper encompasses central composite design for optimization of the most significant 3D printing parameters (extrusion temperature, flow rate multiplier, and layer thickness) to obtain maximum tensile strength of the 3D-printed specimens. Here, only green specimens were examined in order to be able to determine the optimal parameters for 3D printing. The results show that the factor with the biggest influence on the tensile properties was flow rate multiplier, followed by the layer thickness and finally the extrusion temperature. Maximizing all three parameters led to the highest tensile properties of the green parts.


Polymers ◽  
2021 ◽  
Vol 13 (21) ◽  
pp. 3737
Author(s):  
Yousef Lafi A. Alshammari ◽  
Feiyang He ◽  
Muhammad A. Khan

Three-dimensional (3D) printing is one of the significant industrial manufacturing methods in the modern era. Many materials are used for 3D printing; however, as the most used material in fused deposition modelling (FDM) technology, acrylonitrile butadiene styrene (ABS) offers good mechanical properties. It is perfect for making structures for industrial applications in complex environments. Three-dimensional printing parameters, including building orientation, layers thickness, and nozzle size, critically affect the crack growth in FDM structures under complex loads. Therefore, this paper used the dynamic bending vibration test to investigate their influence on fatigue crack growth (FCG) rate under dynamic loads and the Paris power law constant C and m. The paper proposed an analytical solution to determine the stress intensity factor (SIF) at the crack tip based on the measurement of structural dynamic response. The experimental results show that the lower ambient temperature, as well as increased nozzle size and layer thickness, provide a lower FCG rate. The printing orientation, which is the same as loading, also slows the crack growth. The linear regression between these parameters and Paris Law’s coefficient also proves the same conclusion.


2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Alexander T. Clark ◽  
John F. Federici ◽  
Ian Gatley

The refractive indices, attenuation coefficients, and level of birefringence of various 3D printing plastics may change depending on the printing parameters. Transmission terahertz time-domain spectroscopy was used to look for such effects in Copolyester (CPE), Nylon, Polycarbonate (PC), Polylactic acid, and Polypropylene. The thickness of each sample was measured using an external reference structure and time-of-flight measurements. The parameters varied were printer nozzle size, print layer height, and print orientation. Comparison of these parameters showed that a printer’s nozzle size and print layer height caused no change in real refractive index or attenuation coefficient. A change in printing orientation from vertical to horizontal caused an increase both in real refractive index and in attenuation coefficient. In vertically printed samples, the increase in birefringence was proportional to the increase in layer height and inversely proportional to nozzle size. There was no measurable intrinsic birefringence in the horizontally printed samples. These effects should be taken into account in the design of FDM 3D printed structures that demand tailored refractive indices and attenuation coefficients, while also providing a foundation for nondestructive evaluation of FDM 3D printed objects and structures.


Materials ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 3961 ◽  
Author(s):  
Hong Xiao ◽  
Wei Han ◽  
Yueke Ming ◽  
Zhongqiu Ding ◽  
Yugang Duan

Three-dimensional printing of continuous carbon fiber/epoxy composites (CCF/EPCs) is an emerging additive manufacturing technology for fiber-reinforced polymer composites and has wide application prospects. However, the 3D printing parameters and their relationship with the mechanical properties of the final printed samples have not been fully investigated in a computational and quantifiable way. This paper presents a sensitivity analysis (SA)-based parameter optimization framework for the 3D printing of CCF/EPCs. A surrogate model for a process parameter–mechanical property relationship was established by support vector regression (SVR) analysis of the experimental data on flexural strength and flexural modulus under different process parameters. An SA was then performed on the SVR surrogate model to calculate the importance of each individual 3D printing parameter on the mechanical properties of the printed samples. Based on the SA results, the optimal 3D printing parameters and the corresponding flexural strength and flexural modulus of the printed samples were predicted and verified by experiments. The results showed that the proposed framework can serve as a high-accuracy tool to optimize the 3D printing parameters for the additive manufacturing of CCF/EPCs.


