Wear Curve Research Articles

CALCULATION-EXPERIMENTAL DETERMINATION OF THE PROBABILITIES OF APPEARANCE OF DIFFERENT IN MAGNITUDE WEAR OF TRACTION GEARS

The importance of studies aimed at assessing the residual resource of the components and components of the mechanical system of the rolling stock operated on the Ukrainian railways is substantiated. As the basic unit of the rolling stock involved in the suburban transportation of passengers, electric trains are allocated. The importance for the mechanical system of motor-car rolling stock traction gears was noted. The necessity of determining the laws of distribution of the main characteristics of the traction gear operation is substantiated. The expediency of considering the value of tooth wear along the dividing circle as one of the main characteristics of the gear drive operation was noted. Features of the statistical analysis of the results of measuring the gear teeth and the wheels of traction gears of ER2, ER2P and ER2T electric trains operating on the southern railway during a three-year period of operation (2015-2017) are considered. The tooth thickness values for dividing chords are presented in the summary table in the form of arrays for gears and gears with the corresponding value and series of rolling stock, the date of measurement. Based on the results of statistical processing of these arrays, corresponding matrices are formed, the elements of which are the probabilities of occurrence of different wear, the corresponding mathematical expectations and the general variance. Using the obtained matrices for the traction gears of the series of electric trains studied, histograms and corresponding laws were constructed to distribute the probabilities of occurrence of a particular wear. It is noted that during the analysis of the obtained diagrams, laws were obtained which correspond to the steady-state regime on the wear curve and do not exceed the allowable or reject dimensions. Prospects for using the results obtained in predicting the residual service life of traction gears of tractive rolling stock are considered.

Wear and Tool Life Investigation of Carbide Inserts while Hard Machining of Armox 500 Steel

Presented article deals about the experimental investigation of PVD coated cutting inserts of type SNHF 120408EN-SR-M1while hard face milling of steel Armox 500. This study was supported by the Slovak Research and Development Agency under the contract No. APVV-15-0710. All realized measurements and tests have been performed at Department of Engineering in Trencin. It also includes support and cooperation with the University of Defence in Brno, Department of mechanical engineering. The main aim of this experimental work is to focus measurement on the influence of the various values of feed rates per tooth during the hard machining experiments of steel Armox 500. All tested workpiece material is investigated with variable cutting conditions of feed rate per tooth, whereas the cutting speed and depth of cut were specified as the constant cutting parameters. Practical part of presented work also includes some figures of worn flank faces of carbide cutting inserts, microstructure of workpiece material and graphical dependences of tool wear and tool life curve in logarithm graph as the results of these realized experimental investigation.

Simulation Methodology for Prediction of the Wear on Silver-Coated Electrical Contacts With a Sphere/Flat Configuration

A protective coating is generally applied on base materials for better performance and a longer lifetime of electrical contacts. Silver is a widely used coating material, due to the good balance between the high resistance to corrosion caused by oxidation and the cost. Moreover, it possesses high electrical conductivity. Before the wear through of silver coatings, the electrical contact resistance is stable and remains at a low value, and thus, the reliability of electrical contacts can be guaranteed. After the wear through of silver coatings, the base material, typically a copper alloy, is exposed to the environment. The oxides of base materials are generated and accumulated, leading to blocking of the current path and an electrical failure of the contacts. Consequently, it is critical to predict the wear through of the silver coatings, when assessing the reliability of the electrical contacts. However, for a thick coating, it is difficult to forecast the wear through, since the linear wear rate of coatings decreases disproportionately with increasing coating thickness, and various phases exist, such as the running-in phase and the steady-state phase. In this paper, a simulation methodology based on Archard’s wear equation and consideration of both the surface roughness and geometry of the contact area is established in order to interpret the wear process of thick silver coatings with an as-received roughness applied in the electrical contacts with a sphere/flat configuration. The specific wear coefficient is regressed by curve fitting, according to the experimental results in the running-in phase and results from finite element analysis computation. Then, a modification of the regressed specific wear coefficient is conducted, considering the simplification of the roughness on the flat part and the gaps on the roughness ribs introduced by the rolling process. This modified specific wear coefficient is applied in the calculation model for the steady-state phase in order to predict the wear through of silver coatings. A good correlation between the simulated wear curve and the experimental results is obtained.

