Tool Wear Mechanisms Research Articles

Tool life and wear mechanisms of CVD coated and uncoated SiAlON ceramic milling inserts when machining aged Inconel 718

In this study, an investigation has been conducted to fully characterise for the first time the tribological benefits of adding two different types of chemical vapour deposition (CVD) coatings to silicon aluminium oxynitride milling inserts with a chemical composition of (Si3N4 + Al2O3 + Y2O3), known by the trade abbreviation ‘SiAlON’, typically used to cut difficult to machine materials such as Inconel 718. The experimental tests compared the tool life, material removed and wear resistance of the two different CVD coated inserts against that of uncoated SiAlON ceramic milling inserts. Coating A was a multilayer CVD coating and had a composition of (TiN + TiCN + Al2O3), Coating B was a bilayer CVD coating and had a composition of (Al2O3 + TiN). It was determined that at 900 m/min the uncoated SiAlON ceramic milling inserts exhibited the least amount of wear and variation in cutting force when milling precipitation hardened Inconel 718 samples. Coating A demonstrated significantly lower adhesion to the SiAlON substrate but had higher tool life and material removal rates, Coating B demonstrated excellent adhesion to the SiAlON substrate. The interfacial bonding of Coating B allowed for much higher adhesion to the substrate, but it suffered from much lower tool life and higher rates of rake and flank face wear. The flank wear measurements concluded a cutting speed of 900 m/min to be the optimum cutting speed for machining Inconel 718 with uncoated SiAlON ceramic milling inserts.

Tool wear mechanisms of PCD micro end mill in machining of additive manufactured titanium alloy

Tool wear mechanisms of PCD micro end mill in machining of additive manufactured titanium alloy

Approaches for Preventing Tool Wear in Sheet Metal Forming Processes

Sheet metal forming processes, the purpose of which is to give the shaped material appropriate mechanical, dimensional and shape properties, are characterised by different values of unit pressures and lubrication conditions. Increasing the efficiency of tool work by increasing their durability, efficiency and reliability is still one of the main indicators of increasing production efficiency. Tool wear in metal forming technologies significantly differs from the character of wear in other methods of metalworking, such as machining. This article presents the characteristics of tool wear mechanisms used in sheet metal forming. Possibilities of increasing the durability of tools by applying coatings produced by laser techniques, chemical vapour deposition and chemical vapour deposition are also discussed. Great emphasis is placed on self-lubricating and functional materials and coatings. Current trends in lubricants and lubrication methods in sheet forming, including tool texturing, are also presented.

Tool wear and surface integrity in liquid nitrogen clean cutting of cobalt-based superalloy GH605 with AlTiN coated tools

The tool wear is severe and the machined surface quality is low in dry cutting of cobalt-based superalloy. The traditional coolant is harmful to the environment and not in line with sustainable development. The liquid nitrogen (LN2) clean cutting of cobalt-based superalloy GH605 using AlTiN coated tools is proposed in this work. The tool wear mechanism and the machined surface integrity are investigated. The results show that, with the decrease of LN2 injection temperature, the sharp wear stage of the tool can be delayed. The injection temperature directly affects the tool life. Compared with dry cutting, the tool life is increased by 42.5% at LN2 injection of −190 °C. Under the lower liquid nitrogen condition, the coating peeling is reduced on the rake face. The decrease of LN2 injection temperature can effectively reduce the damaged area of the flank face and inhibit the oxidation wear. The injection temperature between −30 °C and −150 °C can significantly reduce the surface roughness. The minimum surface roughness value at the injection temperature of −90 °C is 0.486 μm, which is 39.4% lower than that at dry cutting condition. When the LN2 injection temperature is below −90 °C, the thickness of the white layer is less than half of that in dry cutting condition. The hardness of the machined surface is enhanced and the residual stress is reduced at injection temperature below −150 °C. This work demonstrates the possibility of improving the machinability of cobalt-based superalloy by optimizing the LN2 injection temperature.

