Prediction of Wearing of Cutting Tools Using Real Time Machining Parameters and Temperature Using Rayleigh-Ham Method

Wear of cutting tools is a big concern for industrial manufacturers, because of their acquisition cost as well as the impact on the production lines when they are unavailable. Law of wear is very important in determining cutting tools lifespan, but most of the existing models don’t take into account the cutting temperature. In this work, the theoretical and experimental results of a dynamic study of metal machining against cutting temperature of a treated steel of grade S235JR with a high-speed steel tool are provided. This study is based on the analysis of two complementary approaches, an experimental approach with the measurement of the temperature and on the other hand, an approach using modeling. Based on unifactorial and multifactorial tests (speed of cut, feed, and depth of cut), this study allowed the highlighting of the influence of the cutting temperature on the machining time. To achieve this objective, two specific approaches have been selected. The first was to measure the temperature of the cutting tool and the second was to determine the wear law using Rayleigh-Ham dimensional analysis method. This study permitted the determination of a law that integrates the cutting temperature in the calculations of the lifespan of the tools during machining.

INFLUENCE OF COLD NITROGEN GAS AND OIL MIST IN MACHINING NICKEL-BASE K424 ALLOY WITH CERAMIC CUTTING TOOLS

The role of cold nitrogen gas and oil mist on tool wear and surface roughness is investigated in turning the K424 nickel-base super alloy with Sialon and SiC whisker-reinforced alumina ceramic tools. A new cooling system is developed and used to lower the temperature of the compressed nitrogen gas. Experiments are performed in three different cooling/lubrication modes, i.e. the dry cutting, the cold nitrogen gas （CNG）, and the cold nitrogen gas and oil mist （CNGOM）. Experimental results show that the depth-of-cut notching severely limits the tool life in all the cooling/lubrication modes. Compared with the dry cutting, the use of CNG and CNGOMcan yield higher wear rate of depth-of-cut notching and worse surface finish.

Severe Cut Throat Injury in a Child: A Case Report and Review of Literature

Background: Cut-throat injury is a potentially fatal condition that may be associated with serious morbidity and mortality. The neck region is particularly at risk of serious injuries due to the location of vital structures, including nerves, viscera, and major vessels. Although cut-throat injury is said to be rare in children, its occurrence has been reported in some series. Management of this condition requires a multidisciplinary approach for a better outcome. Aim: The aim of this report is to highlight the successful management of an alarming case of severe cut-throat injury with associated laryngeal injury in a child. Case presentation: A 12-year-old boy presented with a cut-throat following an assault by an unknown person. Examination revealed an acutely ill child, conscious but pale. He sustained a deep transverse laceration that transected the thyroid cartilage, exposing the laryngeal cavity. An assessment of Zone II penetrating neck injury was made. He was resuscitated, and had emergency neck exploration, tracheostomy, and repair of the injuries. The patient was followed up for 6 months, and had a good voice outcome, with no significant complication. Conclusion: Cut-throat injury is rare in children. But it is a potentially life-threatening condition. It is therefore important to recognize this entity and develop effective protocol of management in our environment.

Comparison of TiAlN, AlCrN, and AlCrN/TiAlN coatings for cutting-tool applications

Monolayer and bilayer coatings of TiAlN, AlCrN, and AlCrN/TiAlN were deposited onto tungsten carbide inserts using the plasma enhanced physical vapor deposition process. The microstructures of the coatings were characterized using scanning electron microscopy （SEM） and atomic force microscopy （AFM）. The SEM micrographs revealed that the AlrN and AlCrN/TiAlN coatings were uniform and highly dense and contained only a limited number of microvoids. The TiAIN coating was non-uniform and highly porous and contained more micro droplets. The hardness and scratch resistance of the specimens were measured using a nanoindentation tester and scratch tester, respectively. Different phases formed in the coatings were analyzed by X-ray diffraction （XRD）. The AlCrN/TiAlN coating exhibited a higher hardness （32.75 GPa）, a higher Young＇s modulus （561.97 GPa）, and superior scratch resistance （LcN = 46 N） compared to conventional coatings such as TiAlN, A1CrN, and TiN.

