Explore the vast range of titles available.

In this paper, a state-of-the-art review on cutting tool technology in machining of Ni-based superalloys is presented to better understand the current status and to identify future directions of research and development of cutting tool technologies. First, past review articles related to the machining of Ni-based superalloys are summarized. Then machinability of superalloys is introduced, together with the reported methods used in cutting tool design. The current researches on cutting tools in the machining of superalloys are presented in different categories in terms of tool materials, i.e., carbide, ceramics, and Polycrystalline cubic boron nitride (PCBN). Moreover, a set of research issues are identified and highlighted to improve the machining of superalloys. Finally, discussions on the future development are presented, in the areas of new materials/geometries, functional surfaces on the cutting tool, and data-driven comprehensive optimization.

The wear mechanism of single aggregated cubic boron nitride (AcBN) grains during ultrasonic vibration-assisted grinding (UVAG) is investigated in this study. The experiments involve conventional grinding and ultrasonic vibration-assisted grinding on gamma titanium-aluminum intermetallic compounds, and the grain wear mechanism is comprehensively revealed by observing the radial wear height, normal force, average volume pile-up ratio, and morphology evolution of the grains under different conditions including maximum undeformed chip thicknesses, grinding speeds, and ultrasonic amplitudes. The experimental results demonstrate that the introduction of ultrasonic vibration induces periodic tangential vibrations in the workpiece, leading to intermittent dissociative behavior and effectively reducing the normal force and average volume pile-up ratio of individual AcBN grains during grinding. However, it also causes an increase in instantaneous maximum undeformed chip thickness and introduces periodic impact forces, thereby accelerating the radial wear height of the AcBN grains. Moreover, ultrasonic vibration can significantly diminish material adhesion on the surface of AcBN grains while promoting continuous micro-fracturing for enhanced self-sharpening ability. Nevertheless, excessive ultrasonic amplitude may result in macro-fracture of AcBN grains and expansion of bond cracks, leading to abrasive grain pull-out and partial loss of grinding capability.

This paper presents a comprehensive study of two tool materials designed for the machining of Inconel 718 superalloy, produced through two distinct sintering techniques: High Pressure–High Temperature (HPHT) sintering and Spark Plasma Sintering (SPS). The first composite (marked as BNT), composed of 65 vol% cubic boron nitride (cBN), was sintered from the cBN–TiN–Ti3SiC2 system using the HPHT technique at a pressure of 7.7 GPa. The second composite (marked as AZW) was fabricated from the Al2O3–ZrO2–WC system using SPS at a pressure of 63 MPa. The final phase composition of BNT material differed significantly from the initial composition due to reactions occurred during sintering. In contrast, the phase composition of the AZW ceramic composite before and after sintering was similar. The materials exhibited high quality, as evidenced by a Young’s modulus of 580 GPa for BNT and 470 GPa for AZW, along with hardness of 26 GPa for BNT and 21 GPa for AZW. Both composites were used to prepare cutting inserts that were evaluated for their performance in machining Inconel 718 alloy. While both inserts showed durability comparable to their respective reference commercial inserts, they differed in performance and price relative to one another.

Laser ablation of polycrystalline cubic boron nitride (PCBN) material has been a great interest to cutting tool design and machining community due to distinct advantages offered by laser surface texturing on flank and rake surfaces of cutting tools for improved friction, reduced tool wear, and enhanced effectiveness of coolant application. There are challenges on controlling the ablation depth and surface integrity induced by laser processing on the PCBN material with CBN grains often with secondary phase as titanium and tungsten carbide, aluminum nitride/aluminum diboride. Surface topography and surface integrity impose effects on the resultant wear and thermal fatigue performance on the cutting tool material. This study investigates the process maps concerning the effect of laser processing parameters on ablation depth of PCBN gathered from several research works on laser ablation and proposes a simulation to predict the laser ablation depth and profile on various CBN content substrates. The results on laser ablation depth are validated against the work in literature as well as experiments conducted using high repetition rate nanosecond laser pulses. Additionally, relations between laser and scanning parameters on the ablation depth have been identified using thermal modeling combined with machine learning, bringing a deeper understanding for texture design and planning of laser surface processing of PCBN.

Cubic boron nitride (cBN) with high hardness, thermal conductivity, wear resistance, and chemical inertness has become the most promising abrasive and machining material. Due to the difficulty of fabricating pure cBN body, generally, some binders are incorporated among cBN particles to prepare polycrystalline cubic boron nitride (PcBN). Hence, the binders play a critical factor to the performances of PcBN composites. In this study, the PcBN composites with three binder systems containing ceramic and metal phases were fabricated by spark plasma sintering (SPS) from 1400 to 1700 °C. The sintering behaviors and mechanical properties of the composites were investigated. Results show that the effect of binder formulas on mechanical properties mainly related to the compactness, mechanical performances, and thermal expansion coefficient of binder phases, which affect the carrying capacity of the composites and the bonding strength between binder phases and cBN particles. The PcBN composite with SiAlON phase as binder presented optimal flexural strength (465±29 MPa) and fracture toughness (5.62±0.37 MPa·m 1/2 ), attributing to the synergistic effect similar to transgranular and intergranular fractures. Meanwhile, the excellent mechanical properties can be maintained a comparable level when the temperature even rises to 800 °C. Due to the weak bonding strength and high porosity, the PcBN composites with Al 2 O 3 -ZrO 2 (3Y) and Al-Ti binder systems exhibited inferior mechanical properties. The possible mechanisms to explain these results were also analyzed.

