Wear Mechanism Of Diamond Tools Research Articles

Study on wear of diamond during scratching SiC using molecular dynamics simulations

In this work, molecular dynamics (MD) simulations have been performed to investigate the wear mechanisms of diamond probe scratching 3C-SiC substrate. The number of worn atoms, the number of atoms in contact with the substrate, the friction force and normal force all increased significantly with the increase of the scratching depth. It is also found that as the scratching depth increased, the high stress region gradually shifted from the bottom to the rear end of the probe, indicating the risk of probe failure changing from gradual wear to fracture. Moreover, the SiC substrate undergone high temperature, high compressive stress and structural transformation in the wear process. We also found that only single atoms or atomic clusters are detached from the tip under the attractive interaction, indicating the occurrence of atomic attrition. The insights gained can shed light on the wear mechanism of diamond tool in machining SiC and provide a theoretical reference for controlling diamond tool wear in ultra-precision machining.

Analysis of diamond tool wear mechanism in terms of stress for KDP Fly cutting

Although KDP (Potassium dihydrogen phosphate) crystal is very soft and brittle compared with diamond, the wear of diamond tool still exists in flying cutting, though the wear is much slower than that of diamond cutting copper and aluminum. The high technical requirements of KDP flying cutting has a small tolerance to tool wear. And the tool wear causes the quality of KDP processing uncontrollable, which results in low efficiency of processing and even workpiece scrap. In this paper, through the stress analysis of KDP lattice damage based on the first principle theory and the mechanical analysis of the cutting edge of diamond tool, it is proposed that the stress induces the wear of diamond tool in KDP flying cutting. The understanding of the wear mechanism of diamond tools lays a foundation for further research on the wear law of tools and for exploring the methods of prolonging the service life of tools.

A review of tool wear mechanism and suppression method in diamond turning of ferrous materials

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).

Thermal Behavior of Single-Crystal Diamonds Catalyzed by Titanium Alloy at Elevated Temperature

Single-crystal diamonds are considered as the best tool material for ultra-precision machining. However, due to its low thermal conductivity, small elastic modulus and strong chemical activity, titanium alloy has poor machinability and is a typically difficult-to-machine material. Excessive tool wear prevents diamonds from cutting titanium alloy. This study conducts a series of thermal analytic experiments under conditions of different gas atmospheres in order to research the details of thermochemical wear of diamonds catalyzed by titanium alloy at elevated temperatures. Raman scattering analysis was performed to identify the transformation of the diamond crystal structure. The change in chemical composition of the work material was detected be means of energy dispersive X-ray analysis. X-ray photoelectron spectroscopy was used to confirm the resultant interfacial thermochemical reactions. The results of the study reveal the diffusion law of the single-crystal diamond under the action of titanium in the argon and air environment. From the experimental results, the product of the chemical reaction corresponding to the interface between the diamond and the titanium alloy sheet could be found. The research results provide a theoretical basis for elucidating the wear mechanism of diamond tools in the titanium alloy cutting process and for exploring the measures to suppress tool wear.

A molecular dynamics simulation of wear mechanism of diamond tool in nanoscale cutting of copper beryllium

In the present study, molecular dynamics simulation (MDS) is employed to study the wear mechanism of single crystal diamond tool during nanocutting of copper beryllium (CuBe). Two edge configurations, i.e., both sharp and worn out tools, are chosen to study the tool and workpiece interaction during the nanocutting of CuBe. Further, the study involves the experimental characterization techniques viz. scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and Raman spectroscopy to confirm the simulation results. The results of the molecular dynamics simulation (MDS) show that the presence of Be as a hard particle in workpiece material influences the cutting forces which subsequently causes degradation of the sharp edge of the diamond tool. Furthermore, the carbon (C) atoms removed from the tool react with Be particles and as a result, it causes the formation of beryllium carbide (BeC). Beryllium interaction with the blunt edge configuration of the tool causes amorphization at the tool edge. Raman spectroscopy of the used diamond tool on CuBe reveals the similar phenomena of amorphization of the diamond at the tool edge. Moreover, surface generation is dependent on the tool edge condition as blunt edge tool leads to smoother surface compared to the surface generated by sharp edge configuration.

