A review on the multi-scaled structures and mechanical/thermal properties of tool steels fabricated by laser powder bed fusion additive manufacturing

The laser powder bed fusion(LPBF) process can integrally form geometrically complex and high-performance metallic parts that have attracted much interest,especially in the molds industry.The appearance of the LPBF makes it possible to design and produce complex conformal cooling channel systems in molds.Thus,LPBF-processed tool steels have attracted more and more attention.The complex thermal history in the LPBF process makes the microstructural characteristics and properties different from those of conventional manufactured tool steels.This paper provides an overview of LPBF-processed tool steels by describing the physical phenomena,the microstructural characteristics,and the mechanical/thermal properties,including tensile properties,wear resistance,and thermal properties.The microstructural characteristics are presented through a multiscale perspective,ranging from densification,meso-structure,microstructure,substructure in grains,to nanoprecipitates.Finally,a summary of tool steels and their challenges and outlooks are introduced.

Novel Batch Polishing Method of Ceramic Cutting Inserts for Reducing Tool Wear

Ceramic cutting inserts are a type of cutting tool commonly used in high-speed metal cutting applications.However,the wear of these inserts caused by friction between the workpiece and cutting inserts limits their overall effectiveness.In order to improve the tool life and reduce wear,this study introduces an emerging method called magnetic field-assisted batch polishing(MABP)for simultaneously polishing multiple ceramic cutting inserts.Several polishing experiments were conducted under different conditions,and the wear characteristics were clarified by cutting S136H steel.The results showed that after 15 min of polishing,the surface roughness at the flank face,edge,and nose of the inserts was reduced to below 2.5 nm,6.25 nm,and 45.8 nm,respectively.Furthermore,the nose radii of the inserts did not change significantly,and there were no significant changes in the weight percentage of elements before and after polishing.Additionally,the tool life of the batch polished inserts was found to be up to 1.75 times longer than that of unpolished inserts.These findings suggest that the MABP method is an effective way to mass polish ceramic cutting inserts,resulting in significantly reduced tool wear.Furthermore,this novel method offers new possibilities for polishing other tools.

On dry machining of AZ31B magnesium alloy using textured cutting tool inserts

Magnesium alloys have many advantages as lightweight materials for engineering applications,especially in the fields of automotive and aerospace.They undergo extensive cutting or machining while making products out of them.Dry cutting,a sustainable machining method,causes more friction and adhesion at the tool-chip interface.One of the promising solutions to this problem is cutting tool surface texturing,which can reduce tool wear and friction in dry cutting and improve machining performance.This paper aims to investigate the impact of dimple textures(made on the flank face of cutting inserts)on tool wear and chip morphology in the dry machining of AZ31B magnesium alloy.The results show that the cutting speed was the most significant factor affecting tool flank wear,followed by feed rate and cutting depth.The tool wear mechanism was examined using scanning electron microscope(SEM)images and energy dispersive X-ray spectroscopy(EDS)analysis reports,which showed that at low cutting speed,the main wear mechanism was abrasion,while at high speed,it was adhesion.The chips are discontinuous at low cutting speeds,while continuous at high cutting speeds.The dimple textured flank face cutting tools facilitate the dry machining of AZ31B magnesium alloy and contribute to ecological benefits.

Selection of media tools for community planning:A study from the perspective of communicative planning

In community planning,due to the lack of evidence regarding the selection of media tools,this study examines how a common but differentiated ideal speech situation can be created as well as how more appropriate media tools can be defined and selected in the community planning process.First,this study describes the concept and theoretical basis of media used in community planning from the perspectives of the multiple effects of media evolution on communicative planning.Second,the classification criteria and typical characteristics of media tools used to support community planning are clarified from three dimensions:acceptability,cost effectiveness,and applicability.Third,strategies for applying media tools in the four phases of communicative planning-namely,state analysis,problem identification,contradictory solution and optimization-are described.Finally,trends in the development of media tools for community planning are explored in terms of multistakeholder engagement,supporting scientific decision-making and multiple-type media integration.The results provide a reference for developing more inclusive,effective,and appropriate media tools for enhancing decision-making capacity and modernizing governance in community planning and policy-making processes.

