Wear Morphology Research Articles

Experimental investigation into machinability of hardened AISI D6 steel using newly developed AlTiSiN coated carbide tools under sustainable finish dry hard turning

In the present study, a newly developed AlTiSiN coating material deposited on carbide insert by scalable pulsed power plasma (SPPP) technique is used for machinability investigation of hardened AISI D6 die steel (65HRC) in finish dry turning. Also, the cutting tool is characterized by various diagnostic tests to evaluate the effectiveness of nanocomposite AlTISiN coating material and its cutting performance. A series of machining trials have been performed under varied cutting conditions (feed, depth of cut, speed) to investigate the machinability concerning surface roughness, flank wear, and chip morphology. Further, an approach towards multi-response optimization and predictive modelling for minimization of flank wear and surface roughness have been performed using response surface methodology. Finally, a unique approach has been proposed for economic analysis and sustainability assessment in hard turning. Result shows that the nanostructured AlTiSiN coating developed lower range of tool wear (VB = 0.044–0.076 mm), produced surface finish (Ra) within 0.322–0.905 µm which is approaching the surface quality to that of cylindrical grinding because of minimum friction coefficient, good bonding capability and enhancement in hardness as well as wear resistance of coating material. Statistical analysis reveals that Ra and VB are influenced principally by feed (84.14%) and cutting speed (53.43%), respectively. With the tool life of 34 min, Gilbert's machining economic model calculated the overall machining cost per part of Rs.61.04 in hard turning using coated carbide insert. Chip morphology confirmed the formation of serrated type saw tooth chips. It is established that machining under dry condition provides environment friendliness, techno-economically feasible to improve sustainability.

Machine vision based adaptive online condition monitoring for milling cutter under spindle rotation

Tool condition monitoring (TCM) is an important guarantee for quality evaluation of products and parameter optimization of machining operations. The direct methods of TCM have made significant progress in condition recognition and wear measurement. However, these methods based on a single image that reflects the tool condition inevitably bring downtime to the machine tool. Moreover, a single image cannot reflect the tool wear characteristics integrity because the morphology of tool wear is complex. Regarding the issue above, the aim of this paper was to adaptively online monitoring for milling cutters. Firstly, tool condition image sequence (TCIS) is proposed in successive images to express and enhance tool wear characteristics from multiple angles. Secondly, the time-sequential gradient map between adjacent images is constructed based on histograms of oriented gradient. It is used to capture the initial frame of TCIS. Then, the subsequent images are encoded into the classification model. A logistic regression algorithm is applied to train the classification model to capture the end frame of TCIS. Finally, the tool wear area is located by balancing the rectangular box of wear area and benchmarks of wear measurement and is tracked based on the motion model and the local search. In the experiment of accelerating milling cutter life and three different failure phenomena, the recognition accuracy in the initial and end frame of TCIS is 100%. The average measurement accuracy of flank wear based on the proposed method in two experiments is up to 97.02% and 94.71%, respectively. These operations are automated online and provide complete data support for TCM.

Investigation of novel multiscale textures for the enhancement of the cutting performance of Al2O3/TiC ceramic cutting tools

Currently, the high temperature and severe friction conditions at the tool-chip interface are the main reasons for ceramic tool wear failures. Surface texturing as a geometric extension for cutting tools is a promising way to extend their service life. In this study, a novel type of multiscale texture was developed, and its effect on the cutting performance of an Al2O3/TiC ceramic cutting tool while machining AISI H13 steel was explored in a conventional cooling environment. The cutting force, cutting temperature, and tool wear morphology were investigated at cutting velocities ranging from 80 to 249 m/min. Microgroove textured Al2O3/TiC ceramic tools were prepared for comparison. The results show that the structure of the multiscale textures maintained good integrity over the range of cutting velocities. Thus, the synergistic effect of the microscale and nanoscale textures promoted the introduction and permeation of the cutting fluid. Therefore, the multiscale textures effectively enhanced the cutting performance of the Al2O3/TiC ceramic tools.

