Ring Wear Research Articles

Synthesis and characterisation of rapeseed oil bio-lubricant – its effect on wear and frictional behaviour of piston ring–cylinder liner combination

The primary efforts of this study have been focused on formulating environmental-friendly lubricant with good oxidative stability and improved cold flow behaviour. Rapeseed oil was chemically modified via, epoxidation, hydroxylation followed by esterification process. The formation of epoxide and hydroxyl group was confirmed by Fourier transform infrared spectral analysis. The present work also addresses the issue of friction and wear characteristics of diesel engine cylinder liner–piston ring combination under diesel-contaminated chemically modified rapeseed oil bio-lubricant and diesel-contaminated commercial synthetic lubricant (SAE20W40) using a high frequency reciprocating tribometer test rig. In addition, the investigations were performed using scanning electron microscopy to interpret the possible mechanisms of wear with chemically modified bio-lubricant. The chemically modified rapeseed oil bio-lubricant exhibits good oxidative stability, improved cold flow property and better performance in terms of frictional force and co-efficient of friction.

Failure Analysis of Fatigue Fracture on the Outer Ring of a Cylindrical Roller Bearing in an Air Blower Motor

In order to identify the causes of a fracture incident that occurred on the outer ring of a cylindrical roller bearing within an air blower motor, diverse characterization analyses were conducted in this study. Metallurgical structures and chemical compositions of the bearing’s matrix materials were inspected by metallographic microscope and photoelectric direct reading spectrometer. Scanning electron microscope and energy dispersive spectroscope were applied to detect the microscopic morphologies and micro-area compositions on the fracture surfaces and contact surfaces. The compositions and thermal properties of the lubrication medium, the grease, were also examined. Analysis results revealed that interaction between dry friction and impact both led by the degraded grease due to decomposition and oxidation at elevated temperatures, which resulted in serious wear of the outer ring and the cage, was the main cause that originated and propagated the fatigue cracks on the corners of the outer ring, and eventually resulted in the fracture. Finally, countermeasures and suggestions have been proposed.

On the Analysis of Die Wear in Wire-Drawing Process

In the present article, the wire-drawing process is investigated in order to estimate die wear using an experimental approach. Experiments were carried out on a drawing machine involving industrial conditions. Dies made from tungsten carbide were examined using macroscopic and microscopic observations to measure the wear ring located at the wire–die contact. Two types of wires were used in this work: aluminum and copper materials. The results obtained show that the die wear rate has significant effects on the tolerances of the wire and on the die life.

Statistical analysis of accelerometer data in the online monitoring of a power slip ring in a wind turbine

The use of a shock accelerometer for the continuous in-service monitoring of wear of the slip ring on a wind turbine generator is proposed and supporting results are presented. Five wear defects in the form of out-of-round circumference acceleration data with average radial dimensions in the range 5.9–25 µm were studied. A theoretical model of the acceleration at a point on the circumference of a ring as a function of the defect profile is presented. Acceleration data as a continuous function of time have been obtained for ring rotation frequencies that span the range of frequencies arising with the variation of wind speeds experienced under all in-service conditions. As a result, the measured RMS acceleration is proven to follow an overall increasing trend with frequency for all defects at all brush pressures. A statistical analysis of the root mean square of the time acceleration data as a function of the defect profiles, rotation speeds and brush contact pressure has been performed. The detection performance is considered in terms of the achievement of a signal to noise ratio exceeding 3 (99.997% defect detection probability). Under all conditions of rotation speed and pressure, this performance was achieved for average defect sizes as small as 10 µm, which is only 0.004% of the ring diameter. These results form the basis of a very sensitive defect alarm system.

