Diffusion Wear Research Articles

Influence of the Properties of Surface Polyoxide Structures on Wear Processes in Solid Bodies

The influence of the acidity of oxide structures formed on the contact surfaces of hard-alloy cutting tools of the P cutting application group [1] on the wear resistance of the latter used to machine the materials that cause intense diffusive wear has been investigated. It has been established that the wear resistance of the cutting tools tends to increase with decreasing acidity of the surface oxide film formed on the contact surfaces of the cutting edge.

The influence of ultrasonic elliptical vibration amplitude on cutting tool flank wear

In this article, the effect of vibration amplitude during ultrasonic elliptical vibration–assisted turning on cutting tool flank wear ( VBmax) and tool diffusion wear mechanism has been experimentally studied in machining of AISI 4140 hardened steel. To achieve this goal, an ultrasonic elliptical vibration–assisted turning setup was designed and manufactured. This device was then used in both ultrasonic-assisted tuning and ultrasonic elliptical vibration–assisted turning tests (i.e. one-dimensional and two-dimensional ultrasonic-assisted machining). According to the achieved results, ultrasonic elliptical vibration–assisted turning is more effective than ultrasonic-assisted tuning in reducing tool flank wear; at an amplitude of 13 μm, work velocity of 180 mm/s and feed of 0.09 mm/rev, VBmax were decreased 30.3% and 54.3%, respectively, in case of ultrasonic-assisted tuning and ultrasonic elliptical vibration–assisted turning. It was also observed that increasing the amplitude of ultrasonic vibrations reduces VBmax; at work velocity of 180 mm/s and feed of 0.09 mm/rev, the reduction of VBmax in ultrasonic elliptical vibration–assisted turning with amplitudes of 5 and 13 μm is, respectively, 39.3% and 54.3%, compared with that of conventional machining. The results also show that the application of ultrasonic vibrations weakens the cutting tool diffusion wear mechanism. This attenuation is much higher for ultrasonic elliptical vibration–assisted turning in comparison to ultrasonic-assisted tuning. Besides, the amount of attenuation in cutting tool diffusion wear mechanism decreases with increasing vibration amplitude.

Reliability analysis of the cutting tool in plasma-assisted turning and prediction of machining characteristics

ABSTRACT Heat-assisted machining (HAM) is an alternative method for the successful machining of difficult-to-cut aerospace superalloys. However, the tool wear progression in HAM has been substantially affected by the workpiece external heating temperature along with the machining parameters. It is of great importance to precisely estimate the tool wear progression and reliability of the cutting tool operated in HAM to enhance the machining efficiency and economics. Hardened AISI4340 alloy steel was machined under plasma-arc heating conditions with WC cutting tools. The experimental results reviled that for 200°C of preheating temperature, the surface roughness noted as 2.03µm and tool life as 870s. While at 600°C, the surface roughness as 1.68µm, and tool life extended to 1885s to reach the set threshold value of 0.4mm flank wear. Notch wear as dominant tool wear mechanism at 200°C and 400°C, while it is diffusion wear at 600°C. On the establishment of stochastic tool life distribution and reliability models, tool lives measured at all heating conditions followed a Weibull distribution. Empirical models for tool wear, surface roughness, and material removal rate were postulated and validated statistically as-well-as experimentally. The derived reliability and empirical models can be used to predict the machining characteristics to enhance its performance.

Experimental study on fabricating ball micro end mill with spiral blades by low speed wire electrical discharge machining

This study is focused on developing and fabricating ball micro end mills with spiral blades by using low speed wire electrical discharge machining (LS-WEDM). Firstly, the new type ball micro end mill is designed and the mathematical model of wire movement trajectory is established for optimizing machining parameters and realizing visual prediction. Then, the diameter, spiral width, and the length consistent accuracy of ball micro end mills fabricated by LS-WEDM is investigated in detail, and more importantly, the three-spiral blades ball micro end mill with the diameter of about 278 μm and the length of 1860 μm is firstly and efficiently manufactured by LS-WEDM. Besides, the micro machining performance and tool wear of LS-WEDM fabricated ball micro end mill are evaluated by conducting micro milling experiments on nickel-based single-crystal superalloy DD5 material, and experimental results revealed that the main tool wear of the new type ball micro end mill is friction wear and adhesion wear rather than diffusion wear. Furthermore, the surface roughness of machined surface can be reduced to 183 nm, which indicates that the ball micro end mills with spiral blades fabricated by LS-WEDM are significantly potential to achieve high-quality machining for complex micro structures on hard material.

