Ceramic Inserts Research Articles

Taguchi optimization of surface roughness in the turning of Hastelloy C22 super alloy using cryogenically treated ceramic inserts

Cryogenic treatment has been used in recent years to improve the performance of cutting tools. This study evaluated the machinability of a nickel–molybdenum-based super alloy using cryogenically treated (–80 ℃ and –145 ℃) ceramic inserts under dry turning conditions. Three cutting speeds (350, 400, and 450 m/min), three feed rates (0.1, 0.2, and 0.3 mm/rev), and a 1-mm fixed cutting depth were used in the turning tests. Experiments were conducted using the Taguchi orthogonal array L27 design. The factors affecting the surface roughness (Ra) were determined via analysis of variance. The effect of cryogenic treatment type (shallow and deep), cutting speed, and feed rate on surface roughness was investigated. Results of the analysis determined that the feed rate was the major parameter that affected surface roughness and that the deep cryogenic treatment was more effective. The regression analysis confirmed that the experimental results and the predicted values were within the 95% confidence interval. The most effective parameter affecting the surface roughness was feed rate at a contribution of 57.9%. The contribution of the cutting tool type to the surface roughness was 28.5%. The results obtained showed that the surface roughness can be optimized for turning the Hastelloy c22 super alloy with the Taguchi method.

Selection of milling strategy based on surface integrity investigations of highly deformed Alloy 718 after ceramic and cemented carbide milling

Abstract High speed milling with ceramic indexable inserts is a current practice for manufacturing of gas turbine components in superalloys since it allows for high material removal rates. Ceramic milling is used for rough milling, which is followed by cemented carbide semi- and finish milling. The tool motion play an important role on the resulting surface integrity. The machining strategy of up or down milling will induce different degree of residual stresses and deformations. Increased knowledge of selecting the machining strategy with lowest impact will promote improved productivity by using ceramic milling to a greater extent based on the affected depth. The main objective in this work has been to correlate the residual stresses and deformations to promote a greater utilization of ceramic milling while still producing surfaces with acceptable properties. Prior investigations have shown that ceramic milling induce very high tensile stresses in the surface, exceeding the material’s nominal yield strength. A second objective has been to explain these stress levels by thorough investigations of the deformation after milling. In this study, milling tests with new and worn ceramic and cemented carbide inserts have been performed in Alloy 718. The topography, residual stresses, deformation and hardness have been investigated for up, centre and down milling. Residual stress measurements were performed using X-ray diffraction, followed by evaluation of hardness and deformation, using hardness testing, light optical microscopy as well as electron back scattering diffraction (EBSD). These results have been used to determine an appropriate milling strategy based on lowest possible impact in respect to residual stresses and deformation. The results show a high degree of deformation after milling that differs for the up, centre and down milling. Based on these results, it is shown that up milling is preferable for new inserts but as the inserts wear out, down milling becomes more suitable since a lower degree of deformation and residual stress impact was observed. EBSD and hardness testing showed that the milling, especially ceramic milling, caused severe deformation of the surfaces resulting in grain refinement to a nano-crystalline level. This is most likely the explanation for the prevalence of the high tensile stresses without distorting or causing failure.

Milling with ceramic inserts of austempered ductile iron (ADI): process conditions and performance.

In the work here presented, the high performance of ceramic insert tools in milling of ADI 1000 iron casting is analyzed. Austempered ductile irons (ADI) are ductile iron castings with strength and mechanical properties enhanced after specific heat treatment, achieving 1000 MPa or even more. Sintered carbide tools are state of the art in many industrial applications, including iron casting machining, but ceramic inserts are a feasible and promising option since cutting speed can be improved by 5 or even 10 times. A complete testing campaign was performed, starting with coated sintered carbides and aiming at the use of whisker reinforced Al2O3 ceramics and Si3N4 tools. The two most important conclusions are as follows: firstly, that the milling type so-called up-milling (or conventional) is more recommended than down-milling, also known as climb milling, and secondly, that dry machining enhances ceramics performance in comparison with using emulsion coolants (oil in water). Finally, results regarding economic aspects were analyzed based on the tools cost-performance ratio.

