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Coated carbide tools are widely used in the processing of nickel-based superalloys due to their excellent wear resistance, high strength, and good hardness at high temperatures. In this paper, the high-speed milling experiments and finite element simulation of Inconel 718 are carried out by using PVD TiAlN-coated carbide tools. Simulations of tool temperature, cutting force, and chip morphology were performed to analyze the effect of cutting speed on the degree of sawtooth chip formation and the effect of sawtooth chip formation on the cutting force and tool wear. The results show that the cutting temperature mainly focuses on the rake face, and with the cutting speed increasing from 60 to 120 m/min, the maximum temperature of the rake face increases from 580 to 660 ℃. The maximum temperature region (MTR) on the rake face gradually approaches the tool nose with a decrease in the cutting speed. The generation of sawtooth chips leads to fluctuations in the cutting force component. As the cutting speed increases, the degree of chip sawing increases. The effect of the sawtooth chip on the fluctuation of the cutting force will also increase, thus increasing the degree of tool wear. [ABSTRACT FROM AUTHOR]

Ti1-xAlxN coating is formed by replacing some Ti atoms in TiN with Al atoms, and their properties are closely related to Al content (0 < x < 1). Recently, Ti1-xAlxN-coated tools have been widely used in the machining of Ti-6Al-4V alloy. In this paper, the hard-to-machine material Ti-6Al-4V alloy is used as the study material. Ti1-xAlxN-coated tools are used for milling experiments. The evolution of the wear form and the wear mechanism of Ti1-xAlxN-coated tools are studied, and the influence of Al content (x = 0.52, 0.62) and cutting speed on tool wear are analyzed. The results show that the wear on the rake face changes from the initial adhesion and micro-chipping to coating delamination and chipping. Wear on the flank face varies from the initial adhesion and grooves to boundary wear, build-up layer, and ablation. The main wear mechanisms of Ti1-xAlxN-coated tools are dominated by adhesion, diffusion, and oxidation wear. Ti0.48Al0.52N coating protects the tool well and extends its service life. [ABSTRACT FROM AUTHOR]

Cutting force in lathe work is closely related to tool wear and affects the turning quality. Direct measurement of the cutting force by measuring the strain of the tool holder is challenging because the tool holder design aims to be highly rigid in order to undertake large cutting forces. Accordingly, the most popular dynamometer designs modify the standard tool holder by decreasing the structural rigidity of the holder, which reduces the machining precision and is not widely accepted. In order to solve the issue of the low stiffness of the dynamometer reducing the machining precision, in this paper, the ultra-low strain on the tool holder was successfully detected by the highly sensitive semiconductor strain gauges (SCSG) adjacent to the blade cutting insert. However, the cutting process would generate much heat, which increases the force measuring area temperature of the tool holder by about 30 °C. As a result, the readout drifted significantly with the temperature changes due to the high temperature coefficient of SCSG. To solve this problem, the temperature on the tool holder was monitored and a BP neural network was proposed to compensate for temperature drift errors. Our methods improved the sensitivity (1.14 × 10−2 mV/N) and the average relative error of the BP neural network prediction (≤1.48%) while maintaining the original stiffness of the tool holder. The smart tool holder developed possesses high natural frequency (≥6 kHz), it is very suitable for dynamic cutting-force measurement. The cutting experiment data in the lathe work show comparable performance with the traditional dynamometers and the resolution of the smart tool holder is 2 N (0.25% of total range). [ABSTRACT FROM AUTHOR]

The addition of CaF2@SiO2 and SiC whiskers to ceramic tools can improve their flexural strength and fracture toughness, reduce surface damage, and improve their cutting performance. The cutting experiments showed that under the same cutting conditions, the surface roughness of the workpiece processed with the Al2O3/TiC/SiC/CaF2@SiO2 (ATSC10) tool was significantly lower than that of the workpiece processed with the Al2O3/TiC/ SiC (ATS) tool. Additionally, the main cutting force and cutting temperature when cutting with the ATSC10 tool were lower by 30 and 31.7%, respectively. These results were attributed to the precipitation of CaF2 from the nanocoated particles during cutting and the formation of a uniform and continuous lubricating film on the surface of the tool. The wear on the front surface of the ATS tool was mainly adhesive, and that on the back tool surface was mainly abrasive. For ATSC10, the main forms of wear on the tool front surface were adhesive and abrasive, whereas the main form of wear on the tool back surface was abrasive with slight adhesive wear. The addition of nano-coated particles and whiskers improved the mechanical properties of the cutting tool while maintaining good cutting performance. [ABSTRACT FROM AUTHOR]

