High Tool Wear Research Articles

Effect of V concentration in TiSiN monolayer coating on chip formation mechanism and chip sliding velocity during dry turning of Ti–6Al–4V alloy

The current study examines how the self-lubricating characteristics of the novel TiSiVN coating affect the chip formation process and chip sliding velocity during the dry turning of Ti6Al4V titanium alloy. The serration bands tend to straighten at a cutting speed of 125 m/min, which is the main cause of the chips being straightened without tangling for both coated tools. TiSiVN coated tool accounts for higher chip sliding velocity due to the generation of lubricious phases, whereas the higher VS for uncoated tool indicates high tool wear at the highest cutting speed of 125 m/min. Further, r and θn tend to have an inverse relationship with VS, with 125 m/min cutting speed remaining an exception due to severe changes in tool wear dynamics. The reduction of friction helped to lower the localized strain along the shear bands and the effective stress at the beginning of the formation of the serrated tooth.

Optimizing the Zn and Mg contents of Al–Zn–Mg wrought alloys for high strength and industrial-scale extrudability

High-strength Al alloys of the 7xxx series are promising candidates for further light-weighting of car bodies. However, they are difficult to process by extrusion: complex geometries in particular pose a major challenge due to high extrusion pressures and tool wear. In addition to process optimization, alloy chemistries can be tailored for properties such as good extrudability or high strength. In this work, several experimental alloys based on EN AW 7108A were investigated with respect to the contents of the main alloying elements Zn and Mg, as well as heat treatment (e.g., homogenization), to achieve good extrudability and favourable mechanical properties. The experimental alloys were initially extruded on a small-scale extrusion press and evaluated with regards to their warm formability, microstructure, extrudability, and mechanical properties in T5 temper. Alloy compositions with Mg contents <1.2 wt.-% are optimal and lead to good extrudability as well as high yield strengths well above 350 MPa. The Zn content, on the other hand, has minor influence on the extrudability, but significantly increases strength at higher contents (∼60 MPa). However, the combined Zn + Mg content should not exceed 7 wt.-%. Based on these findings, two optimized alloys were designed, direct chill cast on industrial scale, and extruded on an industrial extrusion press. The alloys showed good extrudability and high strength in the T5 condition. The results also reveal that the limits of the EN AW 7108A alloy are exhausted and higher strengths could only be achieved with the optimized EN AW 7003 alloy.

Alloy modification and ultrasonic-assisted milling of wear-resistant alloys with defined surfaces

The reduction of CO2 emissions is closely linked to the development of highly efficient and economical steel components in plant and process engineering. To withstand the high combined corrosive, tribological, thermal, and mechanical stresses, wear-resistant coatings tailored to the application and steel grade are used. In addition to the increasing demand to substitute conventional cobalt alloys with nickel alloys, there is also a growing need for defined or functional surfaces of high integrity. Due to high tool wear, milling operations required to produce the complex geometries of the components are often not economically feasible for SMEs. By means of alloy modification of the filler metals for nickel-based plasma build-up welded wear-resistant coatings and by the use of innovative ultrasonic-assisted milling processes more favourable machinability shall be achieved without reducing the wear protection potential. In this paper, the influence of the microstructure and precipitation morphology adjusted by means of alloy modification on the machinability is investigated. This is done based on a wear protection alloy NiCrMoSiFeB (trade name: Colmonoy 56 PTA) typically used for screw machines, which substitutes conventional CoCr alloys (Stellite). Metallurgical investigations and in-situ measurements of occurring process forces and temperatures at the tool cutting edge during milling as well as subsequent investigations of tool wear and surface integrity allow a detailed analysis and correlation between microstructural properties and machinability. For the cast samples, a clear change in the microstructure and hardness can be seen through the addition of Al, Ti, or Nb. These differences lead to an improvement in the machining process for Nb. Al and Ti cause long-needled or star-shaped precipitations and hardness increases, which lead to higher cutting forces and increased tool wear.