Experimental study of tool wear and its effects on cutting process of ultrasonic-assisted milling of Ti6Al4V

Ti6Al4V is usually considered difficult to machine, and therefore, it causes severe tool wear and shortens tool life while being machined during conventional milling, leading to loss of quality and accuracy of the machined parts. In this paper, the experiment of ultrasonic-assisted milling of Ti6Al4V was conducted to study the tool wear mechanism in ultrasonic-assisted milling process and investigate the influence of the wear variable state of tool continuous cutting on the cutting process in ultrasonic-assisted milling and conventional milling. The experimental analysis showed that oxidation wear, adhesive wear, and diffusion wear occurred in ultrasonic-assisted milling; however, longer tool life was achieved when machining under the same conditions as compared to that of conventional milling. On the other hand, the curl angle of chip generated from ultrasonic-assisted milling was smaller than that from conventional milling in the same wear time. In addition, the burr produced by ultrasonic-assisted milling was not obvious, and under the coupling effect of ultrasonic-assisted milling, lower cutting force, improved surface roughness, and lower cutting temperature were obtained as compared to those of conventional milling under the same wear time.

Wear mechanism and tool life prediction of high-strength vermicular graphite cast iron tools for high-efficiency cutting

Vermicular graphite cast iron is not used widely because of the challenges associated with to processing. This study investigates the tool wear morphology and main wear mechanism during the turning of high-strength vermicular graphite cast iron using coated ceramic tools. Further, it develops a tool life prediction model, based on the grey theory, for the flank face of the tool. The results show that coated ceramic tools are more suitable than cemented carbide tools for the turning of vermicular graphite cast iron. Coated ceramic tools mainly exhibit adhesive, abrasive, and diffusion wear during low-speed cutting wherein the turning speed Vc≤200m/min. The FeO layer formed by the oxidation of the workpiece attached to the tool tip can appropriately reduce the tool wear. During high-speed cutting (Vc>400m/min), coated ceramic tools mainly show oxidative and diffusion wear and a certain degree of abrasive wear. As the turning speed increases, the diffusion wear of coated ceramic tools initially increases and then decreases. The analysis of the model prediction results shows that the short-term prediction error of the grey model is less than 5%.

Cutting performance of cubic boron nitride-coated tools in dry turning of hardened ductile iron

A novel cubic boron nitride (cBN)-coated silicon nitride(Si3N4) cutting tool was fabricated via the diamond interlayers by electron cyclotron resonance (ECR) microwave plasma chemical vapor deposition (MPCVD) technique. The cutting performance of cBN-coated tools was evaluated by dry turning of hardened ductile iron in comparison with the commercially available titanium aluminum nitride (TiAlN)-coated tools. The effects of cutting parameters on the cutting force and cutting temperature were studied. The results showed that the cutting forces increased with the increase of depth of cut but decreased with the increase of cutting speed, while the cutting temperature increased with the increase of cutting speed. Compared to the TiAlN-coated tools under identical turning conditions, the cBN-coated tools had lower cutting force and cutting temperature, and smaller tool wear. The cBN-coated tools delivered excellent cutting performance and prolonged tool life. Furthermore, the wear patterns and wear mechanisms of cBN-coated tools were investigated. It was found that the dominant wear patterns were crater wear on rake face and flank wear land, and the wear mechanisms were demonstrated to be abrasion wear and diffusion wear. The cutting experiments verified that the cBN-coated tools had attractive potentials in the applications for dry turning of refractory metals and hardened ferrous materials.

