Thermo-mechanical effects in drilling using metal working fluids and cryogenic cooling and their impact in tool performance

Cryogenic machining opens up new industrial perspectives in difficult-to-cut materials like nickel-based alloys. In particular, drilling is an operation that generates high thermal and mechanical loading to the drill. There- fore, tool performance, hole geometry and surface integrity can be highly affected. The objective of this study is to analyse tool performance during drilling of IN718 using conventional metal working fluids (MWF) and cryogenic cooling conditions, and correlate it with the thermo-me- chanical phenomena. This study is conducted with standard coated cemented carbide twist drills, designed to work with MWF. The results show that drill performance under cryogenic cooling is strongly affected by its geometry. The axial force, drilling torque and tool wear/failure are higher under cryogenic cooling when compared to conventional MWF. Therefore, in order to take advantage of the cryo- genic machining, new drill design is required, which cur- rently is not available on the market.Mecachrom

Future research directions in the machining of Inconel 718

Inconel 718 is the most popular nickel-based superalloy, extensively used in aerospace, automotive and energy industries owing to its extraordinary thermomechanical properties. It is also notoriously a difficult-to-cut material, due to its short tool life and low productivity in machining operations. Despite significant progress in cutting tool technologies, the machining of Inconel 718 is still considered a grand challenge.This paper provides a comprehensive review of recent advances in machining Inconel 718. The progress in cutting tools’ materials, coatings, geometries and surface texturing for machining Inconel 718 is reviewed. The investigation is focused on the most adopted tool materials for machining of Inconel 718, namely Cubic Boron Nitrides (CBNs), ceramics and coated carbides. The thermal conductivity of cutting tool materials has been identified as a major parameter of interest. Process control, based on sensor data for monitoring the machining of Inconel 718 alloy and detecting surface anomalies and tool wear are reviewed and discussed. This has been identified as the major step towards realising real-time control for machining safety critical Inconel 718 components. Recent advances in various processes, e.g. turning, milling and drilling for machining Inconel 718 are investigated and discussed. Recent studies related to machining additively manufactured Inconel 718 are also discussed and compared with the wrought alloy. Finally, the state of current research is established, and future research directions proposed.<br/

The effects of liquid-CO2 cooling, MQL and cutting parameters on drilling performance

An investigation is made into the effects of liquid carbon dioxide (LCO2) cooling, minimum-quantity lubrication (MQL) and cutting speed in drilling. Experimental measurements of torque, thrust force and temperature are made over a wide range of process and operating conditions. The resulting empirical models are used to quantify the individual contributions of the controlled parameters on drilling performance, and to facilitate temperature-based process optimization. Of particular interest is the need to carefully adjust the LCO2 flow rate for any combination of MQL flow rate and cutting speed. The optimization is validated both in simulation and actual drilling tests

A Review of Minimum Quantity Lubrication Technique with Nanofluids Application in Metal Cutting Operations

Minimum quantity lubrication (MQL) technique did not only serve as a better alternative to flood cooling during machining but enhance better surface finish, minimizes the cost, reduces the impact loads on the environment and health hazards on the operation personnel. However, the coolant or lubrication media used in MQL technique posed certain restrictions especially at very high cutting speeds where the lubricating oil tends to evaporates as it strikes the already heated cutting tool at elevated temperature. Desire to compensate for the shortcomings of the lubricating media in the MQL technique led to the introduction of nanoparticles in the cutting fluids for use in the MQL lubrication process. Nanoparticles have much higher and stronger temperature-dependent thermal conductivity and enhanced heat transfer coefficient at very low particle concentration, which are key parameters for their enhanced performance in many of the machining applications. Optimizing the nanoparticles concentration leads to efficiency in most of their application. Their ball bearing effect lubrication at the cutting zone through formation of film layer which reduces friction between the contact surfaces thereby reducing cutting force, temperature and tool wear. It has been reported in various studies that nanoparticles introduction in cutting fluids led to excellent machining performance in reduction of cutting forces, reduced tool wear, reduced cutting temperature and improved surface finish of the work piece thereby increasing productivity and reduction of hazards to the health of personnel and the environment better than the pure or conventional MQL process. Thus, the application of various nanoparticles and its performances in metal cutting operations with respect to the cutting forces, surface finish, tool wear and temperature at the cutting zone are evaluated and highlighted

Development and performance evaluation of bioluricant enhanced with nanoparticles for sustainable machining application

