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A variety of cutting tool materials are used for the contact mode mechanical machining of components under extreme conditions of stress, temperature and/or corrosion, including operations such as drilling, milling turning and so on. These demanding conditions impose a seriously high strain rate (an order of magnitude higher than forming), and this limits the useful life of cutting tools, especially single-point cutting tools. Tungsten carbide is the most popularly used cutting tool material, and unfortunately its main ingredients of W and Co are at high risk in terms of material supply and are listed among critical raw materials (CRMs) for EU, for which sustainable use should be addressed. This paper highlights the evolution and the trend of use of CRMs) in cutting tools for mechanical machining through a timely review. The focus of this review and its motivation was driven by the four following themes: (i) the discussion of newly emerging hybrid machining processes offering performance enhancements and longevity in terms of tool life (laser and cryogenic incorporation); (ii) the development and synthesis of new CRM substitutes to minimise the use of tungsten; (iii) the improvement of the recycling of worn tools; and (iv) the accelerated use of modelling and simulation to design long-lasting tools in the Industry-4.0 framework, circular economy and cyber secure manufacturing. It may be noted that the scope of this paper is not to represent a completely exhaustive document concerning cutting tools for mechanical processing, but to raise awareness and pave the way for innovative thinking on the use of critical materials in mechanical processing tools with the aim of developing smart, timely control strategies and mitigation measures to suppress the use of CRMs.

Microtextured cutting tools are widely used because of their excellent performance in cutting difficult-to-machine materials. The cutting performance of cutting tools largely depends on the size parameters of the microtextures used. This study focuses on the machining of titanium alloy Ti-6Al4 V using microgrooved cutting tools under dry-cutting conditions. Special emphasis is placed on exploring cutting performance under specific combinations of microgroove parameters. To determine the optimal parameter combination for cutting, the effects of different microgroove parameters (including the diameter, depth, spacing, and spacing between grooves and cutting edges) on cutting force, tool wear, and chip morphology were investigated. In this study, femtosecond laser technology was used to prepare microgroove-textured cutting tools with different parameters, and the cutting performance of these tools was analyzed. The results show that, when the groove diameter is 80 μm, the depth is 60 μm, the spacing is 80 μm, and the distance between the groove and the tool tip is 120 μm, the cutting performance of the tool is optimal: the cutting force is reduced by 13.9%, the degree of tool wear is minimized, and the degree of chip curling is more uniform. The research results can be applied to the actual processing of Ti-6Al4 V, which can help tool design, selection, and microtexture parameter optimization.

Machining is an indispensable manufacturing process for a wide range of engineering materials, such as metals, ceramics, and composite materials, in which the tool wear is a serious problem, which affects not only the costs and productivity but also the quality of the machined components. Thus, the modification of the cutting tool surface by application of textures on their surfaces is proposed as a very promising method for improving tool life. Surface texturing is a relatively new surface engineering technology, where microscale or nanoscale surface textures are generated on the cutting tool through a variety of techniques in order to improve tribological properties of cutting tool surfaces by reducing the coefficient of friction and increasing wear resistance. In this paper, the studies carried out to date on the texturing of ceramic and superhard cutting tools have been reviewed. Furthermore, the most common methods for creating textures on the surfaces of different materials have been summarized. Moreover, the parameters that are generally used in surface texturing, which should be indicated in all future studies of textured cutting tools in order to have a better understanding of its effects in the cutting process, are described. In addition, this paper proposes a way in which to classify the texture surfaces used in the cutting tools according to their geometric parameters. This paper highlights the effect of ceramic and superhard textured cutting tools in improving the machining performance of difficult-to-cut materials, such as coefficient of friction, tool wear, cutting forces, cutting temperature, and machined workpiece roughness. Finally, a conclusion of the analyzed papers is given.

In recent years, consumers have become increasingly interested in natural, biodegradable and eco-friendly composites. Eco-friendly composites manufactured using natural reinforcing filling materials stand out with properties such as cost effectiveness and easy accessibility. For these reasons, in this research, a composite workpiece was specially manufactured using eco-friendly jute fibers. Two cost-effective cutting tools were specially produced to ensure high-quality machining of this composite workpiece. One of these specially manufactured cutting tools was subjected to DC&T (deep cryogenic treatment and tempering) processes to improve its performance. At the end of the research, when the lowest and highest Fd (delamination factor) values obtained with DC&T-T1 and T1 cutting tools were compared, it was observed that 5.49% and 6.23% better results were obtained with the DC&T-T1 cutting tool, respectively. From the analysis of the S/N (signal-to-noise) ratios obtained using Fd values, it was found that the most appropriate machining parameters for the composite workpiece used in this investigation were the DC&T-T1 cutting tool, a 2000 rev/min spindle speed and a 100 mm/min feed rate. Through ANOVAs (analyses of variance), it was discovered that the most significant parameter having an impact on the Fd values was the spindle speed, with a rate of 53.01%. Considering the lowest and highest Ra (average surface roughness) values obtained using DC&T-T1 and T1 cutting tools, it was seen that 19.42% and 16.91% better results were obtained using the DC&T-T1 cutting tool, respectively. In the S/N ratio analysis results obtained using Ra values, it was revealed that the most appropriate machining parameters for the composite workpiece used in this investigation were the DC&T-T1 cutting tool, a 2000 rev/min spindle speed and a 100 mm/min feed rate. In the ANOVAs, it was revealed that the most significant parameter having an effect on the Ra values was the feed rate at 37.86%.

