Industrial Lubrication and Tribology最新文献

Purpose

This study aims to investigate the impact of varying the number of minimum quantity lubrication (MQL) nozzles, wind pressure, spindle speed and type of lubrication on surface roughness, fatigue life and tool wear in the drilling of aluminum alloy 6061-T6.

Design/methodology/approach

The effect of using different lubricants such as palm oil, graphene/water nanofluid and SiO₂/water in the MQL method was compared with flood and dry methods. The lubricant flow and feed rate were kept constant throughout the drilling, while the number of nozzles, wind pressure and spindle speed varied. After preparing the parts, surface roughness, fatigue life and tool wear were measured, and the results were analyzed by ANOVA.

Findings

The results showed that using MQL with four nozzles and graphene/water nanofluid reduced surface roughness by 60%, followed by SiO₂ nanofluid at 56%, and then by palm oil at 50%. Increasing the spindle speed in MQL mode with four nozzles using graphene nanofluid decreased surface roughness by 52% and improved fatigue life by 34% compared to the dry mode. SEM results showed that tool wear and deformation rates significantly decreased. Increasing the number of nozzles caused the fluid particles to penetrate the cutting area, resulting in improved tool cooling with lubrication in all directions.

Originality/value

Numerous attempts have been made worldwide to eliminate industrial lubricants due to environmental pollution. In this research, using nanofluid with wind pressure in MQL reduces environmental impacts and production costs while improving the quality of the final workpiece more than flood and dry methods.

Peer review

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-01-2024-0021/

Purpose

The purpose of this study is to identify the dynamic parameters of journal bearings in asymmetric rotor systems without additional test runs or excitations.

Design/methodology/approach

An asymmetric rotor-bearing test rig was set up for the identification experiment. Comparations were made between the measured response of the asymmetric rotor and the symmetric rotor. The mathematical model of the asymmetric rotor is established by the finite element method. The identification algorithm is based on the model of the rotor and the measured vibration response to identify bearing parameters. The influence of modeling error and measurement noise on the identification results are numerically analyzed. The dynamic parameters of the journal bearings under different rotational speeds are identified and compared with the theoretical values calculated by the perturbation method.

Findings

The experiment results show that the vibration characteristics of the asymmetric rotor and the symmetric rotor are different. The numerical evaluation of the identification algorithm shows that the algorithm is accurate and has good robustness to modeling error and measurement noise. The identified dynamic parameters agree reasonably well with the parameters derived from the theoretical bearing model.

Originality/value

The proposed identification method uses the unique vibration characteristics of asymmetric rotors to identify the bearing dynamic parameters. As the method does not require excitations or additional test runs, it is suitable for the field test.

Peer review

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-03-2024-0096/

Purpose

This paper aims to understand the vibration characteristics of full ceramic ball bearings under grease lubrication, reduce the vibration of the bearings and improve their service life.

Design/methodology/approach

The Hertz contact stiffness formula for full ceramic ball bearings is constructed; the equivalent comprehensive stiffness calculation model and vibration model of full ceramic ball bearings are established. The dynamic characteristic test of full ceramic ball bearing under grease lubrication was carried out by using the bearing life testing machine, and its vibration was measured, and its vibration acceleration root-mean-square was obtained by software calculation and compared with the simulation results.

Findings

At the rotational speed of 12,000 r/min, the root-mean-square value of vibration acceleration is maximum 10.82 m/s², and the error is also maximum 7.49%. As the rotational speed increases, the oil film stiffness decreases. In the radial load of 600 N, the vibration acceleration root-mean-square is minimum 6.40 m/s², but its error is maximum 6.56%. As the radial load increases, the vibration of the bearing decreases and then increases, so under certain conditions increasing the radial load can reduce the bearing vibration. With different types of grease, the best preload is also different; low-speed heavy load should be used when the viscosity of the grease is large, and high-speed light load should be used when the choice of smaller viscosity grease is made.

Originality/value

It provides a theoretical basis for the application of full ceramic ball bearings under grease lubrication, which is of great significance for reducing the vibration of bearings as well as enhancing the service life of bearings.

Peer review

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-03-2024-0094/

Purpose

This study aims to prepare thymol-based deep eutectic solvents (DESs) and use them as lubricates for friction and wear tests to simulate the wear conditions of hybrid bearings.

Design/methodology/approach

Through the characterization and analysis of the morphology of wear scars and the elemental composition of friction films, the tribological behavior and wear mechanism of sample materials as lubricants were investigated and the anti-wear mechanism of thymol-based DESs was discussed.

