The green improvement of manufacturing high-temperature martensitic alloy steel using minimum quantity lubrication (MQL) involves an MQL device and a scientific method to assess the efficacy of the ...device application. This paper proposed a weight-variable machinability evaluation model based on multivariate heterogeneous data to compare the MQL process with the conventional machining lubrication processes. The proposed model comprises experimental-based intuitive evaluation and numerical machinability index (MI). The assessment model considers a multi-indicator and time-quality-cost-resource-environment (TQCRE) system. The MI is based on static-dynamic proximity, which is calculated according to indicator weights for subjective–objective combinations. The model was applied to a novel MQL system developed for manufacturing high-temperature martensitic alloys by performing milling experiments under four lubrication conditions. Experimental intuitive data indicated the superior feasibility of the MQL device, that is, the developed MQL method enhanced machining efficiency, ensured good machining quality, reduced tool wear by 17%, and cut forces by 7–14%. Moreover, the MQL process achieved the maximum machinability index regardless of the priority allocated to any indicator of machining quality, time, cost, resource loss, and environmental pollution. There was no degradation in machining via MQL under different environments, which validates the feasibility of the field application of the MQL method. The result is consistent with the experimental intuitive assessment, confirming the reasonableness and practical ability of the mathematical assessment model. This study may be considered as further validation of the multi-indicator machinability assessment for the green lubrication process. Future research on more cases might extend the explanations of the stability and hidden factors of the developed model.
For the first time, thrust force, power consumption, flank tool wear using FE-SEM and line scan EDS analysis; hole quality indicators and hole surface analysis using FE-SEM, microhardness and chip ...morphology for drilling Ti-6Al-4V using cryogenic coolants (LN2 and LCO2) and flood coolant are comprehensively investigated. 146 blind holes are drilled for all three cooling conditions. 72% and 50% lesser tool wear is observed for LCO2 and LN2 respectively, compared to flood machining. Adhesion wear mechanism is found to be the predominant factor leading to higher tool wear during flood machining. The demonstrated superior performance of LCO2 for all the machinability indicators in this research is a significant finding for machining Ti-6Al-4V for the high-value manufacturing industries.
•Extensive comparison is made in drilling Ti-6Al-4V with flood and cryogenic LN2 and LCO2.•Thrust force, microhardness and chip morphology are studied for the various cutting fluid strategies.•Industry relevant gauges like tool wear and hole surface indicators are studied.•LCO2 is found to be sustainable providing better machining performance than others.
Si3N4 ceramics now face new applications and challenges in the semiconductor field. The preparation of h-BN/Si3N4 machinable ceramics incorporating 5–30 vol% h-BN via hot-pressing was carried out. ...This study systematically explored how the varying h-BN content influenced the composite's microstructure, mechanical attributes, and machinability. The results showed that some of the h-BN was encapsulated by growing Si3N4 grains to form an intragranular structure during the process of hot-pressing, while the remaining h-BN exhibited uniform distribution along grain boundaries. The Si3N4 phase transition in composites was inhibited by excessive h-BN, accompanied by a higher decrease in densification. The sample containing 20 vol% h-BN exhibited the best comprehensive performance, with high mechanical strength and excellent machinability. The bending strength and fracture toughness remained high at 862 MPa and 10.3 MPa m1/2, and could be effortlessly machined with cemented carbide drills. Additionally, the machinability of the composites was systematically characterized through observations of crack propagation paths, fitting of R-curves, and mechanical drilling tests.
The adverse effects of mineral oil-based metal cutting fluid on environmental sustainability have led to increased industrial concerns. Alternatively, biodegradable lubricants such as vegetable oil ...has a more positive impact with equivalent performance, but insufficient research on their benefits demands further exploration. This work features extensive experimental investigations on machining of Inconel 718 using novel formulations of coconut bio-based oil with enhanced nanoparticles and coco-amido-propyl-betaine. Bio-based with 0.8 wt% of Al2O3 managed to minimise the rapid growth of tool wear and prolong the tool life by 40.17%. Conversely, bio-based with 0.5 wt% of Al2O3 yielded lower values of cutting force (64.32 N), spindle power (2070 kW), specific cutting energy (6.55 W/mm3), and surface roughness (0.29 μm). The outstanding performance of bio-based nanolubricants contributed to superior machinability efficiency and eco-friendly machining environments.
•Machinability efficiency and sustainable machining environments with bio-based nanolubricants.•Dry, SolCut fluid, coconut oil, Al2O3 coconut oil nanofluid cutting with CAPB and SDBS.•Density, viscosity index, kinematic viscosity, and thermal conductivity of all the lubricants were measured prior to machining tests.•Coconut oil + 0.5 wt% of Al2O3 yielded improvement in machinability performances.
