Machining Of Alloys Research Articles

Development of pulse-assisted cryo-micro lubrication architecture for machining of Ti-based alloys: A frugal innovative attempt for a hybrid lubri-cooling technique

In the present study, an Intermittent Spray Cooling (ISC) architecture has been developed for machining process applications for the first time. ISC is a newer cooling strategy through which cutting fluid is delivered into machining zone in a time-controlled pulsating mode. In order to enhance the machining performance for the least amount of coolant/lubricant consumption, the frugal design approach has been adopted including hybrid (liquid nitrogen (LN2) + minimum quantity lubrication (MQL)) cooling strategy and spray flow controller. Pulse assisted Cryo+MQL (PCMQL) integrated the application of a minimum quantity of mango seed oil (MSO) and liquid nitrogen (LN2) from two distinct nozzles in the machining zone. Therefore, to reveal the impact of PCMQL in turning of Ti-3Al-2.5 V, tool flank wear, cutting force, and surface roughness have been investigated. The obtained results have been compared with different environment conditions: dry cutting, MQL, pulse-MQL (PMQL) with 0.5 s pulse time, PMQL with 1 s, LN2, and hybrid Cryo+MQL. For comprehensive analysis, scanning electron microscopy (SEM), energy-dispersive spectrometer (EDS) has been used to analyze Ti-3Al-2.5 V chemical elemental deposition on flank face of the carbide cutting tool. The experimental results showed that PCMQL reduced the fluid consumption while attaining smooth surface finish, minimum flank wear and cutting force as compared to other environment conditions. The developed intermittent spray cooling system is an economical process and showed the positive impact on machining of titanium (Ti) alloys.

INVESTIGATION ON THE ELECTRICAL DISCHARGE MACHINING OF Cu-SHAPE MEMORY ALLOY: A STUDY ON MACHINABILITY AND SURFACE TOPOGRAPHY ASPECTS

Shape memory alloys (SMAs) are an excellent material for producing components for a wide range of industrial applications, such as orthopedic implacers, micro-equipment, actuators, fittings, and screening components, as well as military equipment, aerospace components, bio-medical equipment, and fabrication requirements. Despite its remarkable qualities, the production of SMAs is a problem for investigators all over the globe. The purpose of this research is to evaluate the effects of altering the [Formula: see text], [Formula: see text], [Formula: see text], and GV while processing copper-based SMA in an electrical discharge machining process on the material removal rate (MRR) and surface roughness (SR). The major runs were designed using a central composite design. SEM was also utilized to examine the micro-structure of EDM-processed electrode tools and work samples. SEM scans indicated the presence of debris, micro-cracks, craters, and a newly formed recast layer on the electrode tool and workpiece surface. High [Formula: see text] and prolonged [Formula: see text] provide huge spark energy simply at the work sample-tool contact, resulting in debris production. The experimental results reveal that the least and highest MRR values are 10.333 and 185.067[Formula: see text]mm3/min, respectively, while the minimum and maximum SR values are 3.07 and 7.15[Formula: see text][Formula: see text]m. The desirability technique, teacher learning based optimization (TLBO), and the Jaya algorithm were also utilized to optimize the studied solutions (i.e. MRR and SR) on a single and multi-objective basis. The best MRR and SR were determined using the desirability approach, the Jaya Algorithm, and the TLBO to be 152.788[Formula: see text]mm3/min and 4.764[Formula: see text][Formula: see text]m; 240.0256[Formula: see text]mm3/min and 1.637[Formula: see text][Formula: see text]m; and 240.0257[Formula: see text]mm3/min and 1.6367[Formula: see text][Formula: see text]m.

Effect of local heating by ultrashort pulsed laser on Fe–Si–B–Cr amorphous alloys and its influence on blanking machinability

We propose a novel blanking method to improve the machinability of amorphous alloys by taking advantage of changes in mechanical properties during local heating. The local heating is achieved through an ultrashort pulsed laser with a low thermal effect, allowing us to control the size and structure of heat-affected zones by adjusting laser power, pulse width, and shot numbers. This method hence causes phase transformation only in the blanking area. Namely, heat storage effects increased with a prolonged ablation process, and crystallization was observed at a repetition rate of 200 kHz or more. A fully crystallized microstructure, which formed at elevated temperatures, was seen at the center of the laser irradiation, while, as the distance from the irradiation point increased, small crystallites are found to disperse in the amorphous matrix. In addition, a thin crystalline phase appeared on the surface layer of the crystallized region. In general, the locally heated area was embrittled by the aforementioned structural changes, and consequently, the blanking resistance decreased with an increase in the crystallized area. Yet, it was found that laser irradiation which did not bring about crystallization also led to a decrease in the blanking resistance, showing that thermal effects below the crystallization temperature are still effective in reducing the blanking resistance. Additionally, the blanked cross-section of the locally heated specimen showed good surface quality without defects such as a large shear droop, which often occurs when punching amorphous alloys.

