Abstract. Each printing method and the materials used for prototype construction have distinct advantages and drawbacks. A large part of the 3D printer producers indicates high printing accuracy (positioning accuracies from 100 µm up to 1 µm and layer thickness from 100 µm tо 5 µm). In the process of layers deposition, the material is softened, melted or irradiated with a certain light source to polymerize. Thus, during the printing process, the volume of the materials is changing causing shrinking or expansion which often leads to the occurrence of precision errors in the prototype as opposed to the digital model. This phenomenon leads to distortions of the printed object known as a curling effect. Certain chemical compounds are added by the producers to multiple materials in order to enhance their mechanical and technological properties. However, this often results in changes of some printing parameters influencing the precision and quality of the manufactured object. The aim of the particular study is to establish the allowances with regard to the accuracy during manufacturing precise objects used in micro technologies as well as the necessary adjustments in dimensions because of the shrinkage and the positioning of the SLA 3D printed parts from photopolymer material.
Abstract. The thermochemical treatments of tool steels improve the performance of the components with respect to surface hardness, wear and tribological performance as well as corrosion resistance. Compared to the conventional gas ferritic nitrocarburizing process, the original vacuum oxy-nitrocarburizing is a time-, cost-effective and environmentally-friendly gas process. Because of the oxidizing nature of the gas atmosphere, there is no need to perform subsequent post-oxidation.In this study, a vacuum oxynitrocarburizing process was carried out onto four tool steels (AISI H10, H11, H21 and D2) at 570 °C, after hardening and single tempering. The structural analysis of the compound and diffusion layers was performed by optical and electron microscopy, X-ray diffraction and glow discharge optical emission spectrometry (GDOES) methods. A largely monophase İ-layer is formed with a carbon accumulation at the substrate adjacent area. The overlaying oxides adjacent to the İ-carbonitride phase contained Fe 3 O 4 (magnetite) as a main constituent. A thermodynamic modelling approach was also performed to understand and optimize the process. The "Equilib module" of FactSage software which uses Gibbs energy minimization method, was used to estimate the possible products during vacuum oxynitrocarburising process.
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