Coolant Machining Research Articles

Nanoparticle-enhanced coolants in machining: mechanism, application, and prospects

AbstractNanoparticle-enhanced coolants (NPECs) are increasingly used in minimum quantity lubrication (MQL) machining as a green lubricant to replace conventional cutting fluids to meet the urgent need for carbon emissions and achieve sustainable manufacturing. However, the thermophysical properties of NPEC during processing remain unclear, making it difficult to provide precise guidance and selection principles for industrial applications. Therefore, this paper reviews the action mechanism, processing properties, and future development directions of NPEC. First, the laws of influence of nano-enhanced phases and base fluids on the processing performance are revealed, and the dispersion stabilization mechanism of NPEC in the preparation process is elaborated. Then, the unique molecular structure and physical properties of NPECs are combined to elucidate their unique mechanisms of heat transfer, penetration, and antifriction effects. Furthermore, the effect of NPECs is investigated on the basis of their excellent lubricating and cooling properties by comprehensively and quantitatively evaluating the material removal characteristics during machining in turning, milling, and grinding applications. Results showed that turning of Ti–6Al–4V with multi-walled carbon nanotube NPECs with a volume fraction of 0.2% resulted in a 34% reduction in tool wear, an average decrease in cutting force of 28%, and a 7% decrease in surface roughnessRa, compared with the conventional flood process. Finally, research gaps and future directions for further applications of NPECs in the industry are presented.

Machinability analysis for drilling Ti6Al4V ELI under sustainable techniques: EMQL vs LCO2

As a result of the widespread use of Ti6Al4V ELI in the medical industry for implants that are subjected to high loads, these biomedical implants must be accurately machined to prevent unfavourable joint or muscular inflammatory conditions. This oftentimes involve drilling holes into the implants for joint assembly during surgery. It is well known that titanium is a very difficult to machine material and therefore, requires appropriate cooling and lubrication during machining. With the help of SEM and line-scan EDS analysis, the current study focuses on analysing various sustainable machining techniques, such as electrostatic minimum quantity lubrication (EMQL) and liquid carbon dioxide (LCO2 cryogenic coolant), while drilling Ti6Al4V ELI (Grade 23) holes in terms of hole surface quality, wear mechanisms, and chip morphology. Poor surface quality of the hole was produced under EMQL cutting, with around 42–71% larger surface roughness values (Rz) compared to cryogenic LCO2 conditions. The hole surface consisted of different defects such as adhesion, microfractures, smearing etc., as a residue of the drilling operation under both EMQL and cryogenic LCO2 conditions. Tool life was significantly improved under LCO2 cutting environment (approximately by 416%) in comparison with EMQL technique. Adhesion and abrasion were found to be the main tool wear modes. Likewise, the machined chips exhibited cracks and adhered particles further demonstrating that EMQL coolant did not provide sufficient lubrication and heat extraction capability. Cryogenic LCO2 coolant outperformed EMQL lubrication for all machinability indicators, according to the study, making it a superior cutting environment for machining Ti6Al4V. Moreover, cryogenic LCO2 coolant dissipates into air during the machining process rendering it a sustainable and environmentally friendly machining coolant fluid.

Identification of the effect of strontium and ytterbium addition over magnesium zinc alloy during the drilling process with ARAS and WASPAS techniques

Magnesium (Mg) alloys are widely employed in aerospace and automotive applications owing to their beneficial attributes. Identifying proper process parameters is a critical choice to save costs and increase quality. This necessitates the classification of suitable process parameters in light of numerous competing considerations; hence it must be analyzed by means of the Multiple Criteria Decision Making (MCDM) techniques. This paper handles the MCDM issue using two different approaches namely, the ARAS (Additive Ratio ASsessment) and WASPAS (Weighted Aggregated Sum Product ASsessment). The experiments carried out in Mg Zn10 and adding of Strontium (Sr) and Ytterbium (Yb) were critically evaluated. The independent variable like spindle speed and feed rate were examined by varying the machining tool and coolant supplied. The effect of coated and uncoated carbide was studied with High-Speed Steel. The influence of coconut oil, liquid nitrogen, and vegetable oil over the process parameters was also studied. The responses like thrust force, torque, and surface roughness were studied over the three different materials by varying the numerical and categorical factors. The addition of Yb plays a beneficial effect on all three responses considered. The ideal combination was discovered using ARAS and WASPAS for concomitant reduction of all the considered responses, attained with a coated carbide tool with a spindle speed of 118 m/min. and a feed rate of 0.26 mm/rev. during coconut oil coolant supply over Mg Zn10 Sr2. The ARAS rankings align with the WASPAS rankings in 55.56% of cases, with the interesting observation that both the lower and higher orders are identical. The optimal process parameters for Mg Zn10 were identified as a cutting speed of 56 m/min. and a feed rate of 0.26 mm/rev., using a coated carbide tool and CO coolant. For Mg Zn10 Sr2 Yb2, the study found the optimal parameters to be a cutting speed of 118 m/min. and a feed rate of 0.62 mm/rev., with the use of uncoated carbide and CO coolant.