Findings

The findings demonstrate that because of the formation of a fluid lubrication film and excellent kinematic viscosity, the lubrication effect of the prepared DES is improved by about 50% compared to the base lubricating oil. The prepared [Ch]Cl-thymol DES has a better anti-friction and lubrication effect than citric-thymol, EG-thymol and urea-thymol DESs, with an average friction coefficient of about 0.04.

Originality/value

In this work, the friction reduction properties of thymol-based DESs were studied as lubricants for the first time, and the lubrication mechanism of sample materials was investigated.

Purpose

The purpose of this paper is to develop a new type of embedded solid self-lubricating thrust ball bearing for conditions where grease lubrication cannot be used and to analyze its tribological performance under different lubrication characteristics (lubrication position, width and filling amount).

Design/methodology/approach

Lubrication parameters such as position (a), width (W) and filling amount (Q) were considered. Grooves were made on the raceway with a fiber laser and solid self-lubricating materials were applied through scraping. The frictional behavior of the new bearing was analyzed using a vertical test rig and the bearing’s surface topography was examined with a noncontact profilometer to study wear mechanisms.

Findings

The new inlay thrust ball bearings exhibited excellent lubrication effects and effectively controlled the temperature rise of the bearings. When a is 0 degrees, W is 0.5 mm and Q is 16 mg, the bearing experiences the least wear, and the friction coefficient and temperature are the lowest, measuring 0.001 and 41.52 degrees, respectively. Under the same experimental conditions, compared to smooth bearings without solid lubrication, the friction coefficient decreased by 96.88% and the temperature decreased by 59.74%.

Originality/value

This study presents a self-lubricating thrust ball bearing designed for conditions where grease lubrication is not feasible. A comprehensive investigation was conducted on its surface morphology, wear mechanisms and tribological performance. This work provides valuable insights into the research of self-lubricating thrust ball bearings.

Peer review

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-03-2024-0073/

Purpose

The purpose of this study was to synthesize composite nanoparticles (TiO₂@SiO₂) via the chemical deposition method and investigate their efficacy as additives in polytetrafluoroethylene (PTFE) lubricating grease. The focus was on examining the frictional and conductive properties of the TiO₂@SiO₂ grease using a friction tester.

Design/methodology/approach

Composite nanoparticles (TiO₂@SiO₂) were synthesized using the chemical deposition method and incorporated into PTFE grease. Frictional and conductive properties were evaluated using a friction tester. Surface morphology and chemical composition of wear tracks were analyzed using scanning electron microscope and X-ray photoelectron spectroscopy, respectively.

Findings

Incorporating TiO₂@SiO₂ at a mass fraction of 1 Wt.% led to a significant reduction in friction coefficient and wear width. The wear depth exhibited a remarkable decrease of 260%, while the contact resistance reached its peak value. This improvement in tribological properties could be attributed to the presence of TiO₂@SiO₂, where TiO₂ served as the core and SiO₂ as the shell during the friction process. The high hardness of the SiO₂ shell contributed to enhanced load-bearing capacity. In addition, the exceptional insulation properties of SiO₂ demonstrated excellent electron-capturing capabilities, resulting in improved friction and insulation performance of the TiO₂@SiO₂ lubricating grease.

Originality/value

This study demonstrates the potential of TiO₂@SiO₂ composite nanoparticles as additives in lubricating greases, offering improved friction and insulation performance. The findings provide insights into the design of advanced lubricating materials with enhanced tribological properties and insulation capacity, contributing to the development of more efficient and durable lubrication systems.

Purpose

The aim of this study is to investigate the effects of Al₂O₃ mass fraction on the corrosive-wear and electrochemical performance of NiTi coating in 3.5% NaCl solution.

Design/methodology/approach

The NiTi–xAl₂O₃ coatings were fabricated on S355 steel by laser cladding, and their corrosive-wear and electrochemical performance were investigated using a wear tester and electrochemical workstation, respectively.

Findings

The wear rates of NiTi–5%Al₂O₃, –10%Al₂O₃ and –15%Al₂O₃ coatings are 82.33, 54.23 and 30.10 µm³ mm⁻¹ N⁻¹, respectively, showing that the wear resistance of NiTi–15%Al₂O₃ coating is the best. The wear mechanism is abrasive wear, which is attributed to the increase of coating hardness by the Al₂O₃ addition. The polarization resistance of NiTi–5%Al₂O₃, –10%Al₂O₃ and –15%Al₂O₃ coatings is 3,639, 5,125 and 10,024 O cm², respectively, exhibiting that the NiTi–15% Al₂O₃ coating has the best corrosion resistance.

