Surface Integrity Parameters Research Articles

Assessment of the surface integrity of ground cemented tungsten carbide cutting inserts and its influence on tool wear in turning of ferritic nodular cast iron

In order to improve surface finish, geometric and dimensional tolerances of cemented tungsten carbide cutting tools produced by powder metallurgy, grinding is commonly applied. Due to the high thermal and mechanical loads generated during this process, surface and metallurgical characteristics are directly affected and, as a result, tool performance. Within this context, the influence of grinding wheel characteristics on surface integrity parameters, like surface and edge roughness, hardness and residual stress, was investigated and cutting inserts ground under extreme conditions were applied in rough orthogonal turning of a ferritic nodular cast iron to evaluate their performance regarding tool life. The obtained results showed that higher compressive residual stress values, induced by a vitrified bonded diamond grinding wheel with grain size of 46 µm, contributed to increase tool life, as a protective layer of adhered material was formed on the cutting edge. Flank wear by abrasion was thus avoided and crack formation was the determining factor for the end of the tests. • Finishing process of cutting inserts significantly affects their performance. • Compressive residual stress contributes to increase tool life in rough turning. • Insert surface and edge roughness do not influence tool life in turning cast iron.

Predicting the fatigue life of machined specimen based on its surface integrity parameters

Predicting the fatigue life of machined specimen based on its surface integrity parameters

Experimental Study on Optimization of Surface Integrity Parameters in Machining of Porous Titanium Alloys

In recent years, with the continuous development of my country's industrial level, people's research and exploration in the machining and application of porous titanium alloys has become more and more in-depth. In order to achieve greater breakthroughs and development in the field of optimization test research on surface integrity parameters of porous titanium alloy machining. In this paper, experiments and finite element simulation methods are used to adjust the process of titanium alloy machining by multi-step cutting and prestressed cutting, in order to control the surface quality of titanium alloy machining. Titanium alloys have superior performance and have the advantages of high strength and high corrosion resistance, but the small thermal conductivity and elastic modulus make titanium alloys difficult to cut. In this paper, a simulation model of multi-step cutting and pre-stressed cutting of titanium alloys is established, and the specific laws of multi-step cutting and pre-stressed cutting process regulation affecting chip shape, cutting force and residual stress of machined surface layer are studied. The results show that both multi-step cutting and prestress cutting can increase the residual compressive stress on the finished surface. The final results of the study showed that when the titanium alloy was cut at a distance of 4.63 mm, the corresponding machine wear was 5.41%. In the application process of porous titanium alloy cutting, the wear degree caused by titanium alloy cutting is not affected by its cutting distance, and the wear degree caused by titanium alloy cutting has always maintained an average level of about 5.5%, which is relatively stable.

A Multiscale Study on Machining Induced Surface Integrity in Ti-6Al-4V Alloy

This study adopted a multiscale surface integrity approach (macro, micro, and sub-micro scale) to study the effects of cutting conditions and varying cutting fluid applications on the final surface state in Ti-6Al-4V alloy. Surface integrity parameters that were studied in this work are surface roughness, subsurface microhardness, residual stresses, and microstructural alterations. The results show that there is some correlation between microstructural and mechanical characteristics of machining-induced surface integrity. Also, different residual stress profiles were obtained for TMQF (Targeted Minimum Quantity Fluid) machining (compressive residual stress profile) and flood machining (tensile residual stress profile), which underlines the importance of selecting the right cutting fluid application. This work could aid in choosing the right cutting fluid application for the finish machining operation of Ti-6Al-4V alloy to obtain a desired final superior surface integrity. TMQF application conditions produced better surface integrity metrics (lower surface roughness, compressive surface residual stresses, and no undesirable microstructural damage) compared to flood fluid application while finish machining of Ti-6Al-4V titanium alloy.

Machine Learning based Approach for the Prediction of Surface Integrity in Machining

This paper presents a two-stage procedure to create a surface integrity predictor. The first stage includes data clustering, which allows to evaluate the achievable surface quality. The second stage consists in training the model to predict which cluster the machined surface will belong to. To demonstrate the applicability, an experimental plan for machining of Inconel 718 in milling was developed. The validation through confusion matrix showed that the accuracy of prediction ranged from 64.7% to 84.9% for different test and train sets. Prospect of the research is to expand the set of monitored machining parameters and controlled surface integrity parameters.

