Performance assessment during machining Inconel 718 with different morphology additives-assisted minimum quantity lubrication

The application of minimum quantity of lubricant (MQL) in grinding process is a challenging task. Once the MQL is considered an environmentally friendly technique, its implementation in grinding process is interesting to achieve cleaner production. On the other hand, its use brings some problems to the process, such as intensification of grinding wheel clogging phenomenon and increase of cutting temperatures, which impairs on the attainment of a good surface quality, together with dimensional and geometrical accuracy. Looking for improving the MQL efficiency in grinding process, two eco-friendly techniques were found: the addition of water in the MQL and the wheel cleaning system with compressed air. The present research seeks to evaluate the improvement of MQL application in grinding using the combination of these techniques. Both techniques MQL + water and wheel cleaning system are innovative, since there are almost no articles in literature citing its use. The experiments were performed in an external cylindrical plunge grinding using a vitrified cubic boron nitrite (CBN) grinding wheel. The workpiece material was a quenched and tempered AISI 4340 steel. The cooling methods employed in the process were a conventional method (flood coolant), MQL + water (1:1, 1:3, 1:5 part of oil per parts of water), MQL + water + cleaning system (1:1, 1:3, 1:5 part of oil per parts of water), and MQL with and without cleaning system. Results were analyzed based on some workpiece parameters (roughness, roundness deviation, and microstructure) and on diametrical wheel wear and grinding power. The addition of water allied to cleaning system with compressed air provided the best results among those using the MQL technique, with results comparable to the conventional cooling method.

Investigation of Influence of MQL Machining Parameters on Cutting Forces During MQL Turning of Carbon Steel St52-3

Cutting fluids used in the metal machining industry have exerted serious impacts on the environment and human health. In addition, the very high cutting heat and forces in machining-hardened steels have been a growing concern in the metal cutting field. Hence, new, eco-friendly cooling and lubricating techniques are necessary to study and develop. Minimum quantity lubrication (MQL) and minimum quantity cooling lubrication (MQCL) using nano cutting fluids have been proven as alternative solutions for machining difficult-to cut materials while retaining an environmentally friendly characteristic. Accordingly, this paper aims to analyze and evaluate the hard turning efficiency of 90CrSi (60 ÷ 62 HRC) steel using MQL and MQCL conditions, using Al2O3 and MoS2 nano cutting fluids. The 2k-p experimental design and analysis of variance (ANOVA) were used to study the influence of input parameters including fluid type, lubrication method, nanoparticle type, nanoparticle concentration, cutting speed and feed rate on surface roughness. The obtained results showed that the machinability of CNMG120404 TM T9125 carbide tools was improved and the highest machinable hardness was increased from 35 HRC to 60 ÷ 62 HRC (rising by approximately 71.4 ÷ 77.1%) by using the nanofluid MQL and MQCL methods. Furthermore, MQCL gives better performance than MQL, and the Al2O3 nanofluid exhibits the better result in terms of surface roughness values than the MoS2 nanofluid. Feed rate displays the strongest influence on surface roughness, while fluid type, nanoparticle concentration and cutting speed show low impacts. From these results, technical guidance will be provided for further studies using Al2O3 and MoS2 nano cutting fluids for MQL and MQCL methods, as well as their application in machining practice.

Minimum quantity of lubricant (MQL) in grinding is an alternative for reducing abundant fluid flow and both environmental and health hazards when compared with conventional fluid application. In spite of the fact that MQL is considered an innovative cost-effective and environmentally friendly technique, when used in grinding its inadequate application can increase cutting temperature and wheel clogging, worsening surface roughness, and increasing geometric and dimensional errors. The present study aims to evaluate improvements in MQL in grinding using MQL + water (1:1, 1:3, and 1:5 parts of oil per parts of water), when compared to MQL without water and conventional cooling-lubrication technique. Wheel cleaning by compressed air was also tested, aimed for unclogging of the wheel pores. The tests were performed in a plunge cylindrical grinder with CBN wheel and workpieces of AISI 4340 for different feed rates. The ground workpieces were analyzed with respect to the surface roughness, roundness errors, microhardness, and microscopic changes. In addition, tangential cutting force and diametric wheel wear were investigated. The results observed for the MQL plus water in the proportion of 1:5, with wheel cleaning system (at 30° inclination angle of the air nozzle) were the best, when compared to MQL without water, and close to the conventional flood coolant, implying that this technique is a potential alternative for cooling-lubrication when applied properly.

