Materials Science Forum Vol. 1037

Abstract: The paper describes determining the optimal direct laser deposition mode when processing the results of a two-factor experiment by the steep ascent method. The dependence of the ultimate tensile strength on the volumetric energy density and the lateral pitch was chosen as the target function.

Abstract: An algorithm for identifying the structure and parameters of the aggregation model of additive systems is presented. Simulation modeling is used. For each alternative, the numbers of the strength levels of the materials that are included in the analyzed structure are determined. the scheme of identification of the adaptive structure of the analyzed object is presented. Algorithms of intelligent decision-making support when forming the structure of an object are presented.

Abstract: This paper presents studies about the influence of the surfacing mode on the formation of defects in the deposited metal produced by WAAM using Al-Mg alloy. As the main parameters that affected on the surfacing mode were the travel speed and the frequency of current pulses. Graphs about an influence of the travel speed on a size of pores and an influence the frequency of current pulses on a specific area of pores were constructed. It was concluded that with increasing of the surfacing speed, the size of defects decreased. Increasing the frequency of current pulses affected on increasing the specific area of pores. Changing the frequency of the current pulses leads to a change in the metal transfer. When using large-drop transfer metal, the defect concentration is minimal, but when using small-drop transfer, the arc stability decreases, which contributes to a higher pore concentration in the deposited metal.

Abstract: 3D construction printer - is an innovative construction approach with which building elements can be constructed without the use of formwork and you to get products of various complex shapes with minimal time and material costs. Binder 3D printing technology results in a cheap and high-speed construction method that allows greater freedom in both architectural and structural design of concrete. The principle of operation of a 3D printer is based on the principle of gradual (layer-by-layer) creation of a solid model, which is, as it were, "grown" from a certain binding material. The working mixture must have thixotropic and adhesive properties, it must be workable by the printer and at the same time not spread under the influence of subsequent layers. Therefore, it is important to select the composition of the composition of the working mixture. This paper presents the results of a study on the development of the composition of a working mixture based on a gypsum-cement-pozzolanic binder. The developed composition of the gypsum-cement-pozzolanic binder with a complex of modifying additives is characterized by low spreadability, high viscosity and is easy to lay.

Abstract: The article presents the results of studies of the surfaces of parts processed by the contactless method of laser polishing. The results of technological surface treatment using a laser technological complex based on an ytterbium fibre laser with a power of 5 kW are presented. The results of studies of the surface roughness of the samples after laser treatment, including the non-uniform character due to the redistribution of the liquid metal melt over the surface, are shown. Requirements for metrological support of additive technology have been developed using the example of the process of laser remelting in order to improve quality and further automation.

Abstract: In this work, the authors tried to solve a typical problem of inexpensive 3D printers using FDM technology: material clogging of the hotend. To cope with the problem, it is necessary to solve the problem of optimization the temperature regimes of the hotend. For this, the temperature fields of the heating device were simulated taking into account the physical properties of the printing materials. Modeling was carried out using the ANSYS software package, the verification of theoretical calculations was carried out in a full-scale experiment. The data obtained was used to upgrade the 3D printer hotend.

Abstract: The paper is devoted to the assessment of the possibility to use a new design of a stretch die made of plastics used for fused deposition modeling (FDM) 3 D printing. Studies were conducted to assess the stress-strain state of a stretch die, from the normal pressure of a deforming sheet blank in a NASTRAN solver, using the finite element method. The convergence assessment of the simulation results was carried out for different quantities and corresponding sizes of finite elements. The optimal thicknesses of the hollow structure of the stretch die were determined by step-by-step calculations of its stress-strain state for acrylonitrile butadiene styrene (ABS) and polyethylene terephthalate glycol (PETG). On the basis of the conducted studies, a general algorithm was developed for the structural design of stretch dies made of plastics used for fused deposition modeling (FDM) printing.

Abstract: Fused deposition modeling (FDM) or 3D printing is one of the promising techniques widely preferred to fabricate complex and customized 3D objects or prototypes for various engineering and non-engineering applications. With the growing demands of customized prototypes, researchers are facing a major challenge for maintaining effective part quality with adequate surface finish and strength; and minimizing the cost, defects, and waste in 3D printing. Condition monitoring is one of the strategies to achieve the aforementioned. It has a huge potential to minimize defects and print failures in 3D printing. The main objective of this research work is to perform online condition monitoring of the nozzle status with the help of vibration signals in fused deposition modelling process. The effect of nozzle clogging on the consistency of material deposition and its effect on surface finish has experimentally investigated in this work. The set of experiments were performed by artificially creating the condition of nozzle clogging to investigate the effect of nozzle clogging on print quality (surface finish). Nozzle clogging condition was created by increasing the feed rate of polylactic acid (PLA) filament at a low heat supply rate to the nozzle by modifying the commands of 3D printer. The layer thickness was varied throughout the experiments to observe the nozzle clogging. The vibrations signals were acquired by using an accelerometer that was mounted near the nozzle. The data acquisition frequency of the accelerometer was 12500Hz. Further, the acquired vibration signals were analyzed using the Fast Fourier transformation (FFT) signal processing technique. Results revealed that nozzle clogging severely affects surface quality and geometrical accuracy of the fabricated 3D part due to nozzle vibration and non-uniform material deposition. Moreover, nozzle clogging and its relevant consequences like non uniform material deposition can be monitored using vibration signal-based condition monitoring during part fabrication and based upon that appropriate measures can be taken for defects and waste elimination.

Abstract: The article discusses the mechanical properties and cold resistance of austenitic stainless steel (analogue 07Cr25Ni13) obtained by 3D printing by electric arc surfacing from ER309LSI welding wire on a CNC machine. These properties were investigated in the process of physical tests of samples cut along and across the layers of 3D printing for tensile and impact bending. Using optical microscopy, the microstructures of steel sections were obtained for various temperature conditions of interlayer exposure, as well as the values ​​of the recommended microhardness. In the process of 3D printing, an intelligent system for monitoring the dynamic stability of the electric arc was applied, which made it possible to guarantee the stability of the structure and properties of the obtained samples throughout the entire process of surfacing. Additional heat treatment of experimental samples (austenitization) was considered as a way to improve mechanical properties and cold resistance. It has been established that the dynamic stability of an electric arc, modes of interlayer temperature holding and subsequent heat treatment largely determine the mechanical properties and cold resistance of ER309LSI steel obtained by 3D printing by electric arc surfacing.