Vegetable oil-based biolubricants usage for lubrication and cooling in the industry has been encouraged due to their pleasant attributes of being environmentally benign, lower volatility, biodegradable, good lubricity, and high-quality viscosity index, amongst others. However, failure of biolubricants at elevated temperatures which is attributed to the thermal degradation hinders their efficient performance. The performance limitations may be ameliorated using nano-additives to enhance the oxidation and thermal stability as well as improve the thermophysical and anti-wear properties of biolubricants. However, thermal stability evaluation of vegetable oil-based nano-enhanced biolubricants has not been reported in any literature. The research aimed to formulate and evaluate performance characteristics of nano-enhanced biolubricants dispersed with exfoliated graphene nanoplatelets and maghemite nanoparticles at varying volume concentrations of 0.1%, 0.2% and 0.3% in coconut oil as base biolubricants; denoted by XGO1, XGO2 and XGO3 for graphene enhanced and MGO1, MGO2 and MGO3 for maghemite enhanced nanolubricants. The developed nanolubricants and the base biolubricants were evaluated for thermal stability, thermophysical and tribological properties tests. The volume fraction 0.2% of the XGO and the MGO concentrations indicated best performance in terms of tribological properties. End milling machining experiment was performed using the best concentrations from the XGO and MGO nanolubricants (0.2% volume fractions) based on the outcome of tribological properties evaluation and compared with the base lubricant. From the results, thermogravimetric analysis (TGA) reveals that the addition of nanoparticles improves the oxidation onset temperature for all concentrations, which implies improved thermal stability. The oxidation onset temperature in the presence of nano-additives can be delayed by 36.3 °C and 14.5 °C for XGO1 and MGO1, respectively, at 0.1% volume concentration. An improvement of thermal conductivity for all concentration levels was observed with a maximum enhancement ratio of 15.5% and 7.9% at 0.3% volume concentration, respectively, for the graphene and maghemite enhanced nanolubricants. The tribological studies revealed a significant reduction in coefficient of friction and wear scar diameter. For graphene enhanced nanolubricants, maximum friction and wear reduction were 17.6% and 7.55%, while for maghemite enhanced nanolubricants were 7.39% and 6.25%, respectively. Machinability performance was performed on machining titanium alloy (Ti-6Al-4V) under the minimum quantity lubrication (MQL) technique to supply lubricants. The results reveal that the enhanced biolubricants indicated superior performance over pure biolubricants in cutting force, tool life, and surface roughness. The graphene nanoplatelets enhanced lubricant was better over the maghemite enhanced lubricant. The research has shown a comprehensive understanding of oxidation stability and thermal degradation process of enhanced nano-biolubricants which are rarely investigated. Thermophysical and tribological properties evaluated indicated significant improvement. Furthermore, the developed non-linear correlation will avail researchers and industry operators the opportunity of selecting potential nanoparticles for nano-enhanced biolubricants formulation. This will reduce downtime and save resources as blends of nanoparticle and vegetable oils can be formulated without performance testing, thus promoting the United Nations Sustainable Development Goals (SDGs) to ensure sustainable consumption and production pattern

Performance Evaluation of Minimum Quantity Lubrication (MQL) When Machining High-Performance Materials

The manufacturing sector is among the fastest-growing in today\u27s industrialized world. Manufacturers are concerned about increasing their competitiveness and profitability. Increasing the efficiency and sustainability of manufacturing processes is one way to improve productivity and improve profit margins. Learning about cutting conditions and how they affect machined surfaces and tool life can help improve productivity. Nowadays, the goal is not just to increase productivity but also to make processes more environmentally friendly and cleaner. This research aims to analyze the machinability of difficult-to-cut magnesium alloys through different cooling and lubrication strategies and their impact on the environment. This study conducted controlled machining tests with dry and vegetable oil mist cutting settings to measure surface roughness, tool contact length, chip morphology, and flank wear. The present study provides insight into the cutting performance of coated carbide tools. To improve the machinability of magnesium alloys, the study also investigated tool wear mechanisms, surface roughness, and primary and secondary components of machining, such as effective shear angle, compression ratio, and coefficient of friction. In this study, we found that minimum quantity lubrication (MQL) performed well under various speed ranges for coated tools. Cutting speed and feed rate correlated closely with tool wear, surface roughness, and other output response parameters. MQL-based systems offer great potential to improve the machinability of magnesium alloys, and they should be explored further

ENHANCED SURFACE INTEGRITY WITH THERMALLY STABLE RESIDUAL STRESS FIELDS AND NANOSTRUCTURES IN CRYOGENIC PROCESSING OF TITANIUM ALLOY TI-6AL-4V

Burnishing is a chipless finishing process used to improve surface integrity by severe plastic deformation (SPD) of surface asperities. As surface integrity in large measure defines the functional performance and fatigue life of aerospace alloys, burnishing is thus a means of increasing the fatigue life of critical components, such as turbine and compressor blades in gas turbine engines. Therefore, the primary objective of this dissertation is to characterize the burnishing-induced surface integrity of Ti-6Al-4V alloy in terms of the implemented processing parameters. As the impact of cooling mechanisms on surface integrity from SPD processing is largely unexplored, a particular emphasis was placed upon evaluating the influence of cryogenic cooling with liquid nitrogen in comparison to more conventional methodologies. Analysis of numerical and experimental results reveals that burnishing facilitates grain refinement via continuous dynamic recrystallization. Application of LN2 during SPD processing of Ti-6Al-4V alloy suppresses the growth of new grains, leading to the formation of near-surface nanostructures which exhibit increased microhardness and compressive residual stress fields. This is particularly true in cryogenic multipass burnishing, where successive tool passes utilizing lower working pressures generate thermally stable work hardened surface layers, uniform nano-level surface finishes, and significantly deeper layers of compressive residual stresses

