Ring Wear Research Articles

ДЕЯКІ АСПЕКТИ ПІДВИЩЕННЯ ЕНЕРГОЕФЕКТИВНОСТІ РОБОТИ ШАХТНИХ ВІДЦЕНТРОВИХ НАСОСІВ

Mine drainage systems, which are used at the main drainage of mining enterprises, have a drive capacity of up to 1600kW. To reduce non-productive energy losses, as well as for the continuous operation of the mining company, mine pumps must be energy efficient and reliable. Analysis of downtime of drainage systems shows that the weak point is the unloading device. This fact can lead not only to the failure of the pumping unit, but also to possible prolonged downtime of the mine. The main disadvantage of the existing disk unloading devices of mine pumps is their low reliability and low service life, due to the rapid wear of the components of the unloading unit. The most vulnerable elements of the unloading device are the unloading rings. The need for frequent replacement and adjustment of the elements of the discharge unit is associated with disassembly and assembly of the pump directly in the pump chamber. Such actions require significant costs of unproductive manual labor of service personnel, and rapid wear of parts of the unloading device necessitates their constant replenishment. Malfunctions in the unloading device can cause significant pump failures. To increase the reliability and energy efficiency of mine drainage systems, the method of control of the unloading device was used. During the experimental studies it was found that cavitation phenomena during the operation of pumping units are absent and, accordingly, can not be the cause of wear of the elements of the unloading unit. When the pumps are operating in steady state, the displacement of the rotors was monitored for 3-4 hours on each pump unit. After data processing, it was obtained that the wear of the surface of the unloading rings occurs at a rate of 0.05-0.15mm in one hour. To determine the wear of the rings of unloading during start-up - stop of the pump, at first the indicators of measuring devices at the established mode of operation of the pump unit were fixed. Then the pump was turned off and on again. After starting the pump unit, we made sure that the operating mode of the unloading device did not change and compared the readings of the shaft position indicator before stopping and after starting the pump. From the measurements made it followed that stopping and starting the pump does not lead to noticeable wear of the unloading device. Therefore, it can be assumed that mainly the wear of the discharge rings occurs during the steady operation of the pump unit.

Computer Simulation/Prediction of Wear in Mechanical Components

In this paper, a state of the art on computer simulation and prediction of wear in mechanical components is reviewed. Past and recent developments as well as approaches employed in the simulation and prediction of wear are reviewed. In particular, the wear models, contact analysis schemes, and wear evolution prediction procedures as well as their application to the mechanical components (including cam-follower, gears, bearings, and cylinder/piston/piston ring wear) are reviewed. Recommendations and suggestions on possible directions for further research studies are also presented.

Faktor-Faktor yang Mempengaruhi Personal Hygiene Pedagang Daging dan Sanitasi Lingkungan pada Tempat Berjualan Daging di Pasar Mambal Desa Mambal, Abiansemal

Meat traders in Mambal Market of Mambal Abiansemal Village still do not fulfill the requirement, because of their location are close to vegetable and daily goods traders, so that it affect the sur-rounding odor as well as the air circulation that inhaled by traders and buyers. The aim of this study was to identify factors related with hygiene and sanitation of the meat shops in Mambal Market. The study was a cross sectional design with questionnaire and observation as the data instruments. Based on the results, factors that are related with hygiene and sanitation of the meat shops are: personal hygiene (p-value 0,024), equipment and facilities (p value 0,001), sewerage system (p value 0,001), and meat cutter devices (p value 0,001). Factors which are identified corresponding with personal hygiene and the sanitation of meat shops are: traders do not wear personal protective devices, wear rings and smoke while working, and open sewerage system and no hand-washing facility provided.

Tribological, Thermal, Kinetic, and Pad Micro-Textural Studies Using Polyphenylene Sulfide Retaining Rings in Interlayer Dielectric Chemical Mechanical Planarization

