Minimum Quantity Lubrication Technology Research Articles

Effects of Machining Parameters on Total Cutting Force in Hard Turning Process of Hardened 90CrSi Steel Using Carbide Insert with MoS2 Nanofluid MQL

Minimum Quantity Lubrication (MQL) is widely used in machining, especially hard machining. However, this method has many limitations regarding cooling and lubrication capabilities. In recent years, nano-cutting oils have been researched and applied in machining to improve the lubrication and cooling efficiency of the MQL method. In this research, the machinability of 90CrSi steel with carbide inserts using nanofluid with different concentrations (1%, 1.5%, and 3%) of molybdenum disulfide (MoS2) nanoparticles in emulsion oil was evaluated by applying Box-Behnken optimization model. Carbide inserts commonly used to machine the low hardness steel (below 35HRC) have been used to cut hardened steel with high hardness (59-62HRC) by applying the MQL technology with MoS2 nanofluid. A mathematical model was also used to predict the cutting resultant force value in the hard turning process under MQL conditions using MoS2 nanofluid. The obtained results indicate that the total cutting force reached the minimum value (328 N) with the MoS2 nanoparticle concentration of 1.985%, a cutting speed of 80 m/min, and a feed rate of 0.138 mm/rev. In particular, the work has also provided technical guides for different machining conditions.

Different Aspects of Machinability in Turning of AISI 304 Stainless Steel: A Sustainable Approach with MQL Technology

Machining of AISI 304 austenitic stainless steel is considered to be difficult due to its structural aspects and low thermal conductivity, which leads to increased temperatures during machining. To overcome the challenges of machining AISI 304 stainless steel, several cooling and lubricating techniques have been developed. The main objective of this experimental study is to evaluate the different turning conditions of AISI304 stainless steel under dry and minimum quantity lubrication (MQL) environment conditions. The machining experiments were conducted using a two-level full factorial design method and utilized a TiC-coated cutting tool. The tool-tip temperature, cutting force and surface roughness were analyzed regarding three cutting parameters namely, cutting speed, feed rate and cutting depth. Also, chip macro-morphology was investigated to define the interaction at the tool-chip-workpiece region. The cutting medium affects the surface roughness significantly (more than 100%) for all cutting parameter values. In some environmental cutting conditions, high cutting speed provides 10% lesser surface roughness than low cutting speed parameters. Also, the cutting force decreases by 20% in low feed rate machining conditions. However, the effect of this parameter disappeared for cutting forces in high feed rates and low cutting depth conditions in both MQL and dry environments. Cutting speed was observed as the most influential factor on surface roughness, followed by feed rate. The depth of cut was the main parameter that caused the temperature to increase in the dry machining environment.

Machinability Investigations Based on Tool Wear, Surface Roughness, Cutting Temperature, Chip Morphology and Material Removal Rate during Dry and MQL-Assisted Milling of Nimax Mold Steel

Using cutting fluids is considered in industrial applications and academia due to their increased influence over many aspects such as machinability, sustainability and manufacturing costs. This paper addresses the machinability perspective by examining indicators such as roughness, cutting temperature, tool wear and chip morphology during the milling of mold steel. A special type of steel is Nimaxm which is a difficult-to-cut material because of its high strength, toughness, hardness and wear resistance. Since mold steels have the reverse geometry of the components produced by this technology, their surface quality and dimensional accuracy are highly important. Therefore, two different strategies, i.e., dry and minimum quantity lubrication (MQL), were chosen to conduct an in-depth analysis of the milling performance during cutting at different cutting speeds, feed rates and cutting depths. Without exception, MQL technology showed a better performance than the dry condition in obtaining better surface roughnesses under different cutting parameters. Despite that only a small improvement was achieved in terms of cutting temperature, MQL was found to be successful in protecting the cutting tool from excessive amounts of wear and chips. This paper is anticipated to be a guide for manufacturers and researchers in the area of mold steels by presenting an analysis of the capabilities of sustainable machining methods.