Ultrafine particle emission during high-speed milling of hardened AISI 1045 steel

In this study, the effects of cutting speed, feed rate, and hardness of workpiece material on the particle number concentration ultrafine of particles in the face milling were experimentally investigated. AISI 1045 steel was hardened to 17, 38, and 48 HRC, machining using ceramic insert (honed, T-land edge preparation). Three factors (cutting speed, feed rate, and workpiece hardness) and three levels fractional experiment designs completed (L27) with statistical analysis of variance (ANOVA) were performed. The analysis of the results shows that workpiece hardness has the greatest influence on ultrafine particle (UFP) emission for both tools and that the feed rate and the cutting speed should be selected wisely for each tool edge preparation. Overall, it is shown that the use of honed edge at moderate speed and higher feed rate reduces UFP emission during milling.

Experimental and numerical investigation on thermal performance of a quartz tube solid particle solar receiver

The thermal performance of a quartz tube solid particle solar receiver (SPSR) with the gravity driven packed particles moving down in a semi-annular particle flow channel has been experimentally and numerically investigated, and the particle flow channel in the quartz tube was shaped by a ceramic fiber insert. The SPSR was heated by a solar simulator with 7 Xenon lamps at 130A electric current which generated a mean irradiant flux of 276 kW/m2 on the 0.26 m irradiated length, grey ceramsite sand with the solar weighted absorptivity of 72.34% was used in the study. The experimental results with a 6 mm particle layer thickness indicated the particle temperature increase of 164 K and the thermal efficiency of 50.25%. A thinner particle layer thickness was shown to improve the thermal performance of the SPSR as verified both in the experiments and simulations. Although the particle temperature increase in a single pass was not high enough in the experiments, compared with other types of SPSR, this design obtained an advantageous particle temperature increase in per unit irradiation length. Moreover, the particle temperature increase in a single pass can be promoted by a longer irradiated length, and therefore the requirement for continuous recirculation of the solid particles will be decreased which can greatly reduce the required parasitic power. Besides, according to the numerical model, the thermal efficiency can be further improved by various means such as improving the solar weighted absorptivity of the solid particles, reducing the particle layer thickness, increasing particle mass flow rate and so on. A sensitive analysis illustrated that the mean particle diameter had the minimal impact on the thermal performance among the various influencing factors, but a value of greater than 700 μm was recommended based on the simulation results.

Influence of Structural Parameters of Cutting Ceramics on Quality of Processing of Machine Slideways of Metal-Cutting Equipment in Selective Formation of Instrumentation

Modern methods of machining of bed slideways with the required parameters of accuracy and quality of the processed surfaces are considered in order to increase productivity in the treatment of the surface of machine stands. To improve productivity, the finishing sanding operation has been replaced with finishing milling to ensure the required roughness, flatness and parallelism. The method of replacement of technological operations as exemplified by processing of a bed made of gray cast iron of grade “СЧ-20” is studied. The priority method of increasing the productivity of the processing of machine slideways of metal-cutting equipment, based on the use of cutting ceramics during the processing of the bed as a final technological operation, is determined. Based on the microstructural characteristics of oxide-carbide cutting ceramics, a uniform method of equipping cutters with cutting inserts with equal lifespan is used to increase productivity and achieve the required surface finish. This method of the milling cutter layout allows for longer life and provides the required margin of tool accuracy as well as allows predicting premature wear of the cutting tool. The results of the work are the identification of the patterns of influence of structural parameters of cutting ceramics on the quality of machine slideways of metal-cutting equipment in the selective formation of instrumentation. Studies have shown that the quality of machining depends on the microstructure characteristics of each insert used in the machining process when using interchangeable multi-sided oxide carbide ceramic inserts. The increase in productivity and quality of machining is achieved by monitoring the microstructure of the cutting oxide-carbide ceramics.

