RUDN scientists with colleagues from the UK and China checked the quality of 3D printed metal parts. The authors listed possible problems and gave a list of recommendations for manufacturers. The results are published in Materials.
Newswise — In the field of additive technologies, or 3D printing, there is a need for the so-called reverse engineering. This is a kind of feedback - when ready-made devices are examined. In this way, one can discover previously unforeseen features, improve device settings, or find previously unknown problems. RUDN scientists applied reverse engineering and listed possible defects in metal parts created using additive technologies. The authors have compiled a list of recommendations - what one should pay attention to when manufacturing parts.
“Additive technologies continue to develop. In the future, they will be fully automated, more flexible, faster and more economical. Therefore, additive technologies are becoming more attractive than traditional ones. The standards and requirements have not yet been developed, so the widespread adoption of 3D printing is difficult. Research is needed to optimize print settings. This can be done using reverse engineering. We focused on evaluating the mechanical properties of already existing parts”, said Kazem Reza Kashyzadeh, Professor in the Department of Transport at RUDN University.
The scholars used samples made in China at one of the leading companies in the field of 3D printing. All of them were made using the SLM, selective laser melting. In SLM, they use a fine metal powder which is melted under the action of a laser and turns into a homogeneous mass. Sometimes parts made in this way have defects such as delamination and cracks. The authors of the study did not know any details of the production beforehand. RUDN scholars examined the samples under a microscope, measured their hardness, chemical composition, strength, and resistance to stress.
Cracks were the most common defect in the samples. Looking at the direction of the cracks, we can conclude that they appeared during printing, due to the constant heating and cooling of the metal. However, in one of the samples, a large crack is visible, which appeared due to the fact that the printed part was carelessly removed from the substrate. The samples were able to withstand a pressure of 1662-2190 MPa. Engineers also noticed how the microstructure changes depending on the direction of printing. The examined samples were not intended for any specific purpose, so it cannot be said whether they are suitable or not. However, the indicated problems must be considered during production and paid attention to them, due to the planned loads.
“The microstructure and mechanical properties of the material depend on heat treatment. Therefore, we strongly recommend studying changes in the material due to heating and cooling. In addition, the SLM method must be chosen with an eye on the application and adapted to it. In the future, we plan to study the behavior of samples under cyclic loads. We believe that the properties of parts will be different from those made in the traditional way”, said Kazem Reza Kashyzadeh, Professor in the Department of Transport at RUDN University.
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