Investigation of the thermomechanical loads on the bore surface during single-lip deep hole drilling of steel components

The surface integrity of components is decisive for their fatigue strength and is significantly influenced by applied machining processes. Particularly in drilling, the used coolant strategy affects the process stability and the surface quality produced due to its contribution to chip evacuation and the cooling and lubricating effect of the cutting zone. In this article, different cooling lubrication strategies are investigated in single-lip deep hole drilling of quenched and tempered AISI 4140 steel with respect to their effects on occurring thermomechanical loads and the resulting surface integrity parameters. The results for drilling with cutting oil, water-based emulsion and minimum quantity lubrication (MQL) under varying cutting parameters are analyzed with a focus on their impact on the bores’ subsurface microstructure and resulting hardening generated in the bores’ subsurface.

Advanced experimental setup for in-process measurement of thermo-mechanical load and tool wear when drive shaft turning

The acting thermo-mechanical load during metal cutting and the resulting tool wear influence significantly the surface integrity and thus thecomponent functionality. Therefore, in-process measurement of such process variables is a key strategic approach for monitoring of cutting operations. This manuscript presents a new experimental setup implementing a digital microscope camera and different sophisticated sensors for an automatic measurement of cutting force, temperature, tool wear, acoustic emission and magnetic Barkhausen noise during turning operations. To check the proposed test setup, turning tests on drive shafts from steel 42CrMo4 are performed. The analysis and correlation of the measured process variables with surface integrity parameters show the suitability and robustness of the developed experimental setup.

Contact fatigue life prediction of rolling bearing considering machined surface integrity

PurposeRolling bearings often cause engineering accidents due to early fatigue failure. The study of early fatigue failure mechanism and fatigue life prediction does not consider the integrity of the bearing surface. The purpose of this paper is to find new rolling contact fatigue (RCF) life model of rolling bearing.Design/methodology/approachAn elastic-plastic finite element (FE) fatigue damage accumulation model based on continuous damage mechanics is established. Surface roughness, surface residual stress and surface hardness of bearing rollers are considered. The fatigue damage and cumulative plastic strain during RCF process are obtained. Mechanism of early fatigue failure of the bearing is studied. RCF life of the bearing under different surface roughness, hardness and residual stress is predicted.FindingsTo obtain a more accurate calculation result of bearing fatigue life, the bearing surface integrity parameters should be considered and the elastic-plastic FE fatigue damage accumulation model should be used. There exist the optimal surface parameters corresponding to the maximum RCF life.Originality/valueThe elastic-plastic FE fatigue damage accumulation model can be used to obtain the optimized surface integrity parameters in the design stage of bearing and is helpful for promote the development of RCF theory of rolling bearing.

A comprehensive investigation on machining of composites by EDM for microfeatures and surface integrity

In electro-discharge machining (EDM), the material removal takes place by precisely controlled sparks that occur between tool and workpiece separated with a spark gap in the presence of a dielectric. Generally, the non-contacting type and less material removal rates are attributed to attain a good surface finish and close dimensional tolerances during an EDM of monolithic metals and alloys. But the dimensional accuracy and surface integrity parameters would considerably affect during EDM of composites due to the existence of more than one material phase constituents. Therefore, the present work aims to study and optimize the performance characteristics under various EDM conditions employed in making rectangular channels on AA6061-B4C composite material. Initially, AA6061-4wt.%B4C composites were fabricated by ultrasonically assisted stir-casting, and the improved properties were obtained from various mechanical characterizations. The EDM experiments were conducted according to the full factorial experimental design. The three levels of input conditions such as discharge Current (I), discharge duration (T On), and discharge idle time (T Off) were considered. The considered output responses are material removal rate (MRR),taper (θ) of the machined channel, tool wear rate (TWR), average surface roughness (R) of the machined surface, and average recast layer thickness (ARLT) of the machined zone. These responses are co-related with multi-objective types in the sense that the MRR has to be maximized with all other responses minimized. Hence, principal component analysis (PCA) coupled with grey relation analysis (GRA) was used for optimization in which the results were normalized, and all the responses were converted into a single response named weighted grey relation grade (WGRG) for each trial. The experimental trial, which had the highest WGRG, was considered as a local optimum. The global optimum parameters were obtained by performing the Taguchi method (TM) (higher-the-better) for the maximization of WGRG. The analysis of variance (ANOVA) was performed to know the contribution of each EDM parameter toward the WGRG. The optimum levels of Current, T On, and T Off were identified as 8 A, 25 µs, and 36 µs, respectively. Results showed that all three input parameters significantly affected the WGRG, and a higher contribution of Current (52.11%) followed by the T On (26.72%) was observed. The interaction between the Current and T Off was found to be greater than other interactions. Taper values were observed to be reduced at the combination of 8 A discharge Current and 25 µs T On. None of the input parameters significantly affected the Ra, except for Current, which showed a slight effect. ARLT values showed an increasing trend of T On from 25 µs to 45 µs but decreased slightly at 65 µs for all Current levels. The moderate Current level 6 A was observed to be favorable in reducing ARLT when compared to low (4 A) and high (8 A) for all Ton values.