Investigation of tool wear and energy consumption in machining Ti6Al4V alloy with uncoated tools

This research studies the energy consumption and wear mechanism of carbide cutting tools in dry machining of Ti6Al4V alloy. In the first phase of experiments, full factorial design experiments were employed to study the tool wear rate (R) and specific cutting energy (SCE) with respect to the machining conditions (cutting speed and feed rate). Results showed that machining responses such as tool wear and energy consumption are affected by cutting conditions, thus requiring investigation to understand the wear mechanisms. Therefore, in the second phase, additional experiments were performed to investigate the tool-workpiece interactions at the cutting conditions reported to have low, moderate, and high tool wear. It was revealed that strong adhesion and material transfer between the tool and workpiece caused high wear. Electron dispersive X-ray spectroscopy (EDX) analysis of worn tools showed that the transfer of tungsten (W) and cobalt (Co) to the workpiece and titanium to the tool surface is the primary cause of tool deterioration. As a result, diffusion and dissolution have degraded cutting performance and weakened the tool edge, leading to rapid wear. Furthermore, worn tools resulted in relatively higher energy consumption per unit volume of material removed at the tooltip. The degradation of cutting performance and weakening of the tool edge results in rapid wear and higher energy consumption. The study suggests that minimizing tool wear is crucial for energy reduction, improved sustainability, and cleaner production goals in dry machining of titanium-based alloys.

Analysis of high temperature and mixed tool wear effects on UD-CFRP cutting mechanism in stacks drilling

Analysis of high temperature and mixed tool wear effects on UD-CFRP cutting mechanism in stacks drilling

Laser-assisted surface grinding of innovative superhard SiC-bonded diamond (DSiC) materials

Silicon carbide (SiC)-bonded diamond materials, comprising approximately 50% diamond by volume, represent innovative composites with exceptional mechanical and thermal properties, including high hardness, wear and corrosion resistance, and elevated thermal conductivity. Despite these advantageous properties, the machining of these composites presents formidable challenges due to their extremely high hardness. Grinding with diamond tools is commonly employed among the limited viable machining methods. However, the efficiency of this process is hindered by high grinding forces, elevated temperatures, and significantly high tool wear. Additionally, the surface integrity, form, and dimensional accuracy of the workpiece are compromised by the effects of tool wear and high cutting forces. To address these technological constraints in the grinding of SiC-bonded diamond materials, a laser-assisted grinding process has been developed. Ultra-short pulsed laser radiations were effectively utilized to induce material ablation with controlled structural damages, enhancing the productivity and efficiency of the grinding process through reduced grinding forces, temperatures, and tool wear. Furthermore, this study investigated the influence of grinding tools' specifications, design variations, and parameters on key aspects such as grinding forces, surface quality, and tool wear. Substantial reductions of up to 70% in tangential grinding forces, 83% in normal grinding forces, and a modest improvement in surface roughness achieved. The surface integrity analysis revealed a damage-free ground surface when utilizing laser assistance. Furthermore, there was a substantial enhancement in the grinding ratio (G-ratio), achieving an increase of up to 247%, concurrently with a noteworthy improvement in the actual removal depth, reaching up to 99%, when compared to conventional grinding processes. Compared to the utilized segmented metal bonded diamond grinding wheel, the vitrified bonded diamond grinding wheel induced lower grinding forces and higher actual removal rates.

Investigations on the Surface Integrity and Wear Mechanisms of TiAlYN-Coated Tools in Inconel 718 Milling Operations.

Inconel 718 is a Ni superalloy with superior mechanical properties, even at high temperatures. However, due to its high hardness and low thermal conductivity, it is considered a difficult-to-machine material. This material is widely used in applications that require good dimensional stability, making the milling process the most used in machining this alloy. The wear resulting from this process and the quality of the machined surface are still challenging factors when it comes to Inconel 718. TiAlN-based coating has been used on cutting tools with Yttrium as a doping element to improve the process performance. Based on this, this work evaluated the machined surface integrity and wear resistance of cutting tools coated using Physical Vapor Deposition (PVD) HiPIMS with TiAlYN in the end milling of Inconel 718, varying the process parameters such as cutting speed (vc), feed per tooth (fz), and cutting length (Lcut). It was verified that the Lcut is the parameter that exerts the most significant influence since, even at small distances, Inconel 718 already generates high tool wear (TW). Furthermore, the main wear mechanisms were abrasive and adhesive wear, with the development of a built-up edge (BUE) under a125 m/min feed rate (f) and a Lcut = 15 m. Chipping, cracking, and delamination of the coating were also observed, indicating a lack of adhesion between the coating and the substrate, suggesting the need for a good interlayer or the adjustment of the PVD parameters.