Originality/value

The roles of Al₂O₃ in the corrosive-wear and electrochemical performance of NiTi–xAl₂O₃ coating were revealed through the experimental investigation.

Peer review

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-02-2024-0044/

Purpose

The purpose of this paper is to clarify the influence of low earth orbit space environment on the wear mechanism of TC4 alloy material and crank rocker mechanism.

Design/methodology/approach

In this study, friction experiments were carried out on TC4 alloy friction discs and crank rocker mechanisms, both before and after exposure to atomic oxygen and proton irradiation. Nanoindentation, grazing incidence X-ray diffraction (GIXRD), and X-ray photoelectron spectroscopy were employed to systematically characterize alterations in mechanical properties, surface phase, and chemical composition.

Findings

The results show that the wear mechanism of TC4 alloy friction disc is mainly adhesive wear in vacuum environment, while the wear mechanism of crank rocker mechanism includes not only adhesive wear but also abrasive wear. Atomic oxygen exposure leads to the formation of more oxides on the surface of TC4 alloy, which form abrasive particles during the friction process. Proton irradiation will lead to a decrease in fatigue performance and an increase in hardness on the surface of TC4 alloy, thus causing fatigue wear on the surface of TC4 alloy, and more furrows appear on the crank rocker mechanism after proton irradiation. In the three environments, the characteristics of abrasive wear of the crank rocker mechanism are more obvious than those of the TC4 alloy friction disc.

Originality/value

These results highlight the importance of understanding the subtle effects of atomic oxygen and proton irradiation on the wear behavior of TC4 alloy and provide some insights for optimizing its performance in space applications.

Peer review

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-02-2024-0051/

Purpose

This paper aims to investigate the tribological benefits of a biomimetic teardrop surface texture inspired by snakeskin compared to conventional surface textures with the help of geometrical and flow parameters using computational fluid dynamics techniques.

Design/methodology/approach

The lubricant is assumed to be Newtonian, and the flow is laminar with constant viscosity and isothermal property. The governing equations, continuity and Navier–Stokes equation, are discretised by the finite volume method, and cavitation modelling is included. The discretisation for the momentum equations is carried out using the second-order difference method for the SIMPLEC algorithm of pressure–velocity coupling.

Findings

The results indicate that biomimetic teardrop surface texturing performs better than conventional shapes surface textures in improving tribological performance. Furthermore, the parallel texture orientation along with the flow generates a high-pressure distribution relative to other orientations. Surface texture area density also highly influences the load-carrying capacity, which is optimum at 29%. Zigzag pattern arrangement performs better compared to linear pattern arrangement of texturing.

Originality/value

The paper proposes that this unique biomimetic teardrop shape can give better tribological performance than conventional shapes.

Peer review

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-02-2024-0053/

Purpose

The purpose of this paper is to investigate the silt erosion performance of Bare, 75%Cr₂O₃ + 25%Al₂O₃ and 85%Cr₂O₃ + 15Al₂O₃-coated SS304 under various control parameters such as rotation speed, concentration of silt and particle size of silt used for making slurry. This can provide insight for using chromia and alumina-based coatings for hydro-turbines.

Design/methodology/approach

Taguchi approach was used to identify the effect of three input parameters on the bare and coated alloys. L₁₆ orthogonal array is used for determining the signal-to-noise (S/N) ratio for each process parameter. For each level of parameters taken into consideration about the erosion wear, the arithmetic mean of the S/N ratio is calculated. On the essence of the results of S/N ratios, it is possible to determine the effect of the most dominating parameters of the erosion wear.

Findings

Results show that the erosion increases with an increase in silt concentration (Wt.%). It has been analyzed that the rotational speed has the most significant effect followed by the particle size and concentration on erosion wear for all uncoated and coated SS-304 samples. Maximum resistance to erosion is provided by 85%Cr₂O₃ + 15%Al₂O₃. The least erosion wear for process parameters has occurred at the optimal parametric combination of rotational speed (N) = 415 rev/min, concentration (C) = 15 Wt.% and particle size range as <53 µm for uncoated and coated stainless steel.

Originality/value

The study clearly shows the silt erosion performance of chromia and alumina coatings of different compositions at different input parameters.

Peer review

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-01-2024-0028/