Effect of Lubricant on Lifetime of Au-Plated Slip-Ring and Ag-Pd-Cu Brush System for Small Electric Power

The authors have been investigating degradation process of Au plated slip ring and Ag-Pd-Cu brush system. In almost all cases the lifetime of the sliding system ends, when Au plating layer is worn out, the ring surface is oxidized to be black in color and contact resistance becomes very high. Further, the lifetime is very short without lubricant. So, the lubricant is very effective to make the lifetime longer. However, even with lubricant the lifetime is varied from about 1000 hours to almost 7000 hours in the past experiments. It is an important issue how the lubricant works on the lifetime of the system. In this paper the effect of lubricant on the degradation process of contact resistance is focused on. In the past tests the lubricant is supplied only once before the test. In this test the lubricant is regularly supplied almost every 900 operation hours. Consequently, the operation more than 8000 hours is realized, which is the longest among tests so far. In addition the contact voltage drop increase gradually until 2600 hours and after that it stays almost constant around 70mV. According to the Element Analysis after the test the Ni base plating layer is totally exposed in many tracks. It means that the Au plating layer is gradually worn out probably at the stage of increasing voltage drop. In the previous tests the lifetime ended even when the Ni plating layer remained. So, the reason of long operation in this test is guessed to be that the lubricant not only decreases wear of ring and brush, but also suppresses oxidation of the Ni layer.

The Research on the Friction and Wear Properties of Carbon Fiber Reinforced Polyamide 6 Composites

The effects of Carbon fiber content and wear condition on the tribological properties of the composites were measured using a block on ring wear tester. The worn surface was investigated with a scanning electronic microscope and the wear mechanism was proposed. It was found that Carbon fiber improved the wear resistance of monomer casting polyamide 6 with the optimal content of Carbon being approximately 5 vol.%. The wear of PA6/Carbon fiber composite was lower than that of the PA6 and increased slowly while its friction coefficient decreased gradually with load. However, the friction coefficient of the composite was somewhat larger than that of monomer casting polyamide 6.

Seawater lubricated polymer journal bearings for use in wave energy converters

This study investigates the wear characteristics of polymeric journal bearings while immersed in seawater, and their applicability towards wave energy conversion. A block on ring wear machine was used to test four commercially available bearing materials under unidirectional and oscillatory sliding conditions at low pressure. It was observed that wear generally increases with counterface roughness; however, major deviations to this trend exist, depending on the bearing’s composition. Stable wear rates were shown to vary widely depending on velocity profile, though a general trend could not be established for the sample group as a whole. It was shown that polymer wear rates cannot be attributed to any one parameter, and that detailed testing at several characteristic pressures and velocities is needed to determine a material’s applicability towards wave energy converters operating in real seas.

Optimizing heat treatment and wear resistance of high chromium cast irons using computational thermodynamics

Computational thermodynamics was applied to analyze seven high chromium cast iron compositions in order to optimize their hardness and wear resistance after quench and tempering heat treatments. Five of these materials were candidate alloys to be applied in blast furnace wear rings and two were developed for grinding balls. The methodology consisted of establishing the phase formation sequence of each alloy, calculating the composition of the austenite and the corresponding martensite start temperature (Ms) and selecting the appropriate heat treatment temperature, with the best compromise between martensite C content for hardness, Cr content for corrosion resistance and Ms temperature to avoid excessive retained austenite. Rubber wheel tests and pilot plant ball mill were used to evaluate the performance of the best combinations of chemical composition and heat treatment. The selected alloys and heat treatments were approved for use in the respective industrial applications.

Study on New Bimetal Floating Seal of High Speed Roller Bit Bearing

ANSYS software has been used for high speed rock bit bimetal floating seal finite element analysis, as a result, overlarge pressure of bearing seal, unreasonable pressure distribution and overlarge compression ratio of rubber ring, are main reasons for premature failure of the bearing seal. For this, the optimal design and analysis of bearing seal structure is carried out in this paper. The results showed that: the new structure of the bearing seal has effectively reduced the compression ratio of rubber ring, improved the sealing pressure distribution based on reliable sealing conditions and further reduced the sealing pressure peak. The design of dynamic metal ring flywheel lubrication groove and the application of static metal ring antifriction material surface engineering technology have obviously reduced surface friction factor and wear of metal ring, greatly improved the effectiveness and life of the seal, and further extended the bit’s life.

