Effect Of Tool Wear Research Articles

The effect of pressure gradient and abrasive tool wear when polishing ceramic tiles

A series of experimental investigations were conducted to develop and describe the distribution of the pressure gradient below and across the topological surface of laboratory grinding tools on a ceramic tile during the gloss gaining process. The possibility of controlling the pressure required for the industrial polishing ceramic tiles would prevent excessive wear, directly reducing energy and water consumption. The present research aims to determine the effect of incremental surface pressure distribution in the polishing of ceramic tiles with line contact. For this purpose, two grinding devices were mounted together as a polishing head and built from the machine's base coordinate system on a CNC tribometer with a deflection angle of 2.2°. The grinding pressure was distributed gradually underneath and across the polishing tools by implementing a new polishing tool composed of rotating shaft with pivot joint, helical springs and two abrasive blocks attached on it. Due to the configuration of polishing tools with preferred process parameters, the impact of the material removal and gloss production was found to be minimized or maximized according to the chosen kinematics. Results implied that the process outcome in terms of gloss level and fine surface finish is influenced by the surface pressure (maximum at approximately more than 15 MPa) as well as the abrasive tool surface wear. Furthermore, in the manufacturing line, higher wear rate is posed by the coarser abrasives but less wear rate on the finer abrasives with high gloss gaining.

Wear of electroplated diamond tools in lap-grinding of Al2O3 ceramic materials

Current development of modern products, together with ever-increasing demands for their operation and usage, necessitate the search for new processing methods. Abrasive machining is widely used in many industrial areas, especially for processing difficult-to-machine materials such as advanced ceramics. Grinding with lapping kinematics, also called lap-grinding, is still one of the innovative methods of abrasive processing being under continuous development. It combines the advantages of grinding and lapping, allowing for meeting high design requirements and, at the same time, ensuring efficient and safe machining. This paper presents experimental and modelling results on the application of electroplated wheels with diamond grains (D107 and D64) in the lap-grinding of Al2O3 ceramic materials in a single-disc lapping machine configuration. The grain size along with the thickness of the nickel bond influenced the material removal rate and surface roughness obtained. The relationship between the material removal and the processing time was approximated by asymptotic mathematical functions. Moreover, the empirical models were modified according to the Preston's equation when the unit pressure increased. The linear and nonlinear regression models enabled accurate curve fitting to the surface roughness data. Microscopic images of the active surface of electroplated diamond tools were analyzed in the aspects of the resultant tool wear and technological effects. In addition, the results were referred to the analysis of microscopic images of the suspension taken from the active surface of the tool after subsequent tests. The suspension consisted of particles of fragmented abrasive grains as well as chips removed from the machined surface.

Prediction model of peripheral milling surface geometry considering cutting force and vibration

Milling surface quality is an important factor to assess the performance of a product, which is usually affected by cutting parameters. This paper presents a novel model of peripheral milling surface topography considering tool vibration. The model used the idea of discretization by introducing the milling dynamics and ignored the effect of tool wear, tilting, and thermal deformation. The simulation results were verified and showed good consistence with experimental results. Afterwards, parametric analysis was conducted to investigate the impact of process parameters and showed that feed per tooth impacts most on the surface roughness while axial depth of cut has the least impact. The presented method enables researchers to predict the peripheral milling surface before processing. Moreover, the method helps to build the formula of surface roughness to conduct the parameter optimization.

Effect of tool wear on drilling unidirectional CFRP laminates in different fiber cutting angles

Drilling performance of carbon fiber reinforced polymer (CFRP) aggravates significantly with serious tool wear caused by highly abrasive fibers. Because of the anisotropy of CFRP, the angle between fiber orientation and cutting direction, namely, fiber cutting angle, also plays a crucial part in the drilling performance. To enhance drilling performance, this paper initially conducts a comprehensive experimental study on the effects of tool wear on thrust force, exit temperature, and hole wall defect in different fiber cutting angles in the drilling of unidirectional CFRP. The results demonstrate that the profile of worn cutting edge is an approximate elliptical arc and the half axis lengths of the elliptical arc are utilized to evaluate cutting edge wear. Tool wear on the cutting edge, flank face, and rake face all deteriorates with the number of drilled holes. Tool wear has a more significant influence on thrust force in the fiber cutting angle region of 0~90° than in the fiber cutting angle region of 90~180°. With increasing tool wear, the exit temperature distribution can still be approximate to an ellipse. The variation of exit temperature caused by tool wear in the major axis direction is still no less than that in other directions. In addition, on hole wall, tool wear causes severe crack defects in the fiber cutting angle region of 0~90° and cavity defects in the fiber cutting angle region of 90~180°.