DLC has been applied as coating material in the machining of difficult-to-cut materials, and shows a good cutting performance. In this study, Cr/W-DLC/DLC-coated tools were compared with other three kinds of coated tools (TiC-, TiAlN-, Al2O3-) to investigate the cutting performance in the machining of Al–Si alloy. The influence of Cr/W-DLC/DLC-coated tools on the cutting performance under different cutting speeds was studied. Cutting force, cutting temperature, heat partition coefficient, cutting deformation rate, plastic deformation of machined surface, the interface temperature, and stress were investigated numerically with the aid of finite element method (FEM). Actual cutting experiments were carried out to verify the FEM models by means of the cutting force and cutting temperature measurement. The investigation results show that Cr/W-DLC/DLC-coated tool had the best cutting performance among these four kinds of coated tools. With the increasing of cutting speeds, cutting force and cutting temperature showed an increase trend, while the plastic deformation depth of machined surface and heat partition into cutting tool all showed a decrease trend during the machining with Cr/W-DLC/DLC-coated tool. This investigation can provide the theory basis or technical guidance for the cutting practice with Cr/W-DLC/DLC-coated tools. [ABSTRACT FROM AUTHOR]

The coating effect on the cutting temperature has long been a hot topic in understanding heat transfer mechanism in machining coated tools, and especially the multi-layer coated tools. For multi-layer coated tools, the coating structure, coating thickness, and coating material will affect the cutting temperature of the tools. This paper is devoted to the cutting temperature in dry turning of H13 hardened steel with multi-layer coatings. New analytical models for estimating coating temperature and coating–substrate interface temperature were proposed. The multi-layer coating can be equivalent to mono-layer composite coating, which applies equivalent coating layer approach, and was developed to estimate the cutting temperature in turning by heat transfer model of mono-layer coated tool. The analyzed results were compared with appropriate experimental process data using thermocouples and FEM simulated data. The models can accurately reflect the cutting temperature of two multi-layer coated tools under the same cutting condition. [ABSTRACT FROM AUTHOR]

Since Dr. Carl Salomon proposed the well-known hypothesis on cutting temperatures in 1931, the debate on the hypothesis has never stopped. It shows that evolutions of temperatures with the increase of cutting speed measured at different points are different. From the tool wear and surface integrity point of view, this paper focuses on the evolutions of chip temperature (Chip temp.), tool-chip contact temperature (T-C temp.), and tool-workpiece contact temperature (T-W temp.) with the increase of cutting speed from low (100 m/min) to very high (7000 m/min). First, the cutting heat generation and the temperature increment in machining are theoretically analyzed. Then the influences of chip shape and mechanical property variations with the increase of cutting speed on the temperatures are analyzed. Finally, the cutting temperatures are semiquantitatively derived from chip colors and other heat characteristics in the chip and cutting tool obtained in cutting experiments: evolutions of Chip temp., T-C temp., and T-W temp. with the increase of cutting speed are presented based on the experiment results. The influence of chip shape and temperature variation on tool wear are also discussed. [ABSTRACT FROM AUTHOR]

Lots of heat generated in the cutting deformation zone can cause the temperature rising of cutting tool and workpiece during the cutting process. Tool temperature is mainly depended on the heat energy entering into tool in the secondary deformation zone. Higher working temperature can weaken the cutting tool strength and then deteriorate the tool wear. Advanced coating layer deposited on the tool substrate can change the tool-chip friction and affect the heat partition in the tool-chip interface. In order to reveal the mechanism of heat conduction in the secondary deformation zone, the model of heat partition into cutting tool was built. With the aid of finite element method (FEM), the relative parameters which were necessary for the solving of heat partition model were quantified. Actual cutting experiments were carried out to the verification of the FEM models by means of the cutting force and temperature measurement. Influences of coatings (i.e., coating materials, coating thickness) and cutting speeds on the heat partition were analyzed. And then, rake face temperatures obtained at four kinds of coated tools were compared. The investigation results showed that TiC coating appears as the maximum value and Al2O3 coating appears as the minimum value of heat partition coefficient into cutting tool among these four kinds of coatings (i.e., TiC, TiN, TiAlN, Al2O3). With the increasing of coating thickness and cutting speeds, heat partition into cutting tool all showed a decrease trend. Al2O3-coated tool had the maximum rake face temperature among these four kinds of coated tools; however, the location of peak temperature on the rake face of Al2O3-coated tool was the shortest distance from the tool tip. [ABSTRACT FROM AUTHOR]