Friction Stir Welding/Processing of Various Metals with Working Tools of Different Materials and Its Peculiarities for Titanium Alloys: A Review

A review of the state of research in the field of friction stir welding and processing has been carried out. The features of plastic flow in friction stir welding and their connection with the processes of adhesion friction are shown. The main direction of research is related to the features of friction stir welding of titanium alloys. Special attention is paid to the selection of working tool materials from various alloys for friction stir welding and the processing of titanium alloys. The main advantages and disadvantages of applying different types of tools for friction stir welding of titanium alloys are shown. Different mechanisms of tool wear in friction stir welding associated with the interaction of processed material and tools are demonstrated. Information on the influence of tool and material interaction at welding on the mechanical properties and operational characteristics of obtained joints is given.

Using Nano-Fluids Minimum Quantity Lubrication (NF-MQL) to Improve Tool Wear Characteristics for Efficient Machining of CFRP/Ti6Al4V Aeronautical Structural Composite

The aeronautical industry constantly strives for efficient technologies to facilitate hole-making in CFRP/Ti6Al4V structural components. The prime challenge in this direction is excessive tool wear because of the different engineering properties of both materials. Nanofluid minimum quantity lubrication (NF-MQL) is the latest technology to provide synergistic improvement in tool tribological properties and lubrication function during machining. In the current study, an MoS2-based NF-MQL system was applied during helical milling using a FIREX-coated tool. In-depth analysis of wear, a scanning electron microscope (SEM), and electron deposition spectroscopy (EDS) were used to evaluate workpiece elemental transfer and tool wear mechanisms. Experimental findings showed that 1% nanoparticles concentration in lubricant resulted in low tool wear of 13 µm after 10 holes. The SEM and EDS analyses depicted formation of tribo-film on the surface, resulting less severe wear and a reduced degree of adhesion. However, a low nanoparticle concentration of 0.5% resulted in 106 µm tool wear after 10 holes with slight evidence of tribo-film. Parametric analysis based on eccentricity, spindle speeds (individual for CFRP and Ti6Al4V), axial pitch, and tangential feed showed correlations with mechanical damage. An extended study of up to 200 holes showed diffusion of C element at a high rate as compared to metal elements such as W and Co. The lowest tool wear was observed using eccentricity level 1, spindle speed Ti6Al4V 1000 rpm, spindle speed CFRP 7500 rpm, tangential feed 0.01 mm/tooth, axial pitch 1.5 mm, and 1% of MoS2 nanoparticles.

Investigation on tool wear mechanisms and machining tribology of hardened DC53 steel through modified CBN tooling geometry in hard turning

DC 53 steel has emerged as a possible replacement of AISI D2 steel possessing competitive hardness and better toughness. In the current work, turning of DC 53 steel was conducted via Xcel modified inserts by varying workpiece hardness levels (40 and 60 HRC), cutting speed (130 and 160 m/min), feed rate (0.07 and 0.112 mm/rev), and depth of cut (0.07 and 0.17 mm). A two-level 4-factor full factorial design was employed entailing 16 runs. An analysis of variance (ANOVA) was conducted to statistically analyze the effect and contributions of input parameters on response variables namely tool life, surface roughness, volume of material removed, power consumption, and machining zone temperature. Results show that the tool life, surface roughness, volume of material removed, and machining zone temperature are primarily affected by the hardness of DC53 with PCRs of ~ 96%, ~ 25%, ~ 62%, and ~ 25%, respectively. At a 40 HRC hardness value, true crater wear was observed due to continuous chips sliding at the rake face while for the workpiece having a 60 HRC, discontinuous chip formation produced less prominent crater wear. SEM images revealed complete delamination of the coating from the tool surface with adhesion and attrition wear identified as the main wear mechanisms. The formation of a groove pattern was also noticed on the flank face. The minimum surface roughness was 0.90 µm-Ra for the workpiece having a 40 HRC hardness level, and the same value was obtained for 60 HRC as well. The threshold value of the feed rate for the excellent performance of these inserts was less than 0.20 mm/rev. Additionally, the turning process proved to be productive for this material along with a lower surface roughness value in comparison to the wire EDM process.

