Ring Wear Research Articles

Experimental study on wear of TBM disc cutter rings with different kinds of hardness

To study the wear characteristics of disc cutter rings, cutter-rock wear tests between cutter rings with six types of hardness and three typical types of rock are carried out based on the liner cutting machine (LCM). The wear mechanism and wear depth are also studied with a laser microscope. The research results show that the wear mechanism of cutter rings is micro cutting when the disc cutter rings wear against sandstone. The wear loss, wear depth and morphology of wear debris change insignificantly with the increase of the hardness. When the cutter rings wear against rust stone, the wear mechanism of cutter rings presents furrow deformation, followed by micro cutting with the increase of the hardness. When the hardness is increased to 57.5 HRC, the cutter wear mechanism begins to show brittle fractures. With the increase of the hardness, the wear loss and wear depth are decreased, but the decrease speed slows when the hardness is increased to 57.0 HRC. When disc cutter rings with different types of hardness wear against gneiss, the wear law is, on the whole, consistent with that in the case of rust stone. Finally, the rule for selecting the appropriate blade shape for cutter rings with different types of hardness when wearing against three typical rock formations is obtained based on the shape changes of the cutter blades.

Prediction of lateral continuous wear of cutter ring in soft ground with quartz sand

This note presents an investigation on the lateral continuous wear caused weight loss of disc cutter in soft ground condition with quartz sand. The energy consumed during the wearing process is evaluated by analysing the friction process. The contact pressure on cutter ring is analysed by the cavity expansion theory. A regressed equation is proposed to convert the consumed energy into the weight loss of a disc cutter. A new model to predict the lateral continuous wear of cutter rings is then proposed. The model is validated using the field observed data from tunnel constructed in Shenzhen, China.

Газодетонационное напыление покрытий поршневых колец двигателя внутреннего сгорания СВС-механокомпозитами на основе карбида титана

There are considered ecologically harmless technologies for nano-structural material obtaining by methods of mechanochemistry with carrying out a reaction of high-temperature synthesis in a metal matrix for the application of the powder material obtained in the course of gas-detonation coating processes which may substitute electroplate chromium coating. As a sputtered powder there was used SVS- mechanocomposite having Ti-C-NiCr in its composition. It is determined that the wear of piston rings with the developed coating is lower by 27%, than in similar rings with an electroplate chromium coating.

Experimental Study on Wear Behaviors of TBM Disc Cutter Ring in Hard Rock Conditions

ABSTRACTTo improve the wear resistance of disc cutters for tunnel boring machines (TBMs), this study is devoted to investigating the effects of rocks and cutter ring properties on the wear behaviors of disc cutters and the matching characteristics between the cutter ring properties and hard rocks. Cutter–rock wear tests were performed and the results show that the cutter ring properties and rock types significantly affect the cutter ring wear. The mass losses of cutter ring samples sliding against different types of hard rock are different and vary with the cutter ring properties because of the discrepancies in loads, vibrations, rock properties, and transition of the wear mechanisms. Finally, matching characteristics between the cutter ring properties and hard rocks are revealed.

Performance evolution of a worn piston ring

Abstract Reducing the fuel consumption of a combustion engine has been an important design issue. Engine friction has to be reduced and the piston ring - cylinder liner contact is a major source of friction. However, the piston ring geometry can evolve due to wear, and the ring can acquire a flat part. The current work analytically studies the hydrodynamic friction and load carrying capacity of a twisted parabolic - flat (worn) piston ring. The outcome is presented as a function of twist angle, total width and flat width. With the chosen functional parameters of the piston ring, the evolution of stroke-averaged friction and film thickness with wear (increasing flat width) is studied. One finds that the hydrodynamic friction increases with initial piston ring wear, but the minimum thickness of the generated film increases as well. This ensures the ring can continue to operate safely and last. Imposing a constant film, the hydrodynamic friction can be reduced a little for wide rings by using a narrower parabolic-flat ring. No such reduction is possible for narrow rings.

