Evolution Of Flank Wear Research Articles

Hybrid prognostics to estimate cutting inserts remaining useful life based on direct wear observation

The aim of this study is to monitor tool wear through recurrent direct observation, to automatically and optimally assess when it is really necessary to change tools. To achieve this goal, a hybrid prognosis algorithm is formulated to estimate cutting tools’ remaining useful life. Since cutting speed, and more generally process parameters, influences the rate of tool degradation, an adaptive prognosis strategy is presented on the basis of flank wear measurements through the application of a Particle Filter (PF) framework. The adaptability feature allows tracking changes in flank wear evolution. The idea is to fit available degradation curves of cutting tool flank land measurements, through the use of data-driven models, i.e. Multi-Layer Perceptrons (MLP) and cubic polynomials (P3). The Remaining Useful Life of the cutting tool is estimated together with its probability density function, by using a PF framework to adapt MLP weights (or P3 coefficients) along with online flank wear measurements. The devised algorithm was proven to adapt to wear trends from the field, obtained with cutting parameters not previously tested, making it suitable for a robust implementation. The approach was tested when trained upon a single run-to-failure, and validated upon four run-to-failures in different cutting conditions according to a cross-validation inspired technique. P3 was found to be more reliable (from the metrics perspective), whereas MLP allowed to be accurate with greater advance, offering a practical advantage. The proposed algorithm may also be adapted to integrate physical features, like specific force coefficients, with direct wear measurements.

Reconceptualizing the Prognostics Digital Twin for Smart Manufacturing with Data-Driven Evolutionary Models and Adaptive Uncertainty Quantification

This work presents an integrated architecture for a prognostic digital twin for smart manufacturing subsystems. The specific case of cutting tool wear (flank wear) in a CNC machine is considered, using benchmark data sets provided by the Prognostics and Health Management (PHM) Society. This paper emphasizes the role of robust uncertainty quantification, especially in the presence of data-driven black- and gray-box dynamic models. A surrogate dynamic model is constructed to track the evolution of flank wear using a reduced set of features extracted from multi-modal sensor time series data. The digital twin's uncertainty quantification engine integrates with this dynamic model along with a machine emulator that is tasked with generating future operating scenarios for the machine. The surrogate dynamic model and emulator are combined in a closed-loop architecture with an adaptive Monte Carlo uncertainty forecasting framework that allows prediction of quantities of interest critical to prognostics within user-prescribed bounds. Numerical results using the PHM dataset are shown illustrating how the adaptive uncertainty forecasting tools deliver a trustworthy forecast by maintaining predictive error within the prescribed tolerance.

Built-up edge formation and flank wear evolution in conventional machining of AZ91 magnesium alloy

Magnesium alloys are largely desirable in numerous industries today because of their intrinsically attractive properties. Low density and high strength coupled with significant biocompatibility are the main advantages. Machining of magnesium alloys is challenging as a result of the persistent chip ignition risk as well as material build-up on the tool due to their softness. Therefore, magnesium alloys’ machinability has not been fully assessed in the available literature. The present work aims to address this aperture by assessing flank wear progression and the prevalence of adhesion-driven built-up edge (BUE) and built-up layer (BUL) in different tool coating materials during the dry short-interval conventional orthogonal turning of AZ91 magnesium alloy. A higher and lower combination of feed rates and cutting speeds were utilized for all tools to compare the possible range of maximum flank wear land width, average flank wear land width, and chip contact length while capturing and assessing said parameters through digital and optical microscopy. The data presented a large prevalence of adhesion wear across all tool coating types which is portrayed by the cyclic behaviour of the flank wear land width plots, which resulted from the repeated accumulation and wear of deposited workpiece material. The TiCN-coated tool presented the least amounts of BUL and BUE throughout both levels of testing, while the TiN-coated tool presented the largest amounts of average flank wear land width due to recurrent aberrative local deposition accumulation and extended streak line depositions. TiN-coated, Al2O3-coated, and uncoated tools presented higher average flank wear land width than the TiCN-coated tool by 8.5%, 3.1%, and 27.2% during level 1 cutting conditions and 84.8%, 21.3%, and 37.2% during level 2 cutting conditions. This implies the TiCN coating's increased resistance to elevated cutting temperatures, and in turn, reduced deposition of material through adhesion.