Modelling and optimization of machining parameters during hardened steel AISID3 turning using RSM, ANN and DFA techniques: Comparative study

Nowadays, the relationships linking the cutting conditions to the different technological parameters are becoming a major industrial objective. The present work deals with some machinability investigations involving surface roughness and cutting force in finish turning of AISI D3-hardened steel using carbide, ceramic and coated ceramic inserts. The combined effects of the cutting parameters represented by the cutting depth (ap), the cutting tool (Tool), the cutting speed (Vc), and the feed rate (f) on the output parameters illustrated by both the surface roughness (Ra) and the cutting force (Fy) are investigated using the analysis of variance (ANOVA). The modelling of surface roughness and cutting force is carried out using both Response Surface Methodology (RSM) and Artificial Neural Network (ANN). In order to determine the most efficient technique, the models developed are compared in terms of the coefficient of determination (R2), the Root Mean Square Error (RMSE) and the Model Predictive Error (MPE). Furthermore, a multi-objective optimization using the Desirability Function Analysis (DFA) has been performed. The obtained results show that the ANN models (For Ra: R²=93%, RMSE=0.02%, MPE=4.99% and for Fy: R²=94%, RMSE=2.52%, MPE=3.11%) performed better than those developed using the RSM approach (For Ra: R²=90.4%, RMSE=0.051%, MPE=18.21% and for Fy: R²=79%, RMSE=31.17%, MPE=55.92%). As a consequence, the achieved ANN models for (Ra) and (Fy) are exploited as objective function for the response optimization applying the DFA technique. The optimum level of the input parameters for the combined desirability is finally identified as ap1–Tool3–Vc3–f1 for both (Ra) and (Fy) with a maximum error of 2.94%.

Vibration, tool wear and surface roughness characteristics in turning of Inconel 718 alloy with ceramic insert under LN2 machining

Liquid nitrogen (LN2) machining is considered as a safe, clean, and environmentally friendly machining process. This paper aims to investigate the vibration, tool wear and surface roughness mechanism of the ceramic insert during turning of Inconel 718 alloy under dry machining and LN2 machining. The experiments were performed at three cutting speeds (100, 150, 200 m/min), feed rates (0.04, 0.08, 0.12 mm/rev) and depths of cut (0.2, 0.4, 0.6 mm). The experiment results show better machinability and longer tool life in LN2 machining. The vibration acceleration is reduced by 14–32%. A 17–34% reduction of workpiece surface roughness is observed. Flank wear and notch are the predominant wear forms both in LN2 machining and dry machining, and 16–34% reduction of flank wear is noted in LN2 machining.

Influence of Tool Tip Temperature on Crater Wear of Ceramic Inserts During Turning Process of Inconel-718 at Varying Hardness

Influence of Tool Tip Temperature on Crater Wear of Ceramic Inserts During Turning Process of Inconel-718 at Varying Hardness

Multi-objective optimization of high-speed turning parameters for hardened AISI S7 tool steel using grey relational analysis

Nowadays, die manufacturing industries prefer eco-friendly machining, i.e., high-speed turning for hardened AISI S7 tool steel followed by the conventional grinding process. The effectiveness of this eco-friendly turning depends on selection of appropriate process parameters, which decides the surface integrity of machined components. Hence, the first objective of present research work is to optimize the turning parameters for lower cutting force, machining temperature, surface roughness and higher material removal rate simultaneously using grey relational analysis (GRA). ANOVA utilized to identify the significant effect of each turning parameter on the response variables. Secondly, the effects of turning parameters such as tool nose radius (Rn), cutting speed (Vc), feed rate (Vf) and depth of cut (dc) on tool wear and finished surface topography were studied through scanning electron microscopy (SEM) and atomic force microscope (AFM). Optimal turning parameters for multi-performance responses were Rn: 1.2 mm, Vc: 450 m/min, Vf: 0.05 mm/rev and dc: 0.2 mm. The confirmation test was conducted on the optimal parameter level. According to ANOVA, depth of cut was the major influencing factor on all response variables. AFM and SEM micrograph indicated that excellent surface quality with lower surface roughness (Sa: 64.21 nm and Sq: 90.34 nm) was observed at higher cutting speed. Flank and crater wear were observed in cutting tool faces owing to thermo-mechanical loading. Different wear mechanisms like abrasion, adhesion, built-up edge formation and chipping hammering were found in the alumina-mixed ceramic insert at higher cutting speed and depth of cut.