Performance and wear mechanism of spark plasma sintered WC-Based ultrafine cemented carbides tools in dry turning of Ti–6Al–4V

Cutting performance and failure mechanisms of spark plasma sintered (SPS) ultrafine cemented carbides in dry turning Ti–6Al–4V were studied. The tools of UYG8 (WC-8wt%Co) and UYG8V2B10 (WC-8wt%Co-0.2 wt%VC-1.0 wt%cBN) exhibited higher lifetime and better processing quality than the commercial YG8 cemented carbide tool. The cutting distance of UYG-8 and UYG8V2B10 tools are 1.8 and 1.6 times longer than that of YG8, respectively. Cutting-edge breakage was found as the main failure forms of the SPS cemented carbide tools containing low Co content (≤6 wt%), whereas the SPS cemented carbide tools containing high Co content (≥8 wt%) exhibited flank and rake wear as main failure forms caused by abrasion, adhesion, diffusion, and oxidation. UYG8V2B10 tool wear mechanism was affected by cutting speed and depth. Wear mechanisms of UYG8V2B10 tool are mainly adhesive wear and oxidative wear at low cutting speed, but follow adhesive wear and diffusive wear at higher cutting speed. Moreover, with increasing cutting depth, tool failure forms are mainly breakage and chipping, largely induced by high cutting temperature and severe cutting vibration.

Study on the influence of micro-textures on wear mechanism of cemented carbide tools

Wear behavior of micro-textured insert with lubrication was studied. Micro-pits with different diameters (80–200 μm), depths (3–10 μm), and area occupancies (10–30%) were manufactured on the tool rake face near the main cutting edge. Experimental research was conducted to reveal the effect of micro-pits on tool-chip interface friction characteristics. Besides, the texture parameter with better tribological characteristics was selected to study the wear mechanism of textured insert. Scanning electron microscopy analysis was conducted on the worn area of rake face. The results confirmed that the micro-textures can effectively reduce the average shear strength of rake face and actual tool-chip contact length during machining. The best average friction coefficient can be obtained with texture diameter of 170 μm, depth of 7 μm, and area occupancy of 20%. Adhesive wear, diffusion wear, and oxidation wear appeared on the worn area of rake face. The micro-textures can effectively reduce the diffusion wear and suppress the built-up edge (BUE) by improving tool-chip interface friction characteristics. The findings are of significance for enhancing the application of textured insert with excellent tribological characteristics.

Plastic strength of cutting parts of tools from STM when there is turning heat-resistant alloys

The article is devoted to the modeling of physical and chemical creep process, which determines the plastic strength of cutting parts at the vertices of the tools from STM. The creep process is associated with the phenomena of diffusion and diffusion wear of the tool from STM in the zone of quasi-brittle transition (that is, the temperature transition of tool STM from brittle to plastic state at high cut-ting temperatures) with thin turning of heat-resistant alloys and steels. Turning of heat-resistant alloys at high cutting temperatures, corresponding to the quasi-brittle transition, allows the machining process at ultra-high cutting speeds, which expands the application of tools from STM. We have created mathematical model of wear and destruction of the cutting part at the top of the tool and STM due to diffusion phenomena in the process of thin turning of a heat-resistant alloy.

Metallurgical Soldering of Duplex CrN Coating in Contact with Aluminum Alloy

Coatings deposited by physical vapor deposition (PVD) significantly reduce the wear of high pressure die casting tools; however, cast alloy soldering still has a strong negative effect on production efficiency. Although a lot of research has been already done in this field, the fundamental understanding of aluminum alloy soldering toward PVD coatings is still scarce. Therefore, in this work the performance of CrN duplex coatings with different roughness is evaluated by a modified ejection test performed with delayed (DS) and conventional casting solidification (CS). After the ejection tests, sample surfaces and layers were subjected to comprehensive characterizations of their morphological and chemical characteristics. Considerably lower values of the ejection force were recorded in DS experiments than in CS experiments. Surface roughness played an important role in the CS experiments, while samples with different surface topographies in the DS experiments performed in a similar fashion. The decrease in the ejection force, observed in DS tests, is attributed to the formation of a thick Cr–O layer on CrN coating which reduced soldering and sliding friction against thick Al–O casting scale. The Cr–O layer formed in DS experiments suffered from diffusion wear by cast alloy. The observed oxidation phenomena of nitride coatings may be utilized in a design of non-sticking coatings.