RETRACTED: Development of multi sensor fusion based DAQ for in-process TCMS: Experimental and empirical analysis

In order to manufacture low-cost, high-quality goods, in-process tool condition monitoring is an essential responsibility in the manufacturing industry. In this study, a multisensor fusion technique was used to build and execute an effective and reliable TCM system in turning operations with coated and uncoated tungsten carbide inserts. In dry turning, an attempt has been made to optimize the turning process parameter and monitor the tool's condition. Acoustic optic emission based sensor i.e., Laser Doppler Vibrometer and FLIR E60 infrared thermal camera are strategically placed near the machining zone. Thermal images and vibration signals are recorded using an appropriate charge amplifier. To extract characteristics from numerous sensor data, a National Instruments data acquisition (NI-DAQ) system is constructed utilizing LabVIEW software. Thermal images are used to gather temperatures from tool-work piece locations. Vibration signals are translated into vibration parameters. These characteristics serve as the foundation for establishing in-process TCMS. Tool wear, vibrational displacements (Disp), and cutting temperature are investigated as a result of varied tool insert materials and process conditions (CT). Utilizing ISO 10816-3, ISO 3685, and ISO-18434-2008 standards, the cutting tool condition was assessed using extracted features from multi sensor fusion techniques. For Ti-6Al-4 V, the displacement of uncoated and coated tools increased by 65.28% and 44.71%, respectively. For AISI 316L flank wear, the uncoated insert effected 41% and the coated insert impacted 24.14%, respectively. While machining Al7075, the relationship of depth of cut and feed rate on flank wear maintains an identical trend. It is discovered that both temperature and displacement have a significant role in the evolution of flank wear, which is examined in depth. This paper recognizes the use of multi-sensor data in tool condition monitoring when rotating with various cutting tool inserts.

Tool Wear Modelling of Cryogenic-Assisted Hard Turning of AISI 52100

Cryogenic-assisted hard turning presents an environmentally friendly alternative to manufacture parts with high dimensional accuracy and high surface integrity. Nevertheless, tool wear during hard turning is still a crucial aspect to control due to its high impact on the final part quality. The presence of tool flank wear is reported to alter surface characteristics of the machined component affecting the performance of the final part. In this paper a numerical tool wear model is presented based on a Finite-Difference Method (FDM) thermal approach. This model enables the estimation of tool flank wear evolution during cryogenic-assisted machining providing a process planning tool for the manufacturing industry to optimize cutting conditions. The capability of the model to predict tool flank wear is validated with experimental results obtained during cryogenic subcritical CO2-assisted hard turning tests of bearing steel AISI 52100.

An IoT Architecture for Automated Machining Process Control: A Case Study of Tool Life Enhancement in Turning Operations

Abstract With the advent of the Internet of Things (IoT) in manufacturing applications, current research is aimed at utilization of IoT data for process control. This article presents a novel approach to performing automated process feedback using a cloud-based IoT architecture. Specifically, a case study of automated spindle speed adjustment to enhance tool life in a machining operation is used to evaluate the proposed architecture. A data-driven model of tool flank wear evolution in a longitudinal turning operation is created on a cloud-based platform through measurements of a polyvinylidene fluoride thin film sensor voltage data and machine tool parameters monitored via MTConnect. The data are used to develop a Gaussian process regression (GPR) model to predict the average tool flank wear as a function of the measured quantities, which is then used to predict the remaining tool life. The performance of the GPR model is evaluated using 10-fold cross-validation and is shown to be sufficiently accurate for predicting the average flank wear with the coefficient of determination (R2) and the root mean square error values of 0.96 and 13.45 μm, respectively. A web application running the GPR model on the cloud platform is used to forecast the remaining tool life during a turning operation and when the predicted remaining tool life is less than desired, the web application commands a spindle speed override to automatically extend tool life. The architecture is demonstrated through longitudinal turning experiments on stainless steel 316L to extend tool life by 82 %. In addition, the latency of the architecture is evaluated and shown to be acceptable for the tool life enhancement application considered in this study.

