Flank Wear Land Research Articles

A New Slip-Line Field Modeling of Orthogonal Machining with a Rounded-Edge Worn Cutting Tool

In this study, a new slip-line field model and its associated hodograph for orthogonal cutting with a rounded-edge worn cutting tool are developed using Dewhurst and Collins's matrix technique. The new model considers the existence of dead metal zone in front of the rounded-edge worn cutting tool. The ploughing force and friction force occurred due to flank wear land, chip up-curl radius, chip thickness, primary shear zone thickness and length of bottom side of the dead metal zone are obtained by solving the model depending on the experimental resultant force data. The effects of flank wear rate, cutting edge radius, uncut chip thickness, cutting speed and rake angle on these outputs are specified.

Diffusion Theory Applied to Tool-Life Stochastic Modeling Under a Progressive Wear Process

In this paper, a novel approach to the derivation of the tool-life distribution, when the tool useful life ends after a progressive wear process, is presented. It is based on the diffusion theory and exploits the Fokker–Planck equation. The Fokker–Planck coefficients are derived on the basis of the injury theory assumptions. That is, tool-wear occurs by detachment of small particles from the tool working surfaces, which are assumed to be identical and time-independent. In addition, they are supposed to be small enough to consider the detachment process as continuous. The tool useful life ends when a specified total volume of material is thus removed. Tool-life distributions are derived in two situations: (i) both Fokker–Planck coefficients are time-dependent only and (ii) the diffusion coefficient is neglected and the drift is wear-dependent. Theoretical results are finally compared to experimental data concerning flank wear land in continuous turning of a C40 carbon steel bar adopting a P10 type sintered carbide insert. The adherence to the experimental data of the tool-life distributions derived exploiting the Fokker–Planck equation is satisfactory. Moreover, the tool-life distribution obtained, when the diffusion coefficient is neglected and the drift is wear-dependent, is able to well-represent the wear behavior at intermediate and later times.

The relation between chip morphology and tool wear in ultra-precision raster milling

In the field of ultra-precision machining, the study of the relation between chip morphology and tool wear is significant, since tool wear characteristics can be reflected by morphologies of cutting chips. In this research, the relation between chip morphology and tool flank wear is first investigated in UPRM. A cutting experiment was performed to explore chip morphologies under different widths of flank wear land. A geometric model was developed to identify the width of flank wear land based on chip morphology. Theoretical and experimental results reveal that the occurrence of tool flank wear can make the cutting chips truncated at both their cut-in and cut-out sides, and reduce the length of cutting chips in the feed direction. The width of truncation positions of the cutting chip can be measured and used to calculate the width of flank wear land with the help of the mathematical model. The present research is potentially used to detect tool wear and evaluate machined surface quality in intermittent cutting process.

AN INVESTIGATION ON FLANK WEAR MECHANISM OF TUNGSTEN CARBIDE DRILLS DURING CONVENTIONAL AND MODULATION ASSISTED DRILLING

The aim of this research was to experimentally investigate and compare the wear performance of tungsten carbide drills used in conventional and modulation assisted drilling (MAD). During MAD, modulations of low frequency and high amplitude were superimposed on tool motion in the feed direction. Direct measurement of flank wear land was used as tool condition monitoring method. Since the width of flank wear was not regular along the cutting edge, the maximum flank wear, VBmax , was measured using a toolmaker's microscope. The drills were inspected under the scanning electron microscope to establish the possible wear mechanism. The results indicate that the drills used in MAD were better in resisting tool wear than those used in conventional drilling. However, at higher feed during MAD, a catastrophic failure of drill occurred due to fracture of cutting edge.

Effect of Cutting Tool Geometry on Morphology of flank Wear Land in Turning of Low Carbon Steels

The amount of flank wear is often used as the criterion for tool life assessment because it influences work material surface roughness and accuracy. In this study, the influence of cutting tool geometry (angles) on morphology of flank wear land during turning of low carbon steel is investigated by using image processing techniques and Response Surface Methodology (RSM). The analysis was based on a second order model in which the flank wear (area and shape factors) is expressed as a function of three cutting tool geometry parameters (relief angle, rake angle and cutting edge angle) and the effect of tool geometry parameters and their interactive effect on flank wear land morphology have been investigated. It is found that the area and shape factors of flank wear land are highly affected by the cutting tool geometry parameters considered in the present study.