Standalone Sensors System for Real-Time Monitoring of Cutting Emulsion Properties with Adaptive Integration in Machine Tool Operation.

This paper presents a novel cutting fluid monitoring sensor system and a description of an algorithm framework to monitor the state of the cutting emulsion in the machine tool sump. One of the most frequently used coolants in metal machining is cutting emulsion. Contamination and gradual degradation of the fluid is a common occurrence, and unless certain maintenance steps are undertaken, the fluid needs to be completely replaced, which is both un-economical and non-ecological. Increasing the effective service life of the cutting emulsion is therefore desired, which can be achieved by monitoring the parameters of the fluid and taking corrective measures to ensure the correct levels of selected parameters. For this purpose, a multi-sensor monitoring probe was developed and a prototype device was subsequently created by additive manufacturing. The sensor-carrying probe was then placed in the machine tool sump and tested in operation. The probe automatically takes measurements of the selected cutting emulsion properties (temperature, concentration, pH, level height) in set intervals and logs them in the system. During the trial run of the probe, sensor accuracy was tracked and compared to reference measurements, achieving sufficiently low deviations for the purpose of continuous operation.

Tool Wear and Surface Integrity of γ-TiAl Cryogenic Coolant Machining at Various Cutting Speed Levels

High-speed machining of γ-TiAl alloy is a significant challenge due to high cutting temperatures. From the perspective of environmental protection and improving tool life, appropriate cooling strategies should be adopted. Compared with dry and conventional flood cooling conditions, the feasibility of machining γ-TiAl in cryogenic LN2 cooling conditions was discussed. The cutting force, tool wear and its mechanism, and surface roughness, as well as sub-surface morphology characteristics, were studied by combining macro and micro techniques. The results revealed that the wear morphology of the rake and flank face under the three cooling media shows different degrees. The crater wear of the rake face is expanded at high speeds and then progresses into more serve flaking and notching wear. The main wear pattern on the flank face is gradually transformed from adhesive wear to diffusion and oxidation wear at high speeds in dry machining. In the LN2 condition, the diffusion of workpiece elements and cutting-edge oxidation were restrained. The wear pattern is still mainly adhesive wear. In addition, cryogenic machining shows significant advantages in reducing cutting force, suppressing heat-affected zone, improving surface quality, and inhibiting micro-lamellar deformation.

Design of Real-Time Monitoring System for Cutting Fluids

The paper describes the design and implementation of a cutting fluid monitoring system, as well as the design and development of an algorithm to increase the life of the cutting fluid in the machine tool reservoir. Cutting fluids are the most common type of coolant in machining. During its use, it becomes contaminated and gradually degrades until it needs to be replaced with fresh fluid. To increase its effective service life, its parameters should be monitored at regular intervals, and corrective measures such as topping up the fluid quantity and adding inhibitors and additives should be taken if necessary. For this purpose, a conceptual design of a monitoring device was developed, and a prototype device was subsequently manufactured. The device is designed as a floating probe in the storage tank. Therefore, its shape had to be designed to accommodate multiple sensors, batteries, and electronic components while remaining floating and watertight. The designed prototype was made by additive manufacturing and placed in a cutting fluid while being measured at regular intervals. In the event of non-compliant parameters, the algorithm generated corrective actions, and the machine operator could take the required steps to significantly increase the lifetime of the cutting fluid.

