Predictive modeling of surface roughness in high speed machining of AISI 4340 steel using yttria stabilized zirconia toughened alumina turning insert

An attempt has been made to investigate the surface finish of AISI 4340 steel for high speed machining using indigenously prepared yttria stabilized zirconia toughened alumina (ZTA) cutting inserts. These inserts are prepared through wet chemical co-precipitation route followed by powder metallurgy process. Response surface methodology (RSM) has been used to study the effect of different machining parameters i.e. cutting speed, feed rate and depth of cut on surface roughness of the job. The machining experiments are performed based on standard RSMdesign called central composite design (CCD). Themathematicalmodel of surface roughness has been developed using second order regression analysis. The adequacy of the developed models and influence of each operating factors have been carried out based on analysis of variance (ANOVA) techniques. It can be concluded from the present study that for high speed machining this tool gives good surface finish. Key parameters and their interactive effect on each response have also been presented in graphical contours which may help for choosing the operating parameter preciously. Optimization of cutting parameters has also been carried out and 92.3% desirability level has been achieved using this optimal condition

Force Prediction Model of Zirconia Toughened Alumina (ZTA) Inserts in Hard Turning of AISI 4340 Steel Using Response Surface Methodology

In the present study, an attempt has been made to investigate the effect of cutting parameters (cutting speed, feed and depth of cut) on machining forces (feed force, thrust force and cutting force) in finish hard turning of AISI 4340 steel using developed Zirconia Toughened Alumina (ZTA) insert prepared by powder metallurgy process route. The machining experiments were performed based on standard Response Surface Methodology (RSM) called Central Composite Design (CCD). The mathematical model of each forces have been developed using second order regression analysis. The adequacy of the models and influence of each operating factors have been carried out based on Analysis of Variance (ANOVA) techniques. It can be concluded from the present study that cutting speed and depth of cut have predominant effect on feed force whereas feed and depth of cut are the two most influencing factors for thrust force determination. But, in case of cutting force modeling, all the three parameters (feed rate, depth of cut and cutting speed) have significant effect. Key parameters and their effects on forces have also been presented in graphical contours which may help for choosing operating parameter preciously. Optimized model indicates 76.51% desirability level for economy in conventional machining process

Application of Back Propagation Neural Network Model for Predicting Flank Wear of Yttria Based Zirconia Toughened Alumina (ZTA) Ceramic Inserts

A back propagation neural network model has been adopted for the flank wear prediction of zirconia toughened alumina (ZTA) insert in turning operation. The experiments are performed on AISI 4340 steel using developed yttria based ZTA inserts. These inserts are prepared through wet chemical co-precipitation route followed by powder metallurgy process. Machining conditions such as cutting speed, feed rate and depth of cut are selected as input to the neural network model and flank wear of the inserts corresponding to these conditions has been chosen as the output of the network. The experimentally measured values are used to train the feed forward back propagation artificial neural network for prediction of those conditions. The convergence of the mean square error both in training and testing come out very well. The performance of the trained neural network has been validated with experimental data. The results demonstrate that the machining model is suitable and the optimization strategy satisfies practical requirements

Machinability evaluation and desirability function optimization of turning parameters for Cr2O3 doped zirconia toughened alumina (Cr-ZTA) cutting insert in high speed machining of steel

In present study, mechanical properties, microstructure and machining parameter optimization of Cr2O3 doped zirconia toughened alumina (ZTA) ceramic insert have been investigated for application in high speed turning of AISI 4340 steel with achieving maximum tool life. The yttria stabilized zirconia (YSZ) in α-Al2O3 matrix with varying percentage of co-doped chromia (Cr2O3) is prepared to study the phase transformation behaviour. The samples are uniaxially pressed in the form of cutting inserts and subsequently sintered at 1600 °C to evaluate the mechanical properties. Hardness and fracture toughness reaches the highest value i.e. 17.40 GPa and 7.20 MPa m1/2 respectively at 0.6% Cr2O3 doped ZTA due to more metastable tetragonal ZrO2 phase present in the alumina matrix. After 50 min of machining, the flank wear and surface roughness are found well below the tool rejection criteria. The cutting force also does not affect detrimentally on the job–tool interface. Turning experiments have been adopted as per central composite design (CCD) of response surface methodology (RSM) with varying 3 levels of cutting speed (140 m/min, 280 m/min, 420 m/min), feed rate (0.12 mm/rev, 0.18 mm/rev, 0.24 mm/rev) and depth of cut (0.50 mm, 1.00 mm, 1.50 mm). The effect of each input parameter on output responses is investigated using analysis of variance (ANOVA) and modelled using regression analysis. The influence of cutting speed, feed rate and depth of cut is observed maximum for determination of flank wear, cutting force and surface roughness respectively. Cutting speed of 420 m/min with feed rate of 0.12 mm/rev and depth of cut of 0.5 mm has been shown as optimized condition with 83.32% desirability for minimum tool failure and maximum tool life