Effects of ethanol content on cast iron cylinder wear in a flex-fuel internal combustion engine–A case study

The localized wear within a four-cylinder automotive spark-ignition internal combustion engine was investigated using a dynamometer durability test. The test engine was equipped with flexible fuel technology, popularly known as “Flex-Fuel”, capable of operating under any mixture of gasoline and ethanol in the fuel. A 2-D profilometer analysis was conducted on engine block specimens from the Top-Dead-Center (TDC) and Bottom-Dead-Center (BDC) positions in order to identify localized wear characteristics. The profiles have shown localized wear dependence in regions of the cylinder bore, as did comparative results between two test conditions: (i) an engine fueled with local gasoline (E25) and (ii) an engine fueled with ethanol (E100). Selected localized wear regions have been characterized using scanning electronic microscopy. Complementary piston ring wear analysis was carried out to assess the remaining coating thickness at the end-of-test. The test with ethanol resulted in the highest localized wear, which occurred at the Bottom-Dead-Center position. A condensed literature review was conducted. An attempt was made to correlate the observed wear features with possible mechanistic theories found in the wear literature. Characterization results indicated that three-body abrasion by carbon residues and piston ring particles is one of the important mechanisms contributing to the cylinder bore wear.

Cutter wear mechanisms in hard rock tunnel boring

AbstractCutter consumption and parameters such as cutter ring wear has a great relevance in the overall excavation time and cost in hard rock tunnel boring machines (TBMs), especially in hard rock conditions. Cutter wear involves a complex tribological system that interacts also with the geologicy of the rock mass. Understanding the processes and failure mechanisms during cutter wear (e.g. modes of contact, wear, load effects) and assessing the influence of temperature on cutter ring wear processes enables new knowledge to be applied to get better cutter consumption predictions and future improvements in cutter ring development. In addition, it might be used to evaluate the suitability of the new rock abrasivity test method (Rolling Indentation Abrasion Test, RIAT) for assessing cutter ring wear.

Analysis of lubricating oils in shear friction tests using infrared thermography

The aim of this work is to analyze the ability of Thermography to monitor the behavior of SAE 20 W50 API SJ and ISO VG 10 lubricating oils from the thermal point of view until the moment of the lubricant film rupture, characterized by the sudden increase in friction, noise, vibration and Temperature in a shear friction test. The methodology used is based on the analysis of thermograms that indicate temperature profiles during the friction tests and at the moment of mechanical failure, comparing these results with those obtained by a thermocouple. The specimens, consisting of SAE 1045 steel cylindrical pins, are rubbed against a wear ring consisting of a weld-locked bearing under the condition of a boundary lubrication regime. Tests were performed by increasing load conditions up to 180 N at 10, 15 and 20 Hz rotations (600, 900 and 1200 rpm). The results show the qualitative and quantitative capacity of the Thermography in the detection of scuffing considering the emissivity of the lubricating oil film equal to 0,82. It is concluded that the Thermography can be used for the detection of the breaking of the lubricating film in pin-on-ring friction tests.

Specific Features of Wear of Oil-Scraper Piston Rings with Tin Coatings in Bench Tests for Friction and Wear

We study the process of wear of commercial oil-scraper piston rings of a D100 locomotive diesel generator in a reciprocating friction machine simulating their operating conditions. The degree of wear of these rings is determined by their weight and the increase in the working surface of a ring for different sliding speeds. We also evaluate the changes in their microhardness prior to and after tests. The character of structural changes of the friction surface for different parameters of testing is established by the method of electron-probe microanalysis. It is shown that the run-in tin coating is absent on the leading edges of the rings, where the characteristic friction bands are formed with the appearance of a graphite network of the substrate. A specific feature of structuring of the inclined surface is established in the area, where this surface is adjacent to the working collar. In order to increase the durability of these rings in operation, it is recommended to deposit ion-plasma nanocoatings with additional quality control and guarantee the relaxation of residual stresses.

Communication—Tribology of Retaining Rings in Chemical Mechanical Planarization

Stribeck and Stribeck+ curves helped determine the tribological mechanisms in the ring-slurry-pad interface. Both methods gave consistent results with the lubrication mechanism starting at “boundary lubrication” and transitioning to “mixed lubrication” as pseudo-Sommerfeld numbers increased. COF for PPS rings were higher than PEEK. They were also higher for inter-level dielectric (ILD) processes as compared to copper. Stribeck curves were used to infer wear rate information about the ring, which in conjunction with Stribeck+ curves could help choose process parameters that balanced wafer removal with ring wear. Data cluster shapes were shown to be due to shear and normal force fluctuations.

