Machines. Technologies. Materials.
Vol. 17 (2023), Issue 7

Table of Contents

  • MACHINES

    • Design of lng tank Type C

      pg(s) 244-254

      Cylindrical tank-type c is designed for cruise passenger ships trying to adopt hull space and meet the requirements of propulsion. Tank must be a double wall with the vacuum space in between, which is also fulfilled with the perlite as insulation. The main input for the design was a tank capacity of 430 m3, vapor pressure, and available space inside of hull structure. The holding period of the boil-off gas is limited to 21 days of ship voyage. Trying to satisfy the volume capacity of the inner tank different dished end of tank was observed. The inner tank is divided into segments for the calculation of hydrodynamic pressure. According to classification rules, dnv and igc rules tank thickness, supports, stiffening and vacuum rings are determined to satisfy bending and buckling requirements. Some of the requirements were according to british standards for validation of the results. The material that is used for calculation is stainless steel 304 l. The main goal of this paper is to provide the optimal design of the lng tank type c considering the mass of the whole lng tank, with attendance to reduce the steel mass of the structure by optimizing shell thicknesses and the number of vacuum rings. After analytical calculations are made finite element analysis is used for verification of the given results. According to the given results space for improvements of tank-type c was observed.

    • Example of the maintenance of a machine pero (D 2504-019) for cleaning metal parts in the working conditions of OEM company from the autotive industry

      pg(s) 255-258

      In this article, it will present a example of the maintenance of a machine PERO (D 2504-019) for cleaning metal parts in the working conditions of renowned OEM company in producing filters from automotive industry. The maintenance process is of particular importance in order to use production capacities to the maximum extent. Maintenance is an indispensable segment of any production system. It follows that maintenance should be adapted to these conditions, and be economical and efficient, so as not to slow down the progress of the production system. Various maintenance methods have developed alongside the development of technology, all with the aim of increasing efficiency and reducing costs. This entails the need for increasing knowledge and skills of the workers themselves in the maintenance system. Large sums of money are invested in modern industry, in order to prevent monetary losses caused by system failures. If the machine tools, devices, and accessories are not maintained on time and adequately, there will be a stoppage of production, which is extremely inconvenient for the company. When the machine stops, delivery is delayed, which leads to a psychological effect on the worker, who is then put under pressure to make up for lost time. In this article, the whole procedure of cleaning, mantenance and inspection of machine PERO (D 2504-019) through 13 steps has been studied. The indicators of the reliable operation of the analyzed machine through the analysis of the machine’s operation, the analysis of downtime, and the analysis of the occurrence of failures through the obtained values of MTTR (Mean Time to Repair) and MTBF (Mean Time Between Failures) are presented in details.

  • TECHNOLOGIES

    • Renovation of moulds for high-pressure casting of aluminium by laser cladding

      pg(s) 259-261

      The paper presents the results of an investigation focused on the analysis of the wear of moulds for high-pressure casting with Al alloy. In order to repair and refurbish the mould parts of moulds for high-pressure casting of aluminium alloys, samples of experimental welds were prepared on the base material of grade 1.2343 (Dievar) of dimensions 150x130x30 mm refined to the hardness value of 44-48 HRC. A TruDisk 4002 solid-state disk laser with BEO D70 focusing optics was used for surfacing. Mat.No.1.2343 (Dievar), Mat.No.1.6356 (Dratec) and Mat.No.1.6356 (UTPA 702 and NIFIL NiCu7/Dievar) wires were used as additional material. Light microscopy technique was used to inspect the microstructures on the cross-sections of the welds. Microhardness measurements were performed with a Vickers indenter at a load of 500 g and a mutual indentation distance of 0.4 mm between the indenter impressions.