Mathematical Modeling of Wear Characteristics of 6061 Al-Alloy-SiCp Composite Using Response Surface Methodology

In the light of attractive wear characteristics as well as high strength to weight ratio, extensive research on Al-based Metal Matrix Composite (MMC) have been carried out globally in the last two decades. However, very limited research has been pursued on tribological behavior of Al-based MMC under combined action of rolling and sliding. This study investigates the wear behavior of 6061 Al-alloy/SiC with 10 vol.% SiCp against hardened and tempered AISI 4340 steel under combined rolling-sliding conditions. 23 factorial design of experiments have been carried out to see the effect of few parameters, i.e., contact stress, speed and duration with respect to wear. The interaction effect has also been studied by 3D graphical contours. A mathematical model is developed using regression analysis technique for prediction of wear behavior of the MMC and adequacy of the model has been validated using analysis of variance (ANOVA) techniques. Finally, the optimization of parameter has also been done using Design Expert software. The results have shown that Response Surface Methodology (RSM) is an effective tool for prediction of wear behavior under combined sliding and rolling action. It is also found that the wear of MMC is much lower than hardened; tempered AISI 4340 steel and rolling speed has the maximum influence in wear of both materials under investigation

Multi-criteria optimization and predictive modeling of turning forces in high-speed machining of yttria based zirconia toughened alumina insert using desirability function approach

An attempt has been made to apply the Taguchi parameter design method and multi-response optimization using desirability analysis for optimizing the cutting conditions (cutting speed, feed rate and depth of cut) on machining forces while finish turning of AISI 4340 steel using developed yttria based zirconia toughened alumina inserts. These zirconia toughened alumina inserts were prepared through wet chemical co-precipitation route followed by powder metallurgy process. The L9 (4) orthogonal array of the Taguchi experiment is selected for three major parameters, and based on the mean response and signal-to-noise ratio of measured machining forces, the optimal cutting condition arrived for feed force is A1, B1 and C3 (cutting speed: 150 m/min, depth of cut: 0.5 mm and feed rate: 0.28 mm/rev) and for thrust and cutting forces is A3, B1 and C1 (cutting speed: 350 m/min, depth of cut: 0.5 mm and feed rate: 0.18 mm/rev) considering the smaller-the-better approach. Multi-response optimization using desirability function has been applied to minimize each response, that is, machining forces, simultaneously by setting a goal of highest cutting speed and feed rate criteria. From this study, it can be concluded that the optimum parameters can be set at cutting speed of 350 m/min, depth of cut of 0.5 mm and feed rate of 0.25 mm/rev for minimizing the forces with 78% desirability level

An approach towards optimization of the extraction of polyphenolic antioxidants from ginger (Zingiber officinale)

The present study aims to maximize the extraction of polyphenols from ginger (Zingiber officinale) through the statistical optimization of three influential process parameters ethanol (EtOH) proportion (%), temperature (°C) and extraction time (min). Response Surface Methodology (RSM) was employed to design experiments and study the interaction effects of these parameters on the extraction process. Analysis of Variance (ANOVA) was used for the analysis of regression coefficient, prediction of equation and case statistics. The optimum conditions for the maximum yield of polyphenols from each gram of ginger were found to be 75 % aqueous EtOH, 40 °C temperature and extraction time of 60 min respectively. The order of relative importance of these three parameters was: EtOH > time > temperature. Antioxidant activity of the extracted polyphenols using optimized parameters was also determined by DPPH assay. DPPH radical scavenging activity of ginger extract was compared with Vitamin C and butyl hydroxy toluene (BHT). Finally, this study revealed a cost effective analytical model to maximize the extraction of polyphenols from ginger with higher antioxidant activity. It was also concluded that at lower concentration ethanolic extract of ginger possess high antioxidant activity in comparison with synthetic antioxidants like vitamin C or BHT and thus it can be applicable as potent natural antioxidant in food and pharmaceutical industries for the preparation of functional food