Embedding ceramic components in metal structures with hybrid directed energy deposition

The combined benefit of both additive and subtractive manufacturing within the same gantry system enables hybrid directed energy deposition to create complex geometries with smooth surface finish and superior dimensional accuracy. Moreover, with layer-by-layer access to the structure during both the addition and subtraction of material, the insertion of components is now possible, assuming the components can survive the high temperatures associated with the subsequent metal deposition. Ceramic inserts are of interest for a variety of reasons including (1) to create complex interwoven ductile/brittle composites for ballistics or high-temperature applications or (2) to integrate high-temperature strain or temperature sensors protected within ceramic substrate subsumed into a larger metal structure. In this work, stainless steel substrates were machined to create an internal cavity for the insertion of a ceramic component. During the investigation of several different over-the-ceramic deposition strategies, components were inserted, and different process sequences were allowed to continue to envelop the inserted ceramic with varying success. Unmelted powder was used to serve both as a thermal buffer and to provide a flush surface upon which the laser cladding could continue. Subsequent depositions were attempted with both dry and wet powder (addition of machining coolant to wet). The wet powder has previously been demonstrated to not significantly impact the mechanical properties of a final structure and provided a thermal barrier to protect the ceramic piece from the extreme temperatures of the final metal deposition. The wetting of the powder provided stability and minimized displacement caused by the powder flow from the laser cladding head. Finally, the use of an oblique angle for laser cladding allowed for the redirection of some fraction of the introduced thermal energy away from the ceramic component and, consequently, improved the survival of the ceramic inserts. With this combination of techniques, ceramic inserts survived full embedding within a 3D-printed stainless steel structure.

Dynamics of Hall current and entropy generation in peristaltic transport of hybrid nanofluid

Improvement of high-performance thermal systems to enhance heat transfer has become quite prevalent these days. The main applications of hybrid nanofluids are found in heat exchangers, the automotive industry, solar energy, heat pipes, space, electronic cooling, nuclear systems cooling, HVAC applications, biomedicine, ships, and coolant in machining and manufacturing. Therefore, the present research investigates the generation of entropy for a peristaltic motion of hybrid nanofluid flowing through a symmetric channel under impacts of mixed convection, Hall currents, and Ohmic heating. Novel features of hybrid nanoparticles (copper and titanium oxide dispersed in water) are taken into account. Long wavelength and weaker Reynolds number assumptions are used to simplify the governing equations. Homotopy Analysis Method has been adopted to solve a non-linear system of differential equations. A comparative analysis of numerical scheme (NDSolve built-in command in Mathematica) and analytical methodology (HAM) for heat transmission rate at the boundary are also presented in tabular form. Graphical outcomes predict that entropy generation is reduced by improving the Hall parameter. Hybrid nanofluid temperature is reduced when the concentration of nanomaterials is increased. Heat transfer rates increase through an increment in hybrid nanoparticles. It is anticipated that the current flow model can be useful for enhancing the efficiency of such thermodynamic systems.

Reconnoitering the influence of nanofluid of GnPs enriched waste coconut oil in machining SAE 1045 shaft on modification surface finish

The surface quality is a prime factor in the failures of shaft by fatigue load. Here used coconut oil that is waste coconut oil disposal severities shop of ‘Kerala chips’ are used for preparing nanofluid for machining coolant. Hence this piece of research work investigating the effect of Nano fluid of graphene nanoplatelets (GnPs) enriched waste coconut oil in minimizing Surface Roughness while machining SAE1045 steel shaft by conventional lathe. Control group samples processed by dry (green) machining. The intervention group samples machined by 0.3% GnPs concentrated used coconut oil employed in the flood cooling form for the machining that is clean technology approach. Taguchi analysis and ANOVA used for optimizing the process parameters and developing mathematical model. From the experimental results it was revealed that the proposed GnPs concentrated used coconut oil nanofluid coolant reduced surface roughness significantly by 33.539% and confirmed observations are perfect and obeys statistical assumptions. Hence the same can be recommended to process the SAE 1045 material for shaft manufacturing.