    • AFM morphology of sol gel coatings on glass for photovoltaics

      pg(s) 262-263

      In this paper, we present the results of atomic force microscopy (AFM) characterizing the surface morphology of nanostructured coatings on photovoltaic glass obtained by the sol-gel method. Two organic titanium precursors were used to prepare the TiO2 deposition solution: Titanium isopropoxide (TTIP) and titanium tetrabutoxide – Ti (OC4H9). The hydrolyzing agent is distilled water and the stabilizer is nitric acid /HNO3/and acetylacetone (AcAc). Many samples were obtained at different ratios of the components involved, rate of application of the solution on the glass substrate, and different curing and holding temperatures. The samples were characterized by AFM analysis.

    • Application of reverse engineering techniques in automotive component design

      pg(s) 264-266

      The aim of the work was to digitize an automotive component using reverse engineering. To apply the procedures by which an automotive component can be designed. Reverse engineering belongs in the field of innovation among the first established knowledgeintensive services. Together with the advancing development of technology and utilizing of 3D scanning, the reverse engineering is becoming an important tool for accelerating the product innovation cycles and increasing the potential of lean approach and agility of development processes in Product Design. The paper illustrates the possibilities of using and experience with these tools on examples of the scanning of the geometry of the selected automotive components.

    • Thermal decomposition of biomass, significance of biochar

      pg(s) 267-269

      Biochar is an uniquely useful renewable resource that has significant advantages in solving many environmental problems. It helps to mitigate the harmful soil degradation experienced in recent years (decades), including the restoration of the balance of pollutants in the soil, water and gaseous medium. After all, synergistically, with proper use, it can improve soil, water and air quality, carbon dioxide sequestration and moderate greenhouse gas emissions. We designed and implemented laboratory equipment (with a total weight of 0.5 kg) and industrial equipment (50 – 100 kg of coal/hour) and validated the laboratory results with this industrial equipment.
      Our equipment is a so-called resting-bed design. Drying and carbonization are also carried out by direct heat transfer. The carbonizing material is continuously rotated in the interior due to the material movement with the stirrer lever. As a result, the quality of the material leaving and entering the reactor is balanced. Better heat transfer and uniform distribution of thermal energy is facilitated by the circulation of the hot gas that fills the space. The high-temperature gas is supplied with a gas jet pump. The energy obtained by burning the pyrolysis gases produced during carbonization ensures the heating of the system, so there is no need for significant external energy input.
      According to our results, the quality and other characteristics of biochar vary significantly depending on the type of raw material and pyrolysis conditions. In order to ensure the quality of the created material, the production process must be closely monitored in every detail of the equipment. The continuous quality control of the products cannot be neglected either. According to the opinion of international associations and research groups, significant development of the use of biochar is expected in the future. There is growing interest in the use of biochar to remove pollutants from soil, water and gas, and its potential to replace expensive commercial activated carbon.

    • New optical method in laser phototherapy

      pg(s) 270-271

      In this study we investigate the kinetics of oxygen tension pО2) in skin tissue under the influence of the transcutaneous laser irradiation. The results of in vivo experimental measurements of pО2 by a method of transcutaneous oxygen monitoring (TcOM) are presented. The results show that under laser irradiation the value of tissue oxygenation increases and after approximately 10 minutes of exposure exceeds its initial level up to 1.6 times. The observed increase in pO2 indicates the process of photodissociation of oxyhemoglobin (HbO2) in skin blood vessels, which results in local O2 increase in the tissue. Such laser-induced enrichment of tissue oxygenation can be used in phototherapy of pathologies, where the elimination of local tissue hypoxia is critical.

    • Antibacterial Coatings Containing Nanodiamonds

      pg(s) 272-274

      The aim of this research is to obtain coatings with high antibacterial properties and low toxicity, for various applications. Solgel method was employed to manufacture coating comprising carbon nanoparticles (CNP) of nanodiamonds (ND). Methods of dip-coating and spraying were developed and optimized. The technology was adopted to automatic process using designed and manufactured laboratory and semi-industrial spraying and curing apparatus.

  • MATERIALS