Effect of milling surface topography and texture direction on fatigue behavior of ZK61M magnesium alloy

Material property and surface integrity are key parameters that influence the fatigue properties of metallic material, especially residual stress, microstructure, and surface topography. Multiple surface integrity parameters may change simultaneously during the process of surface formation, which makes it difficult to analyze the evolution rule of the individual parameter. In this paper, the influence of surface topography and texture on tensile fatigue properties of ZK61M magnesium alloy was studied. The ball-end milling method was applied to produce workpiece surfaces with three different morphologies and texture directions but ensuring the consistent residual stress, microstructure, and surface roughness in these three cases. The results showed that the fatigue life (14.5 × 104 cycles) of workpiece with surface texture direction parallel to the fatigue loading direction was even larger than the fatigue life (8.8 × 104 cycles) of the samples after polishing, and the fatigue life (3.2 × 104 cycles) of workpiece was the lowest when the angle of the surface texture was 45 degrees obliqued to the fatigue loading direction, which is about 64% lower than the samples after polishing. The surface texture direction can be controlled independently by this method, which provides a new consideration factor for evaluating the influence of surface topography on fatigue life.

Investigation of surface integrity in laser-assisted turning of AISI 4340 hardened steel: Finite element simulation with experimental verification

This study investigates the laser-assisted turning (LAT) of AISI 4340 hardened steel (∼52 HRC). Despite the various advantages of this process for machining hard materials, the issues related to the machined surface integrity remain the most important challenge. The laser heating used in this process substantially affects the surface integrity characteristics of the workpiece and its mechanical properties. Therefore, it is important to understand, predict, and optimize the workpiece's heat effects at various regions. Due to the complexity of the process, experimental investigations alone cannot reveal thorough information of various phenomena involved. Therefore, a reliable finite element model has been developed to predict the effect of various process input parameters on the metallurgical changes of the machined workpieces. Since general-purpose finite element codes cannot predict the phenomena of interest, three user-defined subroutines have been developed to capture surface integrity parameters such as heat-affected zone, hardness variations of the machined surface, and white layer formation. The developed FE model consists of three parts: mechanical model, thermal model, and coupled thermo-mechanical model. The results of the FE models are verified with experimental data, and a good agreement has been observed. The effect of various process parameters on the surface integrity characteristics of the workpiece has been studied in detail. It has been observed that the laser scanning speed, laser power, and undeformed chip thickness have the most significant influence on the metallurgical effects on the workpiece, respectively.

Evolution of surface integrity of turning TA19 titanium alloy end face under low cycle fatigue

The purpose of this paper was to reveal the evolution law and mechanism of surface integrity parameters of TA19 titanium alloy end face, and to provide a basis for the process control of blisk surface integrity. Taking faced TA19 titanium alloy fatigue specimens as the research objects, the fatigue tests were carried out at 20 ℃ room temperature and 400℃ high temperature. The evolution law of surface integrity parameters during the whole loading process was analyzed by setting detection nodes in the total fatigue cycle number range. The results show that under the action of low cycle fatigue at room temperature, the fracture is near brittle, and under the action of low cycle fatigue at high temperature, the fracture is obviously ductile. The amplitude and frequency of surface waviness increased sharply with the increase of fatigue loading cycles at room temperature and 400℃. Surface roughness is rarely changed under room temperature fatigue tests, but decreased with the increase of fatigue cycles at 400℃. At room temperature, the surface residual compressive stress almost does not change significantly with the increase of fatigue loading cycles, but decreased exponentially at high temperature, which is in accordance with Zener-Wert-Avrami model. Therefore, in the process of material preparation and machining, it is necessary to improve the internal material uniformity of the blank, reduce the corrugation of the machined surface, and increase the amplitude of residual compressive stress on the machined surface, in order to prolong the fatigue life under the action of high temperature fatigue.

Predictive Modelling and Multi-Objective Optimization of Surface Integrity Parameters in Sustainable Machining Processes of Magnesium Alloy.