Assessment of the tribological and wear performance of new duplex AlTiN-based coating systems at high temperatures when threading super duplex stainless steel

During machining, a significant amount of energy is transferred at the cutting interfaces (tool/chip and tool/workpiece) to perform a cut. Tribology is the science of how surfaces interact when cutting metal, describing the physics and mechanics characterized by high loads and temperatures at the cutting interface. This paper explains how to determine the energy consumption required to make a cut, considering different combinations of cutting tool/coated surface and the wear characteristics of each one. Moreover, this paper finds the correlation produced by the effect of the heavy-load high-temperature on the friction condition between the interactive surfaces. Based on these findings, cutting tests (threading operations) were conducted to verify the tool wear mechanisms of the different AlTiN-based coatings, the amount of energy each consumed to perform the cut, and their tribological behaviour. The cutting test confirmed the tribometer simulation result. The AlTiNOS + WC/C coating demonstrated the minimum coefficient of friction in both the experimental and simulation analyses, while the AlTiNOS + TiB2 coating possessed a better combination of wear resistance and mechanical properties.

Tool Wear Mechanism and Grinding Performance for Different Cooling-Lubrication Modes in Grinding of Nickel-Based Superalloys.

Tool wear introduced during grinding nickel-based superalloys was identified as a significant factor affecting the production quality of aero-engine industries concerning high service performance and high precision. Moreover, uncertainties derived from the various cooling-lubrication modes used in grinding operations complicated the assessment of grinding preformation. Therefore, this work investigated the tool wear mechanisms in grinding nickel-based superalloys that adopted five cooling-lubrication modes and investigated how the wear behaviors affected grinding performance. Results showed that chip-deposits covered some areas on the tool surface under dry grinding and accelerated the tool failure, which produced the highest values of tangential force, 7.46 N, and normal force, 14.1 N. Wedge-shape fractures induced by indentation fatigue were found to be the predominant wear mechanism when grinding nickel-based superalloys under flood cooling mode. The application of minimum quantity lubrication-palm oil (MQL-PO), MQL-multilayer graphene (MQL-MG), and MQL-Al2O3 nanoparticles (MQL-Al2O3) formed lubricity oil-film on the tool surface, which improved the capacity of lubrication in the tool-workpiece contact zone and provided 37%, 30%, and 52% higher coefficient of friction than dry mode, respectively. The results of this study demonstrate that lubricated oil-film produced by MQL modes reduces the possibility of fractures of cubic boron nitride (CBN) grits to some extent.

Cutting performance of the nanotwinned cBN tool in nano-cutting of Ni-Cr-Fe alloy

As nickel-based superalloys are broadly used and difficult to machine material, it is challenging to achieve high machining efficiency while improving surface quality and enhancing tool life. Aiming at the cutting of Inconel-718 type nickel-based superalloys, a new type of tool in which the cBN tool incorporated naontwinned structures is proposed. The mechanical properties of cBN tool materials with the introduction of nanotwinned structures are studied by uniaxial tensile simulations of nanotwinned cBN (nt-cBN) and single-crystal cBN (sc-cBN) nanosheets. Compared with the sc-cBN materials, the introduction of nanotwinned structures improved the properties of strength, toughness, and stiffness of cBN materials. The tool performance of the nt-cBN tool and the sc-cBN tool have been studied when cutting a simplified nickel-based superalloys (Inconel-718) model using the molecular dynamics method. Tool wear mechanisms of nt-cBN tools are investigated by calculating and visualizing tool temperature, Von Mises stress, and shear stress distributions. The results show that the wear resistance performance of the nt-cBN tool has improved during high-speed cutting, with less plastic deformation of the tool, less diffusion wear, less adhesion wear, and especially the wear of the flank surface is significantly reduced. As a new type of tool for machining difficult-to-machine materials, nt-cBN tools have promising research prospects.

High-speed milling of hardened steel under minimal quantity lubrication with liquid nitrogen