Investigation into the effectiveness of cutting parameters on wear regions of the flank wear curve and associated cutting tool life improvement

In machining operations, less tool wear and superior tool life are desired. Therefore, the effects of cutting parameters on tool life should be known and optimal cutting parameters should be chosen to reduce tool wear. In this study, the effectiveness values of cutting parameters on each wear region in the cutting tool flank wear curve were investigated to improve cutting tool service life. For this reason, some statistical methods were employed to determine them and the results were verified by experimental studies. In the initial tool wear and the rapid tool wear regions, the most effective parameter was found as the feed and the tool wear increased with increase of the feed. In the steady-state tool wear region, the effectiveness values of the cutting speed and the feed were very close to each other, but the cutting speed was determined a little more effective.

Multiple Sensor Monitoring for Tool Wear Forecast in Drilling of CFRP/CFRP Stacks with Traditional and Innovative Drill Bits

A multiple sensor monitoring procedure is developed with the aim to perform tool wear forecast in drilling of CFRP/CFRP stacks. Experimental drilling tests with a traditional twist drill bit and an innovative step drill bit are carried out using a multi-sensor system to acquire thrust force and torque signals during the process. The tool wear curve for each drill bit under different drilling conditions is obtained by measuring the tool flank wear. An artificial neural network for pattern recognition is developed to find correlations between selected sensor signal features and tool wear state, with the aim to forecast the tool wear values during drilling based on the information extracted from the acquired sensor signals.

Investigation into the effectiveness of cutting parameters on wear regions of the flank wear curve and associated cutting tool life improvement

Investigation into the effectiveness of cutting parameters on wear regions of the flank wear curve and associated cutting tool life improvement

Investigation of tool wear in the turning of Inconel 718 superalloy in terms of process performance and productivity enhancement

Abstract This paper contributes to broadening the knowledge regarding cutting tool wear in the finish turning operations of nickel-chromium-based superalloy Inconel 718. Three cutting tools coated with heat isolating TiAlN/AlTiN layers with different stoichiometry ratios recommended as specially designed cutting tools for aerospace industry applications are tested. The primary comparison of tool wear resistance was based on the wear curves related to the cutting time and the removed material volume. The basic study include the modeling of wear progress and examining tool wear scars based on SME images and EDX analysis. In addition, tool wear progress was recorded along with continuous measurements of cutting forces and determination of relevant amount of the specific cutting energy and the friction coefficient.

Fabrication and testing of a novel biopotential electrode array

This paper focuses on the fabrication and testing of a novel biopotential electrode array for detecting human brainwaves activity signals. A hybrid micro electro-machining process that combines spark erosion with silver deposition to create suitable taper-shaped micropillar and special discharge craters for holding the biopotential electrode in position on the human scalp is proposed. By means of controlling the secondary-electrode wear rate, the required taper-rate (T=1/7) and special surface roughness (Ra=2.9μm) on the designed biopotential electrode are successfully achieved. The trend curves of bottom wear and carbon deposition in the secondary-electrode reveal near linear increases while the residual hole-depth declines with increased machinings. This indicates that the work energy used allows a steady-state wear rate in the secondary-electrode. Silver deposition is conducted to enhance the safety, electrical conductivity of the microprobe array and being antibacterial. Clinical and experimental results demonstrate that the formed biopotential skin electrode with an array of short-tapered pillars realizes quasi-invasive light contact between cerebral cortex and the microprobe. Four brainwave activity frequency signals are confirmed with superior intensity and repeatability to those realized by present-day commercial planar electrodes. Approaches to secondary-electrode formation, traction force testing, novel microprobe formation in batch mode, work capacitance, and pulse current effects, insertion durability tests, and life expectancy tests of the secondary-electrode are all evaluated in detail.

Model development of work roll wear in hot strip mill

This paper, based on the analysis of the main factors(specific roll force, mean roll surface temperature, irregular edge wear and contact arc length) affecting roll wear, designed a new work roll wear model, the test data shows that the model can more accurately reflect the work roll wear, can be on-line prediction of work roll wear. The roll wear curve, including constant wear and irregular edge wear, presents a box shape, and the reasons also are showed in this paper. The top roll wear and bottom roll wear in the same mill are inconsistent, and the reasons are also analysed in this paper. Results show that the construction of the work roll mathematical model accords with the general law of work roll wear and tear; it can more accurately forecast roll wear online.