Simulation and experimental study on effect of surface residual stresses in dry orthogonal micro turning sample

ABSTRACT Turning is a drastically favoured machining process for producing cylindrical components with required dimensions. Prediction of chip formation is essential when damages caused by chips are into consideration during machining. A high amount of residual stresses are generated in the machined component due to a large number of forces and temperature distribution during machining. The scope of this paper is to investigate the percentage of residual stresses induced in a component during the dry micro turning process. Hence, in this work, Inconel 718, A2024-T351, and AISI D2 (62HRC) are selected as a workpiece materials and WC as tool material, simultaneously comparison studies of chip morphology have been carried out. Also, cutting speed and power consumption were investigated experimentally by opting varied tool rake angles (positive, negative, and zero) and a depth of cut. Residual stresses, nose wear, and chip morphology were found experimentally while machining Inconel 718. From the simulation and experimental results obtained, one can adopt a suitable tool rake angle to minimise power consumption during the micro turning process which leads to a sustainable machining process.

Thermal conductivity and wear resistance of cold sprayed Cu-ceramic phase composite coating

Pure Cu and Cu composite coatings with Al2O3, SiC, or WC were used to explore the influence of different ceramic phases on the wear resistance and thermal conductivity of a cold spray coating. Scanning electron microscopy was used to illustrate that the addition of Al2O3 or SiC can improve the coating quality. A Three-dimensional Optical White Light Interferometer was used to characterize the wear morphology of the coatings, and the wear resistance of each coating was qualitatively analyzed. The composite coatings with Al2O3 or SiC have better wear resistance than the other coatings and the thermal conductivity of all coatings is less than the pure Cu coating because of the low thermal conductivity of the ceramic phases. However, the thermal conductivity of the composite coatings with Al2O3 or SiC are significantly improved after annealing at 500 °C. Therefore, the composite coatings with Al2O3 or SiC, especially Al2O3, have better wear resistance and thermal conductivity.

Effect of ultrasonic surface rolling process on the surface properties of QAl10-3-1.5 aluminum bronze alloy

The main purpose of this article is to study the effect of ultrasonic surface rolling process (USRP) on the surface properties of QAl10-3-1.5 aluminum bronze alloy under different rolling reduction and rolling times, providing ideas for improving the poor wear resistance of valve stem nuts and sealing rings. SEM, EDS and optical three-dimensional profiler were used to characterize the microstructure characteristics of the surface modified layer and the surface morphology of the wear traces. The results show that the surface layer of the USRPed sample has undergone severe plastic deformation. The α phase is elongated, and the microstructure structure shows a fine and uniform distribution state. And the grain size of α phases decreased, and the number density of β phases increased. Compared with the untreated sample (only cutting and polishing), the surface roughness of the USRPed sample reaches nearly Ra 0.04 μm; the maximum surface micro-hardness is 323.04 HV, increasing by 75%; the maximum depth of surface hardening layer is about 570 μm. The friction coefficient, wear mass loss and the width and depth of the wear traces of the USRPed samples are significantly reduced, while the wear resistance is significantly enhanced. By comparing the surface wear morphology of the samples under different process parameters, it is found that the main wear mechanism of the untreated samples is adhesive wear, while the main wear mechanism of the USRPed samples is abrasive wear. The improvement in wear resistance is attributed to the refined and homogenized surface microstructure, the smaller surface roughness, the larger surface micro-hardness and surface hardness layer depth after USRP.

Tribological study on the biodiesel produced from waste cooking oil, waste cooking oil blend with Calophyllum inophyllum and its diesel blends on lubricant oil

