Cutter wear has a great impact on machining quality, which is particularly true when demand for machining accuracy is high. Therefore, cutter wear analysis is critical in assuring high machining ...quality and long tool life. However, it is highly dangerous and difficult to monitor and determine tool wear conditions during machining. This paper proposes a method of real-time machining status monitoring using the data collected by external sensors without interfering with the machining process. A tool wear forecast model is introduced in this article. Multiple process parameters and sensor data are collected. Due to missing data, however, data preprocessing is done applying the interpolation or extrapolation approach and data are standardized in order to create an artificial intelligence-based model. The said model will then be used to forecast tool wear during different processing stages and be compared with other different models, such as: AdaBoost, Support Vector Machine, Decision Tree, and Random Forest. The model developed in this study is based on a Branched Neural Network, which generates the best prediction results among all publicly available algorithms. This approach helps reduce the mean absolute error and root-mean-square error values and can improve by 0.11 in R2.
The requirements for speed suitability and fatigue strength of motor spindle bearings are constantly increasing. These challenges can be met by further developing the spindle bearings, e.g. by using ...higher-performance bearing steels. In the following, the experimental investigation results of a spindle bearing made of a new raceway steel tested on a high-speed rolling bearing test rig are presented. Spindle bearings of the type 7008 (hybrid execution) were tested in an endurance run at a rotational speed of 46 krpm and 3 kN axial load. The operating behaviour was validated based on the bearing outer ring temperature and the vibration behaviour. Microscope analysis of the raceways after the test shows that the new steel has good resistance to micropitting and surface fatigue. The calculated contact pressures, wear parameter and lifetime for the bearings in the tests show that the performance limits of spindle bearings are significantly higher than initially assumed.
This document describes the obtaining of different regression models for the surface roughness and wear parameter in abrasive wheels Alumina (Al2O3) and silicon carbide (CSi) under the influence of ...cutting parameters in the frontal grinding process. The methodology used in the present study is based on the use of an experimental design (DOE) using two input variables (factors) feed rate and cut depth at three levels and a categorical variable tool at two levels. The methods used to obtain models were linear regression, multiple linear regression and logistic regression. The findings show that the type of tool and the speed of advance, have greater correlation with surface quality and wear respectively. All the models establish a significant incidence of these factors on the response variables with a confidence level of 95%. The results of the test show that with the use of a carbide tool, a better surface quality can be obtained with the lowest wear parameter. Finally, an SEM test showed the best surface topography obtained with the carbide tool compared to the alumina tool.
Using a 2-dimensional coupled thermo-elasto-plastic finite element model, the thermo-mechanical behaviours of the strand and mold were analyzed. The calculated geometry and temperature distributions ...of the solidifying shell and mold were compared with experimental observations. The calculated geometry around corner region was in good agreement with experimental observations. The mold wear was analyzed by a new dimensionless parameter of "Apparent Wear Parameter" which is inversely proportional to yield stress of the mold at service temperature and directly proportional to the interfacial pressure between the strand and mold. The effects of narrow face taper and carbon concentration of cast steel on mold wear were analyzed using the apparent wear parameter. With increasing narrow face taper, the possibility of mold wear increased due to increasing interfacial pressure. With increasing carbon concentration, the width of worn region of 35 mm at 0.05 and 0.1 wt% C steels decreased to 15 mm of 0.2 wt% C steel due to uniform thermal contraction of 0.2 wt% C steel during solidification. The calculated behaviours of mold wear were compared with used mold in industrial operation. The calculated worn region of mold based on the apparent wear parameter were in good agreement with industrial observations.
This report examines the role of microstructure of a new type of cutting tool material on an existing relationship between its abrasion wear resistance, fracture toughness (K
IC
), and hardness (H). ...Three alumina-silver composites with different amounts of metal particles have been prepared, and their hardness and fracture toughness properties have been determined together with the assessment of their microstructural features such as volume fraction of the second phase, porosity, etc. The mechanical wear on the flanks of cutting tool inserts, made from the developed composites, has also been estimated by machining experiments against 0.45% carbon steel. The results indicate that flank wear resistance of these silver toughened ceramic cutting tool inserts is not proportional to an existing wear resistance parameter K
IC
3/4
H
1/2
. A modified relation between flank wear resistance, hardness, and fracture toughness has been suggested here for these cutting tool materials. The modification incorporates consideration of the volume fraction of the second phase and the porosity in the developed metal toughened ceramics.
This study focuses on experimental and statistical analysis to explore the influence of wear parameters and its optimization for TiCrN thin film deposited tool steel under dry sliding conditions. In ...this order, nine tribological experiments were performed on the TiCrN deposited tool steel against the SAPH370 steel counterbody. Taguchi L9 orthogonal array was applied to design the experimental setup. There was a total of three wear parameters chosen to perform the tribo-experiment and the parameters are applied load (ranges 10-20 N), sliding velocity (ranges from 0.05 m/s to 0.15 m/s), sliding distance (ranges from 500 m to 1500 m). These wear parameters were evaluated using three different wear characteristics of the TiCrN thin film namely: friction coefficient, mass loss of disc, and hardness of the worn surface. ANOVA was also performed to analyze the significant effect and contributions of the wear parameters on the wear characteristics. However, the wear parameter was optimized using the multicriteria decision-making (MCDM) method which includes entropy, best-worst method (BWM), and TODIM (Tomada de Decisao Interativa Multicriterio) method. Entropy and BWM methods were used to determine the compromised criteria weight while TODIM was used to rank the alternative (sets of wear parameters) based on their dominance score. The stability and robustness of the ranking method were examined using sensitivity analysis. Finally, the linear and nonlinear mathematical model was also developed and compared based on the value of R2.