Tool Wear in High-Speed Turning Ultra-High Strength Steel Under Dry and CMQL Conditions

High-speed turning ultra-high strength Steel—300M steel under dry and cryogenic minimum quantity of lubricant (CMQL) conditions was carried out to study the influence of different lubrication conditions on cutting force and tool wear. Through orthogonal test, the influence of cutting parameters such as cutting speed, feed and depth of cut on the flank wear under CMQL condition was studied. Finally, the forecasting model of tool wear under CMQL condition was established, and the cutting parameters were optimized. Compared with dry cutting condition, CMQL condition can better reduce the adhesion wear, oxidation wear and diffusion wear of coated carbide tools. The following cutting parameters v = 212.8 m/min, f = 0.14 mm/z and ap = 0.36 mm can be most effective in reducing tool wear under the CMQL condition.

Research on the Durability of Tools and the Burrs of Workpiece When Milling T700 Carbon Fibre-reinforced Polymer Composites

This research aimed to analyse the life and the wear of the coated tools with a diamond thin film, the uncoated cemented carbide tools, and the quality of machined surface, respectively, when milling T700 carbon fibre-reinforced polymer (CFRP) composite using the optimal cutting parameters. The results indicate that (1) in the same cutting condition, the wear resistance of the coated tools with CVD diamond thin film is better, whose life is 7.5 times that of the uncoated cemented carbide tools. (2) The life of tools directly affects the quality of the machined surface. The size and density of burrs on the machined surface are proportional to the width of blade wear of tool when carbon fibre-reinforced polymer (CFRP) composite was machined. The coated tools with diamond thin film by Chemical vapour deposition (CVD) can effectively prevent the chemical wear and diffusion wear of tools, which will make the blade wear of tools slow and uniform. (3) In practice, based on the quality, efficiency and processing economy, the tools need to be regularly checked when the workpiece is cut to 5.4m, 40.5m length for uncoated tools and coated tools, respectively.

Flank wear and rake wear studies for arc enhanced HiPIMS coated AlTiN tools during high speed machining of nickel-based superalloy

Several studies are available on wear behaviour of the physical vapour deposited as well as chemical vapour deposited coated cutting tools during continuous cutting operations. However, there still exists deficiency in a comprehensive analysis of the dominating wear mechanisms. The present study investigates the wear behaviour of the AlTiN coating on the cemented carbide developed by novel arc enhanced high impulse magnetron sputtering technique (HiPIMS). In this study, micro abrasive blasting (MAB) has been adopted as a surface modification as well as the coating treatment technique. This was done primarily to enhance the performance of the cutting tool by altering the surface and sub-surface properties so that a comparison can be made with only conventionally coated and uncoated tools in terms of wear performance. In order to study the tool wear behaviour, aerospace material Nimonic C 263, possessing high strength owing to the presence of the metallic carbides and work hardening properties, was selected as workpiece material for longitudinal turning. The process parameters such as feed, depth of cut and cutting speed were kept constant to 0.12 mm/rev, 1 mm and 60 m/min respectively. Scanning electron microscopy (SEM) was carried out for detailed investigation of the worn-out regions at the rake and flank faces while energy dispersive X-ray spectroscopy (EDX) was utilized for observing the variation in elemental composition during machining. Diffusion wear studies were carried out under dynamic condition by cutting the cross-section of the worn-out inserts after the machining operation for both uncoated and coated samples, while diffusion under static condition was carried out by coupling the workpiece and tool and then heating at varying temperature. The results indicate the efficacy of the MAB as a surface treatment technique for improving the wear performance of the cutting tools during the machining of the nickel-based superalloy.