Parametric analysis and optimization of hard turning at different levels of hardness using wiper ceramic insert

In this paper, an attempt is made to evaluate the performance of wiper ceramic cutting insert and observe the influence of hardness on Arithmetic Mean Roughness (Ra), Mean depth of roughness (Rz), Total roughness (Rt) and Tool wear (Vb) during the hard turning of AISI4340 steel. Twenty-seven experimental runs were planned according to the Response Surface Methodology based Box-Behnken Design approach and those are performed on a CNC lathe. Analysis of Variance is employed to analyze the significance of the input parameters and in terms of their contribution percentages. Mathematical models for surface roughness characteristics and tool wear were developed using the Response Surface Methodology. Results reveal that the hardness and feed rate have significant effects on the surface roughness characteristics and tool wear. Finally, the experimental data further analysed to predict optimal machining conditions for multiple response factors optimization through Desirability function approach.

Effect of Machining Parameters on Surface Finish and Noise Patterns for Machining EN-19 Steel with PVD-TiN Coated Mixed Ceramic Inserts in CNC Turning Operation

This paper presents a relationship between the surface finish, machining conditions and the noise level generated by the turning operation for machining of EN-19 alloy steel using PVD-TiN coated mixed ceramic (Al 2 O 3 +TiCN) inserts on a CNC turning centre under wet lubrication conditions. The machining parameters considered in this study include cutting velocity, feed rate and depth of cut. The levels of machining parameters for the experimental investigation are determined using full factorial experiment model and ANOVA is applied to find the effect of machining parameters on surface roughness. Additionally, noise generated during the cutting operation for all set of experiment trials is recorded to determines the relationship between machining conditions and the surface finish.

A detailed investigation of residual stresses after milling Inconel 718 using typical production parameters for assessment of affected depth

Production of superalloy gas turbine parts involves time consuming milling operations typically performed in a sequence from rough to finish milling. Rough milling using ceramic inserts allows high removal rates but causes severe sub-surface impact. A relatively large allowance is therefore left for subsequent cemented carbide milling. With increased knowledge of the affected depth it will be possible to reduce the machining allowance and increase efficiency of the manufacturing process.Milling Inconel 718 using typical production parameters has been investigated using new and worn ceramic and cemented carbide inserts. Residual stresses in a milled slot were measured by x-ray diffraction. Stresses were measured laterally across the slot and below the surface, to study the depth affected by milling.The most important result from this work is the development of a framework concerning how to evaluate the affected depth for a milling operation. The evaluation of a single milled slot shows great potential for determining the optimum allowance for machining.Our results show that the residual stresses are greatly affected by the ceramic and cemented carbide milling; both regarding depth as well as distribution across the milled slot. It has been shown that it is important to consider that the stresses across a milled slot are the highest in the center of the slot and gradually decrease toward the edges. Different inserts, ceramic and cemented carbide, and tool wear, alter how the stresses are distributed across the slot and the affected depth.

Machining performances of TiN+AlCrN coated WC and Al2O3+TiC inserts for turning of AISI 4140 steel under dry condition

In this work, the machining performances of TiN + AlCrN coated tungsten carbide (WC) and Al2O3+TiC mixed ceramic inserts for turning of AISI 4140 steel were systematically evaluated by multivariate analysis of variance (MANOVA) with varying cutting speeds in the range of 150−220 m/min. MANOVA results showed that the averages surface roughness of workpiece and flank wear width of tool were significantly affected by the cutting speed, the type of inserts and their interaction at the significant level of 0.05. Additionally, the method of Bonferoni 95 % simultaneous confidence intervals for pairwise comparisons indicated that the cutting speed of 220 m/min was suitable for turning of AISI 4140 steel with both types of inserts. Microanalysis based on electron microscopy revealed that the Al2O3+TiC inserts experienced mild abrasion via microploughing, microcutting and microchipping while TiN + AlCrN coated WC ones got severe abrasive wear due to direct cutting and three-body abrasion.

