Milling Of Alloy Research Articles

Questions of generalization of statistical modeling results on the example of face milling of titanium alloys

The article presents the results of the experiment on face milling of titanium alloy Ti-6Al-4V in coarse-grained and ultra-fine-grained states. The nanostructured state of the alloy was obtained by equal-channel angular pressing that leads to higher strength characteristics of material. The experiment was carried out on a universal milling machine PROMA model FHV-50PD. During the three-factor experiment, the cutting modes were varied: cutting depth (t = 0.4; 0.6; 0.8 mm), feed (s = 65; 100; 185 mm/min) and the rotation speed of the mill (n = 580; 720; 875 rpm). The cutting force was determined indirectly by measuring the displacement of the mill holder using a vibration sensor. The simulation of the dependence of the main component of the cutting force on the processing modes was performed by linear regression for exponential dependence. The model adequately describes the experimental data. A comparison of the results of regression analysis obtained during full and short experiments is presented. The questions of generalization of the results of the obtained force dependencies for processing conditions that differ from the basic ones are considered. The analysis is carried out using a modern method of statistical analysis – bootstrap.

Investigation on influence of hybrid nozzle of CryoMQL on tool wear, cutting force, and cutting temperature in milling of titanium alloys

The titanium alloy has a low thermal conductivity of 1/8th that of common metals and half that of stainless steel. The heat dissipation is poor during dry cutting, so the cutting temperature rises above about 600°C. Due to this, the quality of the cutting surface decreases during machining, and rapid tool wear occurs. To solve this, the use of cutting fluid is essential, but the chemical composition of the cutting fluid has a negative effect on the body and the environment. In the current cutting process, in order to minimize this effect, eco-friendly processing using minimum quantity lubrication (MQL) is performed. The machining method using both MQL and a cryogenic gas separately applies the MQL and the cryogenic gas to both sides of the cutting tool. In this case, the oil mist cannot penetrate the cutting zone due to the spray pressure of the cryogenic gas. Therefore, it is necessary to design a hybrid nozzle that can spray oil mist and cryogenic gas into a single flow. Besides, although the study on the effect of MQL and cryogenic machining on the cutting temperature should be preceded, most of the titanium MQL processing papers only study the material surface and tool wear. Accordingly, in this study, we designed and fabricated the hybrid type nozzle of CryoMQL which combined MQL and a cryogenic gas to improve the spraying concentration. And the cutting temperature generated by the process was measured, and the effectiveness of the proposed nozzle on decreasing the cutting temperature was evaluated. Besides, cutting force and tool wear were analyzed according to each cutting method.

Axial contact points method for improving end-milling productivity

The article analyzes results of a study on the effects of cutting data on cutting forces when end milling titanium alloys. A solid carbide mill was used. Stability of the milling process is ensured by optimal values of axial depth of cut using the axial contact points (ACP) method. The radial depth of cut and feed were varied to achieve a required level of milling productivity. Cutting forces and vibrations were measured when milling. Vibrations were measured in the frequency and time domains. Possibilities of reducing cutting forces without decreasing the productivity level by choosing optimal values ​​of cutting parameters were studied. The practical significance of the research results for planning milling processes in real production conditions was demonstrated. Ways to improve end milling productivity for titanium alloys by reducing loads on the technological system were identified. Avenues for further research on high-productivity end milling of titanium alloys were proposed.

MQL Strategies Applied in Ti-6Al-4V Alloy Milling-Comparative Analysis between Experimental Design and Artificial Neural Networks.

This paper presents a study of the Ti-6Al-4V alloy milling under different lubrication conditions, using the minimum quantity lubrication approach. The chosen material is widely used in the industry due to its properties, although they present difficulties in terms of their machinability. A minimum quantity lubrication (MQL) prototype valve was built for this purpose, and machining followed a previously defined experimental design with three lubrication strategies. Speed, feed rate, and the depth of cut were considered as independent variables. As design-dependent variables, cutting forces, torque, and roughness were considered. The desirability optimization function was used in order to obtain the best input data indications, in order to minimize cutting and roughness efforts. Supervised artificial neural networks of the multilayer perceptron type were created and tested, and their responses were compared statistically to the results of the factorial design. It was noted that the variables that most influenced the machining-dependent variables were the feed rate and the depth of cut. A lower roughness value was achieved with MQL only with the use of cutting fluid with graphite. Statistical analysis demonstrated that artificial neural network and the experimental design predict similar results.

