Piston Ring Research Articles

Investigation of the Effects of 0W20 and 10W40 Lubricating Oils on Cylinder Liner Wear

Proper lubrication regime in engines significantly impacts engine performance, fuel efficiency, durability, and environment. Lubrication regimes reduce friction between engine components, control wear, and ensure long-lasting parts. This study conducted experiments on a wear-testing device to determine the amount of wear between the piston ring and cylinder pair. The experimental work was performed at different loads and speeds. The tribological properties of 0W20 and 10W40 lubricating oils were examined in the study. As a result of the experimental work, when using 10W40 lubricating oil in the wear testing device, lower cylinder wear was observed compared to using 0W20 lubricating oil. The study found that the amount of wear increases as the load on the cylinder sample increases. The maximum cylinder wear was obtained under an 80N load. The minimum cylinder wear was determined under a 40N load. SEM images of the cylinder samples were also examined to determine the damage after wear.

Development of a New Measurement System for Piston Ring Friction Based on the Floating Liner Method

Development of a New Measurement System for Piston Ring Friction Based on the Floating Liner Method

Influence of Base Oil Molecular Structure on the Tribological Performance of Diesel Engine Cylinder Liner and Piston Ring

Highly intensified diesel engines lead to severe lubricating condition, high performance lubricant is important to solve this problem. Base oil is the main composition of lubricant, which plays important role in lubricating performance. In this paper, three kinds of poly-α-olefin (PAO) base oil were prepared. Different olefin materials were used to produce PAO with different molecular structure. The tribological performance of diesel engine cylinder liner and piston ring lubricated with different base oil were evaluated by reciprocating test rig. Results show that PAO base oil synthesized with long carbon chain olefin has high viscosity index. The PC12 reduced the friction coefficient by 15.4%/19.6% in low speed/high speed friction compared with PC8. The wear of PC12 reduced 15.8% compared with PC8. The results were resulted from the long carbon chain of PC12, which produce high viscosity in high temperature and shear thin effect in high speed friction.

Study on the influence of piston ring assembly structure on lubricating oil consumption and optimization design

Study on the influence of piston ring assembly structure on lubricating oil consumption and optimization design

ANALYSIS OF THE GRAPHITE PHASE IN CENTRIFUGED BILLIONS MADE OF HIGH-QUALITY CAST IRON

Purpose. To determine the characteristic geometric parameters of spherical graphite inclusions in the cross-section of a cast iron billet for piston rings.
 Research methods. A cylindrical blank for piston rings was obtained by the centrifugal method. The chemical composition of the blank according to the ВЧ 500-2 brand (DSTU 3925-99). To obtain spherical graphite, nickel-magnesium ligature (15 % Mg) and secondary graphitizing modification with ferrosilicobarium ФС65Ба4 were used. The amount of each additive was 1.0 % of the metal mass. Spherical graphite was evaluated according to GOST 3443 and several characteristic geometric parameters. A computer image analyzer based on a “ZEISS Epityp-2” microscope with a digital video camera “Baumer” was used.
 Results. The geometric parameters of graphite inclusions in the cross-section of a centrifugal billet made of high-strength cast iron are examined. A significant difference in the geometric parameters of spherical inclusions of graphite according to several size groups formed in different layers of the cast iron billet obtained by centrifugal casting was established.
 Scientific novelty. Spherical graphite inclusions in the oil billet are classified according to 6 size groups of GOST 3443 and 11 size groups built in arithmetic progression. Significant differences between the outer and central layers of the casting were established: 2.14 times – by the number of small (5...10 μm) inclusions; 1.59 times – by the number of inclusions with a size of 10...15 μm, 1.4 times – by the number of inclusions with a size of 20...25 μm; 3.9 times – by the number of large (more than 35 μm inclusions).
 Practical value. A comparative assessment of the morphology of spherical graphite in the outer, central and inner layers of the centered workpiece will allow to improve the technological parameters of the production of cast piston rings in order to ensure a high resource of engines or compressors.