We compared the long-term wear performance of 2 different PPS retaining ring materials (E-PPS and O-PPS) provided by 2 different suppliers. After 4 h of wear, O-PPS resulted in higher values of mean pad summit height as compared to E-PPS (26.4 ± 1 vs 23.9 ± 1 μm, respectively). We believed this was due to excessive pad fragment generation (confirmed by its associated higher level of pore obscuration) which caused the asperities to artificially appear taller. Regarding mean summit curvature, O-PPS did not sharpen the asperity tips beyond what had already been achieved through conditioning (341 ± 50 vs 352 ± 50 per μm2, respectively). On the other hand, E-PPS caused the tips to sharpen significantly (508 ± 50 per μm2). The pad-slurry-ring coefficient of friction (COF) was higher for E-PPS (0.69 vs 0.65). This was consistent with the higher observed pad surface temperature for E-PPS and its associated sharper pad asperities. Both rings showed similar tribological behaviors, and the contact mechanism was one of “boundary lubrication.” Both rings caused the pad to wear at comparable rates, but regarding ring wear rate, E-PPS seemed to wear about 30 percent faster than O-PPS. This was deemed to be inconsequential in IC manufacturing due to the estimated excessive life of the ring (regardless of which type of PPS material was used) compared to the useful life of the pad and other consumables such as filters and discs.

Assessment of personnel absorbed dose at an 18-MeV dual beam cyclotron facility

This study aimed to investigate occupational radiation exposure in cyclotron workers in Saudi Arabia and compare the doses received with the International Commission of Radiological Protection dose limits. We conducted a retrospective study of Hp (10) and Hp (0.07) in 144 workers in an 18-MeV dual beam (proton and deuteron) cyclotron facility in Saudi Arabia from 2015 to 2019. The workers included physicists, engineers, chemists, radiochemists, technicians, operators, and quality control chemists. Individual dosimetry was assessed using thermoluminescent dosimeters (TLDs) comprised of Harshaw detector crystals with LiF:Mg, Ti elements. The mean Hp (10) and Hp (0.07) doses averaged over the 5-year study period for all workers were 1.47 ± 0.15 and 1.54 ± 0.16 mSv, respectively. No worker received doses exceeding the annual dose limits. We recommend that workers wear ring dosimeters to estimate the dose to the extremities and dosimeters use an advanced type of absorber to discriminate between different types of radiation.

Research of dependence centrifugal pump efficiency of impeller slit seal design parameters

Efficiency and resource are the two main characteristics of a centrifugal pump. In present study, the dependence of these characteristics from impeller sealing wear ring configuration was considered. Range of models with various configurations has been analyzed using numerical flow simulation. Compromise curves nave been obtained as a result. This information allows select an optimal ratio of dimensions of wear ring hydrodynamic slit seal to achieve a balance between efficiency and reliability of centrifugal pump.

Field-Testing of Biodiesel (B100) and Diesel-Fueled Vehicles: Part 3—Wear Assessment of Liner and Piston Rings, Engine Deposits, and Operational Issues

AbstractThis study investigated the use of biodiesel (B100) and baseline mineral diesel in two identical unmodified vehicles to realistically assess different aspects of biodiesel’s compatibility and durability issues with modern common rail direct injection (CRDI) engine-powered vehicles. Two identical vehicles were operated for 30,000 km under identical operating conditions during a field-trial using biodiesel (B100) and mineral diesel. Exhaustive experimental results from this series of tests are divided into four sections, and this is the third paper of this series of four papers, which covers comparative feasibility and wear analyses, underlining the effect of long-term use of biodiesel on wear of cylinder liner and piston rings compared to baseline mineral diesel-fueled vehicle. Surface microstructures at three locations of the cylinder liner were evaluated using scanning electron microscopy (SEM). Wear was found to be relatively lower at all locations of liners from biodiesel-fueled vehicle compared to diesel-fueled vehicle. Surface roughness of cylinder liners measured at different locations showed that it reduced by ∼30–40% at top dead center (TDC), ∼10–20% at mid-stroke, and ∼20–30% at bottom dead center (BDC) for both vehicles, showing higher wear close to TDC compared to mid-stroke and BDC locations. Loss of piston-ring weight was significantly lower for biodiesel-fueled vehicle. Engine tear-down observations and carbon deposits on various engine components were recorded after the conclusion of the field trials. During these field-trials, engine durability-related issues such as fuel-filter plugging, injector coking, piston-ring sticking, carbon deposits in the combustion chamber, and contamination of lubricating oils were found to be relatively lower in biodiesel-fueled vehicle. Overall, no noticeable durability issues were recorded because of the use of biodiesel in CRDI engine-powered vehicle.