Numerical analysis of the effects of compression ring wear and cylinder liner deformation on the thermal mixed lubrication performance of ring-liner system

The lubrication performance of roughness compression ring-cylinder liner system (CRCL) with axial-asymmetric new/worn compression ring and out-of-round cylinder liner is studied in this paper. By considering the oil film thermal effect, cavitation phenomenon, and surface roughness, the energy equations, mass conservation Jacoboson-Floberg-Olsson (JFO) cavitation algorithm, generalized average Reynolds equation, and Greenwood-Tripp asperity contact model are employed to investigate the frictional behaviors of CRCL. The oil film thickness, friction forces, wear, and power loss of CRCL are investigated at various wear stages of compression ring. The effects of the magnitude of cylinder liner deformation on the frictional characteristics of CRCL are also analyzed with consideration of compression ring conformability. Numerical results show that the deformation of cylinder liner and the wear of compression ring have a significant influence on the lubrication performance. It also suggests that the oil film thermal effect should be considered in the numerical analysis to provide an accurate prediction on the frictional behaviors of CRCL.

Anti-wear Mechanism Analysis of Nano-CaCO3 Additives

In this paper, the wear test was carried on with cylinder piston by the wear test device, receiving the results of the piston ring wear and abrasive characteristics by monitoring the wear process, the thesis analysis and put forward the nano-CaCO3 lubricating oil additive anti wear mechanism by the ferrography analysis technology, and provide the technical reference for the relevant measures to reduce wear and the friction, and provide reference value for further study on the related theories of reducing wear and reducing friction.

Mechanical properties and tribological performance of epoxy/Al2O3 nanocomposite

In this research, a systematic study has been directed to evaluate epoxy matrix nanocomposite performance of Al2O3 nanoparticles incorporated into epoxy resin. An ultrasonic mixing process was utilized to achieve homogenous dispersion of these nanoparticles into epoxy resin. Several mechanical and tribological tests, such as three-point bending test, Izod impact test and pin on ring wear test, were performed to examine mechanical properties and wear performance of epoxy-Al2O3 nanocomposites. Nanocomposites displayed increased bending strength and impact strength due to the incorporation of Al2O3 nanoparticles. In addition, introduction of Al2O3 nanoparticles into epoxy resin matrix at low values resulted in significant reduction of wear rate and coefficient of friction. Such effects could be attributed to dispersion of Al2O3 nanoparticles into epoxy matrix and loading. The influences of the Al2O3 nanoparticle incorporation into epoxy matrix resin are further described in terms of reinforcing methods.

The effect of wear ring clearance on flow field in the impeller sidewall gap and efficiency of a low specific speed centrifugal pump

In this paper, the flow in the impeller sidewall gap of a low specific speed centrifugal pump is analyzed to study the effect of wear ring clearance and the resultant through-flow on flow field in this cavity and investigate the overall efficiency of the pump. Centrifugal pumps are commonly subject to a reduction in the flow rate and volumetric efficiency due to abrasive liquids or working conditions, since the wear rings are progressively worn, the internal leakage flow is increased. In the new operating point, the overall efficiency of the pump cannot be predicted simply by using the pump characteristic curves. The flow field is simulated with the use of computational fluid dynamics and the three-dimensional full Navier–Stokes equations are solved using CFX software. In order to verify the numerical simulations, static pressure field in volute casing and pump performance curves are compared with the experimental measurements. The results show that, for the pump with minimum wear ring clearance, the disk friction efficiency is the strongest factor that impairs the overall efficiency. Therefore, when the ring clearance is enlarged more than three times, although volumetric efficiency decreases effectively but the reduction in overall efficiency is remarkably smaller due to improvement in the disk friction losses.