Response surface methodology (RSM) is used to optimize the process parameters in casting, welding and machinability studies of composite materials. Response surface methodology is commonly used to ...design the experiments and it minimizes the numbers of experiments for specific number of factors and its levels. It has many advantages over Taguchi method of design. Experiments are conducted as per the experimental design and the responses such as output is recorded. Analysis of variance is used to identify the factors which significantly influence the response. Regression equations are developed to predict the response and the process parameters are optimised for obtaining a specific objective function.
Nickel-based Inconel 625 is employed in critical applications because of its excellent properties. But the machinability of this material is very poor. In recent years, the use of minimum quantity ...lubrication has gained prominence to improve machining performance without increasing the oil. However, pure-MQL may be insufficient for machining of difficult-to-machine materials. This paper focused on the development of nano-MQL by adding hBN nanoparticles compared to pure-MQL and dry machining in turning of Inconel 625. Tool life, surface roughness, tool wear and tool-chip interface temperature were analyzed. Wear mechanisms were evaluated by SEM photographs and EDX analysis. The results showed that; 0.5 vol% hBN nanofluid has produced promising results for low tool wear and roughness and high tool life.
•Study of tool life, tool wear patterns, surface roughness and temperature.•Nanofluid-MQL with Hexagonal Boron Nitride Nanoparticles for sustainable machining.•Examining the tool wear mechanisms with SEM and EDX analysis.•Choosing the best operating parameter with single and multi-objective optimization.
Hard and brittle materials (HBMs) are promising materials for aerospace and astronomy applications, due to their excellent mechanical, optical, and chemical properties. However, they are difficult ...and costly to machine using conventional machining methods such as single point diamond turning. Laser assisted machining uses a focused laser beam to heat local areas of the workpiece and remove softened material from the ductile region, leaving high quality and crack-free surfaces. Over the past decades, the study of laser assisted machining of HBMs has been attracting progressively more interest from researchers in academia and industry. This paper serves as a state-of-the-art review with a particular focus on typical HBMs and their machining challenges; the mechanism of laser heating and thermal analysis; pre-heat and in-process-heat laser assisted machining methods; and optimizing the machining quality of laser assisted machining. The review also presents a perspective on future development trends for laser assisted machining technology.
Deformation-induced characteristics of surface layer strongly rely on loading condition-related operating deformation modes. In the current study we reveal the mechanisms governing machined surface ...formation of hard brittle monocrystalline 3C–SiC in ultrasonic elliptical vibration-assisted diamond cutting by molecular dynamics simulations. Simulation results show different deformation modes including phase transformation, dislocation activity, and crack nucleation and propagation, as well as their correlations with surface integrity in terms of machined surface morphology and subsurface damage. In particular, molecular dynamics simulations of ordinary cutting are also carried out, which demonstrate the effectiveness of applying ultrasonic vibration of cutting tool in decreasing machining force and suppressing crack events, i.e., promoting ductile-mode cutting for achieving high surface integrity. The physical mechanism governing the machining differences between the two machining processes are also revealed. Furthermore, the effect of cutting depth on machined surface integrity under vibration-assisted cutting and ordinary cutting is addressed.
This study demonstrates that the addition of the rare earth element Erbium (Er) significantly enhances the machinability and tensile properties of titanium (Ti). Pure Ti alloys and Er-added Ti alloys ...with 0.5-1.1 wt.% Er content were prepared, and their microstructure, machinability, and tensile properties were compared. Two different types of Er secondary phase particles were identified in the microstructure: pure Er and Er-oxide. The amounts of these particles increased with higher Er content. The machinability of the Eradded Ti alloys was significantly improved due to the ability of Er secondary particles to cut machining chips or absorb heat from localized deformation within the Ti matrix. In addition, Er-added Ti alloys exhibited higher strength than pure Ti. The strength enhancement was attributed to grain refinement induced by the Er element. Er secondary phase particles reduced the β grain size during solidification, and they also served as preferential sites for α nucleation during the β → α phase transformation, resulting in a refined microstructure. In addition, the Er secondary phase contributed to the strength enhancement through the well-known precipitation strengthening mechanism. Although ductility decreased with higher Er content due to the increased amount of Er secondary phase particles, 0.5 wt.% Er-added Ti showed no such degradation; its ductility was comparable to that of pure Ti. Er-oxidation was expected to reduce oxygen content within the Ti matrix, enhancing intrinsic Ti ductility; this effect offset the adverse impact on ductility caused by the Er secondary phase particles. Above 0.5 wt.% Er, the adverse effects caused by the Er secondary phase particles overwhelmed the beneficial effect caused by the reduction in oxygen content. The present findings will contribute significantly to the development of highly machinable Ti alloys with superior tensile properties.