Experimental investigation of a slip-line field model for a worn cutting tool

In this study, the slip-line field model developed for orthogonal machining with a worn cutting tool was experimentally investigated. Minimum and maximum values of five slip-line angles ( θ1, θ2, δ2, η and ψ) were calculated. The friction forces that were caused by flank wear land, chip up-curl radii and chip thicknesses were calculated by solving the model. It was specified that the friction force increased with increase in flank wear rate and uncut chip thickness and it decreased a little with increase in cutting speed and rake angle. The chip up-curl radius increased with increase in flank wear rate and it decreased with increase in uncut chip thickness. The chip thickness increased with increase in flank wear rate and uncut chip thickness. Besides, the chip thickness increased with increase in rake angle and it decreased with increase in cutting speed.

Improving the Efficiency of the Cutting Tool Made of Ceramic when Machining Hardened Steel by Applying Nano-Dispersed Multi-Layered Coatings <sup></sup>

The functional role of nano-dispersed multi-layered composite coatings (NMCC) deposited on the working surfaces of cutting inserts (CI) made of the layered high-strength ceramic (LHC) to equip the cutting tools when cutting hardened (high-strength) steels was investigated. It is shown that the variation in the composition, structure and properties of coatings allows controlling the contact processes at cutting, increasing the length of contact, reducing normal contact stresses and probability of micro- and macro-brittle failure of tool cutting edge. The mathematical models of cutting which establish dependences of flank wear land of the tool, the tangential component of cutting force, power of cutting and roughness of the machined surface from conditions of cutting of high-strengthen steels are developed. It is found out that the application of nano-dispersed ceramic multi-layered coatings on ceramic tool significantly increases its wear resistance and improves the quality of machining.

Effect of cutting speed on tool life in ultrasonic-assisted milling process

Machining processes are inherently involved with tool wear, which is an influential factor in cutting forces, surface roughness, and machining costs. In conventional machining of some materials, there are some limitations regarding rapid wear of tool and large machining forces. As a result, new machining techniques have been developed in recent years, among which is the ultrasonic-assisted machining. This machining method is a combination of ultrasonic vibrations with conventional machining process. The goal of this article is to compare the tool life in ultrasonic-assisted milling and conventional milling processes. In experimental tests, one-dimensional ultrasonic vibrations have been applied on workpiece in the feed direction of tool. By varying spindle speed, the width of flank wear land of cutting tool has been obtained in ultrasonic-assisted milling and conventional milling processes, and the results are compared with each other. Due to tool rotation, the direction of workpiece vibrations with respect to edge of cutting tool varies in time. Consequently, there is the possibility of improper and uncontrolled contacts between tool and workpiece. In order to examine this issue, the relative speed of workpiece in normal direction of tool flank surface has been obtained analytically, and the results have been used in explaining the experimental observations. The experimental results have shown that in spindle speeds of n = 500, 1000, and 2000 r/min, tool life in ultrasonic-assisted milling process is less than in conventional milling process; however, for spindle speed of n = 3150 r/min, due to change in tool wear mechanism and decrease of relative speed of workpiece in normal direction of tool flank surface, tool life in ultrasonic-assisted milling process becomes larger than that in conventional milling process.

Wear mechanism analysis in milling of Ti-6Al-4V alloy

This article presents an investigation into the wear of cutting tool during milling operation of Ti-6Al-4V using H13A carbide inserts. Wear tests were conducted using machining parameters (feed, speed, and depth of cut) falling in the permissible range recommended by the supplier of the inserts. A wear map was created to identify different regions that characterize the tool wear intensity. The wear map revealed a region of avoidance characterized by higher wear for cutting speed of around 55 m/min and feedrate of 0.15 mm/tooth. The Ti:Al ratio reached values between 4:1 and 6:1 for the cutting parameters that resulted in lower–tool wear rate. However, for higher wear rates, the ratio of Ti:Al did not exhibit any stability across the flank wear land. Scanning electron microscope and energy-dispersive x-ray analysis were performed on the worn inserts to identify the high–tool wear regions and material composition at different locations. Titanium aluminides (TiAl and TiAlN) were found just in the low–tool wear regions, and titanium nitride was found across the avoidance region in the wear map. Microscope and x-ray analysis of inserts in the safety zone clearly revealed a built-up edge on the cutting edge of the tools.