Molecular dynamics simulation and experiment research of cutting-tool wear mechanism for cutting aluminum alloy

In order to reveal the wear mechanism of diamond tool in precision cutting large-aperture aluminum alloy mirror, molecular dynamics simulation is carried out in this work. The simulation results indicate that diffusion wear is the dominant way of the tool wear, which is in consistent with the cutting experiment. EDS of the aluminum alloy chips shows that Cu elements result in the phenomenon of chemical wear for diamond tool in the precision cutting process. Therefore, the wear mechanism of diamond tool in precision cutting large-aperture aluminum alloy mirror is a combination of diffusion wear and chemical wear. In addition, through the micro topography of the diamond tool wear zone, it can be found that the flank wear is the dominant form of the cutting tool. The results of the orthogonal experiment show that the influence of the tool clearance and feed rate on tool wear is greater than that of the cutting speed and tool arc radius. The results of single-factor experiment indicate that with the increase of the feed rate, the tool wear increases. While with the increase of the tool clearance, the tool wear decreases.

Research of the mechanism and development of the wear model of a diamond tool when turning aluminum-matrix composite materials

The results of a study of the wear mechanism of diamond tools for turning aluminum-matrix composite materials (ACMs) hardened by Al2O3, SiC, and B4C particles are presented. The study of the posterior surface topography of a diamond tool (ASPK-2) shows the presence of parallel scratches in the direction of the vector of the cutting speed; it is characteristic of abrasive wear fatigue. Research on the mass-transfer of the elements of the tool material into the chips of the treated material is carried out; it shows the presence of particles of the tool material of a size comparable to the ACM filler microparticles. The model of the abrasive-wear fatigue of a diamond tool during the turning of ACMs, considering the power of the impact of the reinforcement particles, the hardness of the tool depending on the temperature in the cutting zone, the abrasiveness, and the mass fraction of the dispersed particles reinforcing the matrix and tool geometry is proposed.

The investigation of influence of tool wear on ductile to brittle transition in single point diamond turning of silicon

Single point diamond turning (SPDT) of large functional surfaces on silicon remains a challenge owing to severe diamond tool wear. Recently, tremendous efforts have been made in understanding the machining mechanics, especially wear mechanism of diamond tools in SPDT of silicon. However, the localised transition of machining mode from ductile to brittle as a result of progressive tool wear has not been well understood yet. In this paper both experimental and numerical simulation studies of SPDT were performed in an effort to reveal the underlying phenomenon of ductile to brittle transition (DBT) as a consequence of diamond tool wear. Series of facing and plunging cuts were performed and the profile of machined surface was evaluated together with the progression of tool wear. The transition stages from ductile to brittle were identified by analysing the surface profiles of plunging cuts using a scanning electron microscope (SEM) and a 2D contact profilometer and a white light interferometer. The progressive degradation of the cutting edge of diamond tool and its wear mechanism was determined using Least Square (LS) arc analysis and SEM. The study reveals that at initial tool wear stage, the ductile to brittle transition initiates with the formation of lateral cracks which are transformed into brittle pitting damage with further tool edge degradation. Numerical simulation investigation using smoothed particle hydrodynamics (SPH) was also conducted in this paper in order to gain further insight of variation of stress on the cutting edge due to tool wear and its influence on brittle to ductile transition. A significant variation in frictional resistance to shear deformation as well as position shift of the maximum stress values was observed for the worn tools. The magnitude and distribution of hydrostatic stress were also found to change significantly along the cutting edge of new and worn diamond tools.

Wear Mechanism of Diamond Tool against Mold Steel in Single Point Diamond by Molecular Dynamics

Owing to the extremely rapid tool wear, ultra-precision manufacturing of mold steel through single point diamond turning (SPDT) operation becomes a challenging task. Molecular dynamics (MD) simulation is an appropriate tool to study nanoscale processes occurring at the femtosecond/picosecond timescale. The wear mechanism of the diamond tool is discussed by means of molecular dynamics in which atomic position variation, temperature fluctuations were involved. According to the analysis results, iron atoms have unpaired d electrons, these iron atoms may connect with diamond carbon atoms through chemical bonds which are the driving force to the diamond removal and making diamond convert into graphite. The simulation results demonstrated that, it is possible to mitigate the wear of diamond tools effectively, if those bindings between unpaired d electrons and diamond carbon atoms of the tool can be under control.

Wear mechanism of diamond tools against single crystal silicon in single point diamond turning process

In this paper, a molecular dynamics simulation has been adopted to arrive at a phenomenological understanding of the wear mechanism of diamond tools against single crystal silicon in the single point diamond turning (SPDT) process. The radial distribution function confirms the formation of silicon carbide at the contact interface, which signals the initiation of wear of the diamond tool. A simultaneous mechanism of sp3–sp2 disorder of the diamond tool was also found to proceed in tandem. This mechanism is corroborated by a recent experimental study, where silicon carbide and carbon like particles were observed after machining of single crystal silicon with a diamond tool through X-ray photoelectron spectroscope (XPS) technology.