Magnesium alloys are widely used in numerous engineering applications owing to their superior structural characteristics. However, the machining of magnesium alloy is challenging because of its poor machinability characteristics. Therefore, this paper investigates the machining of magnesium alloys under different sustainable cooling conditions. The machining was performed by varying cutting velocity, feed rate, and depth of cut under dry and cryogenic cooling conditions. The primary focus of the paper is to develop a predictive model for surface roughness under different machining environments. The models developed were found to be in excellent agreement with experimental results, with only 0.3 to 1.6% error. Multi-objective optimization were also performed so that the best surface finish together with high material removal rate could be achieved. Furthermore, the various parameters of surface integrity (i.e., surface roughness, micro-hardness, micro-structures, crystallite size, and lattice strain) were also investigated.

Effects of Machined Surface Integrity on High-Temperature Low-Cycle Fatigue Life and Process Parameters Optimization of Turning Superalloy Inconel 718

Machined surface integrity characteristics, including surface stresses, physical-mechanical properties and metallographic structures, play important roles in the fatigue performance of machined components. This work aimed at investigating the effects of machined surface integrity on high-temperature low-cycle fatigue life. The process parameters were optimized to obtain required surface integrity and fatigue life of the turning superalloy Inconel 718. The relationships between low-cycle fatigue life and machined surface integrity characterization parameters were established based on the low-cycle fatigue tests at a high temperature (650 °C). The sensitivities of turning process parameters to high-temperature low-cycle fatigue life were analyzed, and the optimization parameters were proposed with the goal of antifatigue manufacturing. Experimental results indicated that the impact order of the characterization parameters of machined surface integrity on the high-temperature low-cycle fatigue life were the degree of work hardening RHV, the residual stress in the cutting speed direction S22, the fatigue stress concentration factor Kf, the degree of grain refinement RD and the residual stress in the feed direction S33. In the range of turning parameters of the experiments in this research, the cutting speeds could be 80~110 m/min, and the feed rate could be 0.10~0.12 mm/rev to achieve a longer high-temperature low-cycle fatigue life. The results can be used for guiding the fatigue-resistant manufacturing research of aeroengine superalloy turbine disks.

Influence of a Discontinuous Process Strategy on Microstructure and Microhardness in Drilling Inconel 718

Nickel-base alloys are proven materials in the fields of the aerospace and oil industry, which is due to their characteristic material properties of high temperature strength, high toughness and good oxidation resistance. These properties are beneficial to applications in technical components in general. However, they also represent challenges for machining. Especially while drilling Inconel 718, high temperatures occur in the chip-formation zone that implicate high thermal load in the material and thus, influence the surface integrity, for example, by causing white layers. Hence, the development of strategies to improve the ability to supply cutting edges with cooling lubricant is becoming increasingly important. In this context, an alternative process design, the discontinuous drilling, takes place, characterized by a periodic interruption of feed motion and thus, chip formation. A minor retraction movement from the contact zone enables the cooling lubricant to reach the cutting edges and to reduce their thermal load. In comparison to the conventional process of drilling Inconel 718, the effects of discontinuous drilling with varying numbers of interruptions on the resulting surface integrity and further parameters of drilling qualities are analyzed. Thereby, the prevention of process-related phase transformations due to thermal impact was discovered when a discontinuous drilling strategy was implemented.

Effect of shot peening intensity on surface integrity of 18CrNiMo7-6 steel

The surface integrity of components treated by shot peening is determined by many influencing factors, which are generally divided into shot peening process parameter, procedure parameter and machine parameter. To understand the influencing relationship of these parameters, and thereby obtain the appropriate peening intensity for the engineering practice, this study experimentally examined the effect of different shot peening parameters on the peening intensity, and further explored the influence of which on surface integrity parameters of carburized steel rollers. It is found that the intensity is mainly affected by the shot diameter (36.73%), air pressure (32.07%) and shot flow rate (23.11%). The maximum compressive residual stress and surface hardness increase linearly as the intensity increases, reaching −1250 MPa and 785 HV at the intensity of 0.55 mmA, respectively. Surface roughness parameter Sq can be used to predict the surface hardness due to the approximately linear relationship between them.