Biodiesel or biodiesel–diesel fuel is the current fuel used to power transportation engines. Contamination on lubricating oil is a common issue due to leakage or extensive use of engines. This study explores the lubricant oil blend’s friction and wear with the biodiesel derived from waste cooking oil, waste cooking oil blend withCalophyllum inophyllum oil, and biodiesel–diesel​ blend. The blending of biodiesels and biodiesel–diesel blend with lubricant oil varies from 5% to 25% of biodiesels and biodiesel–diesel with 95% to 75% of lubricating oil based on volume ratio. The test was conducted using a four-ball tribotester according to the ASTM D 4172. The result showed that blending of BWCIL75 with biodiesel–diesel has the lowest friction coefficient (0.072) among tested oil. The wear scar on the ball bearing lubricated with the blending mixture showed an acceptable diameter value. The wear morphology has shown that a worn surface with black spots provides more protection to the tested ball. The result found that fatty acid contained in the biodiesel and the low viscosity of biodiesel significantly reduced the frictional coefficient of the lubricating oil and worked as wear prevention. Mechanical efficiency of machinery component favour low coefficient of friction. This study indicated that biodiesel produced from waste cooking oil blended with Calophyllum inophyllum oil shows better lubricity and can be used as an additive to petroleum-based lubricant for better automotive engine performance.

Correlation between surface textural parameter and tribological behaviour of four metal materials with laser surface texturing (LST)

Laser processing technology was used to fabricate dimple-shaped surface textures on four metal materials (316 SS, NiTi, TA2, and Ti6Al4V). A Taguchi L16 (22 × 42) orthogonal array design was used to determine the correlation between the textural parameters and dry sliding tribological behaviour of the four metal materials. Furthermore, the validity of the optimized textural parameters was determined under oil lubrication conditions. The influencing parameters were texture density, material type, type of counterpart and applied load. The output result of the mass loss was converted into a signal-to-noise ratio (S/N) for the analysis of the optimal parameter combination. Analysis of variance (ANOVA) was applied to determine the significance of the four factors. The results of the S/N analysis and the ANOVA indicated that the influence degrees of the factors on mass loss were in the following order: material type > type of counterpart > texture density > applied load. For the 316 SS, NiTi, TA2 and Ti6Al4V, the optimal texture densities were 5%, 7%, 5%, and 11%, respectively. According to the observation of the wear morphology, it was found that the surface texturing played a positive role in improving the wear resistance of the selected material, especially under oil lubrication conditions.

Experimental investigations on the wear behaviour of micro-EDM-fabricated textured tools during dry turning of Ti6Al4V

PurposeThis paper aims to focus on analysing the wear characteristics of tungsten carbide tools on which various micro patterns are fabricated to study its effect on the machinability of Ti-6Al-4V at dry turning conditions.Design/methodology/approachMicro-patterns such as dimples, linear grooves and a novel combination of dimples and linear grooves were fabricated on rake faces of uncoated tools by micro-EDM process. Impact of these patterns on tool wear and chip morphology characteristics under dry machining conditions were analysed, and their performances were compared with the non-textured tool (NTT).FindingsEncouraging results in terms of minimal tool wear and favourable chip morphology characteristics were observed in case of all the textured tools, which demonstrated better tribological characteristics in contrast to NTT. The average flank wear was reduced by 43.5, 32 and 24.7% in dimple textured tool (DTT), linear textured tool (LTT) and hybrid textured tool (HTT), respectively, as compared to NTT. The average chip curl diameters measured for NTT, DTT, LTT, and HTT were observed to be 6.60, 3.51, 4.0 and 4.31 mm, respectively.Originality/valueThe contribution of this work lies in fabricating innovative patterns using cost-effective micro-EDM process and analysing how the patterns, depending upon their dimensional area and wear debris accumulation characteristics, influence the machinability of Ti-6Al-4V in the absence of any lubrication mediums.

Digital analysis of tooth microwear, a potential application for dental microwear monitor

In general, tooth wear is difficult to be noticed until it leads to toothache in vivo. Developing a dynamic dental wear monitoring system to predict tooth wear in daily life is a necessity. The translation between complex surface wear morphology and corresponding digital signal source is a technical limitation to develop this kind of monitoring system. Microwear texture analysis has been widely employed in predicting diet by a palaeontologist. The main question is whether the microwear texture analysis has potential development space to develop a sensor for monitoring tooth wear. According to obtained results, the microwear texture analysis had enough sensitivity to display the surface morphology variations for different chewing foods and various angles. The corresponding sensitive digital signal of tooth microwear surface morphology makes it possible to develop a dental microwear sensor.

