• Analyze of welding arc parameters in shielded metal arc welding

    pg(s) 80-82

    Shielded metal arc welding is widely used in heavy industries in partly shipbuilding and ship repair. This method didn’t required special personal skills and equipment. Different scientists are analyzed welding parameters, mechanical characteristics and chemical composition in welding seam but interesting is to be investigated welding arc characteristics in different electrodes. The paper deal with analyze of welding arc parameters in shielded metal arc welding. For this purpose on mild steel plates are welded seams with different diameters of electrodes and different welding current. In welding process are measured welding arc burning time, length of electrodes melted part, welding machine voltage and weight of melted electrodes part. For analyze welding arc parameters are used response surface methodology method (RSM). Used RSM in the paper is 2k factorial design where k=2 factors. The influence of each to other factors of welding arc is presented by meta models.

  • Simulation of toolpaths and program verification of a CNC lathe machine tool

    pg(s) 76-79

    This paper presents the simulation and verification of programs created for the CNC Hitachi Seiki Seicos LIII lathe machine tool. The main purpose of program simulation and verification is to ensure the quality and accuracy of the cutting process, which can significantly improve production efficiency. In addition to defining the toolpath, simulation can perform linear and circular interpolation according to specific programs based on G – codes. Therefore, all the motions of the moving parts of the real lathe machine tool can be clearly visualized. The use of simulation is a good solution not only to precise the toolpath, but also verify the program and detect any possible collision between cutting tools and mobile components, before loading the program into the lathe machine tool and starting cutting processes.

  • Technology and technological scheme of a workshop for the production of beehives made of amorphous quartz ceramics

    pg(s) 73-75

    The development refers to an innovative technology and technological scheme of a workshop for the production of beehives made of amorphous quartz ceramics. The conditions for obtaining stable suspensions from quartz glass are emphasized and investigated. The time for the treatment of the glass in the grinding device, the amount of water, the influence of the modifiers in stabilizing the suspension by adjusting the pH level, as well as the most suitable sedimentary composition of the glass particles are established. The factors determining the speed and degree of sintering of the ceramics are investigated and established. They include the density of the raw products, the dispersion of the quartz glass particles and its purity, as well as the environment in the furnace and the sintering mode.

  • Formation of the structure of polymeric products on the based of polyamide 6 produced by fdm-printing

    pg(s) 70-72

    An analysis of the prospects for the development of FDM printing technology has been carried out. The paper studies the possibility of obtaining polymer products based on polyamide 6 and its compositions by layer-by-layer deposition. Tests of the strength indicators of the printed experimental products were carried out. The mechanism of the influence of the composition and modes of formation of printed products on their strength characteristics is proposed. The influence of the composition of the composite polymer material based on PA6 on the quality of printing products has been studied. Methods for controlling the shrinkage parameters of products obtained by
    layer-by-layer deposition are proposed. The obtained results of the study can be used in the development of composites for the production of polymer filament to ensure the process of FDM printing of polymer products, including for the needs of mechanical engineering.

  • Studying the surface and microstructure of a chromium coating with nanodiamond particles deposited on monolithic composite with layered structure

    pg(s) 67-69

    Electrochemical coatings of chromium modified with nanodiamond particles applied directly on niobium-aluminum alloy were obtained. Nanodiamond particles produced by detonation synthesis were used. Chromium coatings were deposited on a monolithic composite with a complex structure based on niobium and aluminum alloys, called later matrix for short. Standard chromium electrolyte and electrolyte with nanodiamond particles concentration of 10 g/l were used. Analyzes were performed by Scanning Electron Microscope system of Bruker Inc. and the Polyvar Met metallographic microscope. The microhardness was measured using a PolyvarMet 4000 microhardness tester. The obtained results of the microhardness were 788 kg/mm2 in the chromium layer and 168 kg/mm2 and 692 kg/mm2 in the matrix. The microstructural and SEM-EDS analysis showed the presence of two intermetallides Nb2Al and Nb3Al in the monolithic composite of niobium aluminum matrix. The average thickness of the chromium coatings modified with nanodiamond particles is 55 μm.

  • Study of Vitamin C stability in thermal water for ecofriendly application in the pharmaceutical industry

    pg(s) 64-66

    Free radicals and reactive species of oxygen are destructive for living organisms. Antioxidants are capable to reduce the effect of free radicals and to recover the organisms’ health. On the other hand, during the fabrication process various chemicals are released into the water ecosystems from the factories, causing harmful effects on the aquatic organisms. The Autonomous Province of Vojvodina in Serbia is rich in thermal waters. Thankfully to the various minerals, they could have antioxidant effect and could be used as raw material for the production of different pharmaceutical products. In this study we examined the possible effect of different thermal water samples on the degradation rate of Vitamin C as an antioxidant with UV radiation. Furthermore, the influence of initial pH value was also investigated. Our results showed that the thermal water reduced the degradation rate of vitamin C. In addition, the lowest removal rate was observed at initial pH 7, which is close to the skin’s natural pH. These findings showed that the thermal water could be used in preparations for skin.