Intelligent fault classification of air compressors using Harris hawks optimization and machine learning algorithms

Due to their complexity and often harsh working environment, air compressors are inevitably exposed to a variety of faults and defects during their operation. Thus, condition monitoring is critically required for early fault recognition and detection to avoid any type industrial failures. In this paper, an intelligent algorithm for reciprocating air compressor fault diagnosis is developed using real-time acoustic signals acquired from an air compressor with one healthy and seven different faulty states such as leakage inlet valve (LIV), leakage outlet valve (LOV), non-return valve (NRV), piston ring, flywheel, rider-belt and bearing defects. The proposed algorithm mainly consists of three steps: feature extraction, selection, and classification. For feature extraction, experimental acoustic signals are decomposed using maximal overlap discrete wavelet packet transform (MODWPT) by six levels into 64 wavelet coefficients (nodes). Thereafter, time domain features are calculated for each node to build each air compressor’s health state feature matrix. Each feature matrix dimension is reduced by selecting the most useful features using Harris hawks optimization (HHO) in the feature selection step. Finally, for feature classification, selected features are used as inputs for random forest (RF), ensemble tree (ET) and K-nearest neighbors (KNN) to detect, identify, and classify the compressor health states with high classification accuracy. Comparative studies with several feature extraction and selection methods prove the proposed approach’s efficiency in detecting, identifying, and classifying all air compressor faults.

Dry sliding wear and friction behavior of powder metallurgy FeCoNiAlSi0.2 high-entropy alloys

Wear behaviors of the FeCoNiAlSi0.2 high-entropy alloy (HEA) and Si-free FeCoNiAl during the reciprocating sliding wear process were evaluated for automotive piston rings. The HEAs were prepared using on advanced powder metallurgy route to solve the inherent shrinkage porosity and segregation defects during casting, poor densification, and wear resistance of HEAs while reciprocating motion. The morphology, hardness, wear, and friction properties were investigated. FeCoNiAl had biphasic face-centered cubic (FCC) and body-centered cubic (BCC) solid solution structures, whereas FeCoNiAlSi0.2 HEAs had a single BCC solid solution structure. Si addition significantly enhanced the hardness and wear resistance of the HEAs under reciprocating conditions because of the increased solid solution strengthening and lattice distortion effects. The maximum hardness of the FeCoNiAlSi0.2 HEA reached approximately 582 HV, which is higher than that of the equiatomic FeCoNiAl HEA (491 HV). The findings depict that FeCoNiAlSi0.2 maintains better tribological behavior than FeCoNiAl HEA against the tungsten carbide (WC) ball indenter. Oxidative delamination and cracking occurred in the FeCoNiAl/WC pair, whereas a mixed adhesive–abrasive wear mechanism was prominent in the FeCoNiAlSi0.2/WC pair because of the harder BCC solid solution phase. This study explores an effective strategy for enhancing the tribology behavior of automotive piston structures under varying loads and reciprocating dry sliding motions.

Analysis on Lubrication Performance of Piston Ring-Cylinder Liner based on Numerical Simulation

This paper mainly studies the tribological performance of friction pairs and poor lubrication during piston movement. Based on the average Reynolds equation and comprehensively considering the variable viscosity and variable density characteristics of lubricating oil, a transient hydrodynamic lubrication model of the piston ring-cylinder liner friction pair is established. By solving the established lubrication model, the lubricating oil film thickness value, friction value and other parameters that can characterize the lubrication performance of the friction pair throughout the cycle are obtained, whilst revealing the surface roughness, lubricating oil viscosity and piston ring barrel surface height. And the influence mechanism of the friction performance of the friction pair is presented on the basis of the previous analysis. The research shows that improving the surface roughness of the piston ring will help to improve the lubrication, increasing the viscosity of lubricating oil will help to improve the lubricating performance of friction pairs and reduce the peak friction at the top dead centre of piston rings and improving the surface texture of the piston rings can reduce the oil film thickness and reduce the friction caused by fluid shear effect in the high-speed region.

The Theory of the Surface Wettability Angle in the Formation of an Oil Film in Internal Combustion Piston Engines.

In internal combustion piston engines, the formation of an oil film is completely different from that seen in industrial machines. The molecular adhesion force at the interface between the surface coating of engine parts and the lubricating oil determines the load-carrying capacity and the ability to form a lubricated film. The geometry of the lubricating wedge between the surfaces of the piston rings and the cylinder wall is created by the thickness of the oil film and the height of the ring's coverage with lubricating oil. This condition is affected by many of the parameters that characterize the engine's operation and the physical and chemical parameters of the coatings used for the cooperating pairs. For lubricant particles that reach energies that are higher than the potential energy barrier regarding adhesive attraction at the interface, slippage occurs. Therefore, the value of the contact angle of the liquid on the surface of the coating depends on the value of the intermolecular force of attraction. According to the current author, there is a strong relationship between the contact angle and the lubrication effect. The paper shows that the surface potential energy barrier is a function of the contact angle and contact angle hysteresis (CAH). The innovation of the current work consists in examining the contact angle and CAH under the conditions of thin layers of lubricating oil, in cooperation with hydrophilic and hydrophobic coatings. The thickness of the lubricant film was measured under various speed and load conditions, using optical interferometry. The study shows that CAH is a better interfacial parameter for correlation with the effect of hydrodynamic lubrication. This paper presents the mathematical relationships relating to a piston engine, various coatings, and lubricants.