A Penalized Convolution Model for Oil Leakage Detection in Electrohydraulic Railway Point Systems

The railway point is one of the most critical systems in railway, which enables trains to be guided from one track to another. Failures of railway point systems often lead to service delays and hazardous situations. With the ever-increasing railway operation, the stable and safe operation of railway point systems becomes more and more important. The electrohydraulic railway point system is widely adopted due to its high efficiency and long service life. However, its operation highly relies on a sufficient volume of oil, which usually leaks gradually due to many practical issues, e.g., the wear of joint rings and the aging and corrosion of oil pipes. The gradual oil leakage often causes failures of electrohydraulic railway point systems, so it is important to develop the effective and reliable technologies for the early detection of slow oil leakage. To achieve this goal, the static oil level is used to construct the monitoring statistic since it is a direct indicator of the oil volume and more suitable for railway point systems than the hydraulic pressure due to the discrete demand for operations and the short duration of every operation. However, it is very challenging to utilize the oil level directly for oil leakage detection due to the large variability caused by the environmental temperature. Therefore, in this article, we propose a penalized convolution-based model to capture the relationship between the temperature and the oil level, whose parameters are estimated by using least squares with a smooth penalty. With the trained model, we obtain the residuals by removing the effect of temperature from the oil-level signal. Then, the CUSUM chart is employed to monitor the residual signal since it is sensitive to the small mean shift. Finally, the proposed method is evaluated through a case study by using in situ data collected from a real point system in Changsha Railway Station.

Mastering the Art of Cylinder Bore Honing

<div class="section abstract"><div class="htmlview paragraph">Honing is a stock removal process intended to perfect bore geometry and size by removing a minimal metal layer while generating a finish pattern to provide optimum lubricant retention. The hone process produces extremely tight tolerances in straightness, roundness, size, and surface finish of cylindrical bores. The material removal is effected by abrasive stones of suitable grit and grade that are expanded against the work surface of the cylinder bore under controlled pressure while being rotated and reciprocated at the same time. Combining these motions produces a characteristic crosshatch pattern with a dedicated surface roughness profile essential for the piston/bore tribology, which in its turn affects the engine performance. Multistep honing processes that combine rough honing with peak or plateau honing are increasingly used to produce state-of-the-art surface finishes without compromising productivity. The outcome of the honing process - not only in terms of the GD&T but also the tribology of the finished component - depends on a great number of parameters including the machine type, working conditions, tools, process fluid, and most importantly the operator experience. As the piston/bore tribology is concerned, mechanochemical processes offers significant advantages over conventional mechanical processes. Thus, the mechanochemical finishing of cylinder bores using the Triboconditioning® process allows one to reduce friction mean effective pressure of the piston/bore system by 5 to 15% at the same time significantly reducing piston ring wear, blowby and oil consumption.</div></div>

Investigation on characteristics of pressure fluctuation in a centrifugal pump with clearance flow

Clearance flow has great impact on pressure fluctuation of centrifugal pumps. Numerical calculations are performed to study the pressure fluctuation characteristics of centrifugal pump with wear ring clearance, especially in the regions of interaction between main flow and clearance flow (IMC) and clearance. The accuracy of numerical calculations is illustrated by comparing the experiments of performance and pressure fluctuation. Results show that, in clearance region the pressure fluctuation is still governed by blade passing frequency (fBPF). Its amplitude of dominate frequency of pressure fluctuation becomes larger as the probe approaches the impeller exit. In IMC region, the pressure fluctuation at impeller outlet is dominated by fBPF. However, the dominate frequency at the entrance of impeller is less than fBPF. In addition, as the flow rate increased, the amplitude of dominate frequency of pressure fluctuation increases at impeller entrance, whereas an inverse trend is observed at wear ring clearance region.

Effect of reformulated fuel strategy on compression ignition engine compatibility using antioxidant additive and clean Karanja methyl ester

The present work aims at investigating the compatibility of antioxidant with biodiesel through the tribological assessment of a compression ignition engine. In this research work, 2,6-di-tert-butylphenol, a novel antioxidant, has been blended with clean Karanja oil methyl ester at the rate of 500 ppm. The compression ignition engine has been operated for 256 h of long-term durability tests in two different phases using clean Karanja biodiesel (KBD100) and 500 ppm antioxidant-blended clean Karanja biodiesel (KBD100@E). The study revealed that the compression ignition engine operated with KBD100@E fuel has exhibited low lubricating oil degradation when compared to clean Karanja biodiesel at same 256 h of operation. The long-term endurance test also showed that the kinematic viscosity, flash point and total base number of lubricating oil collected from KBD100@E-fueled engine were observed to lower than KPD100-fueled engine. Similarly, the wear metal concentrations were higher in lubricating oil of KPD100-fueled engine than that of antioxidant-added KBD fuel and diesel fuels. Furthermore, the surface roughness results also showed that the cylinder liner surface of KPD100-fueled engine was more smoothened compared to KBD100@E-fueled engine. The wear of piston rings was also noted to be more severe for KBD100-fueled engine when compared to diesel and KPD100@E-fueled engines. Finally, it has been concluded that the compression ignition engine life can be improved by the addition of antioxidant with biodiesel fuel.