Effect of Exhaust Gas Recirculation (EGR) on performance, emissions, deposits and durability of a constant speed compression ignition engine

To meet stringent vehicular exhaust emission norms worldwide, several exhaust pre-treatment and post-treatment techniques have been employed in modern engines. Exhaust Gas Recirculation (EGR) is a pre-treatment technique, which is being used widely to reduce and control the oxides of nitrogen (NOx) emission from diesel engines. EGR controls the NOx because it lowers oxygen concentration and flame temperature of the working fluid in the combustion chamber. However, the use of EGR leads to a trade-off in terms of soot emissions. Higher soot generated by EGR leads to long-term usage problems inside the engines such as higher carbon deposits, lubricating oil degradation and enhanced engine wear. Present experimental study has been carried out to investigate the effect of EGR on soot deposits, and wear of vital engine parts, especially piston rings, apart from performance and emissions in a two cylinder, air cooled, constant speed direct injection diesel engine, which is typically used in agricultural farm machinery and decentralized captive power generation. Such engines are normally not operated with EGR. The experiments were carried out to experimentally evaluate the performance and emissions for different EGR rates of the engine. Emissions of hydrocarbons (HC), NOx, carbon monoxide (CO), exhaust gas temperature, and smoke opacity of the exhaust gas etc. were measured. Performance parameters such as thermal efficiency, brake specific fuel consumption (BSFC) were calculated. Reduction in NOx and exhaust gas temperature were observed but emissions of particulate matter (PM), HC, and CO were found to have increased with usage of EGR. The engine was operated for 96h in normal running conditions and the deposits on vital engine parts were assessed. The engine was again operated for 96h with EGR and similar observations were recorded. Higher carbon deposits were observed on the engine parts operating with EGR. Higher wear of piston rings was also observed for engine operated with EGR.

Effects of TIG surface treating on microstructural characteristics and mechanical properties of Al2O3–TiB2 coating by APS

The pulsed DC tungsten inert gas (TIG) method was employed to post-spray treat an electroconductive Al2O3–TiB2 coating by atmosphere plasma spraying (APS) Al2O3–30 wt-%TiB2 powder. The microstructure and mechanical properties of the coatings before and after treatment were comparatively investigated by scanning electron microscopy, laser scanning confocal microscopy, X-ray diffraction, microhardness tester and block on ring wear tester. It was detected that the treated coating presented a two layer structure consisting of the remelted zone and the sintered zone, which was comprised of TiB2 and single α-Al2O3; surface roughness of the treated coating exhibited a remarkable decrease while microhardness and wear resistance showed a significant increase. These experimental results could be ascribed to the effect of high heat input and discharge plasma during the pulsed DC TIG treating.

Simulation of engine life time related with abnormal oil consumption

In this paper, by predicting the real time variation in wears of piston-ring face, ring-groove and cylinder bore altogether, the changing end gap of each ring and the changing volume of gas reservoir are calculated. Next, the calculated amount of parts’ wear and oil consumption are compared with the amount of normal wear of each part and normal oil consumption. Then, the durability limit of a piston-ring pack-cylinder bore system is predicted. Finally, the life time of a test engine in terms of abnormal oil consumption caused by the accumulated wear of ring faces and cylinder bore is estimated.