Simulation based analysis to study the effect of compression ring crown height in ring liner assembly on the performance of four stroke petrol engine

Among different piston rings of an Internal Combustion Engine (IC), the top compression ring-liner assembly shared a momentous amount of the total frictional losses, particularly at the Top Dead Center (TDC) and Bottom Dead Center (BDC) where boundary lubrication subsists. In the present study, the lubrication mechanism in piston ring cylinder liner conjunction for top compression ring using one dimensional Reynolds equation assuming axisymmetric contact was studied. The hydrodynamic and mixed lubrication regimes were taken during the study. Gumbel boundary conditions were used for Reynolds equation solution. For boundary pressure calculation, first, combustion chamber pressure variation was determined, then, interring pressure was calculated assuming orifice volume method by solving mass flow rate through crevice volumes using Runge-Kutta 4th order method. The Reynolds equation was solved using finite difference method. Whole solution process was repeated for different engine speed and crown height of top compression ring to study the effect of them in wear and power loss. First, the solution was found for 3000, 5000 and 7500 RPM keeping constant crown height of 10 µm. Average power loss was found to be increased with the increasing engine speed. There was increased in oil film thickness around mid-stroke with the increased engine speed, but there was no significant change in film thickness with the engine speed at the TDC and BDC positions. Then, the solution was again repeated for different RPM varying the crown height. The compression ring with lower crown height showed the better wear performance by increasing the minimum film thickness in critical zones of engine cycle for all RPM. The crown height of 5,7 and 9 µm gave the minimum power loss (77.89, 163.47 and 297.33 W) for 3000, 5000 and 7500 rpm. Moreover, the power loss in the range of 5-9 µm had no significant differences.

A visual inspection system for detecting end gap and light leakage of the piston ring

A fully automatic visual inspection system for piston ring was proposed in this study. This system can automatically feed the piston ring, and then detect the end gap and the light leakage of the piston ring. Moreover, the piston ring can be classified after detection and the detection data can be saved for further analysis. To achieve this objective, the detection equipment was established for detecting the end gap and the light leakage, and corresponding software was developed based on Labview. The experiment was carried out and the detection performance of the system was evaluated. The result shows that the proposed system has a good accuracy for detecting the piston ring.

Study on the sliding wear map of cylinder liner − piston ring based on various operating parameters

The wear map can directly reflect the wear state and mechanism of the friction pair under different conditions and is widely used in wear prediction and fault diagnosis of steel materials. However, there are few reports on the wear map of the engine cylinder liner and its materials. In this study, the operating parameters were obtained through an engine bench test. The parameters near the cylinder liner's top dead center （TDC） were selected as wear test parameters. Thousands of hours of reciprocating lubrication wear tests were carried out on a multi-function wear tester. By analyzing the wear rate variation under different test parameters, the cylinder liner's wear state was divided into mild, medium, and severe wear. The morphology of the wear scar surface and cross-section of the cylinder liner was analyzed by scanning electron microscope (SEM) and then drawing the wear mechanism map. The results show that the primary wear mechanism under slight wear is spalling wear, accompanied by the plastic deformation phenomenon. Delamination wear is the primary mechanism in the medium wear state, accompanied by a small amount of massive spalling wear. The delamination wear is mainly caused by the crack generated by graphite in or below the deformation layer. The primary wear mechanism of the severe wear state is massive spalling. At this time, the graphite at the bottom of the deformation layer plays the role of primary cracks, which causes the plastic deformation layer to fall off.