Evaluation of the Role of Dry and MQL Regimes on Machining and Sustainability Index of Strenx 900 Steel

Sustainable technologies draw attention in the machining industry thanks to their contributions in many aspects such as ecological, economic, and technological. Minimum quantity lubrication (MQL) is one of these techniques that enable to convey of the high pressurized cutting fluid toward the cutting zone as small oil particulates. This study examines the potency of MQL technology versus dry conditions on the machining quality during the milling of structural Strenx 900 steel within the sustainability index. High strength and toughness properties make this steel a hard-to-cut material providing an important opportunity to test the performances of dry and MQL environments. The outcomes of the experimental data demonstrated that MQL is superior in enhancing the quality of significant machining characteristics namely surface roughness (up to 35%), flank wear (up to 94%), wear mechanisms, cutting energy (up to 28%), and cutting temperatures (up to 14%). Furthermore, after analyzing the main headings of the sustainable indicators, MQL provided the same (+5) desirability value with a dry (+5) medium. This experimental work presents a comparative approach for improved machinability of industrially important materials by questioning the impact of sustainable methods.

Feasibility study of minimum quantity lubrication assisted belt grinding of titanium alloys

ABSTRACT In order to investigate the feasibility of minimum quantity lubrication technique in precision machining titanium alloys using abrasive belt grinding method, theoretical calculations and a series of detailed experimental studies were conducted in this paper. Material removal rate, grinding force, grinding temperature, abrasive belt wear, and machined surface quality were determined as the corresponding evaluation indicators. The signals of force and temperature in the grinding process were continuously collected by dynamometer and infrared thermal imager, respectively. The surface topography of the abrasive belt and workpiece were detected by a scanning electron microscope, and the machined surface roughness was measured by a surface profiler. The experimental results showed that the minimum quantity lubrication technology had obvious advantages in reducing abrasive wear and improving machined surface quality with suitable lubricating and grinding parameters. The observation result indicated that the compact microstructure and preferable fatigue strength can be obtained by using this assisted technique. Moreover, the addition of carbon nanotubes in grinding fluids was proven to be an effective way to further improve the effect of minimum quantity lubrication on assisted abrasive belt grinding of titanium alloys.

Investigation on machining characteristics of TC4 alloy by simultaneous application of ultrasonic vibration assisted milling (UVAM) and economical-environmental MQL technology

Abstract The optimization of machining methods is one of important guiding principles for achieving high-quality, cost saving and environmental protection machining of difficult-to-machine materials in modern manufacturing. Considering the principles and advantages of ultrasonic machining (UM) method and minimum quantity lubrication (MQL) technique, the simultaneous application of UM and MQL methods is anticipated to further improve machining performance in terms of cutting force, surface quality and chip morphology. Theoretical analysis indicates that the MQL system in UVAM could provide enhanced lubrication and cooling performance because of the separate-type cutting mechanism, the surface acoustic and the cavitation phenomenon of resonant workpiece in UM. Conventional milling (CM) trials, general UVAM trials and combined UVAM&MQL trials were conducted to investigate the effect of UVAM and MQL methods on machining performance of TC4 alloy, where the results of CM and general UVAM could provide indispensable reference. Multifaceted comparisons are presented in machining results of CM, UVAM and UVAM&MQL trials in terms of time-domain analysis and frequency-domain analysis of milling force, average cutting force, surface topography, surface profile and surface roughness. The results show that cutting force features could be significantly affected under UVAM and UVAM&MQL condition compared with that in general milling due to intermittent cutting mechanism and the coupling effect of UVAM and MQL methods. The uniform micro-textured surfaces with improved profile fluctuations could be obtained when applying the UVAM&MQL strategy. Compared with surface roughness in CM and UVAM, the surface roughness in UVAM&MQL is improved by about 30–50% and about 20–30%, respectively. The excellent machining performance demonstrates the feasibility and effectiveness of simultaneously applying UVAM and MQL methods.