Minimal quantity lubrication (MQL) can effectively reduce tool wear and improve surface quality in the high-speed milling of hardened steel, but MQL still suffers from poor cooling effect and oil-film failure at high cutting temperature. Compared with MQL, the cryogenic liquid nitrogen (LN2) or LN2 + MQL method with a highly strong cooling ability can further improve the processing conditions of the high-speed milling of hardened steel. However, the knowledge about the characteristics and mechanisms of the high-speed milling of hardened steel under the cryogenic LN2 and LN2 + MQL cooling is scarce. Thus, high-speed milling of hardened steel under cryogenic LN2 and LN2 + MQL cooling was studied in this paper. The machining characteristics were analyzed, and the machining mechanisms of cooling lubrication, tool wear, and surface deterioration layer formation were discussed. The experimental results show that the tool life of LN2 + MQL is remarkably longer than that of MQL, and high surface quality can be maintained at a long cutting distance. In the high-speed milling of hardened steel under the LN2 and LN2 + MQL modes, adhesion has little effect on tool wear, abrasion and chipping/flaking are the main tool wear mechanisms, and chipping/flaking is the main mechanism of tool breakage. MQL reduces the cutting interface friction using oil-film boundary lubrication, LN2 quickly removes the cutting interface heat using a strong cooling and heat transferability, and LN2 + MQL combines the advantages of both cooling and lubrication. Compared with MQL, the surface hardness of the plastic deformation layer of the LN2 and LN2 + MQL modes is considerably increased, whereas the thickness is smaller, and the strong low-temperature cooling is the main reason for this difference. The increase in tool wear will promote the cutting temperature and material slip deformation, increase the depth of high stress and strain zone and eventually increase the thickness of the plastic deformation surface layer in the LN2 and LN2 + MQL modes. In the two modes of LN2 and LN2 + MQL, there are no oxidation, nitridation, secondary quench hardening, and phase transformation in the surface layer. Severe dislocation strengthening caused by severe plastic deformation of the surface layer is the main hardening mechanism of the workpiece surface layer.

The Influence of the Metalworking Fluid on Tool Wear in Milling Inconel 718

The understanding of tool wear mechanisms is fundamental to developing more productive machining processes. Therefore, the influence of different metalworking fluids on tool wear is studied when milling Inconel 718 using a rotating dynamometer, a stationary dynamometer, and a 3D microscope. A newly developed force model allows the interpretation of more than the maximal cutting force and explains the relation between tribological conditions, tool wear and process forces. In a novel setup, the coolant type was changed in the middle of the tool life to differentiate the direct influence of the coolant on the process forces and the indirect effect via tool wear. By fitting the model to the data, it is found that the metalworking fluid and the process parameters not only influence the wear rate globally, but also lead to different wear mechanisms. The 3D data of worn cutting edges confirms the existence of different wear mechanisms.

Dry and MQL Milling of AISI 1045 Steel with Vegetable and Mineral-Based Fluids

The use of mineral-based cutting fluids in machining has the drawback of affecting the environment and industries are under pressures to reduce its use in favor of cleaner productions. In this regard, the vegetal-based cutting fluids can be a superior alternative, provided they improve the technical outcomes. In the milling process, dry cutting is commonly performed, however, the application of cutting fluids using the minimum quantity of lubricant (MQL) method has proven advantageous when compared with dry machining. Furthermore, in the midst of the availability of several cutting fluids in the market, the testing of their individual performance can ascertain their potential and effectiveness for a particular application. This study examined the performances of two vegetable-based and one mineral-based oils applied by the MQL method, followed by their comparison with dry cutting amid end milling of AISI 1045 steel with TiAlN-coated cemented carbide inserts. The cutting temperature, machining forces, power consumption, workpiece surface roughness, tool life, and tool wear mechanisms were chosen as the output parameters. The experiments were conducted using two cutting speeds (150 and 200 m/min) and feed rates (0.07 and 0.14 mm/tooth), and constant axial (1 mm) and radial depths of the cut (25 mm). The temperature was measured using a K-type thermocouple soldered to the part and an infrared camera. The power was monitored with a Fluke 435 energy analyzer, and the machining force components with a Kistler dynamometer. The worn inserts were inspected under a scanning electron microscope (SEM) to analyze the tool wear mechanism. The MQL-assisted application of the cutting fluids notably lowered the cutting temperature and increased the tools’ lives. However, the cutting fluids did not reflect any significant effect on the machining force, power consumption, or surface roughness. Among all the analyzed cutting conditions, the abrasive wear mechanism dominated, damaging the cutting edges, flank, and rake surfaces of the cutting tools. In addition, adhesive and diffusion wear mechanisms were also observed.