Development of the innovative differential tool wear modeling for high-feed milling and its experimental verification

During the high-feed milling process, the vibrations generated by interrupted cutting cause changes in the instantaneous tool posture, as well as in the working angle and the distribution of the thermal stress coupling fields of each tool blade. These changes result in significant differences in the wear distribution of each tool blade. In this research, well-designed experiments for the high-feed milling of titanium alloys were carried out to identify the key factors affecting the differential wear on the milling tool insert blades. A differential tool wear model for the tool blades was developed in order to comprehensively describe the effects of the location error of the blades, the vibrations in the tool posture, and the working angle of each tool blade. The wear status of the milling tool was simulated based on the dynamic tool trajectories and postures derived by the model, and the entire simulated wear distribution was investigated with an innovative wear boundary recognition method. The differential tool wear model was evaluated and validated by the milling experiments and further supported by simulations.

Optimization of machining parameters during end milling of super alloys using Grey based Taguchi method coupled with entropy measurement technique

Optimization of machining parameters during end milling of super alloys using Grey based Taguchi method coupled with entropy measurement technique

Optimization of Cutting Parameters Based on Surface Roughness and Cutting Force During End Milling of Nimonic C-263 Alloy

The surface integrity of machined surfaces greatly influences the functional properties of the components such as fatigue life, etc. Nickel-based superalloy such as Nimonic C-263 is termed as difficult to machine material due to its unique properties as well as high strength at elevated temperatures. This study intends to optimize the cutting parameters (cutting speed, feed, depth of cut) during the end milling of Nimonic C-263 and the machining has been carried out using solid tungsten carbide tool coated with TiAlN and Vertical Machining Center. Experimentation is carried out using Taguchi L9 orthogonal array technique and based on signal to noise ratio data, optimum machining parameters were achieved for preferred observable characteristics such as cutting force and surface roughness. Additionally, Multi-purpose optimization (Grey analysis) of the observable characteristics was conducted to predict the optimum machining parameters combination which offers better producible surface finish and lowest cutting force requirement. Further, the analysis of variance (ANOVA) reveals that the feed rate is the farthest influencing factor followed by the depth of cut, cutting speed, and the variations in cutting force and surface roughness are confirmed through chip morphology using Scanning electron microscopy.

Performance evaluation of MQL with AL2O3 mixed nanofluids prepared at different concentrations in milling of Hastelloy C276 alloy

Since some deficiencies in mist lubri-cooling techniques i.e., minimum quantity lubrication (MQL) in heavy cutting conditions have been noticed, recently nano-cutting fluids which have enrich thermal conductivity than base fluid, are begun to be used in MQL system. One of the critical issues arising in this process is the addition of the appropriate nanoparticle ratio to the base liquid. Therefore, this study aimed to find the optimum distribution rate of Al2O3 nanoparticles having excellent properties and machining parameters. For this purpose, by adding Al2O3 nanoparticles to vegetable-based cutting fluid, nano-cutting fluids were prepared in different volumetric concentrations (0.5, 1.0 and 1.5 vol%). These prepared nanofluids were used in the MQL system when milling of Hastelloy C276. Three cutting speeds (60, 75 and 90 m/min) and three different feed rates (0.10, 0.15 and 0.20 mm/rev) were added to the experimental design to study the performance of nanofluids under several cutting parameters. Apart from this experimental design, to clearly see the effect of concentration rates on tool wear and tool life, three experiments were carried out at each concentration ratio by keeping the machining parameters. Eventually, 1 vol% Al2O3 concentration clearly provided an improvement by up to 23% and 10% in tool life, compared to 0.5 vol% and 1.5 vol% concentration, respectively. In addition, while chipping/fracture, attrition wear and peeling of coating were observed under all cutting conditions, there was no evidence for workpiece material adhesion at 1 vol% and 1.5 vol% Al2O3 based nanofluid-MQL.