Machinability investigation and sustainability assessment in FDHT with coated ceramic tool

The paper addresses contribution to the modeling and optimization of major machinability parameters (cutting force, surface roughness, and tool wear) in finish dry hard turning (FDHT) for machinability evaluation of hardened AISI grade die steel D3 with PVD-TiN coated (Al2O3–TiCN) mixed ceramic tool insert. The turning trials are performed based on Taguchi\'s L18 orthogonal array design of experiments for the development of regression model as well as adequate model prediction by considering tool approach angle, nose radius, cutting speed, feed rate, and depth of cut as major machining parameters. The models or correlations are developed by employing multiple regression analysis (MRA). In addition, statistical technique (response surface methodology) followed by computational approaches (genetic algorithm and particle swarm optimization) have been employed for multiple response optimization. Thereafter, the effectiveness of proposed three (RSM, GA, PSO) optimization techniques are evaluated by confirmation test and subsequently the best optimization results have been used for estimation of energy consumption which includes savings of carbon footprint towards green machining and for tool life estimation followed by cost analysis to justify the economic feasibility of PVD-TiN coated Al2O3+TiCN mixed ceramic tool in FDHT operation. Finally, estimation of energy savings, economic analysis, and sustainability assessment are performed by employing carbon footprint analysis, Gilbert approach, and Pugh matrix, respectively. Novelty aspects, the present work: (i) contributes to practical industrial application of finish hard turning for the shaft and die makers to select the optimum cutting conditions in a range of hardness of 45-60 HRC, (ii) demonstrates the replacement of expensive, time-consuming conventional cylindrical grinding process and proposes the alternative of costlier CBN tool by utilizing ceramic tool in hard turning processes considering technological, economical and ecological aspects, which are helpful and efficient from industrial point of view, (iii) provides environment friendliness, cleaner production for machining of hardened steels, (iv) helps to improve the desirable machinability characteristics, and (v) serves as a knowledge for the development of a common language for sustainable manufacturing in both research field and industrial practice.

Uporedna analiza procesnih parametara kod habanja umetaka za alat sa i bez premaza pri obradi legure Hastelloy C-276

Machining is the most significant process for any manufacturing company to improve the quality of the finished component. The objective of this article is to analyse the process performance of Hastelloy C-276 using PVD (Physical Vapour Deposition) coated, uncoated and alumina-based ceramic tool inserts of high grade quality. Turning process was performed on NC (Numerical Control) machine by varying RPM, feed rate and depth of cut based on the Taguchi L9 orthogonal array approach. In this study, crank wear, flank wear, nose wear, SR (Surface Roughness), MRR (Material Removal Rate), tool temperature and feed force are examined during machining of hardened material and simultaneously static structural analysis of the tool insert along with the tool holder was performed using ANSYS mechanical. This research investigation helps in determining appropriate parameters with varied coated inserts to make the process easier, efficient and economical.

Early low complication rate of ceramic-on-ceramic total hip arthroplasty by direct anterior approach.

Introduction: Ceramic-on-ceramic couplings are an alternative bearing surface to reduce the problems related to polyethylene wear and debris. However, ceramic articulations have their own risk of unique complications: fracture, squeaking, or dislocation. Few studies have assessed the outcomes of ceramic-on-ceramic total hip arthroplasties (THA) by direct anterior approach (DAA). The aim was to evaluate the early complications and revision rate of ceramic-on-ceramic THA by DAA. Material: A retrospective single-center study of 116 consecutive THAs was performed by DAA (106 patients) with ceramic-on-ceramic bearing from January 2015 to February 2018 with a minimum 24 months of follow-up. No patients were lost to follow-up. The mean age was of 55.3 years ± 11.3. The same cementless acetabular shell with a Biolox Delta ceramic insert and head were used. The complication and revision rates were collected at the last follow-up. The positioning of the acetabular implant was assessed on standard radiographs. Postoperative clinical outcomes were assessed by the Harris Hip Score. Results: At a mean follow-up of 31.9 months ± 5.5, no THA was revised. Five patients had late complications: 3 squeaking (2.6%) and 2 psoas impingements (1.7%) and were managed conservatively. All patients had satisfactory bony ingrowth of acetabular component, with no radiolucent lines and no osteolysis. Eight patients (6.9%) had an anterior overhang of the cup. The mean overhang for these patients was 4.1 mm. 111 hips (96%) were perceived as forgotten or having no limitations. Conclusion: This ceramic-on-ceramic coupling and shell by DAA produced excellent clinical outcomes and implant survival rate at a minimum two-year follow-up study. No serious complication was observed during the follow-up.