Numerical and experimental study of underwater friction stir welding of 1Cr11Ni2W2MoV heat-resistant stainless steel

Due to the benefits of solid-state joining, friction stir welding (FSW) has seen an increase in applications in the aircraft and automotive industries. However, short tool life and heat-affected zone (HAZ) softening are the two main issues with the FSW of advanced high-strength steel. In this study, the underwater friction stir welding (UFSW) of 1Cr11Ni2W2MoV steel was investigated and compared to the Normal friction stir welding (NFSW). Besides, a 3-D thermo-mechanical finite element model was developed to understand the effect of the different cooling mediums and tool rotation rates on the thermal cycles, plastic deformation, tool wear, and microstructure evolution. The simulation results revealed that the stir zone (SZ) of the UFSW exhibits lower peak temperatures and smaller plastic strain compared to the NFSW. The experimental results showed that a high tool rotation rate can be used during UFSW without causing overheating of the workpiece and tool materials resulting in high joint quality and low tool wear. The M23C6 and Fe3C carbide fractions in the HAZ at UFSW are lower than that at NFSW. The UFSW reduces the soft HAZ's width and increases its hardness. The ultimate tensile strength was increased by 17 %, and the HAZ width was decreased by 35 % at UFSW compared to that at NFSW.

A systematic approach for data acquisition for tool modelling and analysis of wear-dependent tool deflections during milling Inconel 718

Nickel-based superalloys are commonly used for components in the aerospace industry. Due to their favorable mechanical properties, such as high strength and corrosion resistance, these materials are suitable for use under extreme temperature conditions. However, the poor machinability results in high process forces and high tool wear, and, therefore, large tool displacements, so that high manufacturing tolerances are often difficult to achieve. Simulation systems can be used to optimize the process. The data acquisition for the development of the models required is challenging. In the following, a method for in-situ digitization of the tool is presented. Furthermore, the occurring tool deflections during the machining of Inconel718 are analyzed for different wear conditions to serve as basis for the parameterization of simulation models.

Erosion rate investigation and multi-objective optimisation on electrical discharge machining of Ti64 using deep cryo-treated electrodes

Due to its inherent properties, Ti64 has set many challenges in industries during its machining using conventional machining processes. Traditional machining of Ti64 is not a feasible option considering the economic and environmental perspectives. Non-conventional techniques like electrical discharge machining (EDM) are promising methods for machining Ti64 despite challenges like higher tool wear and lower machining rates. The current paper investigated the erosion rates while machining Ti64 using deep cryo-treated electrodes. The peak current (Ip), pulse on time (Ton) and gap voltage (Vg) were used as control parameters while investigating erosion rates, viz., Material Removal Rate (MRR) and Tool Wear Rate (TWR). Experiments were planned according to the RSM-based Central Composite Design (CCD). Considering the multi-objective nature of the current problem, Grey Relational Analysis (GRA) has been incorporated to find a single parametric condition that will satisfy both MRR and TWR. Peak current, [Formula: see text][Formula: see text]A, Pulse On time, [Formula: see text][Formula: see text][Formula: see text]s and Gap voltage, [Formula: see text][Formula: see text]V was found to be the optimal setting giving [Formula: see text][Formula: see text]mm3/min and [Formula: see text][Formula: see text]mm3/min. Furthermore, topographical analysis of the EDMed surfaces has been performed using SEM, XRD and 3D optical profilometry techniques to characterise the surface and to investigate the possibility of other intermetallic compounds formed on the machined surface.