Investigation on tool wear and chip morphology in hard turning of EN 31 steel using AlTiN-PVD coated carbide cutting tool

Hard turning is a well-known machining technology by which a cylindrical job of hardness above 45 HRC is machined using a single point tool. In hard turning, higher tool wear is the main issue identified by the machinist. In the hard turning activity, tool wear is severely stimulus by cutting parameters, cutting tool materials, and cutting environment. The temperature evolved in the cutting process is the prime factor to accelerate the tool wear. However, there is a requirement to control the temperature intensity by selecting suitable input turning parameters and cutting environment. However, the current research emphasizes the selection of suitable input turning parameters and suitable coated carbide tools in hard turning of EN-31 bearing steel of hardness 56 HRC in conventional flood cooling. AlTiN-PVD coated carbide insert was used to execute the turnings tests using Taguchi L16 orthogonal array, and a detailed study on tool wear and chip pattern formation is investigated. AlTiN PVD coated carbide tool performed excellently in flood cooling as maximum tool wear was found as 0.065 mm which is very less for hard turning concerns. Also, long helical and ribbon chips patterns are identified in the entire investigation. Blue color chips are identified at 240 m/min of cutting speed which confirmed the generation of higher cutting temperature in course of cutting. The present findings can be suitable for the industries that are still using a conventional cooling method in the machining of heat-treated steels having hardness 45–69 HRC.

Tribological properties of rock-bit journal bearings tribo-pair with micro-dimples under contaminated grease lubrication

The failure of bit bearings is one of the main factors that restrict the life of a bit, and studies revealed that sealing and adhesive wear failure are common failure modes of bit bearings. To study the adaptability of the optimal textures to anti-wear and anti-friction performance of an 8 1/2” rock bit journal bearingunder sealing leakage conditions, the rheological properties of grease in the range of 0%–50% of the water-based drilling fluid volume in the compound lithium-based grease (rock bit grease) were tested. For the cylindrical dimples (diameter: 300 μm; depth: 40 μm, area ratio: 5%) and elliptical dimples (major and minor axis of 720 and 360 μm, respectively; depth: 40 μm, area ratio: 10%), the experimental study on the wear resistance of the optimized texture tribo-pairs was carried out as the grease invaded different drilling fluid contents based on the pin-disk pair. Results showed that the drilling fluid volume in the rock bit grease significantly affected the rheological properties of the grease. Furthermore, the cylindrical and elliptical dimples still had good anti-wear and anti-friction effects. Especially when the drilling fluid volume ratios in the grease reached 50%, the elliptical dimples can still reduce the friction coefficient and wear amount of the pair by 19.88% and 56.99%, respectively. With the increase of drilling fluid invasion into grease, the wear morphology of the un-textured tribo-pairs showed that the wear form changed from abrasive to adhesive wear, while that of the preferred textured tribo-pairs indicated slight abrasive wear.

Experimental and numerical analysis of the wear mechanism in spring coil forming die and the effects of die geometry on wear

The present work aimed at understanding the wear mechanism of spring coil forming die and the effects of die geometry on wear. The wear morphology was analyzed by scanning electron microscopy and energy dispersive spectrometer. The main wear mechanism was found to be adhesive wear, and a variant of the Archard wear model was established. The wear distribution in spring coil forming die was numerically analyzed in DEFORM software, and the effects of die geometry parameters on wear were discussed. Numerical results revealed that the wear distribution in the die was uneven and the wear mainly occurred at the sides of the die cavity. The wear depth was greatly affected by the width and angle of the die cavity, whereas the length of the die cavity had little effect. A small cavity width or angle led to severe wear, while a large cavity width reduced the forming quality of the spring coil. Moreover, a simple and effective life prediction method was proposed based on wear results. The findings of this research will be helpful for the effective design of spring coil forming die and the prediction of wear.