Tool wear analysis in micromilling of titanium alloy

Micromachining is a key technology in contemporary society, due to the new requirements of the modern industry. The need of higher accuracy and precision, even for details on the finished product (which may also have very small dimensions), can be fulfilled only with micromechanical machining. Among this family of technologies, micromilling is one of the most important and widespread: the potential of this process is due to the great precision level that can be obtained, when machining high strength materials too. One of the main challenges launched by micromilling concerns the understanding of the processes that generate breakages and deterioration of the tool, and the study of their causes, that are usually different from those observed in conventional milling processes, for which the definition and the prediction of the tool-life are regulated by the ISO-8688 standard (part 1 and 2). This standard is not referred to micromilling and a dedicated regulation has not been compiled yet. In this article the results of an experimental campaign, made to investigate the tool wear in micromilling process, are presented. The aim of the work is to provide fundamental knowledge for the development of a future standard that can fill the normative gap. In particular, results describe that the flank wear evolution follows the typical trend characterized by the decreasing, constant and increasing tool wear slope regions. Cutting force, roughness and tool corner radius evolution are related with tool wear. In particular, a statistical analysis based on the Pearson correlation coefficient is presented in order to quantify the correlation between the flank wear and the considered parameters. Details about the influence of feed rate and mill type in flank wear evolution are also provided. Furthermore, results show that flank wear could actually be used for a tool-life criterion in micromilling processes.

Tool wear and hole quality in drilling of CFRP/AA7075 stacks with DLC and nanocomposite TiAlN coated tools

Drilling of multi-material stacks, constituted by two laminates in carbon fiber reinforced plastic and a core plate in AA7075, was widely investigated. Experiments were performed on a 5-axis CNC machining center, equipped with a dynamometer for the thrust force measurement, using different twist drills coated with DLC and nanocomposite TiAlN. Each hole, 6.8mm in diameter, was obtained with a chip removal cycle involving two passes spaced by a back motion. Optical and scanning electron microscopy techniques were used to quantify tool wear and delamination of composite layers. Finally, hole diameter in the different layers of composite/aluminum stack was measured by means of a coordinate measuring machine.The analysis of experimental results showed that the main wear mechanisms operating during drilling of stacks with the DLC coated drill are chipping, edge rounding and abrasion, while wear is mainly affected by abrasion with the nanocomposite TiAlN coated tool, even though adhesion of AA7075 particles on the rake surface also occurs. The evolution of flank wear with number of holes showed that the DLC coated drill underwent a much lower wear than the TiAlN coated one. Thrust force on both CFRP and AA7075 exhibited an increase with number of holes. Delamination of composite layer was already present in drilling performed with the wear free tool. However, a growth in delamination with number of holes was observed. Progression of hole diameter with number of holes, in the three different layers of multi-material stack, showed that diameter decreases with rising number of holes. Finally, systematic correlations between tool wear, thrust force, hole diameter and delamination factor were defined. Owing to the plot characteristics, the third-degree polynomial regression was found adequate to model interactions among the process results.