Tool wear and surface finish analysis after drilling Al-SiC metal matrix composite with DLC-coated tools at varying feed

Metal matrix composites (MMCs) show enhanced mechanical and physical properties compared to monolithic alloys, which make them attractive for various engineering applications. However, their actual use in industry is limited due to their low machinability. The hard reinforcements present in the matrix may lead to high tool wear and poor surface integrity. In this context, the paper aims at studying the drillability of an Al-SiC MMC when using DLC-coated tungsten carbide tools at varying feeds. After the machining trials, a quantitative evaluation of the tool wear as well as the analysis of the hole surface roughness and damage was carried out. The results demonstrate that, at increasing feed, the tool wear, surface roughness, and surface defect density decrease, leading to the counterintuitive conclusion that increasing feed when drilling causes an increase in the MMC drillability.

Experimental investigations on ultrasonic assisted turning of magnesium silicon carbide

ABSTRACT The conventional turning (CT) of Mg-SiC was found difficult due to high tool wear and surface roughness, which reduced the machinability of the composites. In this paper, a study applying ultrasonic vibration assisted turning (UAT) along with minimum quantity lubrication (MQL) is proposed to improve the machinability of Mg-SiC. The input parameters used in this work are spindle speed (SS), feed rate (FR), depth of cut (DOC), and percentage intensity of ultrasonic power (PIUP). The flank wear morphology of the cutting tool and average surface roughness (Ra) of the workpiece is studied. In addition, the surface topography of machined samples was studied by AFM to assess the surface quality. The results show that UAT with MQL reduces the Ra by 21% and 7% compared to CT and UAT at dry cutting conditions. The flank wear (Vb) decreased by 15% compared to dry UAT.

Towards Industry 4.0 and Sustainable Manufacturing Applying Environmentally Friendly Machining of a Precipitation Hardened Stainless Steel Using Hot Turning Process

This study aims to address the aforementioned challenges, solutions and implementation perspectives with regard to sustainable manufacturing. In this research, the conventional and hot turning of AISI630 hardened stainless steel have been investigated using PVD-(Ti,Al)N/(Al,Cr)2O3 coated carbide cutting tools at various feed rates and cutting speeds. The high hardness of AISI630, along with the low thermal conductivity, has made it one of the most difficult-to-cut materials, and consequently, its machining is associated with high tool wear and poor workpiece surface quality. AISI630 stainless steel is used in the manufacture of pressure vessels and components exposed to high-stress and corrosive environments in the oil and gas industries. In the present research work, tool flank wear and crater wear mechanisms have been studied in different cutting conditions as well as different preheating temperatures using SEM microscopy. Experimental results showed that hot turning operation at temperatures up to 300 °C reduces flank wear by 33% and improves machined surface roughness by 23%. In addition, FEM simulation has been developed to predict tool tip temperature and cutting forces during turning processes. Experimental and FEM analysis shows that cutting force reduction at a preheating temperature of 300 °C is one of the reasons that reduces tool wear compared to conventional turning. Moreover, it has been shown that by increasing preheating temperature in hot turning, the hardness of the carbides in the workpiece decreases more than the hardness of the tool substrate and reduces coating materials, consequently reducing cutting tool abrasion wear phenomenon.

Investigating the performance evaluation of Cu-Cr tool fabricated by powder metallurgy during electrical discharge machining of EN9 steel

Purpose The purpose of this study is to explore the machining characteristics of electrical discharge machining (EDM) when a tool is fabricated using powder metallurgy. Because pure Cu tools obtained using conventional machining pose problems of high tool wear rate, tool oxidation causes loss of characteristics in tool shape. Design/methodology/approach The research investigation carried out experiments planned through Taguchi’s robust design of experiments and used analysis of variance (ANOVA) to carry out statistical analysis. Findings It has been found that copper and chromium electrodes give less metal removal rate as compared to the pure Cu tool. Analytical outcomes of ANOVA demonstrated that MRR is notably affected by the variable’s polarity, peak current, pulse on time and electrode type in the machining of EN9 steel with EDM, whereas the variables pulse on time, gap voltage and electrode type have a significant influence on EWR. Furthermore, the process also showed that the use of powder metallurgy tool effectively reduces the value of SR of the machined surface as well as the tool wear rate. The investigation exhibited the possibility of the use of powder metallurgy electrodes to upgrade the machining efficiency of EDM process. Research limitations/implications There is no major limitation or implication of this study. However, the composition of the powders used in powder metallurgy for the fabrication of tools needs to be precisely controlled with careful control of process variables during subsequent fabrication of electrodes. Originality/value To the best of the authors’ knowledge, this is the first study that investigates the effectiveness of copper and chromium electrodes/tools fabricated by means of powder metallurgy in EDM of EN9 steel. The effectiveness of the tool is assessed in terms of productivity, as well as accuracy measures of MRR and surface roughness of the components in EDM machining.