We investigated the effect of surface coatings on cubic boron nitride (cBN) grains regarding tool wear resistance and processing efficiency. At a low processing rate (50 mm 3 /min), the wear resistance enhancement factor was 1.66 for the B 2 O 3 + CeO 2 coating. Conversely, at a higher processing rate (200 mm 3 /min), the wear resistance enhancement factor decreased to 1.13 for the B 2 O 3 + B 4 C coating. The study demonstrated that under these processing conditions, surface coating of cBN grains with a combination of oxide and carbide (B 2 O 3 + SiC) is preferable. This preference is based on improved grinding wheel wear resistance and reduced surface roughness ( R a ) of the machined surface. Furthermore, at increased grinding efficiency, any coating on cBN grain surfaces decreases the t 50 parameter, thereby decreasing the holding capacity of the rough surface generated during grinding with such wheels.

The effect of boron oxide on the surface of grains from superhard materials on the performance characteristics of grinding tools is studied. The possibility of increasing the strength of cubic boron nitride (cBN) grains by their thermal treatment in air at a low temperature due to the filling of their defective space with a B 2 O 3 film is shown. The results of tests show that the wheel containing cBN powder have higher wear resistance and lower specific grinding energy. It is demonstrated that just boron oxide on the surface of grains from superhard materials is an important factor of increasing their performance characteristics in grinding tools.

Heat generation in cutting process has a great influence on performance and lifetime of cutting tools. Cubic boron nitride (cBN), combination of exceptional thermal conductivity and hardness, is a promising super-hard material as protective coatings on the cutting tools. However, the temperature distributions of micron-thickness coatings on cutting tools are very difficult to be examined by experiment methods. In this paper, finite element method (FEM) simulation was introduced to determine the temperature distribution of cBN/diamond coatings on silicon nitride (Si 3 N 4 ) cutting tools with various parameters compared with titanium aluminum nitride (TiAlN) coatings. The finite element (FE) model of cBN/diamond–coated Si 3 N 4 tools was built and validated by machining experiments. The effects of cutting speed and tool rake angle on temperature distribution of cBN/diamond–coated tools were investigated compared to TiAlN coatings based on developed model. The results show that the temperature is increased with the increase of cutting speed while decreased with the increase of tool rake angle. The temperature of cBN-coated tools is decreased by approximately 20.4–28.6% than TiAlN-coated tools under identical conditions. Additionally, the preferred cutting speed and rake angle were obtained among employed cutting parameters. The results demonstrated that using advanced cBN coatings can substantially improve the cutting performance of the tools. This work may offer a guideline to explore the temperature distribution of cBN-coated cutting tools in mechanical machining application for machining difficult-to-cut ferrous materials.

PcBN (polycrystalline cubic boron nitride) carbide insert were synthesized with cBN/Zr/Al as raw material under high temperature and pressure. The effects of synthesis pressure on the interfacial morphology, wear resistance, microhardness and flatness of PcBN carbide insert were investigated. The test results show that with the increase of synthesis pressure, the composite interfacial bond is more dense and homogeneous, and the bonding strength between the cBN layer and the alloy substrate is higher. Additionally, the density, microhardness and abrasion resistance of the PcBN carbide insert were improved. Meanwhile, under the ultra-high pressure, the thickness deviation of the PcBN carbide insert gradually decreases, the thickness distribution gradually becomes uniform, and the flatness of the samples gradually becomes better.

High-purity, superhard, binderless polycrystalline cubic boron nitride (BL-PCBN) was obtained by direct hBN to cBN transformation in a toroid-type high-pressure apparatus at a pressure of 8.0 GPa and temperature of 2250 °C (HPHT-DCS; high-pressure, high-temperature direct conversion sintering). X-ray diffraction analysis revealed a prominent [111] axial texture in the sintered material when the axis was oriented perpendicular to the end surface of the sample. Vickers hardness tests conducted at a load of 49 N showed that BL-PCBN possessed an exceptional hardness value of 63.4 GPa. Finally, cutting tools made of BL-PCBN and SN-PCBN (Si3N4-doped cBN-based composite) reference materials were tested during the turning of a cemented tungsten carbide workpiece. The results of the cutting tests demonstrated that the wear resistance of the BL-PCBN material obtained with the HPHT-DCS process is 1.5–1.9 times higher compared to the conventional SN-PCBN material, suggesting its significant potential for industrial application.