An Investigation of Flank Wear Land Inclination in Orthogonal Machining

The sharp freshly ground tool forms wear land with machining. The present work attempts to measure the non-zero inclination of flank wear land with respect to cutting direction and study the effect of the machining parameters, like speed, feed, rake angle and clearance angle, on the formation of non-zero flank wear land inclination. The experimental plan was based on the face centred, central composite design (CCD). The results clearly indicated the presence of non-zero flank wear land inclination with the direction of cutting. The interactions between machining parameter strongly influences flank wear land inclination. This information may be helpful in improving existing machining model or to develop a new model.

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.

Influencing the residual stresses in the surface layer by use of appropriate cutting parameters and tool geometries in turning of aluminium matrix composites

AbstractSurface properties of components often determine their proper functioning. More complex and increasing demands on operational systems require detailed understanding in the influence of machining on the surface layer. Besides surface structure, residual stresses are very important, especially for dynamically loaded boundary surfaces. But, for cutting of modern light weight construction materials like aluminium matrix composites there is insufficient information concerning residual stresses. On this account, experimental investigations in turning of SiC particle reinforced aluminium matrix composites with different cutting parameters and tool geometries are presented with the focus on residual stresses. They are determined by X‐ray diffraction analysis. The results show that in general the use of very small feeds, tools with a width of flank wear land of about 100 μm, or with a small corner radius cause high absolute values of the compressive residual stresses. In consequence, knowledge of the relation between machining and the residual stress state of the surface layer allows to selectively induce residual stresses in the surface layer. This can provide, for example, an increase of fatigue strength.

Thin-film sensors with small structure size on flat and curved surfaces

We have developed a fabrication technology for thin-film sensors on metallic substrates with flat and curved surfaces. Physical vapour deposition by means of a magnetron sputtering system is used to deposit an insulating layer and a following functional layer. This layer is structured by distinct photolithographic steps utilizing a self-developed spray coating technique, four-axis robotics with micrometer precision and a UV laser with a spot size below 10 μm. This highly flexible technique allows a rapid change of design to produce various sensor layouts in a short time. Besides the fabrication technology, we present two realized applications for thin-film sensor technology in this paper. First, a tool wear sensor for rotating cutting tools, directly detecting the flank-wear land width, and second, sputtered resistance strain gauges for force measurement. Measurement results showing the potential of thin-film sensors are given briefly.

Influence of Tool Flank Wear on Surface Integrity in Orthogonal Milling of Powder Metallurgy Superalloy

Tool flank wear has the significant effects on machined surface integrity. The influences of tool flank wear on the cutting forces, surface roughness, microhardness and white layer thickness are investigated in this paper through orthogonal milling experiments. FGH95 powder metallurgy (PM) superalloys are machined with coated cemented carbide tools in the milling experiments. The experiment results show that with the increasing of tool flank wear, cutting force, surface roughness and white layer thickness increase. However, the machined surfaces micro-hardness aggravates with the increase of tool flank wear. It is found that, the machined surface roughness, micro-hardness and white layer increase dramatically especially when the tool flank wear exceeds 0.3mm. A conclusion is then be drawn that, the maximum acceptable tool flank wear land is 0.3mm from the view point of surface integrity when FGH95 PM superalloy is machined with coated cemented carbide tools.

Research on Tool Wear and Surface Characteristics in Ultrasonic Milling Carbon Fibre Reinforced Carbon Composite

The experimental research on ultrasonic vibration assisted milling non-ablating carbon fibre reinforced carbon composite was carried out by employing uncoated tungsten carbide milling cutter, in order to reduce the machining cost and improve the surface quality of workpiece. According to the experimental results, the tool wear was reduced and the surface quality of milled carbon fibre reinforced carbon composite was improved. Compared to traditional milling method, the flank wear land was narrowed and it dominated by abrasive particles wear mechanism. The wear trace was even and wide, with width of 7-8μm; while the rake face was worn in the mode of adhesion wear mechanism. Most of carbon fibres were cut off directly and there were little fracture, pull-out and delamination; the matrix phase was removed nearly in hybrid of brittle and ductile regime and surface damage was small.