Investigation of lubricated rolling sliding behaviour of WC/C, WC/C-CrN, DLC based coatings and plasma nitriding of steel for possible use in worm gearing

This paper presents the results of an experimental campaign based on lubricated rolling-sliding tests carried out in the disc on disc configuration for different material solutions.The aim is to find alternative solutions to the couple bronze-quenched and tempered steel, recognised as standard solution for worm gearing. A steel-steel coupling was considered, providing different surface modifications (i.e. plasma nitriding, WC/C, WC-CrN, DLC coatings) in order to enhance the lubricated wear behaviour of the tribo-pair. The severe working condition of worm gearing applications, i.e. high sliding to rolling ratio, lubricant temperature and radial load have been reproduced in laboratory tests, which were conducted up to a very long sliding distance (about 1.6-1.8.106m). During the tests periodic inspection were carried out to evaluate the progressive weight loss and to observe the surface modifications. At the end of the test the wear curves have been determined by correlating the weight loss with the sliding distance and the surface has been examined by optical microscopy to determine whether wear damage occurred. For all materials conditions very limited surface modifications and noticeable performance improvements with respect to the reference bronze-steel coupling was observed, thus suggesting their use as promising alternative solutions in worm gearing applications.

The Seebeck Effect on the Thermal Phenomena of Cutting and Tool Wear

It is a well-known fact that thermoelectric currents, reaching even the scale of ampere, develop during chip formation in the workpiece-tool-chip-machine system. The impact of these currents on tool wear in continuous cutting was examined with a qualitative mathematical model, in which wear is described by an autonomous non-linear differential equation.The constants of the model were tailored to wear curves determined by experiments conducted with a P20 carbide tool on a C45 quality steel workpiece. The differences among the tool isolation measurement results obtained by various researchers may be justified by simulation calculations.According to the model, the thermoelectric system behaves in a chaotic way in certain cases. Further research is necessary to decide if this is only a special characteristic of the model or the model shows the actual processes.

Уточнение параметров модели износа Арчарда для вычисления износа колес грузовых вагонов с осевой нагрузкой 25 тс

Целью исследования являлся обоснованный выбор величины коэффициента износа для сильной и слабой стадий изнашивания в модели абразивного износа Арчарда (Archard J.) и коэффициента трения на гребне и поверхности катания колеса для прогнозирования износа профилей колес с использованием динамических моделей. В статье представлены результаты ресурсных пробеговых испытаний грузового вагона на Экспериментальном кольце АО «ВНИИЖТ», измерений твердости колес в зонах поверхности катания и гребня, математического моделирования износа колес в программном комплексе «MEDYNA».

Dry Turning of Ti6Al4V: Tool Wear Curve Reconstruction Based on Cognitive Sensor Monitoring

Dry turning of Ti6Al4V alloy is a hard process due to the low thermal conductivity and flexibility of this difficult-to-machine material, generating very high temperatures in both workpiece and tool cutting edge, rapid tool wear and high vibrations during machining. The use of coolants offers the advantage to reduce the high process temperatures, but is not suitable in a green technology perspective due to its high environmental impact. With the aim to allow for dry turning of Ti6Al4V alloy, monitoring of tool wear during the process is required. To achieve this goal, a cognitive sensor monitoring procedure based on the acquisition and processing of force, acoustic emission and vibration sensor signals is implemented, allowing for an accurate tool wear curve reconstruction.

Wear mechanism of coated tools in the turning of ductile cast iron having wide range of tensile strength

In this study different specimens of ductile cast iron with tensile strength ranking from 400MPa to 675MPa were turned with K15 carbide, TiN coated and TiAlN coated tool in order to investigate wear mechanism and performance. Cutting forces and cutting temperature were similar for both coated tools, however flank wear and BUE were the lowest on the TiAlN coated tool, for this reason the TiAlN coated tool is suitable in the machining of ductile cast iron. The proposed tool wear mechanism is based on like-intermittent cutting caused by the pass from hard matrix to the soft graphite occasioning wear by adhesion. The analysis of the flank wear on coated tools is proposed by means of the wear curves in logarithmic scale instead of the usual linear scale. In this way, the change in wear rate is easily observed. This phenomenon was related with the wear out of the coating layer. The partial loss of the coating layer on cutting edge was confirmed by the EDS mapping images and SEM photographs.