Failure analysis on abnormal wear of roller bearings in gearbox for wind turbine

Abstract The booming wind power industry as one of the predominant approaches of renewable energy resources is not independent of components reliability within the wind turbines, especially the rotating ones including blades, motors, gearboxes etc. Hence, case studies on failed parts of such components play an important role for failure prevention and deserves to be publicly reported for experience sharing. In this paper, a failure case concerning severe abnormal wear of the roller bearing's inner ring in the gearbox of one 1.5 MW wind turbine in China was reported. Since such roller bearings were imported from a foreign company and operated by a Chinese company, not only economic losses but also international commercial dispute would be induced if this case would not be immediately and properly solved. To this end, by means of comprehensive and systematic investigation into the base materials, process media, surface morphologies, micro-area compositions and even service environments, root causes of this failure were determined, detailed mechanisms were discussed, and pertinent countermeasures were proposed. Achievement of this paper would provide the solid evidence to distinguish the responsibilities for the failure, and would also help to prevent such failures of roller bearings with similar design in wind turbines.

Influence of rotational speed on friction and wear properties of 35CrMo/GCr15 friction coupling

The effect of rotational speed on the friction and wear properties of 35CrMo/GCr15 was studied under the condition of boundary lubrication. The speed was set as 400r/min, 800 r/min, 1200r/min, 1600r/min, and the load were 200N. Working time was 120min. The ring block friction and wear testing machine were used for testing. The surface morphology changes of wear specimen were analyzed by scanning electron microscope (SEM). The results showed that the main form of the wear of the material was different with speed different. When the rotating speed was low, the wear was mainly abrasive wear, and the wear was mainly adhesive wear at high speed. When the speed was 800r/min, the wear rate was minimum, and the friction coefficient also was minimum. It shows that when the load was constant, the speed was too high or too low, would make the wear and tear intensified.

Effects of Material Combinations on Friction and Wear of PEEK/Steel Pairs under Oil-Lubricated Sliding Contacts

The effects of material combinations on the friction and wear of PEEK/steel pairs are studied using blocks on a ring wear tester under oil-lubricated conditions. The rings are made of forged steel (SF540A) and a PEEK composite filled with 30 wt% carbon fibre. The surface roughness is 0.15 and 0.32 μm Ra, respectively. The blocks are also made of the same materials as the rings: the forged steel and the PEEK composite. Finished with an emery paper of #600, the surface roughness is 0.06 and 0.23 μm Ra, respectively. Sliding tests for 4 combinations of two materials are conducted. The load is increased up to 1177 N at 1 N s-1. The sliding velocity is varied in the range of 10 to 19 m s-1. In some cases, the ring temperature is measured with a thermocouple with a diameter of 0.5 mm, located 1 mm below the frictional surface. Results indicate that the forged steel’s ring and the PEEK composite’s block is the best combination among 4 combinations, because seizure does not occur under the increasing load up to 1177 N at the sliding velocity of 10–19 m s-1. In contrast, seizure occurs at 15 and 19 m s-1 in the other three combinations. However, the PEEK composite’s ring shows a lower friction coefficient as compared to the forged steel’s ring, when seizure does not occur. Wear scars are observed with a scanning electron microscope (SEM). The seizure mechanisms are then discussed.

Near-surface and depth-dependent residual stress evolution in a piston ring hard chrome coating induced by sliding wear and friction

The microstructure, texture and residual stresses of a hard chrome piston ring coating, which was subject to sliding wear in tribological contact with a thermally sprayed, iron-based liner coating, were studied using laboratory X-rays and synchrotron X-rays. The near-surface evolution of residual stresses induced both tribologically and thermally was analyzed in the sliding direction and perpendicular to the sliding direction. The tribologically induced residual stresses correlate with the piston ring tribology as a function of the tribological parameters ‘test duration’, ‘sliding speed’, ‘piston ring load’ and ‘piston ring temperature’ and with the evolution of the piston ring wear, particularly as a function of the accumulated dissipated frictional energy. A tribologically impacted residual stress zone of approximately 15μm was identified and a considerable tribological impact on the residual stresses was detected. A smaller impact depth of only 10μm could be assigned to the thermally impacted residual stress zone. Exposed to high temperatures, the residual stresses tribologically induced in sliding direction within the whole depth range are shifted towards compressive residual stresses. There was a very good agreement between the energetic approach to wear and the evolution of tribologically induced residual stresses as a function of the dissipated frictional energy. Furthermore, the evolution of the wear volume as a function of the tribological parameters, such as ‘sliding speed’, ‘piston ring temperature’ and ‘piston ring load’, could be correlated to the depth-dependent evolution of thermally and tribologically induced residual stresses.