Chip morphology and cutting temperature of ADC12 aluminum alloy during high-speed milling

The ADC12 aluminum alloy is prone to severe tool wear and high cutting heat during high-speed milling because of its high hardness. This study analyzes the high-speed milling process from the perspective of different chip morphologies. The influence of cutting temperature on chip morphology was expounded. A two-dimensional orthogonal cutting model was established for finite element analysis (FEA) of high-speed milling of ADC12 aluminum alloy. A theoretical analysis model of cutting force and cutting temperature was proposed based on metal cutting theory. The variations in chip shape, cutting force, and cutting temperature with cutting speed increasing were analyzed via FEA. The results show that, with the increase in cutting speed, the chip morphology changes from continuous to serrated, and then back to continuous. The serrated chip is weakened and the cutting temperature is lowered when the speed is lower than 600 m·min−1 or higher than 1800 m·min−1. This study provides a reference for reducing cutting temperature, controlling chip morphology and improving cutting tool life.

Wear Resistance and Titanium Adhesion of Cathodic Arc Deposited Multi-Component Coatings for Carbide End Mills at the Trochoidal Milling of Titanium Alloy

The work was devoted to the study of the effectiveness of the application of multi-component coatings, TiN–Al/TiN, TiN–AlTiN/SiN, and CrTiN–AlTiN–AlTiCrN/SiN, obtained by cathodic arc deposition to increase the wear resistance of 6WH10F carbide end mills in trochoidal milling of titanium alloy. The surface morphology of the tool with coatings was studied using scanning electron microscopy, and surface roughness texture was estimated. Microhardness and elastic modulus of the coated carbide tool surface layer were determined by nanoindentation. The process of sticking titanium to the working surface of the tool and quantitative evaluation of end mill wear with multi-component coatings at the trochoidal strategy of milling titanium alloy was studied. The CrTiN–AlTiN–AlTiCrN/SiN coating showed the maximum value of the plasticity index at the level of 0.12. The maximum effect of reducing the wear rate was achieved when using a tool with a CrTiN –AlTiN–AlTiCrN/SiN coating when the operating time to failure of end mills was increased by 4.6 times compared to samples without coating, by 1.4 times compared with TiN–Al/TiN coating and 1.15 times compared with TiN–AlTiN/SiN coating.

Thermo-mechanical coupling behaviour when milling titanium alloy with micro-textured ball-end cutters

The high-speed milling of titanium alloy is a very complex nonlinear dynamic cutting process, and there are mutual coupling effects between multiple physical fields of the tool. Therefore, the thermo-mechanical coupling behavior of micro-textured ball-end milling cutters during the cutting of titanium alloy was studied in depth, combined with theoretical calculations, milling experiments and simulation analysis. First, based on the experimental data of milling titanium alloy, the stress field of the micro-textured ball-end milling cutter was solved. Then, the dimensional method was used to solve the temperature field of the micro-textured ball-end milling cutter. Finally, the thermo-mechanical coupling simulation analysis of the micro-textured ball-end milling cutter was carried out, and the stress concentration area and tool breakage area of the micro-textured ball-end milling cutter under the thermo-mechanical coupling effect are obtained. This in turn gives a theoretical basis for further improving the performance and tool life of micro-textured cutters.

Micro-end milling of biomedical Tz54 magnesium alloy produced through powder metallurgy

In this study, micro machinability of Mg5Sn4Zn (TZ54) alloy produced by a hot-pressing process (one of the powder metallurgy methods) is investigated. For this purpose, micro-milling experiments were carried out, considering different cutting parameters. In order to determine the appropriate cutting parameters, the variation of cutting forces, surface quality and burr width were investigated. The cutting forces obtained in micro-milling of the TZ54 alloy are relatively small compared to other biomedical materials. In terms of both cutting forces and surface roughness, the minimum chip thickness is between 7% and 34% of the tool edge radius. However, compared to alloys such as Ti6Al4V and 316 L, the burr width is about 80% smaller. An important contribution of the study is that the minimum chip thickness (0.1 μm) has been confirmed in terms of both cutting force and surface roughness. In addition, even at high material removal rates, the minimum cutting forces are important findings of the study. The predominant wear mechanism in the cutting tool is abrasive wear. In view of tool life, surface roughness and burr formation, it is envisaged that the TZ54 alloy can be an easy machinable, alternative biomedical material.