Progressing towards sustainable machining of steels : a detailed review

Machining operations are very common for the production of auto parts, i.e., connecting rods, crankshafts, etc. In machining, the use of cutting oil is very necessary, but it leads to higher machining costs and environmental problems. About 17% of the cost of any product is associated with cutting fluid, and about 80% of skin diseases are due to mist and fumes generated by cutting oils. Environmental legislation and operators’ safety demand the minimal use of cutting fluid and proper disposal of used cutting oil. The disposal cost is huge, about two times higher than the machining cost. To improve occupational health and safety and the reduction of product costs, companies are moving towards sustainable manufacturing. Therefore, this review article emphasizes the sustainable machining aspects of steel by employing techniques that require the minimal use of cutting oils, i.e., minimum quantity lubrication, and other efficient techniques like cryogenic cooling, dry cutting, solid lubricants, air/vapor/gas cooling, and cryogenic treatment. Cryogenic treatment on tools and the use of vegetable oils or biodegradable oils instead of mineral oils are used as primary techniques to enhance the overall part quality, which leads to longer tool life with no negative impacts on the environment. To further help the manufacturing community in progressing towards industry 4.0 and obtaining net-zero emissions, in this paper, we present a comprehensive review of the recent, state of the art sustainable techniques used for machining steel materials/components by which the industry can massively improve their product quality and production

Development of tri-hybrid nanofluids as cutting fluids to enhance performance of end milling process of aluminium alloy 6061-T6

Machining of aluminium alloys is extensively complex due to the adherence tendency of aluminium to the tool surface. During machining, the tool wear is mainly affected by forming an adhesive layer and built-up-edge, significantly affecting the machined surface's quality. Several studies are carried out to restrict the heat generated in machining. Among the various alternatives available, the cutting fluids remain to be the choice. Therefore, different techniques are explored to replace the use of cutting fluids. Nowadays, using nanotechnology in science and industry improves the yield of different processes. Hence, machining operations are used as nanofluid and coated cutting tools with nanoparticles. However, their usage in machining is a comparatively primary stage and deserves much attention. The hybrid nanofluids are potential fluids to offer better heat transfer performance and thermophysical properties than single nanofluids. The machining process using hybrid nanofluids requires further research to better understand the mechanism of tool wear and the fundamental aspects are not yet ventured. This study aims to develop tri-hybrid nanofluids as cutting fluids to enhance the performance of the end milling process of AA6061-T6. The tri-hybrid SiO2-Al2O3-ZrO2 nanoparticles were dispersed in 60:40 vol.% of deionized water to ethylene glycol, and concentrations 0.08 and 0.12 wt.% were selected to mix with dispersing agent CTAB at a 1:3 weight ratio. After two weeks of daily visual and UV-Vis spectral examination, the tri-hybrid nanofluids were stable. The zeta potential is higher than 30 mV, suggesting well-dispersed nanoparticles. The uncoated tungsten carbide, single-layered CVD TiCN-Al2O3 and dual-layered PVD TiAlTaN tungsten carbide inserts were used. The study was conducted using cutting speed, feed rate, depth of cut, MQL flow rate and concentration and machining responses of surface roughness, cutting temperature, cutting force, flank wear. Response surface methodology with central composite rotatable design approach is used, and experimental data were validated statistically. SEM micrographs and EDX patterns characterized tool damage. At 0.1 wt.% and 70°C, tri-hybrid nanofluids were 41.1, 10.5 and 20.3 % better thermal conductivity than base fluid, SiO2-Al2O3 and SiO2-ZrO2, respectively. The tri-hybrid nanofluids exhibited 50.5% viscosity enhancement at higher concentrations and lower temperatures. At a higher feed rate, uncoated demonstrated lower surface roughness of AA6061-T6, reflecting the effectiveness of tri-hybrid nanofluids. The cutting temperature below 38 °C improved 84% over the conventional technique. The cutting force was below 30 N, indicating a 35% improvement in process performance. Coated tool exhibited higher cutting force due to coated hardness and various tool failures mechanism. Adhesion, attrition and edge fracture were among of tool failures observed. The absence of BUE is attributed to reduced chip adhesion with higher MQL flow rates and concentrations. Due to coating delamination, coated inserts had worse flank wear than uncoated inserts. However, uncoated tool dominated attrition wear. The optimal end milling parameters were established. The optimum uncoated tungsten carbide cutting conditions were 8440 rpm, 50.1 mm/min feed rate, 0.336 mm cut depth, 1.8 mL/min MQL flow rate, and 0.112 wt% concentration using multi-criteria decision making on parallel coordinates. The application of tri-hybrid nanofluids is the first attempt to enhance single and dual-hybrid thermal-physical properties as well as end milling process performance under high-speed machining. It is strongly recommended to use a newly created tri-hybrid nanofluid with MQL technique in various applications of machining industries