Selection of an ideal MQL-assisted milling condition: an NSGA-II-coupled TOPSIS approach for improving machinability of Inconel 690

Through minimum quantity lubrication (MQL) technology, small droplets of cutting fluid accompanied by compressed air are sprayed into the tool-workpiece interface. Hence, it offers effective lubrication/cooling and advances machining performance without using the significant amount of cutting fluids. Conversely, due to the biodegradable and non-pollutant properties of vegetable oils, these are widely employed as a base fluid in MQL technology. Considering the benefits of MQL-vegetable oil synergy, this paper aims to determine the best possible sequence of MQL milling parameters of Inconel 690 using castor oil as a lubricant. Here, response surface methodology (RSM) has been exploited to make a correlation between input and machining responses. To deal with the optimization problem, a two-stage computational approach was adopted. The first theory was non-dominated sorting genetic algorithm-II (NSGA-II) and the second method was technique for order preference by similarity to ideal solution (TOPSIS). NSGA-II has been exploited to explore for the candidate solution, and TOPSIS has been deployed to find out the best compromise solution. Finally, this manuscript compares the outcomes of the adopted approach with experimental outcomes to determine the efficacy of the proposed model. It was revealed from the comparison that the average error obtained between the predicted and the experimental response is less than 1%.

Tribological and machining characteristics of a minimum quantity lubrication (MQL) technology using GO/SiO2 hybrid nanoparticle water-based lubricants as cutting fluids

Minimum quantity lubrication (MQL) technologies using vegetable oil lubricants as cutting fluids have attracted much attention as they have excellent machining performance and are environmentally friendly. Nevertheless, oil-based MQL tends to produce high cutting temperatures owning to the low cooling capability of oil lubricants. In this work, an MQL technology that utilizes graphene oxide/silicon dioxide (GO/SiO) hybrid nanoparticle water-based lubricants as cutting fluids was developed, and its tribological and machining characteristics were comparatively investigated using four-ball and milling testing units. The mass ratio of GO to SiO was also varied to achieve optimal performance. The results showed that GO/SiO water-based MQL reduced coefficient of friction (COF) and worn scar diameter (WSD) significantly, and improved machining performance compared with individual GO and SiO water-based MQLs, as well as showed a comparative performance with traditional vegetable oil-based MQL. The superior performance of GO/SiO water-based MQL was attributed to the fact that GO/SiO hybrid nanoparticle additives entered the rubbing interface and formed a composite protecting film consisting of a self-lubrication layer of GO and a tribo-thin layer of SiO, which prevented the interface from direct contact and smoothened asperities.

Numerical Modeling and Heat Transfer Analysis of Minimum Quantity Lubrication Grinding of Inconel 751

Sustainable Manufacturing has gained a widespread acceptance in today's manufacturing industry. This paper accentuates the need for environment-friendly lubrication with the help of Minimum Quantity Lubrication or Near Dry Machining. Minimum Quantity Lubrication (MQL) uses an atomizing nozzle in order to create fine droplets which on hitting the hot machining zone dissipates the heat and provides lubrication. In contrast to the flood coolant, MQL technology increases the surface area of contact with each droplet hence optimizing the coolant to the maximum extent by reducing harmful fumes, improving cutting performance and favorably reducing coolant consumption. Due to the rotating grinding wheel, a hydrodynamic boundary layer is formed around it, producing a back air flow which possesses enough momentum to oppose the incoming cutting fluid, restricting it to reach the machining zone. Thus, it is of prime importance to penetrate this air cushion forming the boundary layer to effectively cool and lubricate the grinding region. This could be only achieved when the oil droplet velocity is significantly greater than the grinding wheel's tangential velocity. In this work, various parameters including droplet size & velocity have been determined for improving the spray on the basis of flow rate and inlet air pressure in MQL nozzle using commercially available CFD solver Ansys Fluent. Further, Heat Transfer Modeling is also carried out both computationally and analytically in order to find the heat taken away by the MQL oil. The computational results validated the experimental analysis carried out for the droplet diameter and analytical model for the heat flux. Multiphase model DPM was preferred over VOF since it tracks each and every parcel coming out from the injection surface within the computational domain. The oil droplet size if found to be a function of air pressure and flow rate of the atomizer and the Heat flux on workpiece decreased with increase in oil flow rate.