The development of new coated cemented carbide tool grades, based on grain refining and the unidirectional orientation of crystals in the coating layer, allows this material to withstand the severe ...tribological conditions imposed in hard turning. Previously, this was only possible using PCBN or oxide ceramic tool materials. The aim of this research was to determine the limiting conditions for two coated cemented carbide grades (with MT CVD and PVD coatings) aimed at allowing them to withstand at least a machining time of 15 min in the turning of hardened steels, considering the cutting parameters usually adopted for PCBN tools. Turning experiments were performed on AISI 4340, AISI 52100 and AISI D2 hardened steels, and the worn cutting edges were analyzed using focus variation microscopy (FVM) applying the three-dimensional wear parameters. The use of the PVD-coated cemented carbide grade was feasible in the case of AISI 4340 steel with a level of hardness up to 55 HRC, allowing a machining time longer than 30 min. For AISI 52100 and D2 steels, feasibility was only observed with hardness levels up to 50 and 45 HRC, respectively. Interestingly, in these cases, longer machining times were achieved using the MT CVD-coated cemented carbide grade. Wear and consequent coating layer deterioration were found to be the limiting factors for tool life, and the three-dimensional wear parameters allowed these to be identified. The results indicated the appropriate limiting conditions for the application of coated cemented carbide grades in hard turning as a function of the steel microstructure and level of hardness.
•Application of coated cemented carbide tools grades in turning of hardened steels.•Application of focus variation microscope (FVM) and volumetric wear parameters.•Criterion for tool life based on volumetric wear parameter.•Tool life is strongly associated with tools coating deterioration.•Coating deposition technique and steel microstructure influence the tool life.
•Wear tests were conducted on a multilayer 5Y/4Y-PSZ and a monolithic 3Y-TZP.•Wear volume loss and depth were greater in 5Y/4Y-PSZ than in 3Y-TZP.•Worn surface was more rugged in 5Y/4Y-PSZ than in ...3Y-TZP.•The rough surface was due to extensive lateral cracking, leading to spalling.•The presence of different layers had no effect on the wear behavior of 5Y/4Y-PSZ.
To characterize the composition, microstructure and wear properties of a multilayer translucent zirconia relative to the conventional 3Y-TZP.
Two types of ceramics were evaluated: a multilayer zirconia (MULTI, IPS e.max ZirCAD Multi, Ivoclar Vivadent) and a control 3Y-TZP (IPS e.max ZirCAD LT, Ivoclar Vivadent). Pre-sintered CAD-CAM blocks were cut, ground, sintered and polished to 1 μm finish. The phase fraction and grain size were measured using XRD and FE-SEM. For wear testing (n = 12), square-shaped specimens (16 × 16 × 1 mm) were adhesively bonded to a dentin analog. Sliding wear tests were performed using a spherical zirconia antagonist (r = 3.15 mm), with 30 N load at 1.5 Hz for 500,000 cycles in water. Optical and scanning electron microscopes and 3D laser scanner were used for quantitative wear analyses. Data were analyzed using Student’s t-test (α = 0.05).
For MULTI, the enamel layer had the highest cubic content and the largest grain size, followed by the two transition layers, and the dentin layer. 3Y-TZP showed the smallest grain size and cubic content. A significant amount of wear was observed in both materials up to 50,000 cycles until it reached a plateau. MULTI showed higher volume loss and greater wear depth than 3Y-TZP (p < 0.01). The higher volume loss was associated with extensive lateral fracture, leading to material spalling from the surface of cubic-containing zirconias.
The wear pattern in multi-layered zirconia was more severe than 3Y-TZP. Additionally, the different layers of the multi-layered zirconia had similar wear behavior.
Hard turning has been applied in a wide range of mechanical components based on ferrous materials. The application of these components is a function of mechanical properties and microstructure – that ...also has manufacturing process influences, i.e., cutting mechanism. This research aims to discuss the tool wear level and the correlation with the wear mechanisms in turning with PCBN tools, which deals with three steel alloys (AISI 4340, AISI 52100 and AISI D2) and considers six levels of hardness (on the interval from 35 to 60 HRC), applying the novel three-dimensional wear parameters based on Focus Variation Microscope (FVM) to wear evaluation. Considering the wear parameters that represent the amount of material removed from the tool (WRM) and tool affected area (WAA), tool wear intensity and abrasion wear mechanisms have a decreasing trend with the increase of hardness in the range of 35–50 HRC. Above 50 HRC, however, there is a tendency of increased tool wear intensity when steel hardness is increased. The fraction volume of carbides in the steel microstructures intensifies the abrasion wear mechanism. The adhesion wear mechanism showed a reduction with an increase of the steel's hardness – identified by wear parameters WAM (adhered material volume on the tool). Based on crater wear formation, the diffusion wear mechanism had an inverse behavior when compared to adhesion. Better results concerning tool wear can be achieved when turning steels with 50 HRC. It was evidenced that the three-dimensional wear parameters applied open new possibilities to understanding complex and specific phenomena occurring in machining processes, particularly in the machining of hardened steels.
•Three-dimensional wear parameters as a methodology to evaluate tool wear and wear mechanism.•Tool wear level and tool wear mechanism transition in the transition zone from continuous to hard turning – 50 HRC.•Steel microstructure impact in the tool wear and wear mechanisms.
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