Nowadays, environmental concern and the search for environmentally friendly techniques have contributed to industrial development towards sustainability. Production without social and environmental impact is one of the main goals of engineering research. Although analysis is carried out, some manufacturing processes still require studies, such as grinding, for example. In this process, the interaction between the grinding wheel and workpiece generates a significant amount of heat, due to shearing, friction, and scratching caused by the contact of the numerous abrasive grains with the workpiece surface. The heat generated at the interface has a more intense flow to the workpiece, which can cause several microstructural damages, as well as providing shape errors and increased grinding wheel wear. Thus, the application of cutting fluid is indispensable to minimize the harmful effects caused by heat to the grinding wheel and the workpiece during the process. However, the industry commonly uses soluble cutting fluid, having oil in its composition, in addition to chemical components that prevent its degradation, due to recirculation in the system and the need to avoid the accumulation of bacteria, whereas its application has a flow rate of tens of liters per minute. These cutting fluids will be discarded at some point, which will require complex waste treatment processes for proper disposal. An alternative to this type of application is the minimum quantity lubrication (MQL), which consists of a few milliliters per hour, but which has low refrigerant power. Some techniques have been developed to enhance its application and make it more refrigerant, such as the application of a jet of compressed air directed to the grinding wheel cutting surface to perform the cleaning, minimizing the heat generation by the reduced agglomeration of chips in the grinding wheel pores. Therefore, this work analyzed the cylindrical plunge grinding of hardened steel workpiece with cubic boron nitride grinding wheel on different cooling conditions, comparing the conventional cutting fluid application method (flood) with the MQL technique, MQL simultaneously with the wheel cleaning jet (MQL + WCJ) and MQL with cutting fluid applied at 0 °C (MQL + CA). The performance of each method was analyzed by using the measurements of surface roughness (Ra), roundness error, diametral wheel wear, power consumed during the process, specific energy grinding, microhardness, and microstructural analysis to investigate possible modifications of the microstructure of the workpiece. It was found that in none of the cases, there were microstructural alterations, but the MQL application method presented the worst values of the variables among the techniques studied, whereas the application on low temperature showed potential to be used in a large scale. Nevertheless, the MQL application method applied simultaneously with the wheel cleaning jet (WCJ) has presented the closest values of the conventional method; it becomes the most feasible method for application in the industry towards the protection of the environment and health of the workers.

The Minimum Quantity of Lubrication (MQL) in machining is an alternative to dry or flood lubricating system. In the current study, an Artificial Neural Network (ANN) has been employed to analyse the effects of cutting speed, feed rate and MQL on specific cutting force and surface roughness in turning of brass. The research suggests a combination of MQL in medium to high range, higher feed rate with cutting speed in medium range is necessary to minimise specific cutting force. On the other hand, lower values of feed rate and cutting speed with high MQL is essential for minimising surface roughness.

In recent years, hard turning has been found to be a well-known substitute for traditional grinding for acquiring the finish quality of hardened steel without sacrificing productivity. There are many issues that should be carefully understood and dealt with to attain efficacious performance in hard turning. This article discusses modern manufacturing challenges with a focus on analyzing the current state of the art of the hard turning process in terms of ensuring more environmentally friendly manufacturing through the use of greener cooling methods such as dry, wet/flood cooling, the minimum quantity of lubricant (MQL), high-pressure jet cooling, solid lubricant, nanofluids, ionic liquids (ILs), cryogenic cooling, and hybrid cooling. Nanofluids combined with the MQL system were found to be the superior cooling technique in comparison to dry, wet/flood, and MQL. Cryo-machining also provided superior performance by limiting the cutting temperature during hard turning. The performance of hybrid cooling (MQL + cryogenic) seems to have been superior to MQL and cryogenic coolant alone because it combined the benefits of lubrication and cooling from MQL and cryogenic systems, respectively. The addition of ILs to base fluids or nanofluids improves the thermal properties of the mixed fluid, resulting in better surface quality, lower tool wear, and longer tool life. Furthermore, the purpose of this study is to summarize the various LCA software used for analyzing the sustainability of the hard turning process. Overall, this paper can serve as a resource for researchers and manufacturers working in the field of sustainable machining.

This paper evaluates the performances of dry, minimum quantity lubrication (MQL), and MQL with nanofluid conditions in turning of the most common titanium (Ti) alloy, Ti-6Al-4 V, in a solution treated and aged (STA) microstructure. In particular, the nanofluid evaluated here is vegetable (rapeseed) oil mixed with small concentrations of exfoliated graphite nanoplatelets (xGnPs). This paper focuses on turning process that imposes a challenging condition to apply the oil or nanofluid droplets directly onto the tribological surfaces of a cutting tool due to the uninterrupted engagement between tool and work material during cutting. A series of turning experiments was conducted with uncoated carbide inserts, while measuring the cutting forces with a dynamometer under the dry, MQL and MQL with nanofluid conditions supplying oil droplets externally from our MQL device. The inserts are retrieved intermittently to measure the progress of flank and crater wear using a confocal microscopy. This preliminary experimental result shows that MQL and in particular MQL with the nanofluid significantly improve the machinability of Ti alloys even in turning process. However, to attain the best performance, the MQL conditions such as nozzle orientation and the concentration of xGnP must be optimized.