A Review on Wear Behavior of Cutting Tools During Machining of Inconel, Nimonic, and Hastelloy

Objectives: Super-alloys are considered to be hard-to-machine materials; therefore, cutting tool is highly susceptible to be worn out during the machining operation. Because of that, the surface condition of the workpiece is very poor, and the machine is also likely to get damaged. Therefore, it is imperative to estimate the wear traces on the cutting tool along with the calculation of its useful life. Methods/statistical analysis: Various research conducted in this context has been reviewed and discussed in this study. For better understanding, the scope of this review is restricted to Ni-based superalloys, especially Inconel, Nimonic, and Hastelloy. With regard to these super-alloys, tool wear (TW) mechanisms have been discussed. TW mechanism conferred in relation to various cutting speed (CS), feed rate (FR), and cut depth (CD) has also been compiled here in tabular form. Findings: From the review, it can be said that flank wear (FW) is one of the main reasons behind the cutting tool failure irrespective of machining environment, parameters, materials, etc. Along with FW, some conditions based wear mechanisms such as abrasion wear (AW), burr formation, chipping, adhesion wear (AdW), notch wear (NW), crater wear (CW), built-up-edge (BUE), diffusion wear (DW), etc. for TW were also operable in most of the situations. The wear of cutting tool was influenced severely by CS among the various machining parameters. Application/ improvements: Super-alloys are used primarily in the aviation industry because they have certain properties, such as high corrosion resistance, tremendous strength, excellent weldability, high fatigue and creep resistance, etc. High surface finish and precise dimensions of machined aerospace parts are very much needed for a high level of safety, which depends predominantly on the integrity of machining equipment.Keywords: Super-alloy, Inconel, Nimonic, Hastelloy, Machining, Tool Wear

New observations on wear characteristics of solid Al2O3/Si3N4 ceramic tool in high speed milling of additive manufactured Ti6Al4V

Additive Manufacturing (AM) technologies applied to the titanium alloys have attracted attention from industries in recent years. Despite one of the main goals of AM is the reduction of manufacturing steps, semi-finish/finish machining operations are still required so as to obtain the desired geometrical tolerance and surface features. In this study, the solid end mill was manufactured by Al2O3/Si3N4 (Sialon) ceramic materials and employed in high-speed slot milling of Ti6Al4V alloy fabricated by the Direct Metal Laser Sintering (DMLS) AM technology to study the tool wear characteristics during processing. The Raman spectroscopic method was employed to characterize the molecular structures of Sialon ceramics for the manufacturing of the cutting tool. The morphologies and elemental maps of wear region of the ceramic tool were examined by scanning electron microscope and energy dispersive spectroscopy techniques. The results show that the adhesion wear and diffusion wear are the dominant wear mechanisms, and the chemical stability of Al2O3/Si3N4 (Sialon) ceramics fabricated as the solid ceramic tool to the attack of the atoms from additive manufactured Ti6Al4V is relatively weak under the atmosphere. The difference of thermal expansion coefficients of diffusion layer and tool substrate accelerates the initiation and propagation of thermal cracks formed on the diffusion interface. Moreover, fracturing and crater-like groves near the tool edge were finally formed due to the removal of adhered workpiece material.

Microstructural and Mechanical Investigation of WC-TiC-Co Cemented Carbides Obtained by Conventional Powder Metallurgy

WC-Co cemented carbide is one of the widely hard materials used for cutting in machining industry, due to its microstructural and mechanical stability even at high temperature. However, diffusion wear is the most serious problem that WC-Co suffers from. One of the most applied approaches to improve the WC–Co cemented carbide performances is the addition of transition metal carbides such as: TiC, TaC and NbC which prevents diffusion wear thanks to the gamma phase (Ti,Ta,Nb,W)C which is formed during sintering. Therefore, and in order to understand the thermal metallurgical reactions occurred between WC-Co cemented carbide and (Ti, Ta, Nb)C transition carbides and theirs effects on the microstructural and mechanical properties. The WC–TiC– TaC– NbC–Co cemented carbide was elaborated by conventional powder metallurgy then thermal, microstructural and mechanical investigations were performed on the elaborated carbide. A temperature of sintering was determined to be more than 1347 oC by differential thermal analysis (DTA) and differential scanning calorimetry (DSC). Scanning electronic microscopy (SEM) coupled with energy dispersive spectrometer (EDS) observations showed that the microstructure consists in a mixture of angular WC grains and (W,Ti)C rounded grains embedded in the Co-rich binder. X-ray diffraction analysis confirmed the presence of these three phases with free carbon. The results of EDS analysis highlight the solution-reprecipitation phenomena caused by liquid phase sintering and clearly revealed the presence of small amount of free carbon. The mechanical characterizations showed that the WC–TiC– TaC– NbC–Co cemented carbide exhibits excellent hardness-fracture toughness combination.