Milling surface roughness for 7050 aluminum alloy cavity influenced by nozzle position of nanofluid minimum quantity lubrication

In nanofluid minimum quantity lubrication (NMQL) milling of aviation aluminum alloy, it is the bottleneck problem to adjust the position parameters (target distance, incidence angle, and elevation angle) of the nozzle to improve the surface roughness of milling, which has large and uncontrollable errors. In this paper, the influence law of milling cutter speed, helical angle, and cavity shape on the flow field around the milling cutter was studied, and the optimal nozzle profile parameters were obtained. Using 7050 aluminum alloy as the workpiece material, the milling experiment of the NMQL cavity was conducted by utilizing cottonseed oil-based Al2O3 nanofluid. Results show that the high velocity of the surrounding air flow field and the strong gas barrier could be attributed to high rotating velocities of the milling cutter. The incidence angle of the nozzle was consistent with the helical angle of the milling cutter, the target distance was appropriate at 25–30 mm, and the elevation angle was suitable at 60°–65°. The range and variance analyses of the signal-to-noise ratio of milling force and roughness were performed, and the chip morphology was observed and analyzed. The results show that the optimal combination of nozzle position parameters was the target distance of 30 mm, the incidence angle of 35°, and the elevation angle of 60°. Among these parameters, target distance had the largest impact on cutting performance with a contribution rate of more than 55%, followed by incidence angle and elevation contribution rate. Analysis by orthogonal experiment revealed that the nozzle position parameters were appropriate, and Ra (0.087 μm) was reduced by 30.4% from the maximum value (0.125 μm). Moreover, Rsm (0.05 mm) was minimum, which was 36% lower than that of the seventh group (Rsm = 0.078 mm).

Modeling and optimization of machining parameters in milling of INCONEL-800 super alloy considering energy, productivity, and quality using nanoparticle suspended lubrication

Inconel-800 super alloy is a newly difficult-to-cut material. To improve the cutting conditions for this metal, sustainable methods in which minimum quantity lubrication enhanced with suspended nanoparticle were employed. This work also aims to model the relationship between process parameters (cutting speed, feed per tooth, depth of cut, and corner radius of cutting tool) and machining responses (surface roughness, specific cutting energy, cutting power, and material removal rate) using orthogonal array design of experiment and response surface methodology. Non-dominated sorting genetic algorithm was used to solve the multi-objective optimization problems in terms of energy, productivity, and quality of the machining process. The results indicate that the application of the response surface methodology model in combination with non-dominated sorting genetic algorithm is appropriate for this study due to the goodness of fit of response surface methodology and the global optimum solution of genetic algorithm. Because multi-objective optimization gives multiple solutions, Pareto plot and data mining are employed to support the selection of process parameters that can save time and cost and increase energy efficiency, meanwhile, simultaneously improve productivity and surface quality. The research results show that the specific cutting energy and energy consumption can be reduced up to 20.2% and 6.4%, respectively.

Investigations on the effect of nozzle angle and air flow rate during nanofluid Minimum Quantity Lubrication milling of Aerospace alloy Al7075-T6

Present day industries are focusing upon finding various methods and techniques to implement sustainable manufacturing, which is ‘the need of the hour’. With increase in global competition, industries are striving hard to reduce the machining costs, which is a major contributor for ‘manufacturing cost per part’, in an industry. Conventional method of using large quantity of coolant/cutting fluids in several liters per hour, to cool machining zone is causing enormous concern. Strict Government regulations are necessitating industries to replace flood-coolant assisted machining by new techniques like ‘Minimum Quantity lubrication’ (MQL) coolant supply technique. The present work deals with investigating the effect of varying nozzle angle and air-flow rate during MQL assisted surface milling of aerospace aluminum Al7075-T6 alloy, using uncoated carbide tool. Three methods of coolant supply namely Dry, MQL and nanofluid MQL (nano particles us pended oil with MQL) are experimented. Cutting speed [150m/min, 208m/min, 264 m/min], feed rate [95 mm/min, 110 mm/min, 125 mm/min] and depth of cut [0.5 mm, 1.3 mm, 2 mm] are chosen as process variables. Two nozzle angles 25°C and 500, with 1.5 kg/cm2 and 3 kg/cm2 air flow rates were investigated. Best results were obtained for air flow rate of 1.5kg/cm2. Optimumnozzleangle was found to be 25°C. To obtain lowest temperature and reduced heat generation, nanofluid MQL machining is a feasible option. With regards to MQL technique, for obtaining better surface finish with reduced surface roughness of the work piece (Al7075-T6), nanofluid MQL technique is best.