Design of High Precision CNC Vertical Lathe Turning Tool Holder

A large aspect ratio vibration reducing tool holder based on passive damping vibration reduction technology is designed to solve the vibration problem that occurs in deep hole machining of vertical lathes.A dynamic model of passive damping vibration reduction tool holder was established,and the optimal damping ratio,optimal frequency ratio,and maximum relative amplitude were derived.Modal analysis of the passive damping vibrationreduction tool holder was conducted using software.The results showed that the maximum response amplitude of the passive damping vibration reduction tool holder decreased significantly compared to the original one.

Tool Wear and Its Effect on Surface Roughness in Diamond Cutting of Glass Soda-lime

For the technology of diamond cutting of optical glass, the high tool wear rate is a main reason for hindering the practical application of this technology. Many researches on diamond tool wear in glass cutting rest on wear phenomenon describing simply without analyzing the genesis of wear phenomenon and interpreting the formation process of tool wear in mechanics. For in depth understanding of the tool wear and its effect on surface roughness in diamond cutting of glass, experiments of diamond turning with cutting distance increasing gradually are carried out on soda-lime glass. The wear morphology of rake face and flank face, the corresponding surface features of workpiece and the surface roughness, and the material compositions of flank wear area are detected. Experimental results indicate that the flank wear is predominant in diamond cutting glass and the flank wear land is characterized by micro-grooves, some smooth crater on the rake face is also seen. The surface roughness begins to increase rapidly, when the cutting mode changes from ductile to brittle for the aggravation of tool wear with the cutting distance over 150 m. The main mechanisms of inducing tool wear in diamond cutting of glass are diffusion, mechanical friction, thermo-chemical action and abrasive wear. The proposed research makes analysis and research from wear mechanism on the tool wear and its effect on surface roughness in diamond cutting of glass, and provides theoretical basis for minimizing the tool wear in diamond cutting brittle materials, such as optical glass.

Dynamic Reliability Sensitivity of Cemented Carbide Cutting Tool

Influence of geometric and cutting parameters of cemented carbide cutting tool on reliability of cutting tool has become more and more mature, yet influence of its physical and material parameters on reliability is still blank. In view of this, cutting test and fatigue crack growth test of YT05 cemented carbide cutting tool are conducted to measure such data as the original crack size, growth size, times of impact loading, number and time of cutting tool in failure, and stress distribution of cutting tool is also obtained by simulating cutting process of tools. Mathematical models on dynamic reliability and dynamic reliability sensitivity of cutting tool are derived respectively by taking machining time and times of impact loading into account, thus change rules of dynamic reliability sensitivity to physical and material parameters can be obtained. Theoretical and experimental results show that sensitive degree on each parameter of tools increases gradually with the increase of machining time and times of impact loading, especially for parameters such as fracture toughness, shape parameter, and cutting stress. This proposed model solves such problems as how to determine the most sensitive parameter and influence degree of physical parameters and material parameters to reliability, which is sensitivity, and can provide theoretical foundation for improving reliability of cutting tool system.

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.

Effects of Cutting Parameters on Tool Insert Wear in End Milling of Titanium Alloy Ti6A14V

Titanium alloy is a kind of typical hard-to-cut material due to its low thermal conductivity and high strength at elevated temperatures, this contributes to the fast tool wear in the milling of titanium alloys. The influence of cutting conditions on tool wear has been focused on the turning process, and their influence on tool wear in milling process as well as the influence of tool wear on cutting force coefficients has not been investigated comprehensively. To fully understand the tool wear behavior in milling process with inserts, the influence of cutting parameters on tool wear in the milling of titanium alloys Ti6A14V by using indexable cutters is investigated. The tool wear rate and trends under different feed per tooth, cutting speed, axial depth of cut and radial depth of cut are analyzed. The results show that the feed rate per tooth and the radial depth of cut have a large influence on tool wear in milling Ti6A14V with coated insert. To reduce tool wear, cutting parameters for coated inserts under experimental cutting conditions are set as： feed rate per tooth less than 0.07 mm, radial depth of cut less than 1.0 mm, and cutting speed sets between 60 and 150 m/min. Investigation on the relationship between tool wear and cutting force coefficients shows that tangential edge constant increases with tool wear and cutter edge chipping can lead to a great variety of tangential cutting force coefficient. The proposed research provides the basic data for evaluating the machinability of milling Ti6A14V alloy with coated inserts, and the recommend cutting parameters can be immediately applied in practical production.

