Machining Fluid Research Articles

Machining Behaviour, surface integrity and tool wear analysis in environment friendly turning of Inconel 718 alloy

Manufacturing industries strive for the low toxic and environment friendly machining set up to combat climate change. This research article addresses the machining performance, surface integrity, tool and chip morphology analysis of Inconel 718 in an eco-benign environment, i.e., Atomized Spray Cutting Fluid (ASCF) machining. The process parameters of the machining to evaluate the surface roughness (Ra) were optimized using Response Surface Methodology (RSM). The results revealed that ASCF Machining significantly reduced the vibration acceleration about 14–29% compared to dry machining. ASCF machining experienced very less vibration acceleration at higher cutting speed and feed rate due to the less accumulation of chips in comparison with dry machining. Improved surface roughness in the range 17–34% was observed in ASCF machining. ASCF significantly reduced the tool wear in terms of abrasion and notch wear. The reduction was mainly due to the lubrication effect of spray coolant and reduced cutting temperature in the tool–chip interface. The effective lubrication also attributed to the enhanced tool life in ASCF machining as compared to dry machining.

The use of tool flank wear and average roughness in assessing effectiveness of vegetable oils as cutting fluids during turning—a critical review

Vegetable oils have significant potential to replace conventional cutting fluids for green machining due to their lower environmental impact. The effectiveness of these oils when used as cutting fluids has been assessed using several measures, such as tool wear, cutting forces, surface roughness of workpiece, cutting zone temperature, vibration, and chip formation