This study investigates the influence of the Minimum Quantity Lubrication (MQL) technique and spindle speed on the surface roughness of AISI 1020 steel during turning operations. recycled cooking oil was utilized as an environmentally friendly MQL lubricant, offering potential as a substitute for conventional mineral oils. In this experiment, two independent variables were considered: the lubrication condition (MQL and dry cutting) and spindle speed, which was tested at three levels (630 rpm, 800 rpm, and 1000 rpm). The dependent variable was surface roughness. MQL was selected due to its ability to enhance cooling and lubrication efficiency while minimizing environmental impacts. Experimental results indicated that at a spindle speed of 1000 rpm, surface roughness achieved 2,221 µm with MQL, compared to 2,824 µm without MQL. These findings highlight that recycled cooking oil-based MQL significantly improves the surface finish and demonstrate that the proper combination of lubrication parameters and spindle speed enhances machining quality. Moreover, this research supports sustainable manufacturing by promoting the use of Recycled Cooking Oil as a green lubricant alternative.

Under the concept of safety, improving efficiency, or reducing costs in deep hole drilling, the effect of minimal quantity lubrication (MQL) on the dynamic characteristics of drilling shaft is analyzed. A model is presented to describe the pressure function of MQL cutting fluid during drilling process. This model is based on the compressible Reynolds equation in air/oil feature with nonlinearity, and the differential transformation theory is introduced to solve the time-dependent pressure equation satisfied with MQL cutting fluid. Further, with an emphasis on model development, experiments are performed to validate the correctness and effectiveness of the above methods. A series of experimental investigations are carried out on the whirling characteristics of drilling shaft when the rotational speed and drilling depth are changed. Additionally, the vibration trajectories of drilling shaft and the surface roughness of hole are detected under different experimental conditions such as MQL drilling or traditional drilling. The results show that the whirling trajectory of drilling shaft decreases significantly in MQL deep hole drilling but the surface roughness of machined hole is worse due to surface scratches or scales. Nevertheless, there exists an optimal rotational speed of drilling shaft to improve machining precision of hole surface. These results indicate that the MQL method has shown potential to be even more productive as compared to traditional drilling and that the proposed method in this paper can lay a foundation for investigating the dynamic stability of drilling shaft in MQL drilling.

Sustainability analysis of lubricant oils for minimum quantity lubrication based on their tribo-rheological performance

Performance of CuO nanoparticles as an additive to the chemically modified Nicotiana Tabacum as a sustainable coolant-lubricant during turning EN19 steel

Selection of optimal MQL and cutting conditions for enhancing machinability in turning of brass

Inconel 718 is the most widely used nickel-based superalloy in aerospace, automobile and nuclear energy industries for its superior chemical, mechanical and thermal properties. However, the aforesaid properties by themselves offer poor machining characteristics. To overcome machining difficulties, hybrid machining processes have been introduced. A hybrid of an ultrasonic vibration-assisted turning and lubri-cooling technique is considered as one of the similar strategies. In the present study, a hybrid setup combining indigenously developed ultrasonic vibration-assisted turning (UVAT) and minimum quantity lubrication (MQL) has been used. UVAT changes the conventional cutting (CT) process into vibro-impact process whereas MQL makes the cutting process able to minimize the heat from the machining and ultrasonic system as well. MQL is eco-friendly as it answers some of the problems associated with the cutting fluids. Lower cutting force (Fy) and feed force (Fz), and average surface roughness have been obtained with MQL + UVAT compared to CT + MQL.

Fluid delivery in grinding process remains an important matter requiring further research. The growing demand and the rising cost of cutting fluid usage and the environmental aspect of fluid disposal are a key driver for research into alternative fluid delivery techniques. One of the alternative fluid reduction methods employed in machining is minimum quantity lubrication (MQL). In specific grinding operations, MQL is capable of maintaining or even reducing temperature, yet using extremely small amounts of lubricant. Therefore, MQL addresses not only more economical production costs but also a critical matter of the natural and worker environment protection. This article reviews application of the MQL technique in abrasive machining in comparison to conventional and dry grinding. Common steels EN8, M2, and EN31 were ground with a general purpose alumina wheel. Results obtained determined that MQL performance can be compared to flood delivery under the conditions investigated. In some specific conditions, MQL achieved better results. Performance indicators included: grinding power, specific forces (tangential and normal), grinding temperature, and workpiece surface roughness.