An FEM-based approach for tool wear estimation in machining

This study presents an FEM-based approach to predict the rate of flank wear evolution for uncoated cemented carbide tools in longitudinal turning processes. This novel approach combines the concept of experimental design and Response Surface Methodology (RSM) with Finite Element (FE) modelling of the cutting process, which allows for a fairly accurate tool wear prediction with a significantly lower computational cost compared to other available numerical methods.In the current approach, a series of three dimensional (3D) FE simulations were initially performed for different combinations of cutting data and tool flank geometries. The obtained results were used to establish the quadratic relation between the input variables and the responses required for tool wear prediction, such as interface temperature. Later, the flank wear rate equation was developed based on the relation between the volume loss due to wear and the dimensions of the worn tools. The results of the FE simulations were finally integrated with the established wear rate equation to estimate the flank wear evolution. The credibility of the presented approach was then assessed through estimation of the flank wear evolution rate for a wide range of cutting conditions. The predicted flank wear rates showed a good agreement with experimental measurements in most cases. The reasons for minor deviations from the experimental results were finally outlined.

Cutting tools reliability and residual life prediction from degradation indicators in turning process

In the field of cutting tool reliability, an investigation based on four complementary approaches for tool wear assessment is proposed: the approach 1 is a general failure times approach (statistical reliability based on flank wear threshold hitting times), the approach 2 is based on power consumption monitoring (statistical reliability based on power threshold hitting times), the approach 3 is based on vibration signal analysis (statistical reliability based on vibration threshold hitting times), and the approach 4 is based on the evolution of flank wear for each insert (statistical reliability based on predicted failure times). For this study, 30 identical inserts from a same batch were studied with a CNC lathe in identical turning conditions. As the remaining useful life assessment is the final goal, this study highlight four approaches in order to find out the safest one. The results obtained showed that the approach 1 has too many uncertainties, whereas the approach 2 provides more specific and safer replacement times. The approach 3, in the first hand, highlights the fact that cutting conditions are not exactly identical and, in the second hand, leads to a safe conditional replacement of an insert. Finally, it appeared that the approach 4 allows applying a predictive maintenance strategy.

<b>Study of machinability of VP 100 steel with different levels of titanium in end milling operations

During the manufacture of a mould, machining is certainly the most important process. The composition required to provide important properties in the steels used, such as hardness, wear and corrosion resistance, results in a low machinability has resulted in a low volume of material removed by the end of life of the cutting tool, due to the strong wear generate. In this study, we investigated the behavior of steel processing VP 100 is used in manufacturing plastic injection molds. To this end, we used two versions of VP100, one with 270 and another with 350 parts per million (ppm) of titanium. The tests comprise six different cutting conditions in end milling operations. We observed the volume of material removed for each tested condition, considering the evolution of flank wear of tools to a maximum of0.5 mm. Steel VP 100 with 350 ppm of Ti showed a higher volume of material removed in five of six tests showing that, in this case, a higher content of titanium improved the machinability of the steel under study.

Experimental investigation on flank wear and tool life, cost analysis and mathematical model in turning hardened steel using coated carbide inserts

Article history: Received March 16 2013 Received in revised format May 9 2013 Accepted May 9 2013 Available online May 15 2013 Turning hardened component with PCBN and ceramic inserts have been extensively used recently and replaces traditional grinding operation. The use of inexpensive multilayer coated carbide insert in hard turning is lacking and hence there is a need to investigate the potential and applicability of such tools in turning hardened steels. An attempt has been made in this paper to have a study on turning hardened AISI 4340 steel (47 ± 1 HRC) using coated carbide inserts (TiN/TiCN/Al2O3/ZrCN) under dry environment. The aim is to assess the tool life of inserts and evolution of flank wear with successive machining time. From experimental investigations, the gradual growth of flank wear for multilayer coated insert indicates steady machining without any premature tool failure by chipping or fracturing. Abrasion is found to be the dominant wear mechanisms in hard turning. Tool life of multilayer coated carbide inserts has been found to be 31 minute and machining cost per part is Rs.3.64 only under parametric conditions chosen i.e. v = 90 m/min, f = 0.05 mm/rev and d = 0.5 mm. The mathematical model shows high determination coefficient, R (99%) and fits the actual data well. The predicted flank wear has been found to lie very close to the experimental value at 95% confidence level. This shows the potential and effectiveness of multilayer coated carbide insert used in hard turning applications. © 2013 Growing Science Ltd. All rights reserved