Study of the effect of sharpness of cutting tools on the formation of defects in the surface finish in micro cutting titanium alloys

The quality of machining of titanium alloys in the aviation and medical fields, characterized by the presence of micro vias, scales and surfacing on the treated surface, as well as the level of roughness is important in the manufacture of key parts. The quality parameters of the treated surface are influenced by many factors - cutting modes (cutting speed, depth and feed), cutting tool parameters (geometry of the cutting part, hardening coating, sharpness of the cutting wedge, etc.), technological equipment parameters (rigidity and accuracy), etc. The aim of the work was investigation of treated surface of titanium alloy VT1-00 when milling with small thicknesses of the shear layer, commensurate with the sharpness of the cutting wedge of the cutter. Method. The method of investigation of the treated surface during milling of titanium alloy on the micro level with the use of standard and high-quality carbide cutting tools is proposed. Results. Operating experience of the received carbide tool has shown that sharpness of a cutting wedge influences quality of the processed surface characterized by microwaves, scales and burrs, also by the roughness of the treated surface. On the basis of carried out researches it is established that for maintenance of conditions of normal cutting and chip formation it is necessary to provide sharpness of the cutting wedge characterized by the conditional entered radius of a blade rounding having values less than values of the sizes of grains of a processed material, that is re < 5 μm. Field of application. The obtained results of work allow to substantiate the recommendations on the required sharpness of carbide cutting tools used for milling of titanium alloys at the micro level. Conclusions. Experiments on the study of the process of cutting of titanium alloy VT1-00 at the micro level to determine the effect of cutting tool sharpness on the quality of the treated surface (microwaves, scales and burrs), allow to form recommendations on its initial state and determine performance.

The design and performance evaluation of assisted chip removal system in helical milling of CFRP/Ti stacks

Hybrid structures consisting of carbon fiber reinforced plastics (CFRP) and metal have been widely applied in aircraft manufacturing. Numerous holes need to be made in order to assemble the structures. Due to the small size of CFRP chips and the dry cutting conditions, improperly dealing with chips can increase tool wear, degrade hole quality, and contaminate to environment and health. In this study, an assisted chip removal system, mainly including an exhaust hood, a vacuum cleaner, and a tool holder, was used for helical milling of CFRP and titanium alloys (CFRP/Ti stacks). The geometry of the chip exhaust hood model was designed and optimized to clear and collect cutting chips using finite element method (FEM). Based on this system, pressurized air was pumped into cutting areas through the inner cooling channels in the tool. Then, the performance of the assisted chip removal system was evaluated in helical milling of CFRP/Ti stacks under different chip collecting conditions. Results showed that this system had a good ability of chip removal and preventing chips returning into the hole. And the pressurized air could promote chips remained in the hole to be removed and provide cooling effect to cutting tool. As a result, tool wear was reduced, the cutting force and cutting temperature were decreased, and hole quality was improved. Results proved the assisted chip removal system can help to further improve the hole-making process of CFRP/Ti stacks.