Experimental analysis on Feed force reduction performance by nano fluid of nano- alumina particles enriched waste coconut oil in wet machining of SAE 1045 steel shaft

Waste utilization is act of clean technology. The multiple times used cooking oils are called as waste cooking oil. This investigation focuses specific type of such vegetable oil (coconut oil) for synthesizing the nanofluid for metal machining purposes Used coconut oils are considered as waste and disposed on open channel and that is against to eco-friendliest. The use of such liquid waste for machining coolant is investigated in this piece of research. Liquid Waste used for creating nanofluid for metal cutting is novel approach. If it is feasible the coolant cost will be significantly reduced and waste such oil disposal will also be reduced. This piece of research work aims to investigate the effect of Nano- alumina based Nanofluid in machining of steel work in the lathe machine. The novelty in this investigation is the used coconut oil is reused as base fluid for preparing the nanofluid. Feed force response is used for optimizing the parameters of the metal removal process. For investigating the effects, the cutting speed varied as 40 to 190 m/min, feed rate of the tool varied as 0.05 to 0.20 mm/rev and the CVD coated tool with 4 different nose radiuses used such as 0.3 mm, 0.6 mm 0.9 mm, and 1.2 mm, L16 orthogonal array involved to form the minimum experimental combinations. The results compared with existing practice of dry machining. The test revels that the feasibility of use of liquid waste of used coconut oil for coolant as in the proposed Nanofluid form. The new fluid based cutting out performed and its process parameters influences were studied, optimized and mathematical model developed for prediction of feed force. The Nanofluid reduced the cutting force averagely 35.83%

Unprocessed machining chips as a practical feedstock in directed energy deposition

Directed energy deposition (DED) is an additive manufacturing process capable of creating parts or coatings from powder or wire feedstocks, and may be adapted to use machining chips. Re-use of steel chips as opposed to landfilling or even recycling, has implications for CO2 emission savings. This is particularly the case of like-for-like replacement of powder and other feedstocks. This work addresses two key concerns which currently impede the implementation of chip-based DED – the impact of residual coolant present on chips on part properties, and whether chip type feedstocks can be delivered in a consistent, practical manner similar to powders. The study demonstrates that DED can generate dense, repeatable deposits from 304L stainless steel milling chips, using both pre-placed and vibrationally fed strategies. Milling chips created with and without the use of machining coolant can both be successfully deposited, without compromising the density of the part. EPMA/XRD/EBSD analysis showed no evidence of coolant in deposits, explained by rapid evaporation, and micro-hardness analysis showed it had no effect on hardness. Practical implementation of chip-based feedstocks into DED systems is validated via use of a bespoke vibration feeding system, which is calibrated in this work, and capable of controlled delivery beneath the laser. Melting behaviour under low power is also investigated, revealing chips are readily melted into droplets and incorporate surrounding chips, ultimately yielding efficient material incorporation into tracks.

Coupling characteristics analysis of micro-emulsion cutting fluid for thickness on-machine measurement using ultrasonic

Stable and reliable coupling state between piezoelectric ultrasonic transducer and tested workpiece is very important for ultrasonic measurement. Traditional coupling agents need to be smeared manually or recycled separately, which cannot meet the requirement of on-machine thickness measurement by ultrasonic. Herein, a suitable coupling agent is selected for thickness on-machine measurement in industrial application of ultrasonics. The acoustic impedance and the attenuation coefficient are adopted to characterize the coupling effect of coupling agents and appropriate coupled flow field is selected theoretically. The experimental system of ultrasonic on-machine measurement is established with external circulating jet. The coupling characteristics of machining coolant liquid is calculated and analyzed. From experimental comparison with commonly used coupling agents, it is indicated that the micro-emulsion cutting fluid with volume concentration from 8% to 10% could be selected as compatible coupling agent for ultrasonic on-machine measurement, because it can not only meet the ultrasonic measurement requirements, but also perform friendly to industrial environment.

Experimental investigation into tool wear, cutting forces, and resulting surface finish during dry and flood coolant slot milling of Inconel 718

Inconel 718 superalloy is a widely used material in aerospace due to its high strength, corrosion resistance, and high resistance to thermal fatigue. Excellent mechanical and thermal properties also make Inconel 718 one of the most difficult-to-machine alloys. This study aims to take a different approach of analyzing tool wear during machining of Inconel 718 by measuring worn-out area on each flute from three different faces of flute. This paper also includes analysis of cumulative tool wear, cutting forces, surface roughness, topography, burr formation, and chip morphology at various machining parameters and cooling conditions. The cutting speed was kept constant at 60 m/min due to the goal of machining at highest possible speed and the limitation in maximum spindle speed of the machine tool. Experiments were carried out in dry and flood coolant machining using uncoated carbide tools by varying depth of cut and feed rate for four different settings each. It was found that the amount of tool wear varied for different flutes when measured from top, rake, and back faces of each flute, even for the same tool. The back and rake faces exhibit more chipping wear when machining is carried out at higher depth of cut, irrespective of the cooling conditions. At the same machining conditions for the range of parameters selected in this study, flood coolant machining resulted in slightly higher tool wear at the back and rake faces of cutting flutes and generated higher cutting speed, which may be interrelated. The gradual increase in tool wear over time resulted in an increase in surface roughness from entry to exit of a 76.2 mm machined slot. Flood coolant machining resulted in slightly smoother surface finish at the lower settings of depth of cut and feed rate, while the burr formation was marginally higher in flood coolant machining during machining at higher feed rate and depth of cut. The amount of serration was found to increase specifically with the increase of feed rate and was found to be higher for dry machining compared to flood coolant machining at the same parameter settings. Finally, the new approach of tool wear analysis from different faces of individual cutting flute could provide important guidelines for predicting tool life or potential catastrophic tool failure during machining of Inconel 718.