A critical review on tool wear mechanism and surface integrity aspects of SiCp/Al MMCs during turning: prospects and challenges

A critical review on tool wear mechanism and surface integrity aspects of SiCp/Al MMCs during turning: prospects and challenges

Tool wear reduction in ultrasonic vibration-assisted turning of SiC-reinforced metal-matrix composite

In recent years, metal matrix composites (MMCs) have attracted the interest of various industrial sectors thanks to the benefits they offer in terms of lightness and mechanical properties compared to equivalent non-reinforced metallic alloys. Nevertheless, when machining MMCs, their heterogeneous structure, specifically characterized by the presence of hard particles within a much more ductile matrix, induces different thermal and mechanical loads when the cutting edge passes through the various composite constituents. This, in turn, may drastically reduce the cutting tool life as well as deteriorate the part surface integrity leading to poor in-service performances of the part. Nonconventional machining methods are usually employed to manufacture parts made of MMCs, nevertheless at the cost of scarce workpiece surface integrity and increased manufacturing burdens. To overcome the above-mentioned issues, ultrasonic vibration-assisted turning (UVAT) is proposed in this study as an efficient approach to machine MMCs. Turning trials with and without the application of ultrasonic vibration were carried out at varying cutting speeds, feed and volume of removed material. The tool wear mechanisms were identified and quantified. The surface finish and chip morphology were also analyzed as further machinability parameters for comparing the different machining approaches and assessing the advantages of UVAT. The obtained experimental results showed that the adoption of ultrasonic vibrations together with high feed can significantly increase the tool life, representing a suitable approach for efficiently machining MMCs.

Modeling of Dynamic Cutting Force considering Flank Wear and Analysis of Tool Wear Mechanism in Milling 508III Steel

508III steel is widely used to manufacture the key components of water chamber head of nuclear island evaporator because of its excellent performance. Due to the large milling parameters and their high strength, hardness, and adhesion, cemented carbide tools are subjected to large cyclic mechanical load. Serious tool wear and low service life have become more prominent problems in the cutting process. Therefore, the research on the dynamic cutting force and wear mechanism of cemented carbide tools for milling 508III steel is attracting more and more attention. In this study, based on the theory of cutting mechanics and the force balance condition of circular tool cutting unit, the cutting force model under ideal condition was established. On this basis, the tool dynamic cutting force model considering flank wear was constructed. The tool wear experiment of milling 508III steel was carried out under different cutting parameters, and the change curve of tool wear life and the actual dynamic cutting force at different cutting time were obtained. And the accuracy of the established dynamic cutting force model was verified. Scanning electron microscopy and energy dispersive X-ray spectroscopy were used to analyze the wear morphology and mechanism of cemented carbide tools. The research findings can are of great significance for revealing the tool failure mechanism of milling water chamber head, reasonably selecting machining parameters, and improving the machining quality and efficiency of nuclear power parts.

Wear mechanisms of solid carbide cutting tools in dry and cryogenic machining of AISI H13 steel with varying cutting-edge radius

This study presents an experimental investigation on tool wear mechanisms in dry and cryogenic machining when milling AISI H13 steel with varying cutting-edge radius. The aim was to study the effect of cutting-edge radius on the wear mechanism of rounded cutting-edge radius of an uncoated carbide cutting tool under dry and cryogenic machining. Uncoated four flute cemented carbide cutting tools of 6 mm diameter with prepared cutting-edge radius, Rn of 0.03 mm and commercial cutting-edge radius, Rn of 0.018 mm were used in the study. The machining parameters applied were cutting speed, Vc = 200 m/min, feed rate, f = 0.03 mm/tooth and depth of cut, ap = 0.1 mm. The coolant used for cryogenic machining was liquid nitrogen (LN2). The results revealed that longer tool life time was achieved in cryogenic machining rather than in dry machining. Compared to a commercial tool with cutting-edge radius, Rn = 0.018 mm under dry machining, the obtained results showed that a prepared tool with cutting-edge radius, Rn = 0.03 mm under cryogenic machining condition enhanced the cutting tool performance with a 55% increase of tool life time. In mechanisms of wear, adhesive and abrasive wear are the major wear mechanisms which take place under dry and cryogenic machining, of which the formation of adhesive and abrasive wear is more severe in dry machining rather than in cryogenic machining. These important results in cryogenic application have good potential in the future which can be applied commercially in the machining industry.