Tool wear, surface roughness, cutting temperature and chips morphology evaluation of Al/TiN coated carbide cutting tools in milling of Cu–B–CrC based ceramic matrix composites

Ceramics-based composites are a special class of materials carrying combined properties that belongs to alloys and metals according to market demands. This makes composites completely different and paves the way for new applications that requires the utmost properties. Machining of such composites is of great importance to finalize the fabrication process with improved part quality; however, the process implies several challenges due to the complexity of the cutting processes and random material structure. The current study aims to examine the machinability characteristics when milling novel material, Cu–B–CrC composites using Al/TiN coated carbide tools. Further, the influence of machining parameters along with the different weight ratios of the powders amounts used to fabricate the machined reinforced samples on output parameters namely surface roughness, tool wear, chip morphology and cutting temperatures was investigated. One of the key findings of the study is the dominant effect of reinforcement ratio (Cu, B, CrC) on machinability, which showed that 5% additive (2% B, 3% CrC) provides improved properties such as surface roughness, tool wear and cutting temperature. Cutting speed alterations play an important role in the machinability characteristics, i.e., increasing value increases flank wear and cutting temperatures and reduces surface roughness. Increasing feed rate increases the surface roughness meanwhile its effect shows changing behavior on the flank wear and cutting temperatures according to cutting speed and reinforcement ratio.

Influence of surface morphology parameters of steel on tribological properties between glass‐fiber‐reinforced polytetrafluoroethylene composites and steel under dry‐friction and oil‐lubrication conditions

AbstractPolytetrafluoroethylene (PTFE) composites are commonly used engineering materials owing to their good tribological and mechanical properties. In this study, a friction pair was formed by a glass‐fiber‐reinforced PTFE composite and a chromium‐plated nickel‐based stainless steel plate (18Cr2Ni4WA). Under dry‐friction and oil‐lubrication conditions, friction and wear tests were carried out on the metal plate surface in two roughness ranges and three surface‐texture directions. The friction coefficient, wear rate, width and depth of the wear trace, wear morphology, and surface composition were analyzed. The results showed that the 90° texture direction of the steel plate with respect to the moving direction under oil lubrication and the 0° texture direction under dry friction were the texture directions with the best tribological performance. The friction and wear properties of the PTFE composite under dry friction were better than those under oil lubrication. The 0.3–0.5 μm roughness range of the steel plate was the best roughness range for the tribological properties of the matching pairs.

Performance evaluations of Ti-based PVD coatings deposited on cermet tools for high-speed dry finish turning of AISI 304 stainless steel

The aim of this research work is to develop and compare in-house Ti-based coatings with commercial coatings for cermet tools, specifically for the high-speed dry turning of Austenitic stainless steel (AISI 304). In the present study, commercial Ti-based coated cermet tools from different manufacturers are used to evaluate and compare the performance of commercial coatings. This research focuses on the investigation of the performance for the various commercial coatings on cermet tools based on the mico-mechanical properties, tool performance and surface roughness. The results are used to develop a range of in-house Ti-based PVD coatings with different compositions and compare their performance with similar commercial coatings. Coating surface topography and structure were investigated using Atomic Force Microscopy (AFM). The compositions of coating materials and tribo films were determined using Energy-Dispersive X-ray Spectrometry (EDS) and X-ray photoelectron spectroscopy. The results of this research demonstrate that the compositions of various coatings affect the micro-mechanical properties and significantly influence the tool life and wear morphology. The performance of in-house Ti-based coatings with a similar composition to commercial coatings were better than the latter, depending upon their micro-mechanical properties.

EFFECT OF DIFFRENT LOADS ON THE WEAR BEHAVIORS OF 5Cr5Mo2V STEEL AT 700 °C

The effect of different loads on the high-temperature wear behavior of 5Cr5Mo2V steel at 700 °C was investigated. Wear morphologies, oxide compositions and matrix evolution were studied. The results showed that the wear rate increased with an increased test load, and the wear mechanism transformed from abrasive-oxidative wear to adhesive-oxidative wear. The relation between a delaminated oxide layer and cracks in the matrix were investigated. The exfoliation of carbides and displacement difference between the matrix and carbides caused a crack initiation. The wear rate strongly related to carbides, and coarse M6C carbides with poor holding power led to a high wear rate. Besides, a diagram of wear characteristics under different loads was suggested in this work.

