The present paper presents the results of the analysis made on samples obtained by additive manufacturing processes, necessary to realize prostheses and medical instruments. The samples were obtained by melting fine metal powder of Co-Cr by rapid prototyping process -Direct Metal Laser Sintering (DMLS). The examination of the samples (by methods of optical microscopic, scanning electron microscopy (SEM) and the spectroscopy method of X-ray energy dispersion) revealed that the surface of the obtained components contains incomplete melting areas whose size depends on the shape of the surface and the meshing level of the 3D model.
Continuous development of the technological processes led to the necessity of using industrial equipment/installations made of high temperature resisting materials that provide the ability to work in heavily corrosive environments. The paper analyses two fusion welding options of dissimilar welded joints between two alloys, a cobalt based and a nickel based alloy. Here in are presented the results obtained after welding the two different materials using Tungsten inert gas (TIG) and Electron beam (EBW). Based on the results obtained after micrographic and macrographic examinations, it has been concluded that the two welding processes can be successfully used at dissimilar welded joints between the two types of material.
Various applications in industry and medicine require the transmission of movement using systems that do not influence magnetic or electromagnetic fields. These components include systems which transmit linear or rotational motion, change position (switches), attach or detach to objects (latches), grip objects, etc. This paper looks into the possibility of producing such mechanisms using FDM 3D-printed parts from thermoplastic materials with embedded moving parts, which can be pneumatically actuated. In order to make the parts suitable for use in pressurized air systems, different sets of printing parameters have been investigated. PLA annealing is used in the attempt to minimize play and increase air-tightness of 3D-printed parts.
Various types of shielding gases mixes are used for the industrial GMAW applications. The use of the direct current welding process with reverse or direct polarity influences the geometric characteristics of the beads as well as process dilution. In certain situations, such as weld deposits, the penetration should be as shallow as possible and the heat affected zone of the bead should be reduced. The paper presents the experimental procedure, the obtained results and the conclusions concerning the influence of polarity on the shape and geometry of the welding beam, while using various shielding gases and various welding parameters and by changing polarities.
Hardfacing is carried out whenever a local improvement of the mechanical properties of metallic parts is demanded. In this regard, gas metal arc welding technology is one of the most popular choices. One decisive factor of the welded joint quality is governed by the heat affected zone. The present paper proposes a simulation methodology that can be employed for capturing the temperature gradients in any location of the base metal, when such information is required. The model was developed by using ANSYS Workbench simulation software and is based on coupled CFD and Transient Thermal analysis. In the first stage, a welded sample is subjected to 3D scanning for recreating its constitutive surfaces in a CAD environment. In the next stage, the convective heat transfer occurring due to the velocity of the shielding gas is captured by means of CFD analysis. Experimentally derived temperatures are employed for developing a transient thermal analysis, having defined the exterior heat transfer coefficient. In the last stage, the simulation results are verified in an arbitrary location of the base metal that is located outside the heat affected zone.
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