Improvement of tribological properties of co-acting elements by oil pockets creation on sliding surfaces

Sliding experiments were carried out using a block-on-ring friction machine. The tribosystem consists of the stationary block (counter-specimen) pressed at the required load P against the ring (specimen) rotating at the defined speed. The sliding was unidirectional. The block was a part of a bearing sleeve hardened EN-GJS 400-15 cast iron with a hardness value of 50 HRC. The ring samples, 35 mm in diameter, were made from hardened 42CrMo4 steel of hardness 32 HRC. Some variants of specimen surfaces were created by burnishing technique. Two kinds of experiments were done. Seizure tests were conducted at increasing pressure for sliding speeds in the range: 0.27–0.55 m/s. Wear resistance test was carried out under artificially increased dustiness conditions, too. It was found that surface texturing improved seizure resistance for the smallest sliding speed (0.27 m/s) comparing to untextured ground samples. The wear of steel rings with spherical dimples was smaller than of those having dimples of long drop shape for the pit-area ratio range of 7.5–20%.

The Oil Lubricated Sliding Wear Behavior of <i>In Situ</i> TiB<sub>2</sub> Partical-Reinforced Al-10Sn Matrix Composites

Al-10Sn matrix composites reinforced by TiB2 particles were fabricated by Mixed Salt Reaction in situ synthesis process. The oil lubricated sliding wear tests of composites and matrix alloy were conducted on a small thrust ring versus disc wear testing machine at room temperature under different applied loads and the wear surfaces were observed using SEM. The results indicate that the coefficient of friction, friction temperature, and wear weight loss increase with the increase of applied loads, but compared with matrix alloy, the composites exhibit better anti-friction property and higher wear resistance. The analysis of wear surface suggests that light ploughing is predominant for composites and matrix alloy at low loads, and ploughing is still predominant for composites at high loads, but adhesion and delamination are predominant for matrix alloy at high loads

Pump Maintenance Ensures Reliable, Efficient Operation

This article discusses the operation and maintenance of pumps, and how a proper understanding of pump components and regular maintenance can prolong the life of a utility's most energy‐consuming operation. The article discusses several types of bearings found in pumping equipment, proper lubrication of bearings, packing to allow proper leakage, maintaining clearance between wear rings and case rings, and the types of major repair jobs that can be expected for pumps.

Wear measurement of the cylinder liner of a single cylinder diesel engine using a replication method

Published data on piston ring and cylinder bore wear in engines is very limited because of the technical difficulties involved in performing the measurements. Moreover, cylinder bore wear is more difficult to measure than ring wear because it occurs over a much larger surface area, and the wear rates vary widely at different locations on the bore. In this paper, cylinder liner surface roughness and wear measurements were performed through an experimental study of a single cylinder diesel engine operating at a steady-state. A replication method was used to evaluate wear and surface roughness on a cylinder liner, where measurements were made at different locations on the cylinder liner before and after each test. Replicated surface profiles were measured by a WYKO NT 1100 optical surface profilometer. It was found that surface roughness decreased with time and the rate of decrease was higher during the run-in period. A unique wear volume calculation method that includes bearing ratio parameters was proposed, and reasonable results for wear volume were obtained. Cylinder bore wear rates measured by this replication method were consistent with long-term wear observed in different tests of diesel engines.

Tribological property of TiO 2 nanolubricant on piston and cylinder surfaces

In this paper, an arc spray nanofluid synthesis system with complex ultrasonic orthogonal vibration and vortex stirring was proposed and developed for TiO 2 nanolubricant, in which TiO 2 nanoparticles were of equal roundness and consistent size. In the proposed nanofluid synthesis system, one of the electrodes and ultrasonic vibrator were assembled to form an orthogonal model with another electrode installed inside the vacuum chamber of arc discharge system, with 10 W/30 lubricant serving as the dielectric liquid. The tribological behavior of the lubricant with TiO 2 nanoparticles at average particle size 25 nm on the surface of piston ring is compared with that of the lubricant without TiO 2 nanoparticles. Experimental results showed that the coefficients of friction between the piston ring and base lubricant was 0.15; between the piston ring and TiO 2 nanolubricant was 0.14. Furthermore, the piston ring's wear rates of the base lubricant and TiO 2 nanolubricant were 0.0055 and 0.0021, respectively. After operating the piston cylinder for 8 consecutive hours in 15 and 30 days, respectively, the diameter of TiO 2 nanoparticles in the lubricant remained 25 nm in average. As observed from the piston ring surface on the 15th and 30th days through scanning electron microscope (SEM), it had less scraping than the piston lubricated without TiO 2 nanoparticles. Therefore, a lubricant added with TiO 2 nanoparticles can better protect the piston ring surface.