Hardening Effect on Machined Surface for Precise Hard Cutting Process with Consideration of Tool Wear

During hard cutting process there is severe thermodynamic coupling effect between cutting tool and workpiece, which causes quenching effect on finished surfaces under certain conditions. However, material phase transformation mechanism of heat treatment in cutting process is different from the one in traditional process, which leads to changes of the formation mechanism of damaged layer on machined workpiece surface. This paper researches on the generation mechanism of damaged layer on machined surface in the process of PCBN tool hard cutting hardened steel Cr12MoV. Rules of temperature change on machined surface and subsurface are got by means of finite element simulation. In phase transformation temperature experiments rapid transformation instrument is employed, and the effect of quenching under cutting conditions on generation of damaged layer is revealed. Based on that, the phase transformation points of temperature under cutting conditions are determined. By experiment, the effects of cutting speed and tool wear on white layer thickness in damaged layer are revealed. The temperature distribution law of third deformation zone is got by establishing the numerical prediction model, and thickness of white layer in damaged layer is predicted, taking the tool wear effect into consideration. The experimental results show that the model prediction is accurate, and the establishment of prediction model provides a reference for wise selection of parameters in precise hard cutting process. For the machining process with high demanding on surface integrity, the generation of damaged layer on machined surface can be controlled precisely by using the prediction model.

Synergistically Toughening Effect of SiC Whiskers and Nanoparticles in Al_2O_3-based Composite Ceramic Cutting Tool Material

In recent decades, many additives with different characteristics have been applied to strengthen and toughen Al2O3-based ceramic cutting tool materials. Among them, SiC whiskers and SiC nanoparticles showed excellent performance in improving the material properties. While no attempts have been made to add SiC whiskers and SiC nanoparticles together into the ceramic matrix and the synergistically toughening effects of them have not been studied. An Al2O3-SiCw-SiC np advanced ceramic cutting tool material is fabricated by adding both one-dimensional SiC whiskers and zero-dimensional SiC nanoparticles into the Al2O3 matrix with an effective dispersing and mixing process. The composites with 25 vol% SiC whiskers and 25 vol% SiC nanoparticles alone are also investegated for comparison purposes. Results show that the Al2O3-SiCw-SiCnp composite with both 20 vo1% SiC whiskers and 5 vol% SiC nanoparticles additives have much improved mechanical properties. The flexural strength of Al2O3-SiCw-SiCnp is 730＋ 95 MPa and fracture toughness is 5.6 ± 0.6 MPa.m1/2. The toughening and strengthening mechanisms of SiC whiskers and nanoparticles are studied when they are added either individually or in combination. It is indicated that when SiC whiskers and nanoparticles are added together, the grains are further refined and homogenized, so that the microstructure and fracture mode ratio is modified. The SiC nanoparticles are found helpful to enhance the toughening effects of the SiC whiskers. The proposed research helps to enrich the types of ceramic cutting tool and is benefit to expand the application range of ceramic cutting tool.

Cutting Performance and Mechanism of RE Carbide Tools

The research of rare earth elements (RE), added into cemented carbide tools, is one of the recent developments of new types of tool materials in China. Systematic experiments about RE carbides YG8R. (K30), YT14R (P20) and, YW1R (M10) were made to study on the cutting performance in comparison with non-RE carbides YG8, YT14 and YW1. The cutting experiments were as follows: tool life, cutting force, tool-chip friction coefficient and interrupted machining. The action of RE on the carbide materials and the cutting mechanism of the RE carbide tools in the cutting process were verified with the aid of SEM and energy spectrum analysis. Experimental results show that the RE carbide tools have a good overall performance.

