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Micro diamond tools are indispensable for the efficient machining of microstructured surfaces. The precision in tool manufacturing and cutting performance directly determines the processing quality of components. The manufacturing of high-quality micro diamond tools relies on scientific design methods and appropriate processing techniques. However, there is currently a lack of systematic review on the design and manufacturing methods of micro diamond tools in academia. This study systematically summarizes and analyzes modern manufacturing methods for micro diamond tools, as well as the impact of tool waviness, sharpness, and durability on machining quality. Subsequently, a design method is proposed based on the theory of cutting edge strength distribution to enhance tool waviness, sharpness, and durability. Finally, this paper presents current technical challenges faced by micro diamond tools along with potential future solutions to guide scientists in this field. The aim of this review is to contribute to the further development of the current design and manufacturing processes for micro diamond cutting tools. Design methods of micro diamond cutting tools are summarized comprehensively from the perspective of tool geometries and cutting performances. Influences of cutting edge sharpness and waviness on the machined surface quality are analyzed, and corresponding improvement measures are introduced. Different methods to prepare micro diamond cutting tools are compared, including laser processing, FIB processing, and mechanical lapping. Challenges and future directions are demonstrated to provide guidance for the design and preparation of micro diamond cutting tools.

Diamond tools play a critical role in ultra-precision machining due to their excellent physical and mechanical material properties, such as that cutting edge can be sharpened to nanoscale accuracy. However, abrasive chemical reactions between diamond and non-diamond-machinable metal elements, including Fe, Cr, Ti, Ni, etc, can cause excessive tool wear in diamond cutting of such metals and most of their alloys. This paper reviews the latest achievements in the chemical wear and wear suppression methods for diamond tools in cutting of ferrous metals. The focus will be on the wear mechanism of diamond tools, and the typical wear reduction methods for diamond cutting of ferrous metals, including ultrasonic vibration cutting, cryogenic cutting, surface nitridation and plasma assisted cutting, etc. Relevant commercially available devices are introduced as well. Furthermore, future research trends in diamond tool wear suppression are discussed and examined.

Diamond has many outstanding properties, such as high hardness, great toughness, high capability up to a nanometric tool cutting edge, high thermal conductivity, low friction, and high wear resistance. Accordingly, it is employed as an efficient tool in ultra-precision machining (UPM). However, diamond tool wear (DTW) in UPM is an inevitable physical phenomenon and even a little DTW will produce a direct impact on nanometric surface roughness. With a focus on diamond’s physical characteristics, this paper looks at the current investigations of DTW and posits an improved understanding of DTW in UPM. Firstly, the differences in DTW caused by different workpiece materials are reviewed, as are the factors influencing DTW and its effects. Secondly, the DTW mechanisms are summarized, including DTW anisotropy, DTW features, and DTW behaviors, with diamond tool performances. Thirdly, DTW measuring, DTW monitoring, DTW controlling, and DTW modeling are introduced. Thirdly, different methods for DTW suppression are surveyed with a view to improving the cutting performance of diamond tools. Finally, the challenges and opportunities for DTW, which may be of particular interest for future studies, are discussed with several conclusions.

In ultra-precision machining of ferrous materials, diamond tools are easy to graphitize due to chemical reactions with ferrous materials, which can cause severe tool wear. The sharpness of the original cutting edge therefore cannot be maintained to machine mirror-level surface roughness. It cannot through a high-efficiency and low-cost way to obtain the workpiece surface integrity with high quality. Studying the wear mechanism of diamond tools and wear suppression methods is very important to improve the cutting efficiency of ultra-precision machining. In the present research, wear mechanisms and suppression schemes in diamond tools turning ferrous materials are reviewed and focusing on three major wear mechanisms and four effective suppression methods. In the end, this paper discusses the magnetism property of diamond-turnable materials, and introduces the feasibility of the magnetic field-assisted scheme to suppress diamond tool wear (DTW).

Silicon carbide fiber reinforced silicon carbide ceramic matrix composite (SiCf/SiC composite) is characterized by a high strength-to-density ratio, high hardness, and high temperature resistance. However, due to the brittleness of the matrix material and the anisotropy of the reinforcing phase, it is a huge challenge for machining of the material. The milling method has advantages of a high material removal rate and applicability to complex surface geometry. However, no published literature on milling of SiCf/SiC composite has been found up to now. In this paper, high-speed milling of SiCf/SiC composites was carried out under dry conditions and cryogenic cooling using liquid nitrogen, respectively. Polycrystalline diamond (PCD) and chemical vapor deposition (CVD) diamond cutting tools were used for the milling work. The cutting performance of the two kinds of tools in high-speed milling of SiCf/SiC composites was studied. Tool failure modes and mechanisms were analyzed. The effects of the cooling approach on tool wear and machined surface quality were also investigated. The experimental results showed that under identical cutting parameters and cooling approaches, the PCD tool yielded better cutting performance in terms of a longer tool life and better surface quality than that of the CVD diamond tool. In dry machining, the failure modes of the CVD diamond tool were a large area of spalling on the rake face, edge chipping and severe tool nose fracture, whereas for the PCD tool, only a small area of spalling around the tool nose took place. Compared to the dry machining, the wear magnitudes of both PCD and CVD diamond tools were decreased in cryogenic machining. Additionally, the surface quality also showed significant improvements. This study indicates that the PCD tool is highly suitable for machining of SiCf/SiC composite, and that the cryogenic method can improve machining efficiency and surface quality.