WASPAS Based Multi Response Optimization in Hard Turning of AISI 52100 Steel under ZnO Nanofluid Assisted Dual Nozzle Pulse-MQL Environment

Hard turning is an emerging machining technology that evolved as a substitute for grinding in the production of precision parts from hardened steel. It offers advantages such as reduced cycle times, lower costs, and environmental benefits over grinding. Hard turning is stated to be difficult because of the high hardness of the workpiece material, which causes higher tool wear, cutting temperature, surface roughness, and cutting force. In this work, a dual-nozzle minimum quantity lubrication (MQL) system’s performance assessment of ZnO nano-cutting fluid in the hard turning of AISI 52100 bearing steel is examined. The objective is to evaluate the ZnO nano-cutting fluid’s impacts on flank wear, surface roughness, cutting temperature, cutting power consumption, and cutting noise. The tool flank wear was traced to be very low (0.027 mm to 0.095 mm) as per the hard turning concern. Additionally, the data acquired are statistically analyzed using main effects plots, interaction plots, and analysis of variance (ANOVA). Moreover, a novel Weighted Aggregated Sum Product Assessment (WASPAS) optimization tool was implemented to select the optimal combination of input parameters. The following optimal input variables were found: depth of cut = 0.3 mm, feed = 0.05 mm/rev, cutting speed = 210 m/min, and flow rate = 50 mL/hr.

Optimization of PMEDM process parameters for B4C and B4C+SiC reinforced AA7075 composites

MaterialsWith sufficient electrical conductivity can be successfully processed by applying the electrical discharge machining (EDM) method; however, due to the presence of non-conductive particles in composites, which have been produced by adding ceramics particles, problems such as unstable machining, low material removal rate, and high tool wear are observed during the EDM. This study employed powder-mixed electrical discharge machining (PMEDM) by adding electrically conductive nano-size graphite powder into the dielectric liquid to minimize these problems. Moreover, the machinability of AA7075/ B4C and AA7075/ B4C+SiC composites was evaluated using the Taguchi method. The experimental study used L18 orthogonal array (OA) (21 ×32). ANOVA was employed to obtain significant parameters and percent contributions of variable parameters on the material removal rate (MRR). Reinforcement ratio, current and sintering time applied to the workpiece were chosen as variable parameters. The optimum parameters for MRR were obtained at A1B3C3 (reinforcement ratio= 10%, current= 8 A, sintering time=150 min). According to S/N ratio graphs, increasing the reinforcement ratio leads to a decreased MRR. On the contrary, when the applied current increases, MRR increases. Additionally, analysis results show that the discharge current is the most important parameter affecting MRR. In the morphological examinations, it was understood that the amounts of B4C and SiC particles in the composite structure affect the quality of the machined surfaces. It was determined that the surface quality deteriorated with the increase in the amount of SiC and B4C in the composite structure and the increase in the discharge current.

Experimental Setup for In-Process Measurements and Analysis of Wear-Dependent Surface Topographies

Abstract High-strength and corrosion-resistant materials, such as the nickel-based superalloy Inconel 718, are widely used in the energy and aerospace industries. However, machining these materials results in high process forces and significant tool wear. This tool wear negatively influences the resulting surface topography. Nevertheless, the accuracy requirements for functional surfaces are extremely high. Simulation systems can be used to design these processes. However, time-consuming and cost-intensive experiments often have to be conducted to develop and parameterize the required models. To overcome this problem, an analogy test setup for in-process measurements of wear-dependent properties was developed, which allows a multi-level evaluation of the process. By combining different measurement techniques, wear-dependent process characteristics can be determined and analyzed, which is usually only possible for initial and final conditions requiring a significant measurement effort.