Comparative assessment of cooling conditions, including MQL technology on machining factors in an environmentally friendly approach

Manufacturers need to continuously improve productivity and reduce the most disadvantages. In the current work, an experimental study has been carried out in order to evaluate the influence of different cutting parameters on the various machining factors such as surface roughness, cutting force, cutting power, metal removal rate, and tool wear during turning of X210Cr12 steel using a multilayer-coated tungsten carbide insert with various nose radii (r). Tests are designed according to Taguchi’s L18 (21 × 34) orthogonal array. ANOVA has been performed to determine the effect of the cutting conditions, and mathematical models have been developed through response surface methodology (RSM). The results indicate that the feed rate and the tool nose radius are the main affecting factors on surface roughness while both tangential force and cutting power are affected mainly by the depth of cut followed by the feed rate and the nose radius. Other special tests of long term have been established in order to study the wear evolution and consequently to determine the tool life. The results indicate also that minimum quantity lubrication (MQL) leads to an important improvement in terms of the cutting tool life by a gain of 23~40% compared to wet and dry machining. It has been found that the MQL is an interesting way to minimize lubrication cost and protect operator health and the environment while keeping better machining quality.

Grinding Temperature with Nanoparticle Jet Minimum Quantity Lubrication

In recent years, a large number of patents have been devoted to developing minimum quantity lubrication (MQL) grinding techniques for environment friendly, energy saving, and cost-effective grinding fluid alternatives. One patent involves the nanoparticle jet flow in the MQL of grinding lubricant supply systems. An MQL grinding lubricant is prepared by adding nanoscale solid particles into a degradable grinding liquid. The lubricant is turned into pulse liquid drops with fixed pressure, variable pulse frequency, and invariant liquid drop diameter. The pulse liquid drops are sprayed into a grinding region in the form of jet flow by an air-isolating layer formed by high-pressure gas. The system has the advantages of MQL technology, has high cooling performance and excellent tribological characteristic, and plays an important role in effectively avoiding grinding burn, thus enhancing the surface quality of the workpiece and realizing an efficient, low consumption, environment friendly, economic, low carbon, and clean production. The temperature field model of surface grinding with a nanoparticle jet flow of MQL and the proportionality coefficient model of the energy input workpiece were established. The surface grinding temperature fields of 45 Steel and 2Cr13 were numerically simulated. Results show that the surface temperature of the workpiece is significantly higher than the subsurface temperature, thus presenting a relatively large temperature gradient along the direction of workpiece thickness. Grinding depth significantly affects grinding temperature. The values of grinding temperature increase with increasing cutting depth. The uniform distribution rules of the 2Cr13 temperature field are observed in four cooling and lubrication approaches: dry grinding, flood grinding, MQL, and nanoparticle MQL jet flow. Experiments are conducted to verify the simulation results. The results show that grinding temperature increases significantly with the increasing peripheral velocity of the grinding wheel. Furthermore, the movement speed of a workpiece is inversely proportional to the grinding temperature and a larger cutting depth contributes to higher grinding temperature. These results are consistent with theoretical analysis and show the effectiveness of the simulation method. Keywords: Grinding, minimum quantity lubrication (MQL), nanofluids, nanoparticle jet, temperature field.

High-speed turning of AISI 4140 steel by multi-layered TiN top-coated insert with minimum quantity lubrication technology and assessment of near tool-tip temperature using infrared thermography

Minimum quantity lubrication technology is emerging as a potential alternative to flood cooling to effectively control cutting temperature during machining. In this study, an in-house developed minimum quantity lubrication delivery system has been used for minimum quantity lubrication delivery of cutting fluid at the machining zone. An advanced nanofluid coolant was also used for the purpose of minimum quantity lubrication. Different methods have been attempted to measure the near tool-tip temperature during turning of AISI 4140 steel with multi-layered coated insert under dry, flood cooled and minimum quantity lubrication cooled condition. It was further attempted to identify the best technique for assessing near tool-tip temperature. Infrared thermography has shown the closest result to that obtained through a finite element analysis (DEFORM 3DTM) simulation. Potential of multi-walled carbon nanotube–based nanofluid in minimum quantity lubrication application has been thoroughly investigated in this case study, where high-speed turning of AISI 4140 steel was carried out by a multi-layered coated carbide insert. Design of experiments, based on Taguchi method, was used to find out the significance of cutting parameters on machinability under nanofluid environment. Multi-walled carbon nanotube–based nanofluid was found to outperform the rest in all conditions.