Modeling of piston ring wear

A theoretical study of piston ring wear in large two-stroke engines is presented. Piston rings in combustion engines are manufactured with an initially defined shape of the surface contacting the cylinder liner. Further the ring surface working against the cylinder liner is coated with layers of ceramic materials to accommodate the running-in process. Most rings have a nonflat shape (parabolic) when delivered from the ring supplier. After running in which is typically many hours of operation( >1000 h) the ceramic layers are worn and the ring geometry is typically changed significantly by surface wear. It is shown in the present study that the geometry of the worn ring depends on the operation scheme of the engine. Both the load pattern and the order in which the loads are applied influences the final shape of the piston ring surface.

A Novel Method of Laser Coating Process on Worn-Out Cutter Rings of Tunnel Boring Machine for Eco-Friendly Reuse

Cutter rings form an integral part of tunnel boring machines (TBM). These cutters are deployed in various hard rock tunneling projects. The life of the cutter rings governs the economics of tunneling significantly. This paper presents a novel methodology to enhance hardness and wear resistance of used worn out disc cutters in TBM for eco-friendly reuse. Disc cutters are mainly made of H13 tool steel. To improve the hardness and wear resistance, a layer of tungsten carbide is coated on the used cutter rings. Considering the long operating hours of TBM, cutter rings get worn out due to severe interaction with the hard rock both in compression and rolling mode. Replacement of the cutter-ring is costly, and quite a time consuming and cumbersome job. Refurbishment is always a better option and laser cladding is a novel technique for enhanced life of cutters. It increases the hardness and wear resistance of the cutters to a considerable extent. Cladding is carried out with the help of a laser beam. In this method, a layer of nanoparticles of tungsten carbide powder is deposited on the worn-out surface of the cutters. For carrying out the investigation, different coating parameters are selected based on the central composite design (CCD). With different capacities of laser, a total of 13 samples were prepared at various scanning speeds varying between 200 to 300 mm/min and a level of laser power varying between 100 to 200 W. The coating is critically inspected by various means such as an optical microscope, FESEM, and EDS. Hardness testing was accomplished by Vicker’s hardness testing machine. Wear testing was carried out with the aid of pin on disc setup. The results shows an asymmetrical behavior between the yield parameters (hardness and wear rate) and process parameters (scanning speed and laser power). The hardness values increased from 16% to 95%. A correlation test was conducted between the hardness and wear rate. The results depict a clear negative correlation between them, indicating the advantage of laser coating for reducing cutter ring wear in TBM.

Lubricating Ability of Magnesium Silicate Hydroxide–Based Nanopowder as Lubricant Additive in Steel–Steel and Ceramic–Steel Contacts

The friction and wear of sliding surfaces are responsible for important energy losses and negative environmental effects. Magnesium silicate hydroxide–based nanopowder (KM) is an antiwear and self-recovery material that could be applied in the lubricating subsystem of mechanical components. This study investigates the ability of KM to reduce friction and improve the wear resistance of sliding steel surfaces. A ball-on-flat reciprocating tribometer was used with steel–steel contact to evaluate the lubricating ability of KM as an additive in a commercially available motor oil. Experimental results show that by adding 0.23 wt% of KM to the motor oil, friction and wear can be reduced up to 45 and 40%, respectively, under the longer distance studied. In addition to ball-on-flat tests, a bearing test rig was used to investigate the antiwear behavior of KM as an additive in a commercial high-speed grease. Ball bearings of steel–steel and steel–ceramic contacts were lubricated with a high-speed grease. The addition of 0.4 wt% of KM to the grease improved the durability and reduced the ring wear. Optical microscopy, noncontact 3D profilometry, scanning electron microscopy, and energy-dispersive X-ray spectroscopy were utilized to analyze and discuss the wear mechanisms and surface interactions.

