No. 1

Author: Alena Breznická

Abstract: In a submitted paper we are going to deal with possibilities in using statistical instruments and methods of product quality management and with application of simulation modeling in production and maintenance introducing procedures on examples being solved in mechanical engineering companies in Slovakia.

Keywords: Maintenance, Analysis, Statistical process control

Vol. 15, 2021, No. 1, p. 1-6

Download PDF

Author: Róbert Cíger, Igor Barényi, Michal Krbaťa

Abstract: The article deals with dilatometric analysis of M398 steel. It is a chromium steel, produced by Böhler using MICROCLEAN powder metallurgy process. The investigated steel is high-alloy chromium and vanadium with a high carbon content. The steel is characterized by high strength, resistance to abrasive wear and corrosion. The result of the dilatometric analysis will be dilatation curves for selected cooling modes in order to determine the initial austenitization temperatures Ac1 and Ac3 and the beginning of the matrensitic transformation Ms. Since the steel is highly alloyed with Cr and V, its microstructure is formed by a very high content of carbides of the M7C3 and MC type. These carbides affect the resulting mechanical properties of the material M398 and predetermine its use for screws in injection molding machines in the plastics industry, where this steel has the highest use so far.

Keywords: Carbide, Dilatation curve, Tool steel, Microstructure, M398

Vol. 15, 2021, No. 1, p. 7-13

Download PDF

Author: Jana Escherová, Jozef Majerík, Michal Krbaťa

Abstract: The aim of this study is to measure and evaluate of mechanical properties of microstructural components of alloyed tool steel C120U according to STN Standard. The measurement was performed on an experimental device Hysitron TI 950 Triboindeneter, which is a part of CEDITEK Laboratories at FST TnUAD. The testing of alloyed tool steel C120U was performed due to the high demands on tool steels in industrial practice, such as high strength, toughness, fatigue and abrasive wear resistance, corrosion resistance, temperature stability and others. The Berkovich test tip type was used in the research process. Chapter 1 describes the research of foreign authors who focused on the mechanical properties of high-strength steels. Chapter 2 shows the results of own experiments such as chemical composition, mechanical properties, evaluation and description of microanalysis of alloy tool steel C120U by using light microscopy. The calculation of the Young's modulus of elasticity and the experimental method are also found in Chapter 2. Chapter 3 presents the measured mechanical properties of the components of the structure of the tested steel, the distribution of individual indent positions on SPM (Scanning Probe Microscopy)  scans, the nanoindentation curve obtained from indents on SPM scans and a comparison of Young's modulus of elasticity Er and calculated Young's modulus of elasticity phase Es. The conclusion and evaluation of the measured data is given in Chapter 4.

Keywords: Quasistatic nanoindentation, Berkovich test tip, Nanohardness, Reduced Young's modulus, Tool steels

Vol. 15, 2021, No. 1, p. 14-19

Download PDF

Author: Michal KRBAŤA

Abstract: The paper deals with the change in mechanical properties and wear of 1.2842 universal tool steel after plasma nitriding, which is widely used to produce cutting tools with good durability and low operating costs. Plasma nitriding was performed at a temperature of 500 °C for 10 hour period in a standard N2 /H2 atmosphere with 1:3 gases ratio. Microstructure, phase structure, thickness of a nitriding layer and surface roughness of samples were measured with optical microscopes and a profilemeter. Verification of a chemical composition was carried out on the BAS TASMAN Q4 device. Wear resistance was  measured on a universal TRIBOLAB UTM 3 tribometer, through a, “pin on disc“ method. The results of experiments have shown that plasma nitriding process, significantly improves the mechanical and tribological  properties of selected materials.

Keywords: plasma nitriding, microhardness, coefficient of friction, pin on disc

Vol. 15, 2021, No. 1, p. 20-25

Download PDF

Author: Mária Kubasáková, Jozef Majerík

Abstract: The authors' article deals with the research or implementation of long-term testing of the process of wear of the flank surface of indexable carbide cutting inserts with PVD coating. The mentioned wear process is realized through the technological process of milling high-strength steel Armox 500. The material Armox 500 is used in practice in the special engineering industry and in the production of external ballistic protection of combat vehicles. In practice, there is a demand for ever higher parameters, such as increased mechanical properties of such steels. This increases the ballistic resistance of Armox armor sheets, which in practice presents new problems associated with mechanical processing to the desired state. Therefore, the authors' research for this reason is focused on monitoring the technological milling process of Armox 500 steel in terms of the wear process, which is important for the achieved dimensional accuracy and quality of machined surfaces. The face milling experiment was performed on a FA3V vertical milling machine with SNHF 1204EN-SR-M1 geometry cutting inserts with tool material type 8230 (P30) from DormerPramet. The cutting inserts were clamped in a 50 mm diameter Narex face milling cutter. The  experiment consisted of monitoring the process of wear of the flank surface VB with the set criterion of flank wear VB = 0.2 mm.