2019 ◽  
Vol 18 (2) ◽  
Author(s):  
Fajri Sri Ardion ◽  
Heru Sukanto ◽  
Joko Triyono

<div class="WordSection1"><p><em>Rapid prototyping or commonly known as additive manufacturing uses metal and non-metal semi-liquid materials which are compacted layer by layer. Fused deposition modeling (FDM) is one of the methods in the additive manufacturing process that u</em><em>ses</em><em> thermoplastic filaments (PLA and ABS). Poly Lactic Acid (PLA) or poly lactic acid is an organic</em><em> plastic</em><em> or bioplastic made from renewable biomass sources such as corn starch, pea starch and vegetable oils. Important factors affecting the quality of 3D Printing results are nozzle diameter, nozzle temperature, bed temperature, infill patern, </em><em>infill percentage</em><em>, print speed, layer thickness and </em><em>infill overlap</em><em>. </em><em>Infill overlap</em><em> is the percentage of overlapping processes of the filament during the printing process. This research was conducted to determine the effect of </em><em>infill overlap</em><em>on the physical and mechanical properties of 3d printing products. The </em><em>infill overlap</em><em>variations used are 0%, 25%, 50%, and 75% of the nozzle diameter. 50% variation shows better quality when compared to other variations for density test, tensile test, and bending test.</em><em></em></p></div><em><br clear="all" /></em>


2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Mattia Mele ◽  
Giampaolo Campana ◽  
Gian Luca Monti

Purpose The amount of radiated energy is known to be a crucial parameter in powder-bed additive manufacturing (AM) processes. The role of irradiance in the multijet fusion (MJF) process has not been addressed by any previous research, despite the key role of this process in the AM industry. The aim of this paper is to explore the relationship between irradiance and dimensional accuracy in MJF. Design/methodology/approach An experimental activity was carried out to map the relationship between irradiance and dimensional accuracy in the MJF transformation of polyamide 12. Two specimens were used to measure the dimensional accuracy on medium and small sizes. The experiment was run using six different levels of irradiance. For each, the crystallinity degree and part density were measured. Findings Irradiance was found to be directly proportional to part density and inversely proportional to crystallinity degree. Higher irradiance leads to an increase in the measured dimensions of parts. This highlights a predominant role of the crystallisation degree and uncontrolled peripherical sintering, in line with the previous literature on other powder-bed AM processes. The results demonstrate that different trends can be observed according to the range of sizes.


2019 ◽  
Author(s):  
Noha Hamada Mohamed ◽  
Hossam Kandil ◽  
Iman Ismail Dakhli

Abstract In dentistry, 3D printing already has diverse applicability, and holds a great deal of promise to make possible many new and exciting treatments and approaches to manufacturing dental restorations. Better availability, shorter processing time, and descending costs have resulted in the increased use of RP. Concomitantly the development of medical applications is expanding. (Zaharia et al., 2017)Many different printing technologies exist, each with their own advantages and disadvantages. Unfortunately, a common feature of the more functional and productive equipment is the high cost of the equipment, the materials, maintenance, and repair, often accompanied by a need for messy cleaning, difficult post-processing, and sometimes onerous health and safety concerns (Dawood et al., 2015)Low-cost 3D printers represent a great opportunity in the dental and medical field, as they could allow surgeons to use 3D models at a very low cost and, therefore, democratize the use of these 3D models in various indications. However, efforts should be made to establish a unified validation protocol for low-cost RP 3D printed models, including accuracy, reproducibility, and repeatability tests. Asaumi et al., suggested that dimensional changes may not affect the success of surgical applications if such changes are within a 2% variation .However, the proposed cut-off of 2% should be furthermore discussed, as the same accuracy may be not required for all types of indications. (Silva et al., 2008; Maschio et al., 2016)This aim of the present study is to evaluate the dimensional accuracy of the 3D printed mandibular models fabricated by two different additive manufacturing techniques, using highly precise one as selective laser sintering (SLS) and a low-cost one as fused filament fabrication and whether they are both comparable in terms of precision. In addition to evaluation of dimensional accuracy of linear measurements of the mandible in CBCT scans.7 mandibular models will be recruited. Radio-opaque markers of gutta-percha balls will be applied on the model to act as guide pointsTen linear measurements (5 long distances: Inter-condylar, inter-coronoidal, inter-mandibular notch, length of left ramus, length of right ramus; as well as 5 short distances: Length of the body of the mandible at midline, length of the body of the mandible in the area of last left molar, as well as that of the last right molar, the distance between the tip of right condyle to the tip of the right coronoid, as well as that of their left counterparts) will be obtained using digital calliper, to act as the reference standard later. Scanning of the model by CBCT will be next , 3D printing of the scanned image using SLS and FFF printers will be done. Recording of same linear measurment will be done on printed models. Comparison of the recorded values vs reference standard is the last step