Cutting Temperature and Tool Wear of Hard Turning Hardened Bearing Steel

A study was undertaken to investigate the performan ce of PCBN tool in the finish turning GCr15 bearing steel with different hardness between 30～64 HRC. The natural thermocouple was used to measure the cutting tem p erature, tool life and cutting temperature were investigated and compared. The m aterial can be heated by this instrument which using low voltage and high elec trical current, while PCBN can’t be heated by electrifying directly, so the ke ntanium layer coating over the PCBN is heated, so the PCBN is heated and its th ermoelectric property is got by this method. [TPP129,+60mm88mm,Y,PZ#] Fig.1 Effect of cutting depth and workpiec hardness on. the cutting temperatureThe objective was to determine the influence of the workpiece hardness on change s in cutting temperature and tool wear characterize. It can be found from Fig.1 that the cutting temperature show an increasing tendency with the improvement of workpiece hardness within the cutting speed scope when the workpiece hardness i s under HRC50. And on the other hand, it is found that the cutting temperature s how the downtrend with the improvement of workpiece hardness when the workpiece hardness is over HRC50. According to experimental results, the critical hard ness when turning hardened GCr15 bearing steel with PCBN tool is about HRC50. Th e wear causes of PCBN tool have been found out through taking photos on the micr o-shape of PCBN poly-laminate initial surface as well as face and flank of wea r tool and analysis on chemical elements. It is discovered that the PCBN tools a re not suitable for cutting the workpiece at nearly critical hardness, because n ear the critical hardness, PCBN wear at the highest speed. For researching the w ear rule of PCBN tool, the tool wear experiments have been carried on by using b earing steel GCr15 at hardness HRC40 and HRC60 with changing cutting speed. The indexes of tool life equations is gained under two kinds of conditions w hich are bigger than 0.6, so the effects of cutting speed on the PCBN tool are m uch less than that of carbide tool and ceramic tool.

Adhesion Wear on Tool Rake and Flank Faces in Dry Cutting of Ti-6Al-4V

Titanium alloys are very chemically reactive and,therefore,have a tendency to weld to the cutting tool during machining.The deterioration in the tool life caused by adhesion is a serious problem when titanium alloys are cut using carbide tools.The chemical reactivity of titanium alloys with carbide tool materials and their consequent welding by adhesion onto the cutting tool during dry cutting leads to excessive chipping,premature tool failure,and poor surface finish.In the present study,dry turning and milling tests were carried out on Ti-6Al-4V alloys with WC?Co carbide tools.The adhesion on the tool rake and flank face was explored,the adhesive joint interface between the workpiece materials and tools were observed.SEM observation showed that adhesion can be observed both on the rake and the flank face,and was more pronounced in rake face than in flank face.There was evidence of element diffusion from the tool rake face to the adhering layer(vice versa) through the adhesive joint interface,which leads to the tool element loss and microstructure change.While the adhering materials at the flank face can be easily separated from the joint interface owing to the lower temperature and less pressure at the flank face,the adhesive wear attack results in an abrasive wear in the flank face.Moreover,adhesion is more notable in turning than in milling.The proposed research provides references for studying the adhesion between the workpiece materials and the tools,the adhesion mechanisms and their effect on the tool wear.

Cutting performance of micro-textured PCBN tool

To study the efect of micro-texture on the cutting performance of polyrystalline cubic boron nitide(PCBN)tools,five types of micro-textures(circular pits,eliptical grooves,transverse grooves,composite grooves,and wavy grooves)were applied to the rake surface of PCBN tools by an optical fber laser marking machine.Through a combination of three dimensional cutting simulations and experiments,the influences of micro-texture on chip-tool contact area,cutting force,chip morphology,shear angle,and surface roughness during the cuting process were analyzed.The results indicated that the chip--tool contact area and cutting force of both non-textured and micro textured tools increased with increasing cutting speed,while the shear angle decreased with increasing cutting speed.The chip-tool contact area and cutting force of the five types of micro-textured tools were smaller than those of the non textured tool The chip-tool contact area and cutting force obtained by the wavy-groove micro textured tool were the smallest.The chip radius produced by the five types of micro-textured tools was smaller than that produced by the non-textured tool,and the chip morphology was more stable.The transverse-groove micro-textured tool had a better chip breaking efect.The chip rnadius generated by the lliptical groove micro textured tool was 0.96 cm,while that generated by the wavy-groove tool varied from 0.55 cm to 1.26 cm.The presence of a micro-texture reduced the surface roughness of the workpiece by 11.73%-56.7%.Under the same cutting conditions,the five types of micro-textured tools gave a smaller chip--tool contact area,cutting force,chip radius,and surface roughness and a larger shear angle than the non-textured tool.In addition,the elliptical groove and wavy-groove micro-textured tools had better cuting performance.