Machinability improvement of titanium alloys in ultra-precision machining with micro-structured surface

Titanium alloys get wider applications in different areas due to its excellent mechanical properties. However, poor thermal conductivity and low elastic module of titanium alloy induce high tool wear and make it being one of hard-to-machine materials; especially the segmented chip formation accelerates the diamond tool wear in ultra-precision machining (UPM) of precision parts. This study applies micro-structured surface to improve machinability of titanium alloys in UPM by reducing the chip segmentation induced cutting forces fluctuations. Finite element (FE) model is built to study chip formation mechanism and characterize geometries of segmented chips in orthogonal diamond cutting of Ti6Al4V alloy with the aims at the design of micro-structures array. Turning experiments are conducted to compare cutting force, surface roughness, and tool wear for diamond turning of Ti6Al4V alloy on smooth surface and micro-structured surface. The results show that the FE simulated saw chips agree well with the measured ones. Moreover, the micro-structured surface helps to decrease cutting force, reduce diamond tool wear, and improve surface quality for UPM of titanium alloy. Especially, the new method fabricates micro-grooves array on the machined surface in half-finishing process of UPM without the need of any material pre-processing and extra manufacturing equipment, which can also provide the guidance for efficient and sustainable UPM of titanium alloys parts with high surface quality.

Investigation of CFRP damages induced by the interface high temperature and mixed tool wear mechanism in drilling of thin-walled CFRP /Ti stacks

Due to the poor thermal conductivity and machinability of CFRP and Ti6Al4V, significant heat accumulation at the interface and rapid tool wear are considered the main factors restricting the hole quality. This study conducted a thin-walled CFRP/Ti stack drilling experiment to investigate the evolution of the thrust force, temperature and tool wear versus different drilled hole numbers and spindle speeds, affected by which the novel material removal behavior was revealed. Results showed that the thrust force and interface temperature increased with the hole number and spindle speed, causing a significant increase in the cutting edge rounding and flank face wear dominated by the many fiber bundles and metal debris. In turn, the various tool wear led radial interface temperature to alternately transfer between Φ = 45° and 135°. Under the cyclic thermo-mechanical function, the fibers underwent significant bending deformation as they lost the support of the degenerated matrix resin, forming severe subsurface damage when the interface temperature exceeded the matrix glass transition temperature (Tg = 110 °C). Combined with the comprehensive evaluation of exit damages, a relatively higher spindle speed was preferred for selecting the initial drilling of thin-walled CFRP/Ti stack and gradually reducing the spindle speed with increasing tool wear extent.

A REVIEW ON LASER MACHINING OF ALUMUNIA CERAMIC

Alumina, renowned for its outstanding resistance to corrosion and heat, poses a formidable challenge due to its brittle nature when it comes to machining. Nonetheless, laser machining has emerged as a particularly suitable method for working with hard and brittle materials like alumina. While traditional machining techniques can also be effective, they often necessitate prolonged machining durations and significantly high tool wear rates, thereby driving up the overall machining costs. By employing experimentation and optimization techniques, laser machining technologies such as Nd: YAG lasers, fiber lasers, and CO2 lasers have displayed remarkable efficacy in machining alumina. Notably, CO2 lasers offer distinctive advantages owing to their maximum power output of 45 kW and laser wavelength of 10.6 μm, rendering them suitable for macro material cutting applications. This paper aims to consolidate pertinent information on laser machining of alumina into a single document. The primary focus of this paper revolves around key laser machining parameters, including pulse duration, frequency, peak power, laser power, piercing time, gas pressure, and cutting speed, along with their impact on machining quality aspects such as surface irregularity, kerf width, taper angle, and the Heat-Affected Zone (HAZ).