Sensitivity analysis and parameter interval optimization for residual stress in polishing process of GH4169 blisk blade

Surface integrity has a significant impact on the performance and life cycle of the blisk blade. Residual stress, as one of the important characterization parameters of surface integrity, is closely related to the performance of the aeroengine blisk blade. A certain interval of residual compressive stress can significantly inhibit the generation of microcracks. This paper proposes an optimization method of polishing process parameter interval based on sensitivity analysis. This research studied the effect of polishing parameters of the alumina ACW (abrasive cloth wheel) on the surface residual stress of the GH4169 superalloy blisk blade. Firstly, the experiment was designed by four factors and three levels response surface method, the multiple regression of the experimental data based on Minitab software was used to get a prediction model of polished surface residual stress. And an analysis of variance was performed on the model. Subsequently, the model of relative sensitivity was got based on this model. The sensitivity order of polishing surface residual stress to each polishing parameter was obtained. And the judging method of stable interval and instable interval was put forward. Then, a parameter interval optimization method was proposed, and the optimal interval of process parameters was obtained. Finally, a polishing verification experiment was performed. The results show that: for the polishing of GH4169 superalloy blades, the surface residual stress is most sensitive to the feed rate vf of the ACW, followed by the granularity p and the rotation rate ω, and the compression depth ap is the least sensitive. The optimal interval of polishing process parameters is: the rotation rate ω is [11000 r/min, 11500 r/min], the feed rate vf is [100 mm/min, 200 mm/min], the compression depth ap is [0.6 mm, 1.0 mm], and the granularity p is [400 #, 600 #]. The optimized polishing process parameters can obtain a large and stable surface residual compressive stress, which is helpful to increase fatigue strength of the blisk blade.

The prediction of the turned machining induced residual stresses in Ti6Al4V: A Critical Surface Integrity Descriptor

The surface integrity of a turned machined surface is an essential indicator of the fatigue and corrosion performance of a component. A critical descriptor of this property is the residual stress, both on the surface and subsurface of a part. However, experimental determination of vital surface integrity parameters such as surface roughness, hardness, affected microstructure, and residual stresses is costly, time consuming, and involves the destruction of the part. Therefore, prediction of these parameters, such as residual stress versus depth, would be of great value and could aid in the correct machining parameters (cutting speed, feed rate, edge tool radius, rake angle, coolant) for the desired part performance. A study was initiated to determine the influence of a worn tool and multiple cuts on a wide range of cutting speeds on residual stresses induced by machining an outside-turned bar of Ti6Al4V titanium alloy. Thus, a project was initiated to develop a non-linear finite element model to predict the residual stresses thus developed due to the machining manufacturing process.

Correlating tool wear and surface integrity of a CNC turning process using Naïve based classifiers

Surface finish is an important phenomenon in hard turning. There are many factors which can influence the finishing of a product. Literature review reveals that substantial research has been performed on hard machining, still relationship of tool wear and surface finish parameters like [Formula: see text] and [Formula: see text] is not established as the process is so dynamic and transient in nature. As a result, most of the responses like tool wear, surface integrity parameters, cutting force, and vibration are random in nature. In this investigation, Topic Modelling (TM), a relatively new topic particularly used in machine learning is applied to determine a particular stage of tool wear. Tool wear is divided into three distinct groups namely initial stage (IS), progressive stage (PS), and exponential stage (ES) from a number of experimental observations. Then, surface parameters namely [Formula: see text] and [Formula: see text] are measured. A probabilistic model consisting of tool wear and surface parameters is developed using Naïve based classifier. This model is capable to predict a particular stage of tool wear given randomly selected values of [Formula: see text] and [Formula: see text] To validate this probabilistic model, an alternative machine learning method called multinomial logistic regression is used. Each of this method indicates that the tool has reached to exponential stage when [Formula: see text] and [Formula: see text] =. [Formula: see text]

Investigation on effect of process parameter on surface integrity during electrical discharge machining of NiTi 60

PurposeElectrical discharge machining (EDM) of hard materials like NiTi 60 alloys is important as it finds application in different sectors of engineering such as automobile, aircraft, biomedical, oil industries, etc.Design/methodology/approachThe first target of this investigation is to determine the effect of process parameters such as current, voltage, pulse on time and pulse off time on the material removal rate (MRR), surface roughness (SR) and white layer formation (WLT) for NiTi 60 smart material alloy. The secondary aim is to identify the presence of surface integrity parameters such as cracks, WLT, microvoids, globules and debris formation by using the scanning electron microscopy technique and with the use of ImageJ software for die sink EDM machining of NiTi 60 alloy.FindingsThe results reveal that current is significant for MRR, voltage and current influence SR, and for WLT, voltage is a significant factor. The experimentation study also shows the generation of oxide and carbide layers on the machined surface, which were evident with the use of the X-ray diffraction technique. The presence of these oxide and carbide layers causes to form WLT on the machined surface and thereby increases the hardness of the machined surface.Originality/valueHardness test was performed with Vickers hardness tester, which gives evidence for the increase in hardness of machined surface due to the generation of WLT.