Now showing 1 - 10 of 50
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STUDY OF CUTTING AND LABELING OF POLYMETHYLMETHACRYLATE USING A CO2 LASER

2019, Nikolay Todorov Dolchinkov, Lazov, Lyubomir, Jordan Shterev Ivanov, Deyan Dimitrov Nedyalkov, Lyubomir Ivanov Linkov

Progress in direct laser marking when processing plastics with unmatched quality of markings, contrast and speed. This article presents the latest generation of laser materials and laser equipment systems. When properly applied, laser marking can provide quality for production and add value to the appearance and function of the product.Describe the parameters influencing the depth of the laser marking of polymethylmethacrylate (PMMA) products. Experimental results are presented for determining the quality of cuts on the polymer surface at specific parameters - power and speed.

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Investigation of the influence of the processing speed and the linear pulse density of the laser surface texturing process

2023, Adijāns, Imants, Lazov, Lyubomir, 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.

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Evaluation of laser cutting process with auxiliary gas pressure by soft computing approach

2018, Lazov, Lyubomir, Vlastimir Nikolić, Srdjan Jovic, Miloš Milovančević, Heristina Deneva, Teirumnieka, Ērika, Nebojsa Arsic

Evaluation of the optimal laser cutting parameters is very important for the high cut quality. This is highly nonlinear process with different parameters which is the main challenge in the optimization process. Data mining methodology is one of most versatile method which can be used laser cutting process optimization. Support vector regression (SVR) procedure is implemented since it is a versatile and robust technique for very nonlinear data regression. The goal in this study was to determine the optimal laser cutting parameters to ensure robust condition for minimization of average surface roughness. Three cutting parameters, the cutting speed, the laser power, and the assist gas pressure, were used in the investigation. As a laser type TruLaser 1030 technological system was used. Nitrogen as an assisted gas was used in the laser cutting process. As the data mining method, support vector regression procedure was used. Data mining prediction accuracy was very high according the coefficient (R2) of determination and root mean square error (RMSE): R2 = 0.9975 and RMSE = 0.0337. Therefore the data mining approach could be used effectively for determination of the optimal conditions of the laser cutting process.

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INVESTIGATING THE IMPACT OF LASER POWER AND SCAN SPEED ON ENGRAVING ASPEN THERMOWOOD

2023, Rāviņš, Dzintars, Yankov, Emil, Adijāns, Imants, Lazov, Lyubomir, 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.

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Estimation of the most influential factors on the laser cutting process heat affected zone (HAZ) by adaptive neuro-fuzzy technique

2016, Dalibor Petković, Vlastimir Nikolić, Miloš Milovančević, Lazov, Lyubomir

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Investigation of the change in wettability properties and corrosion behavior of AISI 304 after laser surface texturing

2023, Adijāns, Imants, Lazov, Lyubomir, 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.

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RESEARCH OF POSSIBILITIES OF LASER POLISHING OF THE SURFACE OF ALUMINUM

2021, Bulavskis, Kevins, Adijāns, Imants, Lazov, Lyubomir

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.

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Investigation of the influence of the scanning speed and step in laser marking and engraving of aluminum

2021, I Balchev, A Atanasov, A Lengerov, Lazov, Lyubomir

Marking and engraving of aluminum was carried out by a CuBr (copper bromide) laser operating at the wavelength of 511 nm with a pulse duration of 30 ns. The reflection was investigated of the laser-ablated aluminum surface depending on the laser beam scanning speed and the distance between the laser lines. The changes of the aluminum surface were observed before and after laser processing by an optical microscope and visually. The laser marking quality was estimated by measuring the reflection of the irradiated aluminum surface by an optical spectrometer. The dependence was analyzed of the contrast on the speed for different steps in laser marking of areas of the surface of aluminum samples. Marking by a CuBr laser shows a potential for good quality marking of barcodes and QR codes on aluminum products.

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COMPUTER CONTROL THE ACCURACY OF THE PARTS PROCESSED ON CNC MACHINE TOOLS BASED ON STATISTICAL PROCESS CONTROL

2017, Angel Lengerov, Galina Nikolcheva, Julieta Kaleycheva, Lazov, Lyubomir

Statistical process control (SPC) can help manufacturers improve the quality of their products. This paper describes a relatively simple and effective method and algorithm to adjust the accuracy of parts produced on CNC machine tools using the methods of statistical process control. Examined the possibilities of the proposed method by computer simulation of the process. By using the proposed algorithm scattering of size is placed in the middle of the tolerance zone. Various variants carrying out the method are proposed adequate on the machining time during processing details in the sample. This can optimize the total time for processing of the batch.

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Selection of the most influential factors on the water-jet assisted underwater laser process by adaptive neuro-fuzzy technique

2016, Vlastimir Nikolić, Dalibor Petković, Lazov, Lyubomir, Miloš Milovančević