Aluminum alloys are applied in large volumes to various mechanical components. However, during the boring process of such alloys, it becomes necessary that H7 tolerances be obtained. Additionally, when machining aluminum alloys, adhesion problems are often noted due to ductility. Furthermore, owing to the high cutting speeds used in this process, the need arises for the utilization of a cutting fluid, in order to reduce adhesion. Other cooling techniques are used worldwide to replace, reduce, or eliminate cutting fluids. In this study, three factorial designs were used to verify performance and compare cutting fluid abundance (CFA), dry machining (DM), and minimum quantity lubrication (MQL) during the boring process, while using polycrystalline diamond (PCD) tools. The input variables were cutting speed (Vc), feed per tooth (fz), and depth of cut (doc), while the output variables were diameter, roundness, and tool wear mechanism analysis. In total, forty-eight experiments were performed. The results presented for MQL were noted as showing similarity with those for CFA. These results indicated that MQL can replace the CFA technique, thus improving process sustainability.

To investigate the machining mechanism of silicon carbide (SiC) ceramic materials, this study utilized sintered diamond tools to perform drilling and grinding simulations on the material and developed a drilling model for SiC ceramic materials. By analyzing parameters such as surface morphology, stress, and cutting force, the material removal mechanism of SiC ceramic materials was revealed, and the effects of drilling parameters on cutting force, torque, and residual stress were studied. Experimental results indicate that during the abrasive cutting process, the hard contact behavior of irregular abrasive grains significantly affects material removal, leading to failure forms such as chip collapse, hole and groove cracking, and crack propagation. With an increase in the feed rate of the abrasive grains, the drilling force shows a certain range of growth patterns. The axial force is positively correlated with spindle speed and feed rate, with the feed rate having a more significant impact on the magnitude of the axial force. Additionally, as the feed rate increases, the torque also increases. The radial residual stress mainly manifests as residual tensile stress.

Accurately measuring the cutting temperature in micro cutting zone is crucial for characterizing and optimizing the cutting status during ultra-precision machining. This work proposes an innovative method for self-sensing of cutting temperature using a locally boron-doped diamond tool. A longitudinal layered deposition synthesis methodology, instead of the traditional growth method under high temperature and high pressure conditions (HTHP), was developed to enable the fabrication of the locally boron-doped diamond tool. The doping contents, lattice integrity, and electrical properties of the diamond were characterized. Owing to the inherently low thermal capacity and quick carrier migration induced by the thin-layer structure for sensing temperature, the diamond tool has the advantages of rapid response and enhanced sensitivity, compared with traditional cutting temperature measurement technologies. An insulated diamond tool edge without boron doping enables to accurately measure cutting temperature for various conductive materials in ultra-precision cutting processes. The locally boron-doped diamond tool was employed for in-process monitoring of the temperature in micro cutting zone during ultra-precision machining processes. The experimental results demonstrated the capabilities of in-process cutting temperature monitoring of conductive materials using the diamond tool, as well as the high-sensitivity identification of micro/nano morphologies and defects on machined surface based on the measured temperature. It provides a potential approach for advanced status analysis and diagnosis in the process of ultra-precision machining.

Ultraprecision machining of metal matrix composites (MMCs) is observed as a scientific challenge, due to their hard-to-machine property and often the poor surface finish. This paper presents an experimental investigation on surface generation in ultraprecision machining of Al/B 4 C/50p MMCs. The machining trials using straight flute polycrystalline diamond (PCD) tools are conducted on a high precision micro milling machine. Side milling is adopted under varied cutting conditions. Metrology assessments on the workpiece surface roughness, topography, texture and defects/features are undertaken using a ZYGO 3D surface profiler and a scanning electron microscope (SEM). Experimental results indicate that process parameters and their contributions play essential roles in the machining process. By applying the optimal process parameters, e.g. cutting speed of 188.496 m/min, feed rate of 10 μm/rev and axial depth of cut of 150 μm, a better surface generation with surface roughness Ra < 20 nm can be obtained in ultraprecision machining of Al/B 4 C/50p particulate MMCs.

AISI 420 is primarily used for optic molds manufactured through ultraprecision machining with single-crystal diamond tools. Tool wear rapidly occurs due to the diffusion of diamond and iron atoms when cutting ferrous metals with diamond tools. In the machining of optic molds, the diamond tool is uniformly replaced, regardless of the tool status after use for some time due to the difficulty in predicting tool life. This practice results in the wastage of expensive single-crystal diamond tools and reduces productivity. This study addressed the aforementioned issue by developing a tool-life model through theoretical analysis of the effective contact ratio between the tool and the workpiece and a cutting experiment with high-frequency ultrasonic vibration. In addition, the effectiveness of ultrasonic vibration cutting on the suppression of diamond tool wear was demonstrated by measuring tool wear after the cutting experiments.