A novel finding on tribological, emission, and vibration performances of diesel engines linking to graphene-attapulgite lubricants additives under hot engine tests

The cylinder liner-piston ring (CL-PR) that worked under harsh conditions is extremely susceptible to wear, and its friction loss is the primary source of mechanical loss of engines, affecting its equipment reliability and energy consumption. Recently, the use of low sulfur fuel oils (LSFO) aggravated the wear of the CL-PR, further increasing friction loss. Furthermore, the emissions of diesel engines also affect the environment and human health. In this study, the graphene-attapulgite (G-ATP) additive was prepared and applied to engines in response to these challenges. The prepared G-ATP additive was dispersed into 5040 lubricating oil with a 0.25 wt% concentration, then the effects of the additive on engines were investigated under hot test conditions with a speed of 1750 rpm. It was found that the G-ATP additive displayed excellent tribological properties, the wear mass loss of the piston ring was reduced by 64.5% with the addition of the G-ATP additive, and the wear of the cylinder liner was significantly reduced. Meanwhile, owing to the excellent tribological properties and thermal conductivity of the G-ATP additive, the HC and NOx emissions of the engine were reduced by 3.0% and 6.1%, respectively. Additionally, the vibration performances of the engine were improved by 42.1% in the final stage. These findings revealed the potential mechanism of the G-ATP additive for performance enhancements of diesel engines, as well as the relationships between the emission and vibration of engines and tribological properties of CL-PRs, which promote the energy saving and emission reduction of engines.

Experimental modelling and optimisation of electrochemical surface grinding of hybrid metal matrix composite

ABSTRACT The demand of hybrid-metal-matrix composites (HMMCs) is rising continuously in various industries such as aerospace, automobile and biomedical. Therefore, effective machining of HMMCs is essential for their productive utilisation. However, machining processes are usually not feasible for shaping this composite due to inherent properties of matrix and reinforcing material, and melting of reinforcement particles. In the present work, a hybrid Electro-Chemical Surface Grinding (ECSG) setup has been developed by combining the Electro-Chemical Machining and Mechanical Grinding action. The process applied on Al-SiC-Gr composite, which is a key member of HMMC family. It is a better alternative for many parts like piston and piston ring in automobile industries. Central composite design-based Response Surface Methodology has been used for experimental modelling, response prediction and optimisation. The effects of significant control factors such as applied voltage, electrolyte concentration, wheel speed, table speed and electrolyte flow rate on material removal rate (MRR) and surface roughness (SR) have been studied. The results revealed that electrolyte concentration and applied voltage are most significant factors for both MRR as well as SR. Genetic algorithm-based optimisation results confirm 45% and 38% improvements in MRR and surface finish.

A Mixed Lubrication Model of Piston Rings on Cylinder Liner Contacts Considering Temperature-Dependent Shear Thinning and Elastic–Plastic Contact

This work develops a numerical methodology for predicting the performance of an automotive piston ring system by considering contact and lubrication mechanics. The rough surface contact mechanics and lubrication occurs on a scale much smaller than the size of the piston rings and therefore the key aspect of the model is an algorithm that simultaneously solves the multiple mechanisms at different scales. The finite element method will be used to model the mechanical deformations of the piston ring surfaces at large scales. The quasi-steady state model includes heat generation due to solid and viscous friction. This heat generation will then be used to predict the temperature rise and thermal effects in the lubricant and component. A statistical rough surface method that renders asperities as elastic–plastic wavy surfaces predicts the solid contact area. The modified Reynolds equation will be solved to consider the effects of mixed hydrodynamic lubrication while using flow factors formulated for actual piston and ring surfaces. The lubricant viscosity depends both on temperature and shear rate. This will allow for the regimes of boundary, mixed, and full-film lubrication to be considered. The model predicts friction for various loads and speeds that are then compared to experimental measurements. Although the contacts operate mostly in the mixed lubrication regime, the model and experiments show changes in friction with load, speed, and temperature.

Experimental visualization of the wear and scuffing evolution of a flake graphite cast iron cylinder liner

Scuffing is a wear mechanism that can lead to catastrophic failure of various technical applications. Even though the mechanism has been researched in countless publications for decades, it is not fully understood yet. An experimental approach was used in this paper to investigate the origin and evolution of scuffing in a ring-on-liner contact. For this purpose, test runs in an application-oriented test rig were stopped at different points in time. A linear tribometer was used to transfer a reciprocating motion of a real piston ring segment to a specimen made from a real cylinder liner. Based on a comprehensive analysis, a four-stage scuffing hypothesis for a ring-on-liner contact was developed. In the first stage, smearing of the honing structure and the formation of surface cracks lead to the development of a scaly structure on the liner surface. Crack growth induced by adhesive shear forces leads to the formation of breakouts in the liner surface in the second stage. Both stages are stable and only the specific load increase of the used test strategy causes the transition to stage three. Here, large crack growth induced breakouts result in the local destruction of tribofilms and, subsequently in local metallic contact between the specimens. When this local destruction becomes rampant and expands to a macro scale, adhesive bonds lead to macroscopic scuffing. It can be deduced that the first occurring damage stage is a result of a surface fatigue process.