Effect of in-situ formed Mg2Ni/Mg2NiH4 compounds on hydrogen storage performance of MgH2

Magnesium-based hydrogen storage materials (MgH2) are promising hydrogen carrier due to the high gravimetric hydrogen density; however, the undesirable thermodynamic stability and slow kinetics restrict its utilization. In this work, we assist the de/hydrogenation of MgH2via in situ formed additives from the conversion of an MgNi2 alloy upon de/hydrogenation. The MgH2–16.7 wt%MgNi2 composite was synthesized by ball milling of Mg powder and MgNi2 alloy followed by a hydrogen combustion synthesis method, where most of the Mg converted to MgH2, and the others reacted with the MgNi2 generating Mg2NiH4, which produced in situ Mg2Ni during dehydrogenation. Results showed that the Mg2Ni and Mg2NiH4 could induce hydrogen absorption and desorption of the MgH2, that it absorbed 2.5 wt% H2 at 473 K, much higher than that of pure Mg, and the dehydrogenation capacity increased by 2.6 wt% at 573 K. Besides, the initial dehydrogenation temperature of the composite under the promotion of Mg2NiH4 decreased greatly by 100 K, whereas it is 623 K for MgH2. Furthermore, benefiting from the catalyst effect of Mg2NiH4 during dehydrogenation, the apparent activation energy of the composite reduced to 73.2 kJ mol−1 H2 from 129.5 kJ mol−1 H2.

Slot milling of titanium alloy with hexagonal boron nitride and minimum quantity lubrication and multi-objective process optimization for energy efficiency

The implementation of sustainable manufacturing techniques to make machining processes more eco-friendly is a challenging topic that has attracted significant attention from the industrial sector for many years. As one of the dominant manufacturing processes, machining can have a considerable impact in terms of ecology, society, and economics. In certain areas, this impact is a result of using certain cutting fluids, especially during the machining of difficult-to-cut alloys such as titanium, where a large amount of cutting fluid is wasted to ease the cutting process. In such scenarios, identifying suitable machining conditions to supply cutting fluids using eco-friendly techniques is currently a major focus of academic and industrial sector research. In this study, effects of minimum quantity lubrication with different concentrations of hexagonal boron nitride nanoparticles on the surface roughness and cutting force of slot-milled titanium alloy is investigated using analysis of variance and response surface methodology. The results reveal that all responses are sensitive to changes in the feed per tooth, cutting depth, and cutting fluid flow rate. The regression functions generated were combined with particle swarm optimization in order to improve energy-efficiency, as well. Possible sectorial scenarios were generated for wider industrial adoption. With this study, it was proven that utilizing minimum quantity lubrication with hexagonal boron nitride nanoparticles can reduce both cutting force and surface roughness, which makes it to be a promising alternative as a nanoparticle augmented minimum quantity lubrication method for machining titanium alloys.

A study ofthe surface microstructure and tool wear of titanium alloys after ultrasonic longitudinal-torsional milling

In order to obtain a better surface micro-morphology on the difficult-to-machine materials such as titanium alloys, the influence of ultrasonic parameters and cutting parameters on the tool path was analyzed theoretically under the ultrasonic longitudinal-torsional vibration. Ultrasonic longitudinal-torsional assisted milling (ULTAM) of titanium alloy was performed, based on a 20° slope. The effects of the ultrasonic parameters and cucuttintting parameters were studied on the surface morphology and surface roughness. The machined surface was examined using scanning electron microscopy (SEM) and white light interferometry. The characterization parameters of the three-dimensional surface micro-morphology including the arithmetic mean height (Sa), the surface skewness (Ssk), and the density of summits (Sds), were obtained under the corresponding cutting parameters. It was found that the ultrasonic amplitude exhibited a significant influence on the surface micro-morphology, followed by the spindle speed n, while the effect of the depth of cut (ap), and the feed amount per tooth (fz) was relatively less. Under the same cutting parameters for the surface, a comparative analysis for the friction and wear testing was performed between the ultrasonic milling and conventional milling (CM). The results showed that the ULTAM transformed the original ravines and anisotropic surface imperfections into an uniform and orderly scaly micro-texture, thus forming an isotropic surface texture in all directions. Furthermore, ULTAM transformed the surface into a fish-scale micro-texture, and thereby improved the surface quality. The fine and smooth surface morphology was conducive by shortening the running-in time, allowing the stable state of friction to be reached quickly, and thereby offering a higher stability in the friction process. `Compared to CM, the tool wear was reduced by 30%, due to the unique tool-work separation characteristics of the ultrasonic longitudinal-torsional assisted milling. Moreover, the unique intermittent cutting characteristics of the ultrasonic longitudinal and torsional milling not only reduced the cutting force and tool wear, but also inhibited the generation of the burr, thus improving the surface quality.