Lubrication Mechanism of scCO2-MQL in the Assisted Machining of Titanium Alloys

Cutting fluids are often used in the machining of titanium alloys to reduce processing temperature and maximize quality and productivity. The permeability of the cutting fluid in the capillary tube directly influences the effect of lubrication on cooling performance. In this study, supercritical carbon dioxide cryogenic micro-lubrication (scCO2-MQL) is used for the auxiliary machining of titanium alloys. A capillary model for scCO2-MQL-assisted cutting is proposed and established while considering the characteristics of three-phase states produced during the decompression release of scCO2. The injection temperature and characteristics of scCO2 are experimentally investigated, and the dynamic process of scCO2-MQL penetration into the capillary is analyzed. The results show that under the applied experimental conditions, the injection temperature of scCO2-MQL ranges from approximately −45 °C to 60 °C. Because scCO2 presents good solubility in oil, it has the capacity to refine the oil droplets into smaller particles, thus resulting in a higher lubricating oil content in the capillary per unit of time. This leads to enhanced lubricity that can benefit processing applications.

Recent advancements in electro-chemical machining of MMC and alloys

ECM is an unconventional process of machining which is also known as the reverse Electroplating process used to machine conductive material in the presence of electrolyte with the help of a controlled reaction between tool and workpiece. In recent times ECM machines are usually used for machining hard and complex shapes materials like composites, ceramic, Inconel etc. which have applications in space industries, Automobiles, medical, and railways. Because they are less dense than conventional metals, have high mechanical qualities, are more resistant to corrosion and wear, and have a lower thermal expansion coefficient. Considering the processes and their parameters related to Electrochemical machining. Few of the existing literature reviews are presented in this study. This study compiles the latest research concerning the electrochemical machining of MMC and metal alloys. New techniques include electrode design, abrasive particle reinforcement, electrolyte flow rate etc.

Machining of titanium based alloys using wire electric discharge machining: A review

Titanium alloys are used in aerospace and biomedical field because of high strength, light weight and heat resistance properties because of low thermal conductivity it is difficult to machine conventionally hence, non-conventional technologies are frequently employed for various applications. Electric discharge machining with wire electrode (WEDM) is one of the most rapidly developing non-conventional manufacturing technologies for difficult-to-machine materials; However, complexity of process makes it difficult to have proper idea of dependence of controllable factors on response measure of process. This state of the art review has been conducted to identify recent research on machining of Titanium alloys using WEDM. Article reports various tools and procedures used for correlating experimental results and the effect of process parameters on process performance characteristics. In discussion section probable reason behind trend of input output relation are explained. Model based upon Machine Learning methods can greatly enhance the modelling for such kind of complex machining method.

Finite element simulation of electric discharge machining process during machining of NiTi, NiCu and BeCu alloys

Advanced alloys, in addition to high strength, nonmagnetic qualities, high fatigue strength, corrosion resistance and non-sparking properties, also exhibit good wear resistance, corrosion resistance and good fatigue strength. As a result, conventional machining presents machining issues. However, electrical discharge machining provides a practical solution. With experimental validation, the current study is concerned with developing an electrical discharge machining model. In this study a single discharge finite element model was developed and simulated a three-dimensional axis symmetrical model using analysis software. The material removal rate was calculated using the temperature profile. A validation experiment was carried out to verify the numerical results. In the comparison of numerical and experimental results, an average error of 6.189 % was obtained. This shows that the finite element model results are in good agreement with experimental results. Further finite element can mimic the experimental conditions accurately and predict the material removal rate.