Experimental investigation on tool wear characteristics of PVD and CVD coatings during face milling of Ti[sbnd]6242S and Ti-555 titanium alloys

Ti6242S and Ti-555, as two typical titanium alloys, are often used to manufacture high-temperature aeroengine parts and landing gear components, respectively. They have different chemical composition and microstructure, which make them have different mechanical properties, and also affect their machinability. In this paper, face milling experiments were carried out to evaluate the wear performance by using CVD-Ti(C, N) + Al2O3 + TiN, PVD-(Ti, Al)N + TiN coated and uncoated tools. The results show that Ti-555 has the worse machinability than that of Ti6242S. When milling Ti6242S, all tools suffered adhesive wear and diffusion wear; the wear of Ti(C, N) + Al2O3 + TiN coated tool was more serious than that of other tools due to the blunt cutting edge; (Ti, Al)N + TiN coated tool suffered micro chipping and coating peeling with the minimal wear loss. When milling Ti-555, uncoated tool suffered serious chipping, abrasive wear and adhesive wear; Ti(C, N) + Al2O3 + TiN coated tool suffered serious chipping and coating peeling with short tool life; (Ti, Al)N + TiN coated tool suffered coating peeling, adhesive wear and diffusion wear. Overall, (Ti, Al)N + TiN coated tools have the longest tool life and are preferred for face milling of Ti6242S and Ti-555 titanium alloys.

Cutting performance and wear mechanism of Sialon ceramic tools in high speed face milling GH4099

This work aims to reveal the cutting performance and wear mechanisms of Sialon ceramic tools for the high-speed face-milling of GH4099, with the goal of improving this process as well as designing more advanced ceramic cutting tools in the future. At the outset of this study, several single-factor experiments were designed with speed as a variable to gather various data on such tools. Failure patterns and tool life curves were first obtained through cutting tests. Afterwards, the tools were split at their place of wear (middle of notch and 1/2 depth of cut) to prepare for further analysis. Wear morphology and element composition distribution in the depth direction of the corresponding interface were then analyzed using a field emission scanning electron microscope (FE-SEM) and energy dispersive spectrometer (EDS) to explore potential diffusion and/or chemical wear. Finally, studies were conducted into the tools’ chemical wear under specific cutting conditions, finishing with a theoretical verification based on the thermodynamic principle of chemical reactions. This research discovered that notch wear was the main failure pattern for the high-speed face-milling of GH4099 under the suitable cutting conditions. Overall, the optimal cutting speed was 1000 m/min, with a tool life of about 3 min. Compared with cemented carbide tools, the machining efficiency for Sialon ceramic tools increased by over a factor of 16. The wear mechanisms for such tools demonstrated a mixture effect of abrasive, adhesive, diffusive and chemical wear. Diffusive wear mainly occurred in their flank faces, but did not constitute the main mechanism of notch wear; chemical wear proved to be a key reason for notch wear at higher temperatures. Based on the aforementioned research, this paper concludes with a proposed comprehensive model for notch wear.

Tool Wear Analysis during Turning of Hard Material by Simulink

Present work is an attempt to develop a simulink model of tool wear by machining of Bearing Steel (62 HRC) using cubic boron nitride (CBN) tool. The available mathematical model in the scholarly literature is used to make the simulation model using MATLAB software. Three components of tool wear adhesive wear, abrasive wear & diffusion wear are considered separately for their modeling and later modeling of total wear is done. Variation of tool wear is studied with respect to cutting speed. The developed simulink model is capable to do the similar type of study by changing the workpiece and tool material combination.