Simulation Study of Cutting Forces, Stresses and Temperature during Nanometric Cutting of Single Crystal Silicon

Wear of diamond tool has always been a limiting factor in ductile regime machining of large size silicon components. In order to understand the tool wear phenomena, it is non-trivial to know the process outputs especially cutting forces, stresses and temperature during nanometric turning. In this paper, a realistic potential energy function has been deployed through molecular dynamic (MD) simulation, to simulate the process outputs of single diamond turning operation against single crystal silicon. The simulation result suggests that wear mechanism of diamond tool is fundamentally governed by these process parameters and thus critical.

C21 Wear Mechanism of Diamond Tools in Ductile Machining of Reaction-bonded Silicon Carbide(Ultra-precision machining)

Wear mechanisms of single-crystal diamond tools in ductile machining of reaction-bonded silicon carbide (RB-SiC) were investigated. It was found that tool wear could be generally classified into two types. One is microchippings on the cutting edge, which were induced by micro impacts between the cutting edge and SiC grains. The other is two kinds of gradual wear patterns on flank face caused by different mechanisms: non-periodical scratches caused by scratching effects of the SiC grains, and periodical grooves caused by transcribing effect of tool feed marks on the machined surface. A tool-swinging cutting method was proposed to improve the service life of diamond tools.

Thermo-Chemical Wear Mechanism of Diamond Tool in Machining of Ferrous Metals

To understand the wear mechanism of diamond tool in machining of ferrous metals, an erosion test simulating wear process and ab-initio molecular orbital calculation are carried out. The results of the tests and analyses show that the essential wear mechanism at the temperature higher than 1000K is the dissociation of carbon atoms on diamond surface due to the interaction with iron surface. The wear rate is controlled by the removal rate of dissociated carbon atoms from the tool-work interface such as diffusion into workpiece. At the temperature lower than 900K, the mechanism involves the removal of carbon atoms due to oxidization of diamond accompanied with deoxidization of iron oxide.

A new look at the atomic level virial stress: on continuum-molecular system equivalence

The virial stress is the most commonly used definition of stress in discrete particle systems. This quantity includes two parts. The first part depends on the mass and velocity (or, in some versions, the fluctuation part of the velocity) of atomic particles, reflecting an assertion that mass transfer causes mechanical stress to be applied on stationary spatial surfaces external to an atomic‐particle system. The second part depends on interatomic forces and atomic positions, providing a continuum measure for the internal mechanical interactions between particles. Historic derivations of the virial stress include generalization from the virial theorem of Clausius (1870) for gas pressure and solution of the spatial equation of balance of momentum. The virial stress is stress‐like a measure for momentum change in space. This paper shows that, contrary to the generally accepted view, the virial stress is not a measure for mechanical force between material points and cannot be regarded as a measure for mechanical stress in any sense. The lack of physical significance is both at the individual atom level in a time‐resolved sense and at the system level in a statistical sense. It is demonstrated that the interatomic force term alone is a valid stress measure and can be identified with the Cauchy stress. The proof in this paper consists of two parts. First, for the simple conditions of rigid translation, uniform tension and tension with thermal oscillations, the virial stress yields clearly erroneous interpretations of stress. Second, the conceptual flaw in the generalization from the virial theorem for gas pressure to stress and the confusion over spatial and material equations of balance of momentum in theoretical derivations of the virial stress that led to its erroneous acceptance as the Cauchy stress are pointed out. Interpretation of the virial stress as a measure for mechanical force violates balance of momentum and is inconsistent with the basic definition of stress. The versions of the virial‐stress formula that involve total particle velocity and the thermal fluctuation part of the velocity are demonstrated to be measures of spatial momentum flow relative to, respectively, a fixed reference frame and a moving frame with a velocity equal to the part of particle velocity not included in the virial formula. To further illustrate the irrelevance of mass transfer to the evaluation of stress, an equivalent continuum (EC) for dynamically deforming atomistic particle systems is defined. The equivalence of the continuum to discrete atomic systems includes (i) preservation of linear and angular momenta, (ii) conservation of internal, external and inertial work rates, and (iii) conservation of mass. This equivalence allows fields of work‐ and momentum‐preserving Cauchy stress, surface traction, body force and deformation to be determined. The resulting stress field depends only on interatomic forces, providing an independent proof that as a measure for internal material interaction stress is independent of kinetic energy or mass transfer.