Comparison of Tool Wear, Surface Morphology, Specific Cutting Energy and Cutting Temperature in Machining of Titanium Alloys Under Hybrid and Green Cooling Strategies

Cutting energy must be reduced in order to make machining processes more eco-friendly. More energy was expended for the same amount of material removed, hence a higher specific cutting energy (SCE) implies inefficient material removal. Usually, the type of coolants or lubricants affects the SCE, or the amount of energy needed to cut a given volume of material. Therefore, the present work deals with a study of SCE in the turning of Ti–3Al–2.5V alloy under green cooling strategies. In spite of this, the research effort is also focused on the mechanism of tool wear, surface roughness, and cutting temperature under hybrid cooling, i.e., minimum quantity lubrication (MQL) and cryogenic. The tool wear rate, were explored with tool mapping analysis, and the results were compared with dry, MQL, and liquid nitrogen (LN2) conditions. The tool wear rate analysis claims that the dry condition causes more built up edge (BUE) formation. In addition, the hybrid cooling conditions are helpful in reducing the SCE while machining titanium alloys.

A Comprehensive Review on the Conventional and Non-Conventional Machining and Tool-Wear Mechanisms of INCONEL®

Nickel-based superalloys, namely INCONEL® variants, have had an increase in applications throughout various industries like aeronautics, automotive and energy power plants. These superalloys can withstand high-temperature applications without suffering from creep, making them extremely appealing and suitable for manufactured goods such as jet engines or steam turbines. Nevertheless, INCONEL® alloys are considered difficult-to-cut materials, not only due to their superior material properties but also because of their poor thermal conductivity (k) and severe work hardening, which may lead to premature tool wear (TW) and poor final product finishing. In this regard, it is of paramount importance to optimise the machining parameters, to strengthen the process performance outcomes concerning the quality and cost of the product. The present review aims to systematically summarize and analyse the progress taken within the field of INCONEL® machining sensitively over the past five years, with some exceptions, and present the most recent solutions found in the industry, as well as the prospects from researchers. To accomplish this article, ScienceDirect, Springer, Taylor & Francis, Wiley and ASME have been used as sources of information as a result of great fidelity knowledge. Books from Woodhead Publishing Series, CRC Press and Academic Press have been also used. The main keywords used in searching information were: “Nickel-based superalloys”, “INCONEL® 718”, “INCONEL® 625” “INCONEL® Machining processes” and “Tool-wear mechanisms”. The combined use of these keywords was crucial to filter the huge information currently available about the evolution of INCONEL® machining technologies. As a main contribution to this work, three SWOT analyses are provided on information that is dispersed in several articles. It was found that significant progress in the traditional cutting tool technologies has been made, nonetheless, the machining of INCONEL® 718 and 625 is still considered a great challenge due to the intrinsic characteristics of those Ni-based-superalloys, whose machining promotes high-wear to the tools and coatings used.

Investigation into machining performance of microstructurally engineered in-situ particle reinforced magnesium matrix composite

Magnesium and magnesium in-situ composites have significant potential in the application of design and manufacturing for automotive and aerospace industries because of their high specific strength and reduced fuel consumption. But there are many challenges for machining of Mg based alloys and composites because of the high tendency of fire and oxidation. These challenges can be minimized through microstructural engineering. In this present study, the machining performances of AZ91 Mg alloy and in-situ hybrid TiC+TiB2 reinforced AZ91 metal matrix composite was investigated. The effect β-Mg17Al12 phases and grain refinement with and without in-situ particles on machinability were studied through microstructural engineering via aging and friction stir processing. The end milling operation was carried out at different cutting speeds ranging from 25 mm/min to 90 mm/min under dry environment by using an AlTiN-coated tungsten carbide tool. The optimum cutting speed for machining was found to be 75 mm/min based on the surface roughness values of all conditioned materials. The base material with dendritic microstructure was found to have poor machinability in terms of inadequate surface finish and edge-burrs formation. The combined effect of in-situ TiC+TiB2 particles addition and grain refinement enhanced the machining performance of the material with superior surface finish, negligible edge-burr formation and better tool wear resistance. The influence of in-situ TiC+TiB2 particles, β-Mg17Al12 phases and grain refinement on machining characteristics are explained based on the tool wear mechanisms, chip behavior and machining induced affected zone.