Tool wear induced modifications of plastic flow and deformed material depth in new generated surfaces during turning Ti-6Al-4V

The thermo-mechanical loads induced by tribological interfaces complicate the descriptions of the local plastic deformation behaviours in high-speed machining. This study utilized finite element simulation technique and microstructural observation to investigate the local plastic deformation behaviours of new generated chips and machined surface in turning Ti-6Al-4 V. The plastic deformation behaviours modifications of plastic flow and deformed material depth under different tool wear states were discussed. On one hand, the Arbitrary-Lagrangian-Eulerian (ALE) modelling based on hybrid sticking-sliding friction model was proposed with dependence of tool wear geometrical changes. The multi-physics variables distributions such as cutting temperature, strain, and strain rate were acquired to provide the basic analysis of thermo-mechanical loads induced by tribological effects. On other hand, the experimental evidences of local plastic deformation behaviours including intensive microstructural changes in primary/secondary/tertiary deformation zones were analysed in details. Both simulated and experimental results indicated that thermo-mechanical loads due to tool wear effects were the critical driving factor for local plastic behaviours evolution. The deformation strength of primary/secondary/tertiary zones increased because of the gradual increasing contact areas and heat generation. This study can help to control the microstructural evolutions by limiting tool wear and enhance the surface quality.

Machinability of inconel 718 during turning: Cutting force model considering tool wear, influence on surface integrity

Abstract Machining accuracy can be compromised by elastic workpiece deformation and subsurface residual stress introduction during cutting. In order to anticipate the impact of cutting forces and surface integrity evolutions on finished surface and its geometrical errors, it is necessary to better understand the influence of cutting conditions and tool wear. In this study, machinability of Inconel 718 using a round carbide tool in finish turning conditions is assessed. Cutting forces evolution during tool life are analysed and accompanied by advanced investigations of cutting phenomena. An original mechanistic cutting force model is developed, identified and tested. It includes the effect of tool wear over time in its local formulation. This model allows predicting cutting forces evolution along tool pass for a wide range of finishing cutting conditions. Furthermore, a thorough analysis of residual stress profiles at different tool wear levels is led. It features quantitative results for fresh and worn tools. A study on the influence of cutting parameters and tool wear on residual stress profiles in the machining affected zone is highlighted.

Tool wear, surface quality, and residual stresses analysis of micro-machined additive manufactured Ti–6Al–4V under dry and MQL conditions

Achieving the reasonable tool life, surface quality, and residual stresses in the micromachining of difficult-to-cut materials is still a challenge. Titanium alloys are notorious among hard materials for poor thermal conductivity and hardness at elevated temperature leading to premature tool failure. The additive manufactured titanium is one-step beyond in hardness and put forward a real challenge, especially in the micro-milling. In these conditions, a minuscule cooling/lubrication is imperative to apply to reduce the accelerated tool wear and surface burning effects due to heat generation. This comparative study aims to analyze the lubri-cooling effects of minimum quantity lubrication (MQL) in the micro-milling of additively manufactured Ti–6Al–4V using coated tungsten carbide micro endmills under varying cutting speeds and feed rates.

Indirect online tool wear monitoring and model-based identification of process-related signal

Tool wear monitoring using vibrations is a complex task, due to various simultaneously occurring vibration sources and due to distortion of the signals acquired. This work investigates the mechanism by which tool wear information is concealed within acquired process-intrinsic vibration signals. Excluding other sources of vibration, such as machine-related, is attempted utilizing process simulations. As a case study, face milling is performed for three different cutting speeds. At first, the resulted simulated wear curves have been compared with experimental ones resulted under the same cutting conditions. Then, a quantification of the effect of tool wear on the acquired signals is presented.