Tribological Influences of CuO Into 3Y-TZP Ceramic Composite in Conformal Contac

The aim of the study was to investigate the friction and wear phenomena of 3 mol % yttria-stabilized tetragonal zirconia polycrystals (3Y-TZP) ceramics with the inclusion of copper oxide (CuO) in large area conformal contact geometry. The pin-on-disk tribometer was used to conduct the dry sliding test using CuO/3Y-TZP as pin and alumina as counter surface. The coefficient of friction (μ) for CuO-added 3Y-TZP was decreased by ∼38% compared to pure 3Y-TZP due to formation of protective tribo film to the substrate. In addition, the experiments also showed that the specific wear rate (k) was reduced by ∼54% with the inclusion of CuO in to 3Y-TZP matrix. The different phases of the zirconia, copper, and yttria as well as the phase transformation before and after sliding test were identified by X-ray diffraction (XRD) analysis. Field emission scanning electron microscopy (FESEM) and energy dispersive X-ray (EDS) analysis revealed the existence of CuO in the patchy layers in the worn-out surface of the tested CuO/3Y-TZP sample leading to lower coefficient of friction and improve the wear resistance against alumina counterface in conformal contact geometry. Severe wear mechanism was the dominating factor due to the local plastic deformation of the large number of asperities since the pair of contact was conformal

Tribological property enhancement of 3Y-TZP ceramic by the combined effect of CaF2 and MgO phases

Calcium fluoride (CaF2) often provides enhanced lubricating properties into ceramic composites when combined with other metal oxides to form some lubricating substrate. Present work unveils the superiority of small amount of CaF2 (1 wt%) as solid lubricant with the addition of metal oxide such as magnesium oxide (MgO) into 3 mol% yttria stabilized tetragonal zirconia polycrystals (3Y-TZP) ceramic matrix. With addition of 0.5 wt% MgO in CaF2/3Y-TZP ceramic composite, the mean coefficient of friction (μ) was down to ∼42% and the subsequent wear rate (k) was reduced to ∼31% as compared to pure 3Y-TZP due to the presence of smooth tribo layer at the contacting interfaces. The tribological tests were performed against a hard-abrasive silicon carbide (SiC) counter surface under dry sliding condition. The wear mechanisms and elemental distributions in the worn surface were studied by field emission scanning electron microscopy (FESEM) coupled with energy dispersive X-ray (EDS) setup. X-ray diffraction (XRD) analysis was carried out to identify different phases present in test specimens as well as in wear track. The presence of chemical states in the tribo layer was investigated by means of X-ray photoelectron spectroscopy (XPS) analysis

Development and machinability evaluation of MgO doped Y-ZTA ceramic inserts for high-speed machining of steel

In current high productivity manufacturing era, it is necessary to develop non-conventional newer tool materials. Here, an attempt has been made for developing MgO doped zirconia-toughened alumina (Mg-ZTA) using powder metallurgy process route. The 3 mol% yttria stabilized zirconia (YSZ) (10 wt%), alumina (Al2O3) (90 wt%) with varying percentage of magnesium oxide (MgO) (0–1 wt%) are mixed to study the phase transformation and uniaxially pressed into square inserts with 0.8 mm nose radius and sintered at 1,600ºC for 1 h in pressure less condition. The maximum hardness of 17.04 GPa, fracture toughness of 5.09 MPa m1/2 and flexural strength of 502 MPa, respectively, has been reached at 0.6 wt% of MgO due to more metastable tetragonal phase. The performance of the insert has been evaluated by machining AISI 4340 steel (radius 75 mm) in lathe. The performance with respect to flank wear, cutting force and surface roughness is quite impressive at different cutting speed even after 20 min of machining. It can be inferred that MgO doped ZTA insert can be used for medium to high-speed machining in current manufacturing scenario and is very promising to replace carbide or coated carbide inserts in coming days