Investigation of layer height influencing the impact strength of polylactic acid (PLA)

The aim of this study is to investigate the effect of layer height used during 3D printing on the impact strength, their standard deviations, and the printing time by using UNI EN ISO 180 unnotched specimens manufactured by FDM 3D printing technology. Every specimen is made of PLA, which is the most basic material of the FDM printing technology by using the same 3D printer. In this study it plays a key role to find out whether the layer height can be used to optimize the researched mechanical property within an economical framework or not. What is more, the possibly observable tendencies and crucial influential parameters will be analysed as well.

Analysis of the behaviour of 3D samples printed by FFF/FDM technologies under bending stress with a focus on infill

The focus of this paper is to explore the possibilities of optimizing 3D printed elements produced by FFF/FDM technology based on bending tests according to ČSN EN ISO 178 (64 0607) with variations in the settings of the printing itself. The principle of FFF/FDM is the printing of a continuous fiber made of thermoplastic material, which is applied by machine to the previously printed fiber. There are many combinations of possible print settings, and one of them is the geometry of the inner density with variable density. Their resulting maximum values of the achieved load were then compared with the weight (amount of material used) and printing time. The result is a comparison to achieve economical printing with the greatest possible load capacity.

Multi-physics properties of thermoplastic polyurethane at various fused filament fabrication parameters

Purpose 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. Design/methodology/approach 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. Findings 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. Originality/value 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.

A Multi(two)-Nozzle Cable-Driven Parallel Robot For 3D Printing Building Construction: Path Optimization and Vibration Analysis

This paper proposes a multi-nozzle cable-driven parallel robot for 3D printing building construction. This system has two independently moving nozzles mounted on the existing printing head. The printing time can be reduced dramatically with this system as the travel path of the printing head can be reduced to almost half thanks to those two nozzles that print almost half of the printing contour. To fully take advantage of two nozzle structures effectively, the path of the printing head is optimized to secure the minimum travel length of both the printing head and two nozzles. The smoothness of the optimal path is secured by applying the non-uniform rational B-splines (NURBS). In addition, free vibration of the proposed CDPR printer’s structure is analyzed to improve the printing quality and help the control of the proposed CDPR plain by using a finite element formulation of cables of the proposed robot.

3D Printing Optimization for Environmental Sustainability: Experimenting with Materials of Protective Face Shield Frames

The motivation for research on 3D printing of protective face shields was the urgent societal demand for healthcare in the fight against the spread of COVID19 pandemic. Research is based on a literature review that shows that objects produced by additive technologies do not always have consistent quality suitable for the given purpose of use. Besides, they have different effects on the environment and leave different footprints. The overall goal of the research was to find out the most suitable thermoplastic material for printing shield frames in terms of mechanical properties, geometric accuracy, weight, printing time, filament price, and environmental sustainability. Fused deposition modeling (FDM) technology was used for 3D printing, and three different filaments were investigated: polylactic acid (PLA), polyethylene terephthalate (PETG), and polyhydroxyalkanoate (PHA). The weighted sum method for multi-objective optimization was used. Finally, PHA material was chosen, mainly due to its environmental sustainability, as it has the most negligible impact on the environment.

Sistem Pembayaran Hasil Cetak Printer Berbasis Mikrokontroler dan Near Field Communication (NFC)

The print-out price for printer services varies according to the density of the paper and the amount of ink used, and the payment is made manually by calculating the total print output. Therefore a system is created that can display rates and total invoices automatically based on time printed, as well as automatic payments that make it easier for service providers and service users. The design of this system consists of Arduino mega, ESP8266, relay, Near Field Communication (NFC), and printer. This system can distinguish the print price rates according to the time of printing, the time span of printing and the tariff is Rp. 300.00 with a printing time of 1-6 seconds, Rp. 500.00 with a time of 7-13 seconds, and finally Rp. 700, 00 with a time span above 14 seconds. The success rate of this system in classifying print tariffs is 95%.

Comprehensive study of objects of judicial and technical examination of documents in solving issues regarding the establishment of their making

The article is devoted to the analysis of the essence of integrated research during the judicial and technical expertise to establish the prostitution of documents. The attention is drawn to the fact that the forensic examination with the establishment of the preparation of documents is the most difficult among other species of this kind of examinations and to be complex. The authors consider the peculiarities of this type of expertise and emphasizes that such examinations have difficulty in carrying out the use of special equipment and physicochemical research methods. The paths of determining the preparation of the paperwork are emphasized: determining the specific time of manufacture of each of the details with a further comparison of the results obtained among themselves; establishing conformity between the time of signature and handwritten records; the printing time of printing and text printing time, establish a chronological sequence of details in the document. It was concluded that the decision of the expert problem with establishing the prescription of the document requires the use of so-called "destructive methods". The main complexity of the examination of the process of making the preparation of the document is that when conducting any actions with a document (cutting, selection of ink samples), the document can be fully or partially destroyed. In this regard, expert institutions that take an obligation to carry out such examinations, pay attention to the ability to damage the document and in this connection declare a relevant request for permission to carry out such actions. Such permission should be in the document on the appointment of expertise or in the letter. Attention is drawn to the fact that not the provision of information about the time of receipt of the document may lead to the impossibility of determining the prescription of the document. After a long time and complex research process, the expert is forced to give a conclusion "is not possible."

Production of technological plugs for engine box and oil system using additive technologies

Today, technological plugs designed to protect the internal cavities of parts and assembly units are manufactured using such production methods as casting or stamping. At the same time, their subsequent processing is a time-consuming process. Additive technologies can save material, save time and reduce expenses. This study considers the possibility of manufacturing technological plugs for engine box and oil system using additive technologies. The cover plugs were printed using the Fusion Deposition Modeling (FDM) method on a Russian-made ZENIT printer. PLA plastic was chosen for 3D printing. The plug models were optimised, which allowed correcting and reducing the estimated printing time. In particular, some plugs were made assemblable, which helped to avoid a large number of printing supports. The production of technological plugs using additive technology allows reducing the cost of the finished product, the weight of the plugs and the estimated time of their production.