Progressive Tool Wear 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. Minimizing the tool wear is of great significance in order to achieve the satisfactory surface quality and dimensional accuracy. For in depth understanding of the tool wear mechanisms, experiments of diamond turning with cutting distance increased gradually was carried out on soda-lime glass in this work. Experimental results indicate that the flank wear was predominant in diamond cutting glass and the flank wear land was characterized by micro-grooves, some smooth crater on the rake face was also seen. The mainly mechanisms inducing tool wear in diamond cutting of glass are diffusion, mechanical friction, thermo-chemical action and abrasive wear.

Online tool wear monitoring using portable digital assistant (PDA)

Real-time tool wear monitoring is an important technique need to be developed to fulfill the demand from the fast development in machining industry. This paper proposed a new method of online tool wear monitoring using portable digital assistant (PDA)-based device to monitor progression of flank wear land during turning process by on-line detecting and analyzing the machining force signals. The machining tests were carried out on turning machine, and Kistler 9255B dynamometer was used to measure the cutting force signal, which was amplified and displayed in the DasyLab software. The measured cutting force signals stored in Dasylab was then analyzed using I-kaz 3D. The analysis was successfully done using newly developed program, C++ language and Visual Basic embedded to display the result on the PDA. This new developed program was installed on PDA to monitor the tool flank wear progression by three modes of different color which include: green (good condition), yellow (transition zone) and red (end of cutting). Therefore, it gives early warning related to the damage and failure of cutting tool, consequently helps the operation of machine to be smoothly operated in order to produce an acceptable quality in manufacturing process. Key words: Real time monitoring, tool flank wear, I-kaz 3D, cutting force signal, portable digital assistant (PDA).

Influence of the tool corner radius on the tool wear and process forces during hard turning

Hard turning has become an alternative machining process for grinding processes of hardened steels. One challenge during hard turning is the increasing wear during the operation time of the tool and the hereby influenced workpiece surface and subsurface properties. This causes unfavorable changes of the microstructure and residual stress state or rather damages of the subsurface. Important factors are the contact conditions between the tool and the workpiece. The width of flank wear land influences the size of the passive force significantly. This has a direct impact on the subsurface properties of the workpiece. One solution is to modify the contact conditions and thereby the specific mechanical and thermal loads that are applied to the tool as well as to the workpiece. This article presents an experimental approach of modified corner radius geometry of cutting tools for hard turning processes. Hereby, the size and direction of the contact length of the cutting edge are adjusted as well as the load impact during machining. The aim is to reduce the tool wear performance. The results show the potential of the load-specific tool design concerning the tool wear and the workpiece subsurface properties. Furthermore, a new approach for predicting the process forces during hard turning is presented.

Enhancement of Surface Integrity in Turning of Particle74 Reinforced Aluminium Matrix Composites by Tool Design

Particle reinforced aluminium matrix composites (AMCs) are high-strength lightweight materials consisting of a comparatively soft aluminium alloy and hard embedded ceramic particles. The high hardness of the particles results in excellent abrasion resistance. However, this property lends poor machinability involving high tool wear and surface imperfections on the workpieces. For this reason, CVD diamond tipped indexable inserts were used for turning AA2124 with 25% volume proportion of SiC particles. The surface integrity is influenced by the tool geometry, which affects the stress condition in the shear zone. In the research described the influence of modified corner geometries and the width of flank wear land were investigated. The results showed that surface roughness values can be decreased by using tools with a wiper geometry. An increasing flank wear land width of the inserts led to a reduction of the surface imperfections.

Tool-Swinging Cutting of Binderless Tungsten Carbide

Tool wear reduction is very important in cutting of ultra hard and brittle materials. In this paper, a tool-swinging cutting method was applied to reduce the wear of round-nosed diamond tools in cutting of tungsten carbide (WC). In this method, the geometrical center of the cutting edge was adjusted to be in coincidence with the rotation center of the B-axis table, and thus the cutting point could be changed along the cutting edge by swinging the tool about the B-axis center. Experimental results showed that the width of the flank wear land was greatly reduced compared to that in the conventional cutting. This work can shed light on ultraprecision machining WC parts without or with less need for subsequent polishing process.