Tribological Performance of Silver Nanoparticle–Enhanced Polyethylene Glycol Lubricants

ABSTRACTThis article introduces a new type of nanoparticle additive for tribological purposes. A nanolubricant was synthesized and studied that consists of metallic silver nanoparticles suspended in polyethylene glycol (PEG). Silver nanoparticles were prepared directly in liquid PEG by introducing aqueous silver nitrate and subsequent reduction by PEG. The nanolubricant exhibits excellent stability due to poly(vinyl pyrollidone) used as the coating agent. Thorough tribological analysis was performed on the nanolubricant, including rheology, friction, wear, and Stribeck curve analysis. Results show that the nanoparticle additives are capable of reducing both friction and wear at low concentrations. Stribeck curve analysis also revealed that the particles are effective in reducing friction in both the boundary and mixed lubrication regimes. The possible friction and wear reduction mechanism of silver nanoparticles is also discussed in the current work.

Enhancing the sliding-wear resistance of SiC nanostructured ceramics by adding carbon nanotubes

SiC nanostructured ceramics without and with carbon nanotubes (CNTs) were prepared by aqueous colloidal processing plus liquid-phase assisted spark-plasma sintering, and their sliding wear behaviour compared. It was found that the SiC nanoceramic is highly resistant to wear, with specific wear rates in the order of 10−8mm3/Nm or lower under the tribological conditions used, but also that the SiC/CNT nanocomposite is even more so. Qualitatively, the nanocomposite displayed a simple wear curve with a steady-state wear rate, over the wear curve of the nanoceramic with two wear rates, the second being one order of magnitude greater than the first. Quantitatively, the nanocomposite wore less overall with smaller worn volume, and especially had a lower wear rate (particularly marked for moderate and prolonged sliding distances). It was also found that the superior wear resistance of the SiC/CNT nanocomposite is due to combined effects of lubrication and toughening provided by the CNTs, the former reducing the severity of the sliding-contact conditions and the latter hindering the propagation and coalescence of the short cracks responsible for nanograin pull-out. CNT addition thus emerges as a hopeful line for processing ceramic nanocomposites that are both toughened and highly wear resistant for use in contact-mechanical and tribological applications.

The mathematical modelling of the impact of electric (Seebeck) effects on end-milling

It is a well-known fact that thermoelectric currents, reaching even the scale of ampere, develop during chip formation in the machine-workpiece-tool-chip. The impact of these currents on tool wear in end-milling was examined with a qualitative thermoelectric model, in which wear is described by an autonomous non-linear differential equation. Cutting temperature was measured by a so-called natural thermoelement with C60 and P35 carbide pair, which were submerged into heated Sn bath at validation. The mathematical model can be solved by a numerical method, where the inverse of the differential equation of wear was used. The wear curves determined by calculation fitted well with the measurement results. The results were achieved by cutting experiments using P35 carbide conducted on the C45 quality steel workpiece. It was found that the optimal solution with respect to the wear of the tool behaving as a natural thermal element might be achieved if the current is compensated by an external power source. Based on the model, anomalies might occur in some cases in the thermoelectric system. Further research is necessary to decide if this is only a special characteristic of the model or the model is interpreting really the actual processes.

ИССЛЕДОВАНИЕ ДОЛГОВЕЧНОСТИ И РАБОТОСПОСОБНОСТИ ШАРНИРНЫХ СОПРЯЖЕНИЙ НАВЕСНОГО ТЕХНОЛОГИЧЕСКОГО ОБОРУДОВАНИЯ ЛЕСНЫХ МАШИН

The article describes the main provisions of the study of the wear curve for different friction conditions in order to identify the durability and performance of hinge mates attachment process of forest machinery. Research wear of the hinge mating in conditions most acceptable method of micrometraje performed serial measurement by special tools using relative measurements.

Neural Networks Tool Condition Monitoring in Single-point Dressing Operations

Cognitive modeling of tool wear progress is employed to obtain a dependable trend of tool wear curves for optimal utilization of tool life and productivity improvement, while preserving the surface integrity of the ground parts. This paper describes a method to characterize the dresser wear condition utilizing vibration signals by applying a cognitive paradigm, such as Artificial Neural Networks (ANNs). Dressing tests with a single-point dresser were performed in a surface grinding machine and tool wear measurements taken along the experiments. The results show that ANN processing offers an effective method for the monitoring of grinding wheel wear based on vibration signal analysis.

Strengthening the Blades of a High-Speed Mixer on the Basis of Wear Curves

This article describes the pattern of longitudinal wear of the blades of high-speed mixers. It has been established that it is best to strengthen the blades by reinforcing them with hard-alloy plates of variable thickness.