Keywords: Armox 500 steel, long term testing, flank wear VB, hard milling, cutting parameter

Vol. 15, 2021, No. 1, p. 26-32

Download PDF

Author: Pavol Mikuš, Maroš Eckert

Abstract: Tribodiagnostics deals with the problems of lubrication, friction and analysis of oils in technical fluids. Based on the results of parameter monitoring and chemical analysis of the oil, it is possible to determine the impending failure of the entire system very accurately. Today, this relatively young field of technical diagnostics is gradually becoming very viable and its results are fully in line with classical vibroacoustic diagnostics or thermodiagnostics. It is used in all mechanical systems containing oil systems. This is one of the methods of non-disassembly technical diagnostics, which is based on the knowledge that the lubricant after a certain period of use in the lubrication system reflects the condition of the equipment and the conditions in which this equipment was operated.

Keywords: Tribodiagnostics, Lubrication fluid, Wear, Friction, Oil

Vol. 15, 2021, No. 1, p. 33-38

Download PDF

Author: Miroslav Polášek, Matúš Danko

Abstract: In the process of small-caliber ammunition production, the quality of the setting of the deep drawing technology of CuZn30 brass and its subsequent recrystallization is essential. The quality of the setting of this technological process is also very important for the final quality of the whole ammunition, as the cartridge case, or even the projectile, is produced by the technology of deep drawing. In deep  drawing technology in cartridge case manufacturing, when CuZn30 brass already reaches the value required for recrystallization, the brass structure changes the grain size of the structure. And at the same time,  makes it difficult to achieve a uniform grain size in the entire cartridge case cross-section after recrystallization or after some steps of the technological process.

Keywords: metallography, cartridge case, CuZn30 brass, grain size, deep drawing, recrystallization, 9x19 Luger

Vol. 15, 2021, No. 1, p. 39-44

Download PDF

Author: Henrieta Chochlíková, Jana Escherová

Abstract: The material 90MnCrV8 was used for the valuation of mechanical properties of microstructural components of tool steel. Tool steel has to satisfy high demands in industrial practice such as high strength, toughness, wear resistance, temperature stability and so on. Experimental measurements were performed on a Hysitron TI 950 Tridoindenter with Triboscan evaluation software. The Berkovich type was used as a test tip. The quasi- static nanoindentation is used as a methodology of measurement. The methodology and evaluation of microanalysis of tested tool steel by light microscopy is described in chapter 2. Chapter 3 contains own measurements and evaluation of measured data of tested tool steel using the method of quasi- static nanoindentation.

Keywords: Young modulus, Nanoindentation hardness, Microstructural, Steel 90MnCrV8

Vol. 15, 2021, No. 1, p. 45-50

Download PDF

Author: Rudolf Pernis, Milan Škrobian

Abstract: The knowledge of deformation resistance is needed for simulation of forming processes at higher and high temperatures. A static tensile test does not give an answer how deformation resistance depends on deformation rate. Deformation resistance was measured using dilatometer DIL805A/D equipped with hydraulic unit. This setting allows compression tests during hightemperature material forming. Material forming can be carried out under controlled conditions. Such conditions are deformation level, deformation temperature and deformation rate. Deformation rate can be set between 0.001 and 20 s-1. Temperature can be kept from ambient temperature up to 1500 °C. BCT steel was used for experiments. Deformation resistance was measured for experimental matrix of 5 deformation temperatures by 5  deformation rates. The experimental results were described by a proposed mathematical model where deformation curve is a function of deformation. In addition, an equation is proposed for calculation of deformation resistance as a function of two variables: degree of deformation and temperature of deformation. Prediction of deformation curves was done using above equation for the temperatures of (850, 950,
1050, 1150) °C. A visualization of curves for various temperatures is shown in a paper.

Keywords: high temperature deformation, compression test, boron steel, peak stress, deformation curve

Vol. 15, 2021, No. 1, p. 51-55

Download PDF

Author: Juraj Majerský, Jozef Majerík, Igor Barényi, Henrieta Chochlíková

Abstract: In the article there are investigated materials, which are used for production of the injection molding machine´s screws used for processing of plastic materials with content of glass fibers up to 30%. These materials are produced by the powder metallurgy – by the HIP (Hot Isostatic Pressing). Structures of materials are analysed by optical microscope and compared with conventionally produced materials. Based on literature sources there are specified conditions of further processing of materials or rather conditions which are recommended for the test of these materials nitridation.

Keywords: mold, powder metallurgy, screws, glass fibers

Vol. 15, 2021, No. 1, p. 56-62

Download PDF

Author: Maroš Eckert

Abstract: The aim of the work was to compare currently available and expanded materials for 3D printers using FFF technology. This technology is currently one of the most widespread additive technologies and therefore great attention is paid to the material for this type of 3D printing. The materials used in the experiments were PLA, ABS, PET-G, NYLON and a flexible material with the trade name FLEX. The  experimental part consisted of printing test samples from each of these materials. The test sample had randomly selected geometric elements, which were then measured with a caliper and averaged values from 3 identical samples. The results show that a test sample was printed from all the set materials. The best results of accuracy and surface quality were achieved by ABS and PLA materials. In the case of ABS, there was a slight problem with thermal deflection. PET-G material also achieved very good accuracy results, but it required tuning of process parameters. NYLON and FLEX materials are problematic materials for 3D printing, which was also confirmed in tests. Samples from these materials did not achieve the required accuracy and the surface quality was very low. By optimizing the printing process and the input CAD model, some errors could be eliminated, but the print quality would still not reach the value of standard materials.

Keywords: Additive technology, 3D printing, Filament, ABS, PLA

Vol. 15, 2021, No. 1, p. 63-69

Download PDF