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 concept of high-entropy alloys has been extended to ceramics, polymers, and composites. “High-entropy materials (HEMs)” are named to cover all these materials. Recently, HEMs has become a new emerging field through the collective efforts of many researchers. Basically, high mixing entropy can enhance the formation of solution-type phases for alloys, ceramics, and composites at high temperatures, and in general leads to simpler microstructure. Large degrees of freedom in composition design as well as process design have been found to provide a wide range of microstructure and properties for applications. There are many opportunities for HEMs to overcome the bottlenecks of conventional materials. In this article, several possible breakthrough applications are pointed out and emphasized for turbine blades, thermal spray bond coatings, high-temperature molds and dies, sintered carbides for cutting tools, hard coatings for cutting tools, hardfacings, and radiation-damage resistant materials. In addition, more possible breakthrough examples are briefly described.

During machining processes, a large amount of heat is generated due to plastic deformation, in a very small area of the cutting tool. This high temperature strongly influences chip formation mechanisms, tool wear, tool life, and workpiece surface integrity and quality. In this sense, knowing the temperature at various points of tool, chip, and workpiece during machining processes is of utmost importance to effectively optimize cutting parameters, improve machinability and product quality, reduce machining costs, and increase tool life and productivity. This paper presents a review of the various methods for temperature measurement and prediction in machining processes, being the different methods discussed and evaluated regarding its merits and demerits. The most suitable method for a given application depends on several aspects, such as cost, size, shape, accuracy, response time, and temperature range. Lastly, some future perspectives for real-time cutting temperature monitoring in the scope of Industry 4.0 and 5.0 are outlined, as well as being presented a new field of tools capable of measuring and controlling cutting temperature, called smart cutting tools.

Machining of hard-to-cut materials with conventional processes is still considered as a challenge, as the special properties of these materials often lead to rapid tool wear and reduced surface integrity. For that reason, it is preferable to combine conventional machining processes with other technologies in order to overcome the problems of machining these materials. In the present work, laser-assisted turning experiments on a Ti-6Al-4V workpiece were conducted using AlTiN coated cutting tools in order to investigate the effect of laser heating on cutting forces, cutting temperature, tool wear and microstructure alterations. Two series of experiments were performed under varying cutting speed, laser spot diameter and workpiece diameter values; the first series involved only laser heating of the workpiece and the second both laser heating and cutting. The findings revealed the effect of process parameters on cutting forces and temperature determining the importance of workpiece diameter size, indicated the formation of martensite phase at the top of the heat-affected zone of the workpiece and also showed that high temperatures can lead to intensive tool wear, instead of having a beneficial effect for the cutting tool. Finally, finite element (FE) simulations were carried out in order to study the time evolution of the temperature field and calculate the heating and cooling rates during the process. From the FE results, relatively high heating and cooling rates were observed for smaller workpiece diameters and lower cutting speed, whereas the high magnitude of these rates justified the creation of the martensite phase through a diffusionless transformation.

The aim of this work was to investigate mechanical and cutting properties, as well as the nature of wear and failure of carbide cutting tools with modifying coatings of two types: nano-structured multi-layered coating Zr-ZrN-(ZrCrAl)N, applied through the use of the technology of filtered cathodic vacuum arc deposition, and multi-layered nano-structured and gradient coating Ti-(TiAl)N-(TiAl)N, applied through the use of the technology of LARC ® (lateral rotating cathodes). It is found out that the both types of coatings under test significantly improve tool life of a carbide cutting tool. The studies of mechanisms of wear and failure of carbide tools with coatings under test, conducted at macro and micro levels, have identified their major differences and revealed their most preferable field of application. The carbide tools, equipped with cutting inserts with the nano-structured multi-layered coating under study, provided a significant increase in cutting properties (tool life) of the tool in comparison with the uncoated carbide tool and in comparison with the reference carbide tool with TiN coating. The tool with the coating Ti-(TiAl)N-(TiAl)N under study demonstrated the increased wear resistance during 30–35 min of cutting, and then, the process of coating failure and tool wear was sharply intensified. For the tool with coating Zr-ZrN-(ZrCrAl)N, the tests revealed more evenly balanced wear during the whole operating time between failures. It should be noted that NMCC Zr-ZrN-(ZrCrAl)N are substantially thinner, and that fact predetermines their better resistance to failure because of crack formation, and the technology of its generation is more cost-effective.

In recent years, the application of the difficult-to-machine materials has increased gradually, and the challenging requirements have been placed on cutting. The difficult-to-machine materials suffer from limitations such as large cutting force, high cutting temperature and serious cutting tool wear during processing. In order to improve the cutting performance of cutting tools and attain sustainable development, the green cutting technology has been gradually developed. The cutting tool surface micro-texture and coating represent the key technologies for attaining the green cutting performance. These technologies can improve the cutting performance, thereby prolonging the cutting tool life and improving the workpiece surface quality. This study systematically expounds the latest progress in the field of micro-textured cutting tools, coated cutting tools and micro-textured coated cutting tools. It introduces the existing micro-texture and coating preparation processes and analyzes the mechanism of micro-texture and coating. The compiles the recent developments in the materials and structures, along with summarizing the effect of micro-texture, coating and micro-texture coating synergy on cutting tool performance, cutting performance and workpiece surface quality. Finally, it presents the future development trend for the micro-textured cutting tools, coated cutting tools and micro-textured coating cutting tools. Overall, this study acts as a benchmark for the follow-up development in the field of green cutting technology.