Environmentally sustainable cooling strategies in milling of SA516: Effects on surface integrity of dry, flood and MQL machining

Abstract The recent move towards ‘Environmentally Sustainable Manufacturing’ (ESM) is leading heavy industries (e.g. oil & gas, nuclear) to explore low-impact manufacturing strategies. In machining, however, most processes are still performed using traditional cooling method using flood or high pressure lubricant emulsions. These emulsions are expensive in their maintenance and disposal, and present a significant environmental concern. This novel study combines evaluations of the performance of low-impact cooling strategies, such as dry milling or minimum quantity lubrication (MQL), in the manufacture of an industrially important pressure vessel carbon steel (SA516) using coated carbide inserts. Tool wear, surface roughness, residual stress and energy consumption were measured during metal cutting trials for each strategy and then compared. Likely tool wear performance when using candidate lubricants was screened prior to machining trials using standard tribological high frequency reciprocating tests. Significant improvements in surface integrity and tool wear were observed when machining with dry and MQL when compared with traditional flood coolant. Measured energy footprints for dry and MQL were also lower when compared to flood coolant machining providing cost savings and environmental advantages in manufacturing using ESM approaches.

Use of palm olein as cutting fluid during turning of mild steel

ABSTRACT This research evaluated surface roughness and cutting forces using an alternative vegetable oil, namely, ‘super palm olein’, as cutting fluid on turning of mild steel. The outcomes of the proposed alternative cutting fluid were compared with that of conventional mineral-based cutting fluid (coolant machining) and dry machining. Taguchi orthogonal array was employed to set design of experiments and results were analysed based on signal-to-noise ratio and analysis of variance (ANOVA) to rationalise multi-parameter experiments, namely, cutting speed, feed rate and depth of cut. It was found that depth of cut influences most significantly on surface roughness, that is, 49.02% for dry machining, 73.35% for coolant machining and 53.86% for super olein machining. On the other hand, the highest contributor to cutting force performance was cutting speed with 51.44% for dry machining, 87.28% for coolant machining and 75.46% for super olein machining. The experimental outcome shows that surface roughness under super olein machining tends to improve as the depth of cut and cutting speeds increase and surpasses that of conventional coolant machining and dry machining. Additionally, regression equations were proposed, based on experimental results, to predict surface roughness and cutting force for given parameters.

Machining performance of Inconel-718 alloy under the influence of nanoparticles based minimum quantity lubrication grinding

Abstract Environmental and health problems associated with the conventional mineral-based cutting fluids has enhanced the quest of researchers to search for environment-friendly lubrication techniques. Minimum Quantity Lubrication (MQL) is the latest technique developing to reduce the use of coolants in machining. In the present work grinding of Inconel-718 (Ni-Cr alloy) has been examined under the influence of Al2O3 based Nanofluid Minimum Quantity Lubrication (NFMQL) technique using vegetable oils as the base oils in view of environmental conscious grinding. The grinding performance of Inconel-718 was evaluated in terms of surface roughness, grinding energy, cutting forces, temperature, and G-ratio. Nanofluids were prepared by adding 0.5 wt% and 1 wt% Al2O3 nanoparticles to the sunflower and rice-bran vegetable oils. From the results, it is observed that Al2O3 based nanofluid MQL with sunflower as base oil has given better results with respect to G-ratio, grinding energy, surface roughness, and coefficient of friction. Better value of surface roughness (0.5 μm) is achieved with 0.5 wt% concentration of nano-particles, whereas G-ratio (1.52), grinding energy(32.91 J/mm3) and tangential forces improved under nanofluid MQL condition with 1 wt% concentration of nanoparticles as compared to flood cooling. This might be due to the fact that while nanofluids flow through the wheel-workpiece interface, it results in the formation of a lubrication film that acts as ball bearing and reduces the sliding friction. Thus vegetable oils with the appropriate amount of Al2O3 nano-particles can give sufficient tribological properties with the environment and economic advantages.