Minimum Quantity Lubrication (MQL) in Automotive Powertrain Machining

This paper summarizes the advancements and challenges of minimum quantity lubrication (MQL) technology in automotive powertrain machining from both industrial and academic perspectives. MQL refers to applying a small amount of cutting fluid in the form of mist to the cutting zone rather than flooding the workpiece. Elimination of coolant systems creates significant saving from energy and equipment, the flexibility to relocate the machines, reduction of waste stream and floor space, and a cleaner and healthier work environment. Ford Motor Company has demonstrated these advantages, and currently has a total of over 400 MQL CNC machining centers in numerous global transmission and engine plants running MQL operations, with further implementation planned for new programs globally. Technical challenges to realize 100% implementation includes tool design, delivery system, chip management, and thermal related problems, particularly in high-energy density processes and difficult-to-machine metals, such as deep-hole drilling and compacted graphite iron (CGI). This paper provides a review of current status and limitations of MQL machining and highlights opportunities for research and development of the next-generation MQL technology in automotive powertrain machining.

Workpiece Temperature During Deep-Hole Drilling of Cast Iron Using High Air Pressure Minimum Quantity Lubrication

This research investigates heat generation and workpiece temperature during deep-hole drilling of cast iron under a high air pressure minimum quantity lubrication (MQL). The hole wall surface (HWS) heat flux, due to drill margin friction and high temperature chips, is of particular interest in deep-hole drilling since it potentially increases the workpiece thermal distortion. This study advances a prior drilling model to quantify the effect of higher air pressure on MQL drilling of cast iron, which is currently performed via flood cooling. Experiments and numerical analysis for drilling holes 200 mm in depth on nodular cast iron work material with a 10 mm diameter drill were conducted. Results showed that the low drill penetration rate can cause intermittent chip clogging, resulting in tremendous heat; however this phenomenon could be eliminated through high air pressure or high feed and speed. Conversely, if the drilling process is stable without chip clogging and accumulation, added high air pressure is found to have no effect on heat generation. The heat flux though the HWS contributes over 66% of the total workpiece temperature rise when intermittent chip clogging occurs, and around 20% to 30% under stable drilling conditions regardless of the air pressure. This paper demonstrated the significance of HWS heat flux and the potential of high air pressure used in conjunction with MQL technology.

Development of a micro-graphite impregnated grinding wheel

This paper introduces a newly designed grinding wheel where micro-graphite particles are impregnated in an aluminum oxide matrix to form a grinding wheel to lubricate the grinding site; these are known as graphite-impregnated grinding wheels. The graphite particles were heat-treated under a layer of hydrogen ions at a temperature of about 500°C for 30min to disperse them uniformly in the aluminum oxide matrix. In this study, grinding wheels with five different graphite contents (0.1, 0.5, 1, 3, and 5wt%) were investigated. Different aspects of the grinding performance (e.g., surface roughness, morphology, wheel wear ratio, grinding temperature, and grinding forces) using these grinding wheels under two different coolant strategies (dry and minimum quantity lubrication with pure water) were compared with the corresponding values for a conventional grinding wheel. The experimental results indicate that using graphite-impregnated grinding wheels considerably improves the grinding process performance compared to using a conventional grinding wheel. A graphite content of below 0.5wt% is recommended because this provides not only better surface roughness and topography, and lower grinding temperature and force but also less grinding wheel consumption; hence, the wheel life was extended. In summary, combining graphite-impregnated grinding wheels with minimum-quantity lubrication technology has the potential to effectively eliminate the use of any oils or toxic organic lubricants in the grinding process.

MQL Cutting of Inconel 718 with a Super Lattice Coating Tool

MQL (Minimum Quantity Lubrication) technology was applied to finish-turning of a nickel base superalloy, Inconel 718, with a PVD coated carbide tool with a super lattice coating of TiN/AlN. Cutting lubricant used for MQL was a biodegradable synthesis ester, which was supplied to the cutting point with compressed air from the both sides of flank and rake faces of the tool. At a cutting speed of 1.0 m/s and an air supply pressure of 0.4 MPa, MQL cutting showed longer tool life and better surface finish than both the dry cutting and wet cutting. When increasing the pressure of the air supply from 0.40 MPa to 0.60 MPa, however, the corner wear, the most predominant wear in all the cutting conditions in this study, increased. When the cutting speed was increased to 1.5 m/s, the tool life in MQL decreased drastically. These results suggested that when finishing Inconel 718, the special care must be taken for choosing the pressure of air supply and cutting speed. The obtained results provided a useful understanding of the complicated influence of MQL on the cutting performance of Inconel 718.