  • Influence of the window profile on the final quality of the product

    pg(s) 58-63

    The current product on the market offers a wide range of diverse profiles for producing windows that are made of different materials, width and order of grills depending on the profile. Within the framework of this research the windows with same dimensions shall be elaborated, those which are made of the same production capacity and use the same fittings but different types of PVC profiles. The aim is to prove what kind of influence the used profile has over the final quality of the product. For this research, two groups and six subgroups will be tested. In each subgroup, one tests five windows made of the same profile. The groups are divided according to the used fittings. The testing of the quality shall be conducted in accordance with the European norms EN 1026:2016 (Windows and doors – Air permeability – Test method), EN 1027:2016 (Windows and doors – Water tightness – Test method), EN 12211:2016 (Windows and doors – Resistance to wind load – Test method).

  • Design for Sustainability: A Review

    pg(s) 35-37

    Sustainability is topic of great concern since the last decade and still today does not lose of its popularity. Reason for that is that the contemporary way of living is causing great damages to the environment. Designers have been talking about changing the ways in which the products are designed in order to have sustainable product. But, for achieving sustainability many aspects need to be addressed, such as: cultural, social, economical and technological. Nowadays, we believe that these aspects are on higher level and we can talk about sustainable design.
    Every product development process starts with the design phase and this is why we believe that it is most important for making improvements of the products. In this paper we have the premise that good and appropriate design can have positive influence on the sustainability. In order to check the validity of the premise we are reviewing paper dealing with sustainability, eco design, and engineering materials.

  • Basic Analytical and Geometric Synthesis of Conic Convolute Helical Surfaces of Spatial Rack Drives. Software and Graphic Study

    pg(s) 28-34

    This study treats a study oriented to the basic synthesis of the conic convolute helicoid. On the base of the elaborated mathematical model, the written equations show a theoretical possibility, depending on the basic geometrical characteristics of the designed conic convolute worm, to generate the active flanks of the helical teeth as parts of these conical convolute helicoids. Analytical dependences of the cross-section and the axial section of the conic convolute surfaces are obtained. These relations, as well as the performed studies of the graphic images of these sections, precede the process of constructing the algorithms for computer synthesis and design of these conic helical surfaces. The realized studies of the graphic images of these sections are the basis of the algorithms for computer synthesis and design of these conical helical surfaces. The appearance of singular points on these surfaces is examined, which is of particular importance for their technological synthesis. Based on the developed algorithm, a computer program for the synthesis and visualization of conic helical surfaces is realized and illustrated.

  • Visualization and analysis of gear drives parameters with the help of computer-aided mathematics systems

    pg(s) 24-27

    The visualisation capabilities of the main software systems for computer-aided mathematics are reviewed. The advantages of the software system Matlab are described. The system is appropriate when visualization and analysis of engineering data are required. The author sets out to highlight the three-dimensional graphics and optimization synthesis of gear drives.

  • Welding technology of martensitic steel P91 and austenitic steel 304H – State of the art

    pg(s) 21-23

    Many industries nowadays with the development of technology require joints between different types of steel due to its various benefits such as production of lightweight machine parts, production of less expensive components with acceptable properties, high strength, acceptable corrosion resistance. One of the dissimilar welding challenges is the joint between martensitic steel P91 and austenitic steel 304H due to the dissimilarities in their chemical, physical and metallurgical properties. In this paper is going to be analysed the best way of joining the two different types of steel, the proper welding technique, the choice of filler material which according to carbon content can match only to one of the steels. At the end is discussed if the welding performance can meet the requirements of high-quality weld.

  • Study of the radial shear rolling effect on the gradient microstructure formation in technical titanium and mechanical properties changes

    pg(s) 18-20

    The work is devoted to experimental studies of the influence of radial shear rolling on the microstructure evolution of the VT-1 titanium alloy and its gradient distribution over the cross section, as well as changes in mechanical properties. In the course of the conducted studies, two different types of microstructure were obtained. At the periphery of the bar near the surface, a relatively equiaxed ultrafine-grained structure with a grain size of 300-600 nm was obtained, while in the axial zone of the bar, an oriented striped texture was obtained. The resulting structure difference of the peripheral and central zones indicates the gradient nature of the structure distribution. This type of distribution is confirmed by the results of the microhardness study over the cross section of a bar rolled to a diameter of 15 mm. The ultimate strength after deformation increased by 58%, while the elongation decreased by 15%.