Friction and wear resistance of Al2O3 40TiO2 (AMDRY 6250) coating of a pump shaft sleeve bearing

The equipment of wastewater treatment plants is continuously subjected to different kinds of wear, as corrosion, abrasion, cavitation, erosion etc. The most affected components are those of slurry pumps, the slurry producing intense abrasive wear. The service life of pumps (wear rings, sealing, bearings, impellers, and casings) can considerably be extended by proper coating. Before the implementation of a new coating in equipment, its friction and wear behaviour must be determined beside corrosion resistance. This paper presents the results of friction tests carried out on AMSLER machine. The tribological pair was composed by Al2O3 40TiO2 (AMDRY 6250) coating deposited on substrate of a pump shaft sleeve running against a rolling bearing steel disk in dry lubrication conditions. The experimental results are compared against those obtained for uncoated steel.

Hand Hygiene Practices and Risk and Prevention of Hand Eczema during the COVID-19 Pandemic.

Hand Hygiene Practices and Risk and Prevention of Hand Eczema during the COVID-19 Pandemic.

ПЕРСПЕКТИВЫ ИСПОЛЬЗОВАНИЯ ТЕХНОЛОГИИ МДО ДЛЯ ДВИГАТЕЛЕЙ ВНУТРЕННЕГО СГОРАНИЯ

microarc oxidation (MAO) technology. The authors reveal an engine development tendency to replace cast-iron blocks and liners with aluminum ones with special coatings obtained by electroplating methods. It is noted that this method does not involve the use of repair technologies, which signifi cantly aff ects consumer costs. The paper shows the prospects of using MAO technology both in the manufacturing of engine parts and restoration operations. To assess the eff ectiveness of the proposed technology, practical study was performed on covering the working part of the cylinder used in small-size agricultural machinery. The engines were tested at 5.1 kW at 3,600 rpm for 300 hours. After testing, no defects or wear were found on the cylinder face. Preliminary test results of the assembled engine showed no loss of power over 10,000 hours of car mileage, which indicates that the geometric parameters of the parts are preserved. The authors emphasize that the most optimal combination is the friction pair of two parts with an MAO coating. It has been established that the introduction of nano-additives in a MAO-coating leads to a decrease in the coeffi cient of friction between the cylinder and the piston ring and reduces the wear of piston rings and the cylinder face in more than 10 times. A conclusion is made about the feasibility of introducing the considered technology into the mass production of engines and pistons, as well as developing a set of repair equipment.

Mathematical Interpretation of Open-Pit Dump Trucks Diesel Engine Durability

The durability of internal combustion engines is determined by the engine operating time, which is established by the service life of the most critical parts and assemblies that undergo normal mechanical abrasion in the process of engine operation. Factory diesel repair is performed when there is a need to repair the crankshaft. Current maintenance involving disassembly of the cylinder-piston group is performed due to the wear of piston rings and cylindrical bushings.

Numerical minimisation of abrasive-dust wear in internal combustion engines

This paper presents a mathematical model to predict the abrasive wear of piston ring and cylinder sleeve in internal combustion engines due to dust particles. A parametric study is conducted on different group factors such as the abrasive action of the medium, engine design parameters, and engine physio-mechanical properties of the materials. The model reveals that it accurately predicts the effect of numerous factors on the wear process for the piston ring and cylinder sleeve. The model capabilities are demonstrated by the impact of air filtration efficiency on the engine component wear rate. It is found that dust particle size and concentration have significant effects on piston ring and cylinder sleeve wear rates. The numerical results show that the wear rate of both the piston ring and cylinder sleeve can be reduced by 80% when the air filter efficiency is increased from 97.8% to 99.4%.

Experimental investigation on effects of positive texturing on friction and wear reduction of piston ring/cylinder liner system

It has been observed that well designed parameters of surface texturing can enhance the tribological performance of lubricated surfaces under relative sliding motion. These micro-features develop hydrodynamic lift at the interface of sliding surfaces. These textures can be positive (protruded out of surface) and negative (recessed out of surface). This paper focused on the effects of positive texturing on reduction of friction and wear of piston ring/ cylinder liner (PR/CL) system under lubricated conditions by providing rotary sliding motion between textured ring and un-textured liner surfaces. The square shaped textures of different heights were produced by photo chemical etching method. The experiments were conducted on pin on disc friction and wear test rig to determine the effects of load, sliding speed and texture geometric parameters including texture height and area density. From the results obtained, it is reported that there existed a set of optimal parameters of texture height, area density, normal load and sliding speed to obtain reduction in friction and wear of PR/CL system.The maximum reductions in friction and wear rate were observed with the textured patternsat an optimal height and area density of 25 µm and 10% respectively.