Now showing 1 - 10 of 10
  • Publication
    Investigation of the Change in Roughness and Microhardness during Laser Surface Texturing of Copper Samples by Changing the Process Parameters
    (2023)
    Risham Singh
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    ;
    Emil Yankov
    ;
    Nikolay Angelov
    The aim of this research is to achieve a high-quality and long-lasting laser marking of ammunition, which is of interest to the defense industry. The study is about the effects of speed, raster pitch and power on the roughness and microhardness of the marked areas of copper samples. The experiments were carried out with a fiber laser and a copper bromide laser—modern lasers widely used in industrial production. Laser power, scan speed and raster step were varied to determine their effects on the resulting microhardness and surface roughness. The lasers operate in different wavelength ranges, with the optical laser operating at 1064 nm in the near-infrared region and the copper bromide laser at 511 nm and 578 nm in the visible region, allowing the influence of wavelengths on the process to be investigated. The roughness and microhardness velocity dependence for three powers and two pulse durations for the fiber laser were obtained from the experimental data. The dependence of roughness and microhardness on the raster step for both types of lasers was also demonstrated.
  • Publication
    METHOD FOR COLOR LASER MARKING PROCESS OPTIMIZATION WITH THE USE OF GENETIC ALGORITHMS
    Optimization of color laser marking process mostly depends on effective identification of optimal values of laser marking parameters. This is a difficult combinatorial optimization problem, which is still essential for companies that use laser marking systems. The study proposes a new approach to the process optimization through the use of genetic algorithms, carrying out preliminary experimental investigation, analyzing the laser marking results, and presenting possible improvements to the current implementation of genetic algorithms.
    Scopus© Citations 9
  • Publication
    RESEARCH OF LASER MARKING AND ENGRAVING ON BRASS ALLOY 260
    Brass Alloy 260 is widely used in mechanical engineering (odometer contacts, radiator cores), electrical engineering (electrical connectors, screw shells), plumbing (bathroom fixtures), consumers (watch parts, buttons, lamps) etc. The paper presents an analysis of the laser marking and engraving process. The ability Rofin powerline f20 laser system to engrave on Brass Alloy 260 is described. Recommendations are given on choosing the right parameters for laser marking and engraving of Brass Alloy 260 products.
    Scopus© Citations 1
  • Publication
    IMPACT OF LASER ON MICROORGANISMS IN THE DIGESTATE
    At the biogas plant total of 40 digestate samples have been collected and investigated. The microbiological composition of digestate has been analysed before and after laser processing with wavelength λ 445 nm with power 2 - 4 W. Salmonella spp. has not been stated in any of the samples, Escherichia coli and Enterococcus spp. amount does not correspond Eiropean Union regulation R142/2011 requirements in any of the investigated samples; Staphylococcus aureus has been stated in 24 samples out of 40. By decreasing laser scanning speed and increasing power, the total number of microorganism colonies in digestate has decreased.
  • Publication
    ON THE POSSIBILITY OF MARKING EGGS WITH A CO2 LASER
    (2021)
    Pēteris Čeirs
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    ;
    A number of policies and standards regarding food safety issues and quality management have been established for the food industry. One of these requirements is related to the marking of food products describing the expiration date, content and quality.  The report examines the possibility of using laser technology to mark chicken eggs. The contrast of the laser marking is the main criterion for determining its quality. The study examines the functional dependences of the contrast on the main technological parameters of the marking process: laser output power (7 – 20.3 W) and processing speed (50 - 300 mm/s). As a result of the research, optimal parameters for marking with a technological laser system CO2 have been determined.