Micro-milling force modeling with tool wear and runout effect by spatial analytic geometry

One of the major limitations of micro-milling applications in industries is its fast tool wear, which leads to low machining precision and efficiency. An accurate force model is fundamental for optimization micro-milling processes and minimize the tool wear. However, a generic model with tool runout and wear effect has not yet been established, which limits its practical application under varied working conditions. In this paper, a new idea is introduced by applying the spatial analytic geometry (SAG) method, under this framework the micro-milling force model is established based on the analysis of the geometrical relationship among the cutting edge positions, pre-processed workpiece morphology, and cutting force directions considering tool runout and wear effect. In this model, the tool runout is identified exclusively by only one parameter, namely the distance away from the center that perpendicular to the feed direction, so that it could be calibrated conveniently by calculating the ratio of resultant forces corresponding to different cutting edges. The tool wear–induced force is then modeled as increment of force coefficients to the original model. Therefore, the new force model with considering tool wear has the same form as the fresh tool. Finally, the accuracy and efficiency of the model are validated by experiments under varied working conditions.

Deterministic polishing of micro geometries

Ultraprecision polishing of miniature components and features with small curvature radii is limited by surface accessibility, availability of suitable tools and the capability to control material removal with sufficient spatial resolution. This paper presents the development of an approach for the application of nearly deterministic micro polishing using miniature tools with 400 μm radius. To enable implementation of the proposed approach, the effect of tool wear and polymer relaxation on the control of local contact pressure is characterized and compensation of tool wear along the tool path is introduced. The process is experimentally validated by application to features in nickel phosphor with lateral dimensions down to 2 mm, yielding roughness down to less than Sa 1 nm and profile accuracy better than 10 nm P-V.

Process signals characterisation to enable adaptive drilling of aerospace stacks

When drilling multi-material stacked structures, carrying out adaptive drilling would allow for the utilisation of optimal parameters throughout the drilling cycle. This research work focuses on establishing relationships between process incidences and signals recorded from different sensors when drilling aerospace stacks, as well as the effects of tool wear on these relationships. Drilling tests were carried out while recording cutting forces, acceleration and acoustic emission, at different stages of tool wear. All signals were found to strongly correlate with process incidences, suggesting that they could be used as sources of information for decision-making in a process monitoring system.

Effect of progressive tool wear on the functional performance of micro milling process of injection molding tool

In micro milling process, tool wear is one of the significant research area and tool behavior during machining is rather unpredictable. As tool wear progress, the cutting edge geometry change and leading to lower performance and failure of the machined surface integrity. This work investigate the influence of the progressive tool wear during micro end milling of a functional surface (micro ridges) on the injection molding tool with H13 tool steel material. In order to monitor the tool wear progress, five different TiAlN coated carbides micro end mills with 500 µm diameter were used to carry out the experiments in different cutting distances 64 cm to 320 cm. The chip formation, burr formation and surface quality in different tool wear conditions were evaluated. The burr form and size were affected by cutting edge wear and dissimilar results obtained at the end of cut. Moreover, the analysis of chip geometry in microscopic scale allows evaluating the chip morphology and cutting mechanisms in different tool wear conditions. The machined slots by the profile analysis and the surface quality of parts decreased as the tool wear growth. This work contribute to improved knowledge of cutting mechanisms with worn tools causing dissimilar material removal and surface integrity during machining process.

Quantitative evaluation of experimental wear behaviour for CrN-coated tool steels in sheet metal forming process of TRIP 1180

The damage to the tool surface earlier than expected in the sheet metal forming process of ultra high strength steel (UHSS) sheet is due to the high reaction force of the materials, which is directly related to the decrease of productivity and product quality and increase the maintenance cost of the forming tool. In this study, the wear behaviour of the tool surface was quantitatively analysed by experimental database. The contact conditions of the tool surface in the sheet metal forming process was confirmed by finite element analysis. Based on this analysis of contact characteristics, continuous wear tests with UHSS sheet were conducted with progressive punch and die sets. The quantitative wear behaviour of the tool was evaluated by measuring the wear depth of the tool and the roughness of the tools and the products. The effect and sensitivity of tool wear for tool-making and process conditions were quantitatively analysed through the experimental database of tool wear per hits.