Performance evaluation of minimum quantity lubrication by vege-table oil in terms of cutting force,cutting zone temperature,tool wear,job dimension and surface finish in turning AISI-1060 steel

In all machining processes, tool wear is a natural phenomenon and it leads to tool failure. The growing demands for high productivity of machining need use of high cutting velocity and feed rate. Such machining inherently produces high cutting temperature, which not only reduces tool life but also impairs the product quality. Metal cutting fluid changes the performance of machining operations because of their lubrication, cooling and chip flushing functions, but the use of cutting fluid has become more problematic in terms of both employee health and environmental pollution. The minimization of cutting fluid also leads to economical benefits by way of saving lubricant costs and workpiece/tool/machine cleaning cycle time. The concept of minimum quantity lubrication (MQL) has been suggested since a decade ago as a means of addressing the issues of environmental intru- siveness and occupational hazards associated with the airborne cutting fluid particles on factory shop floors. This paper deals with experimental investigation on the role of MQL by vegetable oil on cutting temperature, tool wear, surface roughness and dimen- sional deviation in turning AISI-1060 steel at industrial speed-feed combinations by uncoated carbide insert. The encouraging results include significant reduction in tool wear rate, dimensional inaccuracy and surface roughness by MQL mainly through reduction in the cutting zone temperature and favorable change in the chip-tool and work-tool interaction.

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.

Machinability of Hastelloy C-276 Using Hot-pressed Sintered Ti(C_7N_3)-based Cermet Cutting Tools

C-276 nickel-based alloy is a difficult-to-cut material. In high-speed machining of Hastelloy C-276, notching is a prominent failure mode due to high mechanical properties of work piece, which results in the short tool life and low productivity. In this paper, a newly developed Ti（C7N3）-based cermet insert manufactured by a hot-pressing method is used to machine the C-276 nickel-based alloy, and its cutting performances are studied. Based on orthogonal experiment method, the influence of cutting parameters on tool life, material removal rates and surface roughness are investigated. Experimental research results indicate that the optimal cutting condition is a cutting speed of 50 m/min, depth of cut of 0.4 mm and feed rate of 0.15 mm/r if the tool life and material removal rates are considered comprehensively. In this case, the tool life is 32 min and material removal rates are 3000 mm^3/min, which is appropriate to the rough machining. If the tool life and surface roughness are considered, the better cutting condition is a cutting speed of 75 m/min, depth of cut of 0.6 mm and feed rate of 0.1 mm/r. In this case, the surface roughness is 0.59μm. Notch wear, flank wear, chipping at the tool nose, built-up edge（BUE） and micro-cracks are found when Ti（C7N3）-based cermet insert turned Hastelloy C-276. Oxidation, adhesive, abrasive and diffusion are the wear mechanisms, which can be investigated by the observations of scanning electron microscope and energy-dispersive spectroscopy. This research will help to guide studies on the evaluation of machining parameters to further advance the productivity of nickel based alloy Hastelloy C-276 machining.

WEAR AND LIFE OF PCBN TOOLS WHEN DRY-CUTTING BEARING STEEL GCr15

The wear forms and reasons of PCBN tools when dry-cutting bearing steel GCr15are studied systematically. The effect law of the workpiece hardness on PCBN tools is gained andtool wearing with the quickest speed at the workpiece critical hardness is proved. The life equationat two kinds of workpiece hardness demonstrates that the effect of the cutting speed on the PCBNtool life is less than that of carbide tools and ceramic tools.

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.