3D modeling for effect of tool eccentricity on coupled thermal and material flow characteristics during friction stir welding

A novel three-dimensional numerical model is proposed to investigate the effect of tool eccentricity on the coupled thermal and material flow characteristics in friction stir welding(FSW) process.An asymmetrical boundary condition at the tool-workpiece interface,and the dynamic mesh technique are both employed for the consideration of the tool eccentricity during tool rotating.It is found that tool eccentricity induces the periodical variation of the heat densities both at the tool-workpiece interface and inside the shear layer,but the fluctuation amplitudes of the heat density variations are limited.However,it is demonstrated that tool eccentricity results in significant variation of the material flow behavior in one tool rotating period.Moreover,the material velocity variation at the retreating side is particularly important for the formation of the periodic characteristics in FSW.The modeling result is found to be in good agreement with the experimental one.

Numerical Investigation of Thermal Behavior of CNC Machine Tool and Its Effects on Dimensional Accuracy of Machined Parts

The dimensional accuracy of machined parts is strongly influenced by the thermal behavior of machine tools (MT). Minimizing this influence represents a key objective for any modern manufacturing industry. Thermally induced positioning error compensation remains the most effective and practical method in this context. However, the efficiency of the compensation process depends on the quality of the model used to predict the thermal errors. The model should consistently reflect the relationships between temperature distribution in the MT structure and thermally induced positioning errors. A judicious choice of the number and location of temperature sensitive points to represent heat distribution is a key factor for robust thermal error modeling. Therefore, in this paper, the temperature sensitive points are selected following a structured thermomechanical analysis carried out to evaluate the effects of various temperature gradients on MT structure deformation intensity. The MT thermal behavior is first modeled using finite element method and validated by various experimentally measured temperature fields using temperature sensors and thermal imaging. MT Thermal behavior validation shows a maximum error of less than 10% when comparing the numerical estimations with the experimental results even under changing operation conditions. The numerical model is used through several series of simulations carried out using varied working condition to explore possible relationships between temperature distribution and thermal deformation characteristics to select the most appropriate temperature sensitive points that will be considered for building an empirical prediction model for thermal errors as function of MT thermal state. Validation tests achieved using an artificial neural network based simplified model confirmed the efficiency of the proposed temperature sensitive points allowing the prediction of the thermally induced errors with an accuracy greater than 90%.

Application of Fuyang Paper Cutting Art in Cultural and Creative Design from the Perspective of Rural Revitalization

The application significance of Fuyang paper cutting art in cultural and creative design from the perspective of rural revitalization was discussed,and the implementation principles and specific practices of applying the elements and techniques of Fuyang traditional paper cutting art in cultural and creative products with local features were analyzed to provide reference for rural revitalization and development of cultural industry.

Relationship Between Thermal Shock Behavior and Cutting Performance of a Functionally Gradient Ceramic Tool

Based on the deep understanding of the requirements of cutting conditions on ceramic tools, a design model for functionally gradient ceramic tool materials with symmetrical composition distribution was presented in this paper, according to which an Al 2O 3-TiC functionally gradient ceramic tool material FG-1 was synthesized by powder-laminating and uniaxially hot-pressing technique. The thermal shock resistance of the Al 2O 3-TiC functionally gradient ceramics FG-1 was evaluated by water quenching and subsequent three-point bending tests of flexural strength diminution. Comparisons were made with results from parallel experiments conducted using a homogeneous Al 2O 3-TiC ceramics. Functionally gradient ceramics exhibited higher retained strength under all thermal shock temperature differences compared to homogeneous ceramics, indicating the higher thermal shock resistance. The experimental results were supported by the calculation of transient thermal stress field. The cutting performance of the Al 2O 3-TiC functionally gradient ceramic tool FG-1 was also investigated in rough turning the cylindrical surface of exhaust valve of diesel engine in comparison with that of a common Al 2O 3-TiC ceramic tool LT55. The results indicated that the tool life of FG-1 increased by 50 percent over that of LT55. Tool life of LT55 was mainly controlled by thermal shock cracking which was accompanied by mechanical shock. While tool life of FG-1 was mainly controlled by mechanical fatigue crack extension rather than thermal shock cracking, revealing the less thermal shock susceptibility of functionally gradient ceramics than that of common ceramics.

