International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

Rolling element bearing fault detection is of significant importance due to the widespread use of bearings across numerous industrial applications. In this study, vibration measurements using an accelerometer and a laser displacement sensor are carried out on a laboratory bearing test rig under different operating conditions, including a healthy state and bearings with localized inner- and outer-ring faults. Measurements are conducted at a constant rotational speed of 1700 rpm and the acquired signals are analysed to extract characteristic features associated with potential bearing faults. The results demonstrate that the applied methodology enables indicative bearing fault detection using both measurement approaches.

The intensification methods for carburizing and nitrocarburizing investigated in this study include the use of biochar, preliminary oxidation, and plastic deformation. The possibility of combining oxidation and plastic deformation was also examined.

Cane chains are very important transmission elements which are carefully designed according to fatigue strength and wear resistance. To increase the life of cane chains, the resistance of the surface failure should be increased. In this investigation, experiments were carried out to evaluate the wear resistance using wear test rig designed and manufactured for this purpose. Three types of steels were used, namely 16MnCr5, 17CrNiMo6, and 18MnCrB5. Discs manufactured from these steels were carburized for different periods of time (6, 10, and 12 hours). Tempering process was carried out at different temperatures to obtain hardness values of 48, 52, and 56 HRC. The accumulated weight loss was measured and the wear rates were determined for each case hardened steel at the constant normal test load of 800 N. The accumulated weight loss was measured as a function of the number of revolutions. Wear rate was calculated and presented with case hardened depth and hardness for all steels. The hardness distribution and carbon content of carburized layer was presented as a function of the distance from the surface. Carburized layer microstructure and carbide percentage were presented and measured. From test results, it was concluded that the wear rate for all steels under investigation decreases with the increase of their case hardness. Minimum wear rate was obtained at hardness 56 HRC. Wear rate for all steels decreases with the increase of carburizing time tending to reach a minimum at carburizing time 10 hours. Wear rate for steel 16MnCr5 is less than that of the wear rate for 17CrNiMo6 and 18MnCrB5 by about 15℅ and 45℅ respectively under the same testing conditions. Carburized layer, carbon content and case depth increase with the increase of carburizing time.

The main characteristic of the powder metallurgical materials that distinguishes them from the summer ones is the presence in them of residual porosity. For this reason, the processes of their thermochemical treatment are differ significantly from those occurring at saturation of dense ones. In the present paper the impact of technological processes such as boronizing, chromizing, siliconizing, carburizing, borocarburizing, etc., is monitored on the kinetics of diffusion layer growth in powder materials with a porosity of 5÷35%. The specimens of iron powders NC 100.24 and those doped with 2% Cu were subjected to study. The samples were pressed with an effort of 200 ÷ 800MPa and sintered for 0.5h at 1150°C in dissociated NH3 medium. Thermochemical treatment was conducted at 950°C for 4 hours in semi-permeable saturation media. Graphical dependencies for varying the thickness of diffusion coatings in different thermochemical treatment modes are presented, depending on the porosity of the saturation materials.

The subject of our study is the effect of the tempering duration /for up to 7 hours, at 180°C/ on the mechanical properties of 20CrMo5 quenched steel samples. Possibilities were studied, including through eddy currents, to control the final tempering of parts which have gone through carburizing, double-quenching and interim high-temperature tempering. The parts were 20CrMo5 steel shafts, which had their carburized layer removed in certain zones before the thread was made.

It has been established that a strong correlation exists between the HV50 quality indices and the eddy currents characteristic Z.

The process of low-temperature tempering has been studied by eddy current testing and measuring the hardness HRC at a constant temperature as well as at increasing temperature and duration. Technological factors of tempering were considered in their interdependence, according to the Hollomon-Jaffe equation. It has been argued that the factor levels, temperature and duration, are determined by the carburization and quenching results. Eddy current testing has been introduced as an indicator of quality with high sensitivity to changing technological factors; it has integral importance in terms of structural changes and electromagnetic properties of the parts. Hardness and electromagnetic characteristics, as indicators of quality after low-temperature tempering, were presented as a function of the tempering parameter Pa.