Impact of operating parameters on electric discharge machining of cobalt-based alloys

The goal of this investigation is to examine how operating parameters (voltage, peak current, pulse-on & pulse-off times) affect the MRR of satellite-6 material that has undergone EDM processing. To carry out the trials, an L9 orthogonal array (OA) for the 4 machining variables at 3 levels each was chosen. Three successive trials were performed in the studies in random order. The best levels for maximising the responses were identified after performing an analysis of variance. The important factors in MRR are current & pulse-on-time. The effects of pulse-off-time & voltage on MRR are negligible. The ANOVA's results also show that discharge current contributes significantly to overall performance with a contribution of (67.87%). The contribution % age for “pulse-on-time, pulse-off-time, voltage & pulse-on-time” are lower at 25.45%, 2.27% & 4.8% respectively.

Manufacturing Methods Induced Property Variations in Ti6Al4V Using High-Speed Machining and Additive Manufacturing (AM)

Additive manufacturing techniques are replacing conventional subtractive machining processes; however, the surface quality and defects have been a key roadblock to expanding AM’s uses. This paper describes experimental investigations in the high-speed dry machining and additive manufacturing (AM) of titanium alloy (Ti6Al4V), discussing the effect of machining and AM conditions on the surface characteristics due to the micro-deformation layer. Analysis of the machined surfaces shows the deposition of microparticles at a high cutting speed of 170 m/min at moderate feed rates. The predominant thermal softening effect at a high cutting speed causes restructuring of the micro-deformation layer. Thus, the machined surface shows fewer alterations and a correspondingly lower surface roughness. A high cutting speed also favors the induction of high residual stresses that are compressive. Shallow grooves are seen throughout the surface along the feed spacing with a higher depth of cut of 0.8 mm. An increase in the cutting speed from 170 m/min to 190 m/min leads to a 61% increase in the surface finish owing to a rise in machining temperature leading to thermal softening, and subsequent restructuring of the machined surface layer occurs. For the feed rate, the surface finish values decrease gradually as the feed rate increases, and the worst finish of 1.37 µm is attained at a feed rate of 0.875 mm/rev. This study also compares different AM processes for Ti6Al4V based on the defects and their effects on mechanical properties, such as tensile and fatigue strength. It was observed that the ultimate tensile strength and the yield strength were approximately 20% more in SLM and direct energy deposition as compared to electron beam melting. The mechanism of these effects is also explained by elaborating on the influence of grain size, phase, and other microstructural behaviors on the final mechanical properties of the produced part.

A hybrid short electric arc and electrochemical machining of the Ti6Al4V alloy

ABSTRACT In this study, the persistent challenges of high surface roughness and large thickness of the re-solidified layer (RSL) and the heat-affected zones (HAZ) in short electric arc machining (SEAM) are confronted by a hybrid simultaneous SEAM and ECM (SEACM) technique. The SEACM is investigated in low conductivity NaCl electrolytes as the working medium with an additionally applied air pressure, which can meet the requirements of both SEAM and ECM. Firstly, the effect of feed rate and electrolyte conductivities on material removal rate (MRR), roughness, line profiles, and surface morphologies were studied. Later, the current-voltage waveforms, topographies, PSD curves, and dimensional accuracy at different feed rates and electrolyte conductivities were analyzed. The SEACM significantly reduced the roughness and the thickness of RSL and HAZ at an appropriately optimized electrolyte conductivity and feed rate. The developed technique provides the basis for transferring from rough machining to finishing in SEAM.

Study on the effect of air and argon assisted short electric arc machining on Ti6Al4V titanium alloy

The use of an argon–water medium rather than air–water medium is proposed to increase the material removal rate (MRR) and decrease surface oxide production for short electric arc machining. To provide a more stable discharge state during high-temperature processing, this approach uses argon to reduce the production of highly resistant refractory materials (e.g. titanium oxide). For short-arc machining of Ti6Al4V titanium alloy, the effects of the voltage, milling depth, electrode speed and gas flow rate on the MRR, relative electrode loss rate and surface roughness were compared for air–water and argon–water mixtures. It was discovered that the milling depth and voltage had the greatest impact on the MRR, voltage and electrode rotational speed had the greatest impact on the relative tool electrode wear rate (REWR), and voltage had the greatest impact on the surface roughness. In contrast to the air–water mixture, the MRR with the argon–water working medium was as high as 9391 mm3/min, with a 13% improvement in MRR, as well as a smooth and flat surface of the machined workpiece. Nevertheless, the REWR increased to 2.46% and the surface roughness was at least 432 μm with the argon–water medium, increasing by 59 μm compared with the air–water medium. Moreover, the addition of argon reduced the types of surface compound on the workpiece and decreased the residual stress defects, including the recast layer, microcracks and holes.