Further Analysis of Machine Tool Dimensional Accuracy and Thermal Stability under Varying Floor Temperature

Machining is as old as humanity, and changes in temperature in both the machine’s internal and external environments can be of great concern as they affect the machine’s thermal stability and, thus, the machine’s dimensional accuracy. This paper is a continuation of our earlier work, which aimed to analyze the effect of the internal temperature of a machine tool as the machine is put into operation and vary the external temperature, the machine floor temperature. Some experiments are carried out under controlled conditions to study how machine tool components get heated up and how this heating up affects the machine’s accuracy due to thermally induced deviations. Additionally, another angle is added by varying the machine floor temperature. The parameters mentioned above are explored in line with the overall thermal stability of the machine tool and its dimensional accuracy. A Robodrill CNC machine tool is used. The CNC was first soaked with thermal energy by gradually raising the machine floor temperature to a certain level before putting the machine in operation. The machine was monitored, and analytical methods were deplored to evaluate thermal stability. Secondly, the machine was run idle for some time under raised floor temperature before it was put into operation. Data was also collected and analyzed. It is observed that machine thermal stability can be achieved in several ways depending on how the above parameters are joggled. This paper, in conclusion, reinforces the idea of machine tool warm-up process in conjunction with a carefully analyzed and established machine floor temperature variation for the approximation of the machine tool’s thermally stability to map the long-time behavior of the machine tool.

Research on the Resistance of Cutting Mechanism of Mining Longitudinal Roadheader

In order to accurately obtain the dynamic characteristics of the cutting mechanism of the mining longitudinal roadheader,combined with the working principle of the mining longitudinal roadheader,the theoretical analysis and derivation are carried out in detail.By using ADAMS to simulate,the resistance curve and torque curve of the cutting mechanism in different directions are obtained.The results show that ADAMS can effectively predict the excavation resistance and torque of the cutting mechanism of mining longitudinal roadheader,which has certain reference value for future optimization design.

A critical review on the chemical wear and wear suppression of diamond tools in diamond cutting of ferrous metals

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.

Dynamic modeling of ultra-precision fly cutting machine tool and the effect of ambient vibration on its tool tip response

The dynamic performances of an ultra-precision fly cutting machine tool(UFCMT)has a dramatic impact on the quality of ultra-precision machining.In this study,the dynamic model of an UFCMT was established based on the transfer matrix method for multibody systems.In particular,the large-span scale flow field mesh model was created;and the variation in linear and angular stiffness of journal and thrust bearings with respect to film thickness was investigated by adopting the dynamic mesh technique.The dynamic model was proven to be valid by comparing the dynamic characteristics of the machine tool obtained by numerical simulation with the experimental results.In addition,the power spectrum density estimation method was adopted to simulate the statistical ambient vibration excitation by processing the ambient vibration signal measured over a long period of time.Applying it to the dynamic model,the dynamic response of the tool tip under ambient vibration was investigated.The results elucidated that the tool tip response was significantly affected by ambient vibration,and the isolation foundation had a good effect on vibration isolation.

Research on the Cutting Performance of Cubic Boron Nitride Tools

There were only two kinds of superhard tool material at the past, i.e. diamond and cubic boron nitride (CBN). Manmade diamond and CBN are manufactured by the middle of 20th century. Various manufacturing methods and manmade superhard materials were developed later. They were widely used in different industry and science areas. Recently, a new kind of superhard tool material, C 3N 4 coating film, had been developed. American physical scientists, A. M. Liu and M. L. Cohen, designed a new kind of inorganic compound C 3N 4 with the theory of molecule engineering. According to calculation, it can reach or even exceed the hardness of diamond, so material scientists and technique circles draw their attention to it. A high speed steel twist drill coated with C 3N 4 film is applied to the drilling hole process on steel workpiece in cutting tests, the tool life is increased greatly. When the C 3N 4 film is coated on the cemented carbide inserts, the cutting performance is improved, but is not good enough. The data of mechanical performance and cutting tests about this kind of new tool material is given in this paper, it shows that C 3N 4 has a promising future. The anti-wear ability of cutting tool increases sharply after C 3N 4 being coated on HSS tool. Coated HSS drill also has some benefit after being reground. The tool life prolongs after C 3N 4 being coated on cemented carbide inserts, but is not so long as that of C 3N 4 coated HSS tool. When machining PRCM with C 3N 4 thin-film coated cemented carbide tool, the cutting performance is poor and it is much better when machining PRCM with PCBN, PCD compound plates and CVD thick-film coated cutting tool. Some relative aspects need to be deeply discussed and researched, e.g. the existing coating techniques is not good enough and should be improved in the future, the film thickness should be optimized and try to find out the most effective value, the binding force and mutual effect between coated film and substrate need to be studied furtherly, etc.