Wear behavior and mechanism of TiB2-based ceramic inserts in high-speed cutting of Ti6Al4V alloy

Starting from TiB2, Mo, Co, and C powders, TiB2-based ceramics for cutting tools were prepared by hot-pressing at 1900 °C. The densification, microstructure and mechanical properties of TiB2–Mo–Co and TiB2–Mo–Co–C samples were evaluated. More importantly, the cutting performance of these ceramics were examined by high-speed turning of Ti6Al4V alloy (vc = 150 m/min, ap = 0.5 mm). It was found that the hardness of these two specimens was comparable (~19 GPa) and the tool life of TiB2–Mo–Co was longer than that of TiB2–Mo–Co–C. In order to investigate the wear behavior, the dominant wear mode of TiB2-based cutting tools with different feed rate was compared with commercial WC-Co cutting tool. The combination of microstructure and composition results revealed that the superior cutting performance of TiB2-based ceramic cutting tools could be mainly attribute to their better oxidation resistance, better high-temperature mechanical properties, and lower affinity with titanium alloy than WC-Co composite tools.

Machinability Study of Hardened 1045 Steel When Milling with Ceramic Cutting Inserts.

Intermittent machining using ceramic tools such as hard milling is a challenging task due to the severe mechanical shock that the inserts undergo during machining and the brittleness of ceramic inserts. This study investigates the machinability of hardened steel AISI 1045 during face milling using SiAlON and whisker (SiCW) based ceramic inserts. The main focus seeks to identify the effects of cutting parameters, milling configuration, edge preparation and work material hardness on machinability indicators such as resultant cutting force, power consumption and flank tool wear. The effects of these varying cutting conditions on performance characteristics were investigated using a Taguchi orthogonal array design L32 (21 44) and evaluated using ANOVA. Results indicate lower resultant cutting forces were recorded with honed edge inserts of SiAlON ceramic grade. In addition, a decrease in resultant cutting forces was associated with reduced feed rates and increased hardness. The feed rate and cutting speed were also identified as the greatest influencing factors in the amount of cutting power. The main wear mechanisms responsible for flank wear on the ceramic inserts are micro-scale abrasion and micro-chipping. Increased flank wear was observed at low cutting speed and high feed rates, while micro-chipping mostly ensued from the cyclic loading of the radial tool edge form, which is more susceptible to impact fragmentation. Thus, the use of tools with chamfered tool-edge preparation greatly improved observed wear values. Additional confirmation tests were also conducted to validate the results of the tests.

Machinability Investigation of HSLA Steel in Hard Turning with Coated Ceramic Tool: Assessment, Modeling, Optimization and Economic Aspects

The present study addresses the machinability investigation in finish dry hard turning of high strength low alloy steel with coated ceramic tool by considering cutting speed, feed and depth of cut as machining parameters. The technological parameters like surface roughness, flank wear, chip morphology and economical feasibility have been considered to investigate the machinability performances. Twenty seven set of trials according to full factorial design of experiments are performed and analysis of variance, multiple regression method, Taguchi method, desirability function approach and finally Gilbert’s approach are subsequently applied for parametric influence study, mathematical modeling, multi-response optimization, tool life estimation and economic analysis. Results indicated that feed and cutting speed are the most significant controlled as well as dominant factors for hard turning operation if the minimization of the machined surface roughness and tool flank wear is considered. Abrasions, adhesion followed by plastic deformation have been observed to be the principal wear mechanism for tool life estimation and observed tool life for coated ceramic insert is 47[Formula: see text]min under optimum cutting conditions. The total machining cost per part is ensued to be lower ($0.29 only) as a consequence of higher tool life, reduction in downtime and enhancement in savings, which finds economical benefits in hard turning. The current work demonstrates the substitution of conventional, expensive and slow cylindrical grinding process, and proposes the most expensive CBN tool alternative using coated ceramic tools in hard turning process considering techno-economical and ecological aspects.