A novel approach of tool condition monitoring in sustainable machining of Ni alloy with transfer learning models

Cutting tool condition is crucial in metal cutting. In-process tool failures significantly influences the surface roughness, power consumption, and process endurance. Industries are interested in supervisory systems that anticipate the health of the tool. A methodology that utilizes the information to predict problems and to avoid failures must be embraced. In recent years, several machine learning-based predictive modelling strategies for estimating tool wear have been emerged. However, due to intricate tool wear mechanisms, doing so with limited datasets confronts difficulties under varying operating conditions. This article proposes the use of transfer learning technology to detect tool wear, especially flank wear under distinct cutting environments (dry, flood, MQL and cryogenic). In this study, the state of the cutting tool was determined using the pre-trained networks like AlexNet, VGG-16, ResNet, MobileNet, and Inception-V3. The best-performing network was recommended for tool condition monitoring, considering the effects of hyperparameters such as batch size, learning rate, solver, and train-test split ratio. In light of this, the recommended methodology may prove to be highly helpful for classifying and suggesting the suitable cutting conditions, especially under limited data situation. The transfer learning model with Inception-V3 is extremely useful for intelligent machining applications.

Performance evaluation of spot cooled vibration assisted turning for Ti6Al4V alloy

In the present work, a hybrid modular machining technology was designed for machining of Ti6Al4V alloy. Ultrasonic machining was integrated with vortex tube based spot cooling system with CO2 gas as working fluid for achieving the cumulative advantage of both, which is termed as Spot Cooled Vibration Assisted Turning (SCVAT). Its performance is evaluated and compared with Conventional turning, Vibration Assisted Turning and Vortex tube based spot cooling under constant machining conditions. The vibration and cooling parameters were also kept constant wherever applicable. The results showed a significant reduction in cutting temperature (30.98%), surface roughness (65.97%), and tool wear (75.03%); however, cutting forces are increased slightly compared to dry cutting. Compressive surface residual stresses were generated on the machined surface in SCVAT.

Studies on Geometrical Features of Tool Wear and Other Important Machining Characteristics in Sustainable Turning of Aluminium Alloys

The aerospace and automotive industries make extensive use of aluminium and its alloys. Contrarily, machining of aluminium (Al) alloys presents a number of difficulties, including, but not limited to, poor surface finishing, excessive tool wear, decreased productivity etc. Therefore, it’s very important to measure the machining characteristics during machining of aluminium alloy with sustainable cooling strategies. In this work, a new approach of measurement was adopted to measure the critical geometrical aspects of tool wear, surface roughness, power consumption and microhardness while machining AA2024-T351 alloy under dry, minimum quantity lubrication (MQL), liquid nitrogen (LN2) and carbon dioxide (CO2) cooling conditions. Initially, the various aspects of tool wear were studied with the help of Sensofar Confocal Microscope integrated with Mountains map software and then, the other results such as surface roughness, power consumption and microhardness were measured as per the ISO standards. The outcome of these measurement studies confirms that LN2 and CO2 cooling is helpful in improving the machining characteristics of AA2024-T351 alloy. When compared to dry conditions, the surface roughness values of MQL, LN2, and CO2 all have values that are lowered by 11.90%, 30.95%, and 39.28% respectively, and also power consumption values were lowered by 3.11%, 6.46% and 11.5% for MQL, CO2 and LN2 conditions, respectively.

Energy consumption and surface roughness maps for low and moderate speed machining of Aluminum alloy 2014: An experimental study