Degradation modes and tool wear mechanisms in finish and rough machining of Ti17 Titanium alloy under high-pressure water jet assistance

This article presents the results of an experimental study on the Ti17 titanium alloy, which was carried out to analyze tool wear and the degradation mechanisms of an uncoated tungsten carbide tool insert. Two machining conditions, roughing and finishing, have been studied under different lubrication conditions. The experimental procedure included measurement of the cutting forces and the surface roughness. Different techniques have been used to explain the tool wear mechanisms. Distribution maps of the elemental composition of the titanium alloy and the tool inserts have been created using Energy Dispersive X-ray Spectroscopy (EDS). An area of material deposition on the tool rake face, characterized by a high titanium concentration has been observed. The width of this area and the concentration of titanium, decrease when increasing water jet pressure. The study shows that wear mechanisms, with and without high-pressure water jet assistance (HPWJA) are not the same. For example, for the roughing condition using conventional lubrication, the temperature in the cutting area becomes very high, this causes plastic deformation of the cutting edge which results in its rapid collapse. By contrast, this problem disappears when machining with HPWJA. In addition, the evolution of flank wear (VB) is stabilized with high-pressure lubrication. In this case, the most critical degradation mode is due to notch wear (VBn) leading to the sudden rupture of the cutting edge.

Behaviour of PVD Coatings in the Turning of Austenitic Stainless Steels

The market of turning tools is coped majority by hard metal tools with CVD coating. However, availability of tools with sharp cutting edges is essential in light turning of small parts. In this context, PVD process is optimum for obtaining sharp edges. Therefore, a methodology is presented to evaluate the performance of PVD advanced tools for turning of difficult to machine materials. Four coatings were tested: AlTiSiN (nACo®), AlCrSiN (nACRo®), AlTiN and TiAlCrN. The analysis was developed carrying out wear tests and analyzing different signals such as cutting forces, EDX analysis of inserts, part roughness and insert image analysis. Results indicate that the best coatings for turning of difficult to machine materials as austenitic stainless steels are nACo® and AlTiN coatings, since they offer the best performance. Several factors demonstrate it: better tool flank wear evolution, less tangential cutting force or lower part roughness.

Estudio del desgaste del flanco de carburos recubiertos y cermet durante el torneado de alta velocidad en seco del acero AISI 1045

This work deals with the experimental study of the flank wear evolution of two coating carbide inserts and a cermet insert during the dry finishing turning of AISI 1045 steel with 400, 500 and 600 m/min cutting speeds. The results were analyzed using the variance analysis and lineal regression analysis in order to describe the relationship between the flank wear and machining time, obtaining the adjusted model equation. The investigation demonstrated a significant effect of cutting speed and machining time on the flank wear at high speed machining. The three coating layers insert showed the best performance while the two layers insert had the worst behaviour of the cutting tool wear at high cutting speeds.

Detection process approach of tool wear in high speed milling

The cutting tool wear degrades the quality of the product in the manufacturing process, for this reason an on-line monitoring of the cutting tool wear level is very necessary to prevent any deterioration. Unfortunately there is no direct manner to measure the cutting tool wear on-line. Consequently we must adopt an indirect method where wear will be estimated from the measurement of one or more physical parameters appearing during the machining process such as the cutting force, the vibrations, or the acoustic emission, etc. The main objective of this work is to establish a relationship between the acquired signals variation and the tool wear in high speed milling process; so an experimental setup was carried out using a horizontal high speed milling machine. Thus, the cutting forces were measured by means of a dynamometer whereas; the tool wear was measured in an off-line manner using a binocular microscope. Furthermore, we analysed cutting force signatures during milling operation throughout the tool life. This analysis was based on both temporal and frequential signal processing techniques in order to extract the relevant indicators of cutting tool state. Our results have shown that the variation of the variance and the first harmonic amplitudes were linked to the flank wear evolution. These parameters show the best behavior of the tool wear state while providing relevant information of this later.