Internal Flow Analysis of Seawater Cooling Pump using CFD

This research focuses on simulation and visualization of flow field characteristics inside a centrifugal pump. The 3D numerical analysis was carried out by using a numerical CFD tool, addressing a Reynolds Average Navier-Stock code with a standard k-Ɛ two-equation turbulence model. The simulation accounts for friction head loss due to rough walls at suction, impeller, discharge areas and volumetric head loss at impeller wear ring. A comparison of performance curves between simulation and experimentation is included, and it reveals a same trend of those results with a small difference of maximum 5 %. At best efficiency point, velocity vectors are smooth but it changes significantly under off-design point, a strong recirculation appears at the outlet of impeller passages near tongue area. A relatively uniform preassure distribution was observed around the impeller in despite of the tongue. Within the volute, because of its geometry, spiral vortexes formed, proving that the flow field in this region was relatively turbulent and unsteady.

Including Housing–Casing Fluid in a Lateral Rotordynamics Analysis on Electric Submersible Pumps

Stability and synchronous-response predictions, which were presented by Childs et al. (2014, “A Lateral Rotordynamics Primer on Electric Submersible Pumps (ESPs) for Deep Subsea Applications,” 43th International Pump Users Symposium, Texas A&M University, College Station, TX, pp. 1–18), are re-evaluated to include the effect of the fluid between the pump housing and well casing. Conclusions are made based on these new findings. The same two-line rotor–housing model is used to model the pump's rotor and its housing. The model dimensions are based on direct measurements of an ESP. The pump rotor and pump housing are only connected together at each stage by reaction forces and moments from seals and bushings. The rotor model is pinned to the housing at the rotor's ends. The housing model is pinned to ground at its ends. Synchronous response predictions are presented for: (1) relative rotor–housing motion and (2) housing velocity-response amplitudes. When handling viscosity of water, the rotor–housing model is predicted to be stable at new (centered) 1× clearances but rapidly becomes unstable with enlarged clearances (2× and 3×), primarily due to rapidly dropping rotor–housing natural frequencies. The impact of introducing effective swirl brakes for the stages' wear ring seals was investigated for a pump running at 3600 rpm. Their predicted impact on stability and synchronous response was: (1) Onset speeds of instabilities (OSIs) were elevated well above running speed and (2) synchronous response amplitudes were reduced modestly. Housing-response amplitudes varied considerably with the choice of housing-termination locations. For a pump rotor length of Lr, varying the lengths of a centered housing over 1.5 Lr, 2 Lr, and 3 Lr changes the housing's natural frequency. This natural frequency can coincide with the running speed with proper termination conditions. If the running speed and natural frequency coincide, large housing vibration amplitudes associated with resonance would exceed most vibration regulations; however, relative rotor–stator response amplitudes were a small fraction of clearances for all the cases. When handling emulsions at markedly higher viscosities, with a pump speed of 3600 rpm and new centered clearances, the predicted OSI was below 300 rpm. The OSI rapidly increased as the seals were displaced eccentrically, quickly elevating the first rotor–stator natural frequency above 1800 rpm and the OSI above 3600 rpm. With the model stabilized at 0.2 eccentricity, the synchronous relative rotor–housing amplitudes were a small fraction of seal clearances. Swirl brakes were not predicted to be effective in elevating pump OSIs for high viscosity fluids with new clearances; however, they became effective as clearances were increased. An ESP housing can contact the well casing in many possible scenarios (axial locations, contact-area length or girth, etc.). A midspan, point radial contact was examined and modeled as a stiff-spring connection from the housing to ground. For both water and oil–water emulsions, a stiff housing-to-casing contact produced major elliptical housing motion (versus circular motion without contact). However, it had a comparably minor impact on relative rotor–housing response amplitudes or rotordynamic stability.