  • Publication
    Investigation of the change in wettability properties and corrosion behavior of AISI 304 after laser surface texturing
    (2023) ; ;
    Ilieva, Mariana
    ;
    Plamenova Nikolova, Maria
    Stainless steel is a widely used material in industry, architecture, and medical instruments. However, after various thermal processing of stainless steels, chromium carbides can be formed, which locally depletes the chromium available to form a passive film and reduces the corrosion performance. Laser surface treatment can change the surface chemistry of the steel and improve some electrochemical characteristics. However, these characteristics are influenced by the laser power, pulse width, distance between the lines, scanning speed, etc., which all change the surface chemistry and characteristics of laser surface texturing. Simultaneously, the ability to repel liquids that cause corrosion actions could combine to enhance corrosion performance. Since the wettability of a solid surface depends both on its topography and chemical nature, the micro structuring of an austenitic steel surface is an effective way of fabricating hydrophobic or super hydrophobic corrosion-resistant surfaces. For this reason, this study discusses the effect of laser power in the impact zone and the distance between raster lines on the microstructure, wettability, and corrosion resistance of austenitic steel (AISI 304) when exposed to nanosecond fiber laser radiation. The results indicate that parameter-controlled micro structuring can be used to form both hydrophilic and hydrophobic surfaces with different electrochemical performances.
  • Publication
    Investigation of the influence of the processing speed and the linear pulse density of the laser surface texturing process
    (2023) ; ;
    Ilieva, Mariana
    ;
    Plamenova Nikolova, Maria
    Fine-tuning laser parameters is necessary to achieve the desired quality of the process of laser surface texturing. This requires a set of experiments to assess the influence of the main process parameters on the quality of the surface of a treated alloy. By varying the laser parameters, different laser-material interactions, such as heating, melting, or evaporation can be observed. This study analyzes the influence of two interrelated processing parameters in laser surface texturing – the speed of beam motion on the surface on the one hand, and, on the other, the linear pulse density. They ultimately have a direct impact on the resulting microstructure, hydrophilicity, and electrochemical properties of austenitic steel (AISI 304). By adjusting the pulse repetition rate of a 1064-nm fiber laser from 500 kHz to 1000 kHz at a constant speed of 100 mm/s, the surface wettability changes from hydrophobicity to hydrophilicity. All surfaces treated with laser scanning speeds varying from 20 mm/s to 200 mm/s at a constant rate of 500 kHz are hydrophobic. As a result, the changed ability to repel liquids alters the corrosion properties of the steel in a 0.5 M H2SO4 solution. The results allow one to distinguish ranges of laser-beam parameters that could be useful in selecting certain properties of the stainless-steel surface layer.
  • Publication
    RESEARCH OF POSSIBILITIES OF LASER POLISHING OF THE SURFACE OF ALUMINUM
    (2021)
    Bulavskis, Kevins
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    ;
    The report considers the possibility of reducing the roughness after laser polishing of Aluminum plates. A CHANXAN CX-20G fiber laser with a wavelength of 1064 nm is used for the research. As a result of the experiment, 4 matrices were marked with a fiber laser on 3 samples for each series of the experiment. Then, using a multifunctional microscope, the roughness of the treated and untreated aluminum surface was measured. At the end of the research, conclusions were made about the changes in roughness in the course of this experiment.
  • Publication
    INVESTIGATING THE IMPACT OF LASER POWER AND SCAN SPEED ON ENGRAVING ASPEN THERMOWOOD
    (2023)
    Rāviņš, Dzintars
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    Yankov, Emil
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    ; ;
    Rāviņš, Daivis
    This study examines the effect of pre-heat treatment on laser engraving of aspen thermowood. We used an infrared CO2 laser with a wavelength of 10640 nm to engrave aspen thermowood samples with different pre-treatment temperatures, including one non-treated sample (base). The samples had a similar moisture content of about 6 - 8%, but exhibited different shades of brown depending on the pre-treatment temperature. The engraving depth and width were measured for each sample, and 8 graphs were constructed to analyze the results. Our findings show that pre-treatment temperature has a significant effect on the efficiency of laser engraving, with higher pre-treatment temperatures resulting in deeper engraving lines. The study provides valuable insights into the optimization of laser engraving parameters for aspen thermowood, and demonstrates the potential of pre-heat treatment to improve the quality of laser-engraved wooden products.