Cutting performance of TiCN–HSS cermet in dry machining

This work is focused on the cutting performance of a new cermet based on high-speed steel (HSS) matrix with hard phase TiCN. The processing route to manufacture the cermet M2 + 50 vol.% TiCN is described. Orthogonal cutting tests, carried out in a lathe showed the ability of the new cermet to achieve turning operations, showing reasonably wear resistance performing dry cutting operations. Tool life was significantly increased, when the cermet was compared with the reference material M2 without reinforcement and with commercial HSS M2. Evolution of flank wear and chipping wear, being the dominant wear patterns, were analysed.

Tool flank wear influence on workpiece heating in dry machining

Following a lathe turning operation modification in order to work in dry machining condition, it appears that new tools and cutting condition modifications where insufficient to recover surface quality previously obtained with cutting fluid. Indeed, workpiece temperature evolutions produced with a single tool insert have conducted preventive replacements but no law where found for this substitution. Some responses have been found in literature review, especially on cutting zone temperature estimation in orthogonal and dry cutting with a new tool. But no solutions are provided to avoid production drop due to the important temperature raise in the cutting zone. The aim of this paper is to study tool flank wear influence on workpiece temperature distribution during dry cutting operations. The first part stands up a new analytical model, which takes account of tool wear and elastic deformation of the workpiece in heat generation in the cutting zone. The second part shows by an experimental procedure that temperature growth in cutting zone during machining process is dependant on the tool flank wear evolution.

Characterisation of machinability of sintered steels during drilling operations

This study deals with the quantitative evaluation of the machinability of sintered steels during drilling operations. A characterisation technique using scanning electron microscopy and image analysis was developed to characterise quantitatively the amount of flank wear on drillbits. It was shown experimentally, using a drilling test bench, that the evolution of flank wear was proportional to the rate of variation of the thrust force as measured during drilling. Thus, the results show that the slope of the linear region measured on the curve of the thrust force v. the amount of material removed is a more accurate criterion to characterise the machinability of PM products than the average thrust force, which is often suggested in the literature.Furthermore, the effect of the technique used to add MnS to PM powders was investigated. Quantitative characterisation of machinability during drilling operations showed that parts made with steel powders of the type FC–0208 + 0·5 wt-%MnS machine better when the manganese sulphide particles are pre-alloyed rather than admixed. Finally, machinability of parts made with two sinter hardening powders was characterised including a pre-alloyed MnS powder. The results showed that the ‘drillability’ of this type of part is improved when they are in the presintered state rather than when they are in the green state, i.e. unsintered. Moreover, parts made with the sinter hardening powder pre-alloyed with manganese sulphide particles (MnS) showed superior machinability characteristics.

Relationship between cutting force and PCD cutting tool wear in machining silicon carbide reinforced aluminium

This paper presents a study of the relationship between cutting forces and tool wear of polycrystalline diamond (PCD), measured when machining the composite A356/20/SiCp-T6 (aluminium with 7.0% silicon, 0.4% magnesium reinforced with 20 vol.% particles of silicon carbide (SiC); heat treatment: solutionising and ageing T6 for 5 h at 154°C). The experimental work was developed considering the drilling and turning operations, through the continuous measurement of the cutting forces with appropriate piezoelectric dynamometers. The wear type was identified and its evolution with cutting time was measured. The wear mechanism was analysed by a scanning electron microscope (SEM). We tested drills and turning inserts with PCD. In turning, correlations were obtained between the evolution of flank wear of the insert and the feed and depth forces. Similar correlations have been obtained in drilling between the evolution of flank wear of the drills and the feed force. It was verified that this can be an indirect method of monitoring the wear of the inserts and drills.