Optimization of CFRP Micro Drilling Parameter using 2-Level Factorial Method Towards Thrust Force

Carbon Fiber Reinforced Polymer (CFRP) is extensively used in aircraft and automotive industries due to it exceptional material properties such as high strength to weight ratio and corrosion resistance. Nevertheless, micro drilling process of CFRP material poses various challenge as it has irregular material properties along the structure. High cutting force which lead to poor hole quality is one of the issues that always occur when drilling this material. Hence, the understanding on the relationship between process parameter and material behavior is vital to achieve optimum performance of machining process. The experiment was carried out using 2-level factorial design with variable spindle speed range of 8,000 – 12,000 rpm and feed rate range of 0.01-0.015 mm/rev. Micro drill bit with diameter of 0.9 mm was used and new fresh drill were used for every run to avoid tool wear effect. As a result, lower thrust force of 6.3742 N is obtained from the combination of spindle speed 10k rpm and feed rate 0.0125 N. Therefore, it can be concluded that, optimum parameter falls between the range of 8,000 – 12,000 rpm of spindle speed and 0.01-0.015 mm/rev of feed rate. Validation of the optimum parameter suggested from 2-level factorial which are 8,000 rpm and 0.01 mm/rev is executed. The final result obtained shows 4.5% of error from targeted value and this result is absolutely acceptable and portray the reliability of the experiment.

Investigation on Micro-milling of Ti–6Al–4V Alloy by PCD Slotting-Tools

Ti–6Al–4V is characterized by various protruding characteristics and has been found extensive applications in aerospace, biomedical device industries and other fields. However, these properties in turn bring about the increase in cutting forces, make the chips intractable to control and also shorten the tool service life, etc. A preliminary exploration of micro-milling of Ti–6Al–4V by PCD slotting-tool (MST-PCD) was launched in this paper. The most prominent advantage was the PCD slotting-tools could reach a higher linear velocity even the spindle speed was lower, which can strongly ensure the strength and stiffness of micro cutters and suppress the vibration occurrence due to the high spindle speed. The machining processes of using PCD slotting-tool and carbide micro-end mill (MEM-WC) was compared in detail. The wear experiments were conducted to confirm the effectiveness and advantage of MST-PCD. The cutting forces and surface quality, as well as the effects of tool wear on these output responses were investigated. Then model establishment and multi-objective parameter optimization were performed based on the orthogonal experiment results. Finally, verification experiments were also carried out to confirm the effectiveness of the developed models and MST-PCD. The findings in this paper can also be applied to other difficult-to-machine materials.

A study to determine the onset of catastrophic wear of a processing tool by statistical parameters of acoustic emission

In the present study, experimental research was carried out to determine the effect of the processing tool wear on the mutual change in the average statistical amplitude parameters of acoustic emission signals. Acoustic emission signals were recorded when turning silumin. The research was aimed at finding parameters to determine the occurrence of critical wear of the processing tool. It is shown that the recorded signals are continuous. The statistical amplitude parameters of the acoustic emission signals were processed under normal and catastrophic wear of the processing tool. It has been determined that the development of normal and catastrophic wear of the tool leads to a decrease in the values of the statistical amplitude parameters of the recorded signals. However, no peculiarities were found in their change to determine the developing type of wear. Meanwhile, at different time intervals, there was an anticipating increase or decrease in one of the statistical amplitude parameters of the acoustic emission signals. The processed parameter was a coefficient characterising a mutual change in the statistical amplitude values of the recorded signals. It has been determined that absence of the tool wear is characterised by stable values of the calculated coefficient in time. The occurrence and development of catastrophic wear leads to an outburst of the value of the calculated coefficient with its subsequent accelerated decrease to the destruction of the tool. The emergence and development of normal wear leads to an increase in the value of the calculated coefficient with a subsequent transition to a sawtooth change and a gradual decrease of its size. The obtained regularities can be used when devising methods for controlling and monitoring the condition of the tool during the mechanical processing of materials, including monitoring the state of the processing tool in robotic industries

An analytical approach on stochastic model for cutting force prediction in milling ceramic matrix composites