The interaction between grain boundary and tool geometry in nanocutting of a bi-crystal copper

Anisotropy is one central influencing factor on achievable ultimate machined surface integrity of metallic materials.Specifically,grain boundary has a strong impact on the deformation behaviour of polycrystalline materials and correlated material removal at the microscale.In the present work,we perform molecular dynamics simulations and experiments to elucidate the underlying grain boundaryassociated mechanisms and their correlations with machining results of a bi-crystal Cu under nanocutting using a Berkovich tool.Specifically,crystallographic orientations of simulated bi-crystal Cu with a misorientation angle of 44.1°are derived from electron backscatter diffraction characterization of utilized polycrystalline copper specimen.Simulation results reveal that blocking of dislocation motion at grain boundaries,absorption of dislocations by grain boundaries and dislocation nucleation from grain boundaries are operating deformation modes in nanocutting of the bi-crystal Cu.Furthermore,heterogeneous grain boundary-associated mechanisms in neighbouring grains lead to strong anisotropic machining behaviour in the vicinity of the grain boundary.Simulated machined surface morphology and machining force evolution in the vicinity of grain boundary qualitatively agree well with experimental results.It is also found that the geometry of Berkovich tool has a strong impact on grain boundary-associated mechanisms and resultant ploughing-induced surface pile-up phenomenon.

Study on the Cutting Temperature of the Textured Tool by 3D FEA Simulation

Temperature plays an important role in the life of cutting tools.However,it is sometimes difficult to observe instantaneously because of limited data acquisition,especially for the textured tool.In this paper,the performance of microgroove textured cutting tools for three-dimensional(3D)oblique dry turning of AISI 1045 steel was studied by finite element simulation.The effects of width,depth and spacing of strip micro-texture on cutting temperature and the effect of cutting speed on cutting temperature of strip microtexture tool were studied.The results show that the maximum temperature of the tool and the tip temperature first increase and then decrease with the increase of micro-texture width.When the micro-texture depth increases,the maximum temperature and the tool tip temperature decrease first and then increase.The highest temperature and tip temperature of the tool gradually increase with the increase of micro-texture spacing.The highest temperature and tip temperature of the tool increase with the increase of cutting speed,feed speed and cutting depth.In addition,the effective mechanism of micro-texture parameter for the temperature was proposed.It provides profound guidance for optimizing the microstructure parameters and cutting process of cutting tools according to cutting temperature in this study.It also provides an effective and practical method for the design,innovation and development of microtextured tools.

Influence of the Magnetic High-speed Steel Cutting Tool on Cutting Capability

The high-speed steel cutting tool has advantaged i n modern cutting tool for its preferable synthetical performance, especially, in a pplication of complicated cutting tools. Therefore, the study of the high-speed steel cutting tools that occupied half of cutting tools has become an importa nt way of studying on modern cutting technology. The cutting performance of hi gh speed-steel cutting tools will be improved by magnetization treating method. Microstructure of high-speed steel will be changed as a result of magnetizatio n, and the effect of mechanism and electromagnetism. Magnetic domain was re-arr anged under outer magnetic field for the magnetism of high-speed steel. When th e high-speed steel tools were treated in pulse magnetic field, the intensity H of which is get to 19 Kves, the boundary of magnetic domain will be replaced ham mered by this kind of intensive pulse, causing flexibility deformation and elast ic stress. The interaction between the elastic field and the initial dislo cation field will lead to expansion and transfer of dislocation, fining of g rains, distortion of crystal lattice, and increase of hardness. Obtained by expe riment, the hardness is raised HRC 0.6～0.9, it is to whole tool. Magnetized in p ulse magnetic field without measure, too many dislocations will accumulate on th e interface of, and the tool will be brittle. Many factors such as magnetic filed intensity, magnetization time and chemical c omponent of high-speed steel will influence the capability of magnetized cuttin g. This paper, according to the test, analyzed and compared the difference effec ts between the magnetized high-speed steel cutting tool and the non-magnet ized high-speed steel cutting tool on cutting force, power, heat, accuracy, ser vice life and etc. It also put forward the relation of cutting factor and cuttin g capability, and the relation of magnetic parameter and cutting capability.