A review on preparation process and tribological performance of coatings for internal combustion engine piston ring

Reducing the energy consumption and exhaust emission, and improving the combustion efficiency of internal combustion engine are important for solving the problems of climate change and environmental pollution. The piston ring-liner system is one of the most serious friction pairs in internal combustion engine, accounting for 26% of the total friction loss. Depositing strengthened coatings on the surface of piston rings is an effective method to reduce the friction coefficient and wear rate. This paper reviews the research progress of several representative technologies for preparing coatings, such as electroplating, physical vapor deposition (PVD), thermal spraying and chemical vapor deposition (CVD), and so on. Various coatings, such as Cr-Al2O3 coating prepared by representative electroplating process, CrN and DLC coatings prepared by physical vapor deposition, and Mo-based and C-based coatings prepared by thermal spraying process, are briefly discussed. Furthermore, the positive and negative aspects of commonly used piston ring coatings are compared, and their development trends are summarized.

The effect of using biodiesel B50 from palm oil on lubricant oil degradation and wear on diesel engine components

Alternative fuels in diesel engines are getting attention due to the current world energy crisis. Biodiesel is a fuel where the main composition from palm oil, it is an alternative fuel may can replace fossil diesel fuels. However, the use of biodiesel has several impacts on the engine if its not maintained. The using biodiesel usually results decrease of lubricating oil viscosity and increases the metal wear rate. This research will present results effect of biodiesel B50 on lubricating oil degradation and metal wear on engine components. The method used is an experiment by testing engines for a long time with the Engine Manufacturer Association (EMA) standard. The use of B50 biodiesel causes significant degradation of lubricating oil than Pertamina Dexlite. The lubricating oil test results that with B50 biodiesel decreased viscosity by 16.17%. Lubricating oil also contains the metallic aluminium 8 ppm, 27% metallic iron, and 1 ppm metallic chromium. Using B50 biodiesel also causes journal bearing worse and significant piston ring gap. In addition, the deposit resulting from the using B50 biodiesel was 30.97% greater in the diesel engine component.

Coated Piston Ring Pack and Cylinder Liner Elastodynamics in Correlation to Piston Subsystem Elastohydrodynamic: Through FEA Modelling

A finite element model is developed to assess the effects of the TiSiCN thin film coating of the piston ring on the structural strength of the piston subsystem. The complex, cyclically variable forces are considered in load and boundary conditions. The model included combustion dynamics, contact kinetics, piston subsystem primary and secondary motions, and lubricated contact conditions to evaluate the applied forces. A comparative analysis is performed for coated and uncoated cases. Four different crown geometries are tried for selecting the best case of crown design for coated piston subsystem components. The analysis predicts better strength in coated cases compared to uncoated ones. The type-A crown design develops less stress, while the compression ring suffers the most due to elastic deformation and is more prone to fatigue failure.

Evaluation of microstructural, tribological and tensile characteristics of AA7075 surface composites fabricated through friction stir process

Superior wear resistance and a high level of tensile strength in piston ring materials are achieved using AA7075 surface composites (SCs) that are fabricated by reinforcing the steel slag (SS) particulates through proper selection of friction stir process (FSP) parameters using the multipass technique. The optical structure elucidates that fine and equi-axed grains are ascertained in the stir zone of the processed region, and by increasing the number of passes from one to three, a homogenous dispersion of particulates and a reduced grain size (9 µm) is obtained. In particular, a clear and defect-free interface is prominent on the resulting composite surface. Field emission – scanning electron microscopy (FESEM) identifies the dispersion of reinforcements, while X-ray diffraction (XRD) technique and energy dispersive spectroscopy (EDS) mapping confirm the existence of reinforcing elements. The Orowan strengthening effect and reduced oxygen content around the SiO2 and CaO elements in the three-pass FSP SC specimen tend to increase its load-bearing capacity and result in superior hardness (353.3 VHN) and tensile strength (792.6 MPa). However, the same specimen exhibits a reduced percentage (%) elongation due to multiplied fragmentation of reinforcements, which eventually restricts the plastic movement of the AA7075 matrix. The SEM fracture morphology indicates that failure occurred through a combination of ductile and brittle modes. Furthermore, the SC specimen with two passes prominently decreases the wear rate (333 × 104 mm3/m), which can be attributed to the commendable trilayer formation, and the worn morphology indicates the abrasive wear was the dominant wear mechanism. This fabricated specimen with high-strength characteristics can be beneficial for design engineers. During piston ring design, an increased level of the factor of safety can be achieved.