<abstract> <p>The rising energy prices and soaring environmental concerns have put an immense pressure on the wide usage of machining processes. The total power consumption during machining includes the power consumed by the machine itself and the power used to remove the material from the workpiece. An accurate prediction of energy consumption during the machining process is the basis for energy reduction. In this study, the specific cutting energy and surface finish for low and moderate-speed orthogonal machining of the aluminum alloy 2014 are evaluated. The measured values for the specific cutting energy and surface roughness are presented as maps on a grid, which is based on the machining parameters including the following: (1) cutting speed and (2) undeformed chip thickness. The specific cutting energy map depicts low energy consumption values of 0.52 J/mm<sup>3</sup> for the aluminum alloy 2014 at medium speed machining. The roughness maps depict high roughness values at high cutting speeds. Both maps help in optimizing the machining process to achieve a required surface roughness with minimal energy consumption. A review of a specific cutting energy map demonstrates that energy consumption decreases by increasing the cutting speeds. The decrease in energy consumption at moderate speeds corresponds to the low cutting forces. This potentially happens as a result of thermal softening of the material caused by adiabatic heating. This subsequently leads to an increase in the machinability of the aluminum alloy 2014 at moderate cutting speeds. Furthermore, the decreasing chip thickness and increasing shear angle as a result of increasing the cutting speed confirms the increased machinability of the workpiece at moderate speeds.</p> </abstract>

Investigation of the Machinability of CoCr Alloys in Orthogonal Cutting

Investigation of the Machinability of CoCr Alloys in Orthogonal Cutting

Simulation and analytical studies of chip formation processes in the cutting zone of titanium alloys

The low machinability of titanium alloys is determined by the physical, mechanical, and chemical properties of these materials and their mechanical characteristics. It is also evident in the hardened state of the material being processed during cutting, as well as in the initial state. This phenomenon is caused by thermodynamic parameters that determine the properties of titanium material at elevated temperatures. The peculiarities of the cutting and chip formation processes during titanium alloy machining are presented in this article. The peculiarity of the described approach is the analysis of the results of simulation modeling of cutting in Deform 2D software. It is proved that the frictional factor in the formation of the thermal characteristics of the cutting process, which arises as a result of the chip sliding along the tool, dominates the load factor (caused by force and deformation processes in the chip root). It has been established that the length of contact between the chips and the tool’s rake face has a certain tendency to change: the contact length first increases and then decreases with increasing cutting speed. An analysis of the dependence of the chip compression ratio on changes in cutting speed has shown that with an increase in cutting speed, the average value of the compression ratio practically does not change, but the amplitude of its oscillation increases significantly, which is equivalent to a change in the shear angle. This parameter changes dynamically due to the adiabatic nature of chip formation

A review on conventional and nonconventional machining of Nickel-based Nimonic superalloy

Superalloys have gained prominence in recent years in various sectors, namely, spacecraft, marine, power, defense, vehicular and others, due to their ability to withstand high temperatures of up to 980 °C without deformation. Nimonics are Nickel-based superalloys usually known to be hard-to-machine materials due to their high strength at high temperatures, higher hardness, low thermal conductivity, and tendency to react with tool material. All these factors increase the level of difficulties in the machining of Nimonic superalloys. Numerous studies have examined various facets of machining of Nimonic alloys. This article summarizes the observation from 152 research articles to offer a reasonable engineering overview of the study of Nimonic alloys. An overview of Nimonic superalloys and their applications is given first. Then, various conventional and non-conventional machining processes, problems associated with multiple machining processes and methods to rectify the issues concerning the machining process have been reported. Thus, this summary will certainly help industrialists and academic researchers for further research work in machining Nimonic alloys.

Effect of wire EDM process parameters on material removal rate of duplex stainless steel (S31803)

Machining of high-strength alloy is needed for special requirements requiring less wear, such as sliding objectives in applications like cams, gears etc. High-strength alloy material profile machining is challenging in conventional machining; Wire-EDM is one of the machining processes to fulfil the requirement with a good surface finish. The present work is an experimental study on material removal rate in Wire-EDM machining on S31803 Duplex Stainless Steel (DSS) material at different thicknesses. Thickness is considered as 5 mm, 10 mm, 15 mm and 20 mm where the nozzle distance altered as 19, 29, 39 and 49 with pulse off time 1,2,3,4 s. L16 orthogonal array from Taguchi method of experiments considered for the present study. Material of 10 mm thickness with 4 s pulse off time at 29 nozzle distance gives better material removal rate when compared with other samples.

Influence of Process Parameters on Surface Crack Density in Electrical Discharge Machining of Ni35Ti35Zr15Cu10Sn5 high-temperature high entropy shape memory alloy by Response Surface Methodology Approach

Influence of Process Parameters on Surface Crack Density in Electrical Discharge Machining of Ni35Ti35Zr15Cu10Sn5 high-temperature high entropy shape memory alloy by Response Surface Methodology Approach