Fiber-reinforced ceramic matrix composites are increasingly applied in the aerospace, energy and electronic industries. Nevertheless, the milling process of ceramic matrix composites is considerably difficult owing to the presence of heterogeneous, anisotropic and brittle nature. This paper presents a novel stochastic model of cutting forces in milling process of ceramic matrix composites. The algorithm model of randomly distributed carbon fibers is developed by incorporating the cutting mechanism. The obtained instantaneous relative content of fibers is introduced for dividing the resultant cutting forces into fiber and matrix components in the shear deformed region, the friction deformed region and the ploughing region, respectively. In addition, a probabilistic approach based on the particle filter is used to predict the random tool wear progression, linking online measurement data with the state of tool wear. Then, the empirical uncertain components of cutting forces considering tool wear can be established by using a radial basis function (RBF) neural network. The predicted cutting forces are in good agreement with the measured values. The effects of stochastic fiber distributions, tool wear and machining parameters on cutting forces are investigated by the proposed model.

Effect of Progressive Tool Wear on the Evolution of the Dynamic Stability Limits in High-Speed Micromilling of Ti-6Al-4V

Abstract Micromilling can fabricate complex features in a wide range of engineering materials with an excellent finish but the limited flexural stiffness of the micro-end mill can result in catastrophic tool failure. This issue can be overcome by using high rotational speeds. Note that the combination of high rotational speeds and low flexural stiffness can induce process instability which is aggravated by the accelerated wear of the micro-tools at high speeds, specifically, for Ti-alloys. The effect of progressive tool wear on the stability has been investigated in micromilling of Ti-6Al-4V. For incorporating tool wear, the cutting force coefficients are modeled as a function of initial and instantaneous cutting edge radius (CER) and feed per tooth. The initial CER of the micro-tool is considered due to the inherent variability in the tool grinding process. A significant increase (85–114%) in the instantaneous CER is observed with an increase in the length of cut. A 2DOF time-domain model based on semi-discretization method has been used to characterize the evolution of stability limits with an increase in the length of cut. The progressive tool wear affects the stability limits along with the initial CER and the feed per tooth. At higher speeds (90,000–110,000 rpm), the effect of progressive tool wear is pronounced and the stability limits reduce by ∼30% in that range.

Wear and breakage of coated carbide tool in milling of H13 steel and SKD11 hardened steel

In the present paper, the wear and breakage mechanisms of coated carbide tools are investigated in milling of H13 steel (HRC 30–35) and SKD11 hardened steel (HRC 58–62). The experiment results indicate that the hardness of workpiece has a dominant effect on tool failure patterns. Due to the low hardness of H13 steel, low-stress-repeated impact load on the tool induces the generation of cracks, but not enough to cause tool fracture. Thus, tool failure pattern is flank wear in milling of H13 steel. In contrast, the high-stress-repeated impact load facilitates the initiation and propagation of cracks and ultimately leads to breakage of rake face when milling SKD11 hardened steel. The geometry model of tool wear and breakage is established to explore the variation of tool angle. It is found that the flank wear reduces the clearance angle, while the breakage of rake face decreases the rake angle. In addition, the effect of tool wear and breakage on the cutting forces and chip formation is studied. The flank wear increases the friction coefficient between tool and H13 steel, and the breakage of rake face increases chip deformation and reduces the sharpness of cutting edge, both of which result in the increase in cutting forces. Furthermore, the wave-shaped chips are formed throughout milling of H13 steel, while the breakage of rake face results in the curling and separation of sawtooth chips when milling SKD11 hardened steel.

Peck drilling of CFRP/titanium stacks: effect of tool wear on hole dimensional and geometrical accuracy

The effect of tool wear on dimensional and geometrical accuracy of holes machined by peck drilling in carbon fibre reinforced plastic (CRFP) and titanium (Ti) stacks is studied. Coated and uncoated tungsten carbide drills of both fine and ultra-fine microstructures are employed to assess the importance of grain size and coating on hole accuracy. Hole profiles show two maxima: one at the hole entry and the other at the CFRP/Ti interface. Hole cylindricity as function of tool wear shows a minimum. It firstly decreases due to flank wear and subsequent reduction of the drill diameter. Then the rise of tool instability prevails with the result that an increase of the cylindricity with tool wear is brought about. Less wear-resistant drills attain this minimum in a shorter time of cutting.