In the field of ceramic tool processing, the incorporation of solid lubricants into self-lubricating ceramic tools forms a supportive lubricating film during the cutting process, effectively enhancing the cutting performance of the tools. Concurrently, Nanofluid Minimum Lubrication Technology (NMQL), as an emerging lubrication method, holds the potential to improve tool performance. However, due to significant cutting forces, NMQL faces challenges in effectively reaching the machining area, thereby limiting its cooling and lubricating efficiency. To overcome this challenge, our study proposes an innovative strategy by combining self-lubricating ceramic tools with nanofluids, aiming to enhance ceramic tool performance through synergistic lubrication effects. We conducted experimental studies under various lubrication conditions, comparing the performance of self-lubricating ceramic tools with traditional ceramic tools in cutting operations. A comprehensive evaluation of parameters such as tool life, cutting temperature, and cutting forces was performed. The results demonstrate that self-lubricating ceramic tools enable more efficient penetration of nanofluids into the machining area. In comparison to sole nanofluid lubrication, the synergistic effect significantly improves tool performance while substantially reducing production costs. This research contributes to advancing the development and widespread application of self-lubricating ceramic tools in the field of mechanical processing. • Synergistic lubrication effect of nanofluids and self-lubricating ceramic tools. • Co-lubrication significantly improves cutting temperature and tool life. • Co-lubrication significantly improves the surface quality of the workpiece. • Lower tool wear under co-lubrication conditions. • Co-lubrication helps to reduce machining costs and realize sustainable manufacturing. [ABSTRACT FROM AUTHOR]

A gradient nano self-lubricating ceramic cutting tool material was prepared by vacuum hot-pressing sintering technique. The composition of each layer is designed in a gradient so that the nano-sized solid lubricant content is gradually reduced from the surface to the center, and residual compressive stresses are formed in the tool surface. The components and microstructure of the prepared ceramic tools showed gradient changes, with clear and well-bonded interfaces between the gradient layers. Compared with the mechanical properties of homogeneous tool, the flexural strength, fracture toughness, and hardness of this ceramic tool were increased by 74.0%, 3.9%, and 5.0%, respectively. The gradient design had little effect on the friction coefficient, but the improved mechanical properties and the presence of residual compressive stresses in the surface layer improved the wear resistance of the tool. The higher the friction speed and load, the more effectively the gradient design will improve the wear rate. [ABSTRACT FROM AUTHOR]

A cBN-Al 2 O 3 -Al cutting tool material was prepared by a dual power spark plasma sintering method, and the effects of sintering temperature, holding time and Al 2 O 3 content on the microstructure and mechanical properties of cBN-Al 2 O 3 -Al cutting tool material were studied. The results showed that the dual power sintering method strengthened the spark plasma generated between the particles, increased the uniform discharge effect of the metal Al in the sintered body, generated a local high temperature and reacted with the activated cBN to produce AlN, and inhibited the phase change of cBN. When the sintering temperature was 1500 °C, the holding time was 5 min, and the pressure was 50 MPa, the overall mechanical properties of cBN-Al 2 O 3 -Al cutting tool material with 50 wt% Al 2 O 3 content were the most optimal, with a hardness of 24.45 GPa, a fracture toughness of 5.92 MPa·m1/2, and a flexural strength of 423 MPa. • cBN-Al 2 O 3 -Al cutting tool material was prepared by pulsed direct current and 200 kHz high-frequency dual power SPS sintering. • The conversion from cBN to hBN was inhibited by dual power supply sintering. • Find the best sintering temperature, holding time, Al 2 O 3 content, respectively 1500 °C, 5 min, 50 wt%. • The maximum hardness and flexural strength are 24.45 GPa and 423 MPa respectively. [ABSTRACT FROM AUTHOR]

In order to improve the mechanical property of self-lubricating ceramic cutting tool, (W,Ti)C based ceramic composites with the additions of nano-sized CaF 2 solid lubricants were produced by vacuum hot pressing. Results showed that nano-sized CaF 2 was mainly located in matrix grains and formed the intragranular self-lubricating nanostructure. The optimal mechanical properties were achieved at 1650 °C and 15 min. The flexural strength, hardness and fracture toughness reaches the maximum of 497 MPa, 16.3GPa and 6.48 MPa·m1/2, respectively. Compared with the ceramic composite without CaF 2 , the fracture toughness was increased by 13.0%. Dry machining tests of hardened 40Cr steel were performed with these ceramic cutting tools. It indicated that with the additions of nano-sized CaF 2 as solid lubricant, the main cutting force and cutting temperature were reduced by 13.2% and 26.9%, the average friction coefficient of rake face was reduced from 0.59 to 0.32. SEM micrograph showed that a self-tribofilm was consistently formed on the rake wear area which has a good self-lubricating effect. • Nano-sized CaF 2 solid lubricant is introduced into ceramic cutting tools. • (W,Ti)C-based ceramic composites with nano-sized CaF 2 solid lubricants were prepared by vacuum hot pressing method. • The flexural strength, hardness and fracture toughness reaches the maximum of 497 MPa, 16.3GPa and 6.48 MPa·m1/2. • CaF 2 effectively reduces the coefficient of friction on the front face of the tool. [ABSTRACT FROM AUTHOR]