Proceedings ◽  
2020 ◽  
Vol 69 (1) ◽  
pp. 40
Author(s):  
Matheus Godoy Fonseca do Carmo ◽  
Thiago Glissoi Lopes ◽  
Verena Soares Bombonatti ◽  
Paulo Roberto Aguiar ◽  
Thiago Valle França

The fused deposition modeling (FDM) process, commonly known as three-dimensional (3D) printing, deals with the manufacturing of parts by the subsequent addition of layers of fused plastic filament. The parts obtained during this process can be used for domestic applications, rapid prototyping, or final applications. During the preparation of the printing model (slicing), different process parameters must be defined, such as extruder speed, extruder height in relation to the bed, and bed temperature. Parameters that, if incorrectly defined, can lead to a series of deficiencies in the parts, such as low dimensional accuracy, low surface quality, reduced mechanical resistance, and, eventually, the occurrence of several printing defects in the parts, impairing or even preventing its use. The 3D printing process has a critical period at its beginning during the manufacturing of the piece’s first layer. The present work aims to study some of the geometric anomalies observed in monolayer pieces when some of the printing parameters are improperly defined. Printing tests on monolayer parts were carried out with a polylactic acid (PLA) filament. Herein, a home grade 3D printer, model Graber i3, was used. The height of the extruder to the bed was altered in relation to the recommended value, and three pieces were printed for each height used. The printed parts were scanned with a 1200 × 1200 dpi resolution, using a DCP-L2540DW model scanner. The images obtained were then analyzed using the Matlab® software and the geometric characteristics of the pieces were compared. The study is a first step towards a better understanding of the geometric defects obtained when an incorrect definition of basic parameters occurs when processing the three-dimensional model.


2021 ◽  
Vol 13 (3) ◽  
pp. 185-190
Author(s):  
Iakovos Xenikakis ◽  
◽  
Konstantinos Tsongas ◽  
Emmanouil K Tzimtzimis ◽  
Dimitrios Tzetzis ◽  
...  

Microneedles (MN) are miniature devices capable of perforating painlessly stratum corneum and delivering active ingredients in the inner epidermal layers. Hollow microneedles (HMNs) are highly detailed objects due to their internal microchannels and thus, their fabrication with Additive Manufacturing (AM) is a challenging task. Vat polymerization techniques provide a sufficient accuracy for such microstructures. Differentiated from other approaches where stereolithography and 2-photon polymerization were adopted, this paper presents the 3D-printing of HMNs purposed for insulin delivery, using the more economic Liquid Crystal Display (LCD) method. First, different geometries (hexagon, square pyramid, beveled) were 3D printed with constant height and varying curing time, printing angle and layer resolution. Quality features in each case were captured with optical and scanning electron microscopy (SEM). The most promising geometry was found to be the beveled one due to the more refined tip area and the feasibility of non-clogged microchannel formation. Among printing parameters, printing angle proved to be the most influential, as it affects resin flow phenomenon during printing process. Lastly, optimized HMN geometry was the beveled configuration, where the average height was measured 900μm, 3D printing angle was set at -45°, the curing time was 10s per layer and the optimal layer height was 30μm.


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