Age Strengthening of Grey Cast Iron Alloys for Machine Cutting Tools Production

This work was carried out with the aim of using alloying and ageing processes to develop new alloys from grey cast iron that will have optimum properties suitable for the manufacturing of machine cutting tools. Four different alloys of grey cast iron with alloying composition of Fe-3% Al-2.5% Cr-2% Mo;Fe-3% Al-2% Cr-2% Mo;Fe-3% Al-2.5% Cr-1.5% Mo and Fe-3% Al-1.5% Cr-2% Mo were produced. The chemical analysis of both as-received base metal and produced alloys was determined using Spetro-CJRO Arc-Spectrometer. The microstructural properties and mechanical properties (hardness, impact toughness and ultimate tensile strength) of the produced alloys were determined for both as-cast samples and aged samples. The results showed that the addition of these alloying elements slightly decreased carbon, silicon and phosphorus content and thereby changed the hypereutectic cast iron to hypoeutectic by reducing the carbon equivalent. Also the morphology of graphite flake was changed as a result of the formation of nitrides and carbides of different phases. The results of the mechanical properties showed that the maximum hardness values obtained for each of the four alloys produced and aged at 300?C are 71.5 HRc, 69 HRc, 66.5 HRc and 65.4 HRc respectively. The maximum values for impact toughness obtained for each of the same produced alloys are 66 J, 63.6 J, 62 J and 60.3 J respectively. Also the maximum ultimate tensile strength values obtained for each of the alloys are 1380 N·mm-2, 1311 N·mm-2, 1260 N·mm-2 and 1190 N·mm-2. Comparing the properties obtained from the produced alloys with those of the commercial cutting tools, it was found that cutting tools manufactured from these produced alloys can compete favourably with cast cobalt tool, high speed steel (HSS) and tool steel.

Comparing the Effectiveness of Coatings on Carbide andCermet Cutting Tool Inserts

A series of metal cutting experiments was performed on a CNC lathe to evaluate the performance of various coatings on different tool substrates. The workpiece material was plain medium carbon steel and the cutting tool materials were carbide and cermet inserts coated with various single as well as multilayer coatings. Machining was done under various cutting conditions of speed and feed-rate, and for various durations of Cutting. The output parameters studied were the cutting forces (axial, radial and tangential), the surface roughness of the workpiece, as well as the tool wear (crater and flank wear). From these results, the performances of the various cutting inserts are evaluated and compared. Results show that cutting forces are significantly lower when using coated cermets than when using coated carbides although different coatings on the same substrate also result in different cutting forces. However, there is less difference in the surface roughness of the finished workpiece for the various coatings and substrates.

Structural scheme and theory behind feedback compensation of new parallel machine tools

Analyses the errors of new parallel machine tools and presents a structural scheme for feedback compensation of machine tools to eliminate these errors, the theory behind and the relation between direction consine of normal vector of the workpiece surface and the rotation angles α,β,γ of the cutter head.

Improvement Properties of the Cutting Tools Using Technical Plasma Treatment

In spite of the considerable progress made in the domain of the sciences of materials, cutting tools subjected to an intense abrasive wear and a very high temperature of edge. They record during their use an reduced working life. The operations of machining on lathe are regularly stopped for replacing these tools, which influences enormously the production process. Indeed, the search the new materials of substitution, remain a domain very coveted, owing to the fact, it belongs to one stake very significant industrial, in particular, in the mechanical domain and its varied sectors. The recourse to the thermal treatments traditional, limiting in an interval, reduces the wear and the excessive consumption of these cutting tools, but the principal concern of the experts and researchers, in the domain of the mechanical engineering, remain posed. The goal of this study is the introduction of the technique of plasmas, as physical phenomenon, for making material of coating at base of titanium nitrides doped at iron, at the different concentrations. To this objective, one magnetron sputtering with plasma was used for the realization of the coatings deposed on the active parts of the cutting tools. During the experimentation, it was noted that the cutting tools which are treated by plasma, subjected to the machining operations on lathe and the hardness tests, presents one improvement of their hardness and a remarkable increase in their lifespan.