Nanofluid as an Alternative Coolant in Machining: A Review

This review paper is concerned about the important of nanofluid in machining. It is discussed in several parts such as cutting force, surface roughness, tool life and tool wear. Various type of nanofluid is discussed in this paper with an effect on the surface roughness, force, tool life, and wear. Nanofluid plays a significant role in the increment of tool life and reducing tool wear. Nanofluid creates an artificial layer on top of the workpiece, and this reduces wear at the cutting tool. It seems that nanofluid can be the next alternative coolant in machining.

The effect of vibration and cutting zone temperature on surface roughness and tool wear in eco-friendly MQL turning of AISI D2

Today, developments in technology have gained momentum more than ever, and the need for efficiency in production as well as in the ecological domain has increased significantly. Studies examining dry machining and coolant removal have been superseded by those presenting new cooling and lubrication techniques. The effects on surface roughness directly related to final product quality are being investigated in terms of tool life and employee health. This has resulted in more frequent use of the eco-friendly minimum quantity lubrication (MQL) technique, which has now become a major competitor to dry and coolant machining. In this study, AISI D2 cold work tool steel, a material widely used in the mold industry, was used as the workpiece. Tests were carried out under dry and MQL conditions and the temperature, cutting tool vibration amplitude, tool wear, surface roughness and tool life were evaluated. The experiments were carried out using two different cutting tool coating types (CVD-chemical vapor deposition and PVD-physical vapor deposition) and three different cutting speeds (60, 90 and 120 m/min) at a constant cutting depth (1 mm) and feed rate (0.09 mm/rev). Results revealed that tool wear, cutting temperature and cutting tool vibration amplitude were lower by 23, 25, and 45%, respectively, compared to dry cutting. Because of these improvements, the surface roughness of the workpiece was improved by 89% and tool life was increased by up to 267%.

Metal-oxide based nanofluid application in turning and grinding processes: A comprehensive review

Nanofluids are a colloidal mixture of metallic or non-metallic nanoparticles (<100 nm) and conventional cutting coolants. Recently, nanofluids have got special attention from researchers and machinists due to the capability of improving the heat transfer rate, wettability and lubricious of the parent cutting fluids. Since recent years, metal oxide nanoparticles seemed to be important engineering materials for cutting fluids used in environmentally favourable machining operations. As per the literature available, there was no article available which presents the comprehensive summary of metal oxide-based nanofluid application in machining. Considering this research gap, the authors have been presented a summarized work of previously published literature on turning and grinding operations considering metal oxide-based nanofluids. Al2O3 and TiO2 based nanofluids were mostly used in turning as well as in grinding operations. SiO2 is a low-cost nanoparticle but its application in grinding is very less. Application of Fe2O3 dispersed nanofluids are rarely used, while no works are available on Fe3O4 based nanofluid in machining although it's thermal conductivity is high and the cost is less. Similarly, CuO and ZnO based nanofluid application as a machining coolant is very low i.e. more research will be required on it. ZrO2 nanoparticle has the least thermal conductivity and also has a higher density which restricts its use as a nano cutting coolant in machining.

Investigating the microstructure and morphology of chips in dry, flood coolant and MQL machining of Ti-6Al-4V alloy

The objective of this research is to investigate the morphology and microstructure of the chips formed during milling of Ti-6Al-4V alloy using conventional flood coolant and sustainable dry and MQL machining conditions. It was found that the chips formed in dry machining suffered a higher degree of serration indicating higher chip temperature and ineffective cooling of the chips. The bi-modal structure of Ti-6Al-4V remained the same in the bulk part of the chips. However, phase transformations were seen for all three machining conditions at the shearing plane of the chips. The chips formed in dry machining had comparatively higher percentage of β-phase due to phase transformation. For the chips obtained in flood coolant machining, the transformed β-phase possibly returned to martensitic α-phase due to rapid cooling. The MQL machined chips had the least transformation of β-phase, indicating minimal changes in mechanical properties of the machined parts in sustainable MQL machining.