Performance prediction of exfoliated graphite seals: 2. A theoretical basis for its optimisation

A finite element model of the response of exfoliated graphite to stress is used to predict the decline in radial sealing stress as a function of sealing ring wear. The model which results allows the number of stem cycles to leak to be calculated, and from this result, an optimum initial clamping stress can be calculated. However, in view of the simplifications made in deriving the model, this stress should probably be treated as an upper limit in most cases.

Impact of Finger Rings on Transmission of Bacteria During Hand Contact

To investigate the impact of finger rings on the transmission of bacteria from the hands of healthcare workers and the impact on the microflora on the hands of healthcare workers in clinical practice. Our study had a nonequivalent control group posttest-only design (pre-experimental). Healthcare workers who wore finger ring(s) on 1 hand and no ring on the other hand (n = 100) and a control group of healthcare workers who did not wear any rings (n = 100) exchanged standardized hand shakes with an investigator wearing sterile gloves. Samples from the gloved hands of the investigators and the bare hands of the healthcare workers were thereafter obtained by the glove juice technique. Two Norwegian acute care hospitals. Healthcare workers (n = 200) during ordinary clinical work. A significantly higher bacterial load (odds ratio, 2.63 [95% confidence interval, 1.28-5.43]; P = .009) and a significantly higher number of bacteria transmitted (parameter estimates, [corrected] 2.43 [95% confidence interval, 1.44-4.13]; P = .001) were associated with ringed hands, compared with control hands. However, a multiple analysis of covariance revealed no statistically significant effect of rings alone. The prevalence of nonfermentative gram-negative bacteria (42% vs 26%) and Enterobacteriaceae (26% vs 13%) was also significantly higher among persons who wore rings than among persons who did not wear rings. However, no statistically significant differences in the incidence of transmission of these pathogens were detected after hand contact. The prevalence of Staphylococcus aureus and incidence of transmission of S. aureus were the same in both groups. Wearing finger rings increases the carriage rate of nonfermentative gram-negative bacteria and Enterobacteriaceae on the hands of healthcare workers. However, no statistically significant differences in the incidence of transmission of nonfermentative gram-negative bacteria or Enterobacteriaceae were detected between the healthcare workers who wore rings and those who did not.

Abrasive wear resistance of textured steel rings

The fundamental aim of the present research is to study the effect of dimple shape and area density on abrasive wear in lubricated sliding. The other aims are to recommend a method of obtaining the local linear wear of a textured ring on the basis of profilometric measurement and to analyse the changes in the surface topography of this ring with selection of parameters that could monitor the “zero-wear” process. The experiments were conducted on a block-on ring tester. The stationary block made from cast iron of 50 HRC hardness was ground. The rotated ground ring was made from 42CrMO4 steel of 32 HRC hardness. The rings were modified by a burnishing technique in order to obtain surfaces with oil pockets. Oil pockets of spherical and of drop shape were tested. The pit-area ratios were in the range: 7.5–20%. The tested assembly was lubricated by oil L-AN 46. Because of the great hardness of the co-acting parts the wear resistance test was carried out under artificially increased dustiness conditions. The dust consists mainly of SiO 2 and Al 2O 3 particles. Measurement of local microscopic ring wear was made using a three-dimensional scanning instrument. The tendencies of ring surface topography changes during wear were analysed. Various methods of obtaining the local wear value during a low wear process were proposed and compared. We found that a spherical shape of dimples was superior to a drop shape with regard to wear resistance of steel rings.