Modelling process parameters and morphology of wear out brass wire surface during WEDM of Nimonic75 alloy

Wire electrical discharge machining is a modern machining process that finds potential applications in the aerospace and automotive industries. This paper investigates the effect of wire electrical discharge machining process parameters such as peak current, pulse on time, pulse off time and servo voltage on wire wear ratio after proof-machining of Nimonic 75 alloy. Response surface methodology based on Box-Behnken’s design has been used to perform the experimental runs. This paper develops the quadratic regression model for wire wear ratio for effective machining of Nimonic75 alloy. The developed model was used for direct evaluation wire wear ratio in advance. It may save the machining time and cost as well. The key wire electrical discharge machining process parameter influencing wire wear ratio, according to the analysis of variation, is a pulse on time (40.28%). The percentage contributions of peak current, pulse off time and servo voltage on wire wear ratio are 32.20%, 23.62%, and 3.9% respectively. This research discovered the optimal setting of process parameters (servo voltage = 50 V, peak current = 80 A, pulse on time = 0.6 µs, and pulse off time = 46 µs) to minimizes the wire consumption. The surface morphology of the wear out wire electrode surfaces has been examined. It is identified that there are erosion craters and indents formed on the wire electrode surface. The erosion craters become wider and deeper with an increase of peak current and pulse on time. The energy dispersive spectroscopy is carried out on the used wire electrode surfaces and observed that the elements diffusion from the workpiece to the wear out brass wire electrodes surface vary according to the periphery of the deformed wire.

Experimental Research on Longitudinal Ultrasonic Assisted Vibration Drilling of 0Cr17Ni4Cu4Nb

In the present study, by adding ultrasonic vibration in the longitudinal direction to assist the drill bit to drill on 0Cr17Ni4Cu4Nb stainless steel, in order to obtain high-quality deep small holes and prolong the service life of the drill bit. By establishing the movement mathematical model of the drill bit under ordinary drilling and longitudinal vibration drilling, the movement trajectory of the main cutting edge of the drill bit in two different drilling methods is compared and analyzed, and the anti-friction mechanism of longitudinal vibration drilling is analyzed. The conventional drilling and longitudinal ultrasonic drilling of 0Cr17Ni4Cu4Nb stainless steel are carried out on a longitudinal ultrasonic vibration drilling device. After drilling test, the wear morphology of the drill bit, the surface roughness of the hole wall and the chip morphology are observed and analyzed by the detection equipment. The result shows: the wear degree of the drill bit after longitudinal ultrasonic vibration drilling is lower than that of conventional drilling, which can prolong the service life of the drill bit. The surface roughness of the hole wall is reduced, and the drilling chips are more finely divided and easier to discharge.

Ceramic Inlay Bonded Interfaces in Minimally Invasive Preparations: Damage and Contributing Mechanisms in Sliding Contact.

In the preparation of inlay cavities, a choice must be made between conventional standard and minimally invasive preparation designs; in the long run, this choice can affect the integrity of the bonded interface. To evaluate the effect of minimally invasive cavity preparation designs on the extent and contributing mechanisms of damage to ceramic inlay bonded interfaces. Tooth blocks with 90°, 120° and 75° marginal angles were prepared, representing tooth cavities with conventional standard and minimally invasive preparations with large divergence and convergence angles and bonded to monolithic ceramic (IPS e.max CAD). Vickers indentations were placed at various distances from the bonded interface. The indentation morphology and crack length were observed. Reciprocating wear tests were performed on the bonded interface with a 20-newton (N) vertical load. The wear depth and wear-scar morphology were characterized after increments of cyclic sliding contact. The 120° group exhibited longer indentation cracks in the ceramic, whereas the 75° group showed larger indentations in the enamel when compared to the 90° group (p<0.001). Consistent with the weaker edge crack resistance, the 120° group experienced the greatest wear (p=0.008), and the wear depth in the enamel of the 75° group exceeded that of the 90° group (p<0.001) in the early stage (5×102 cycles). However, no significant difference in the wear depth (p>0.147) and morphology were found at the later wear stage among the three groups. Within the limitations of this study, minimally invasive preparations with 120° and 75° marginal angles can result in early sever damage at the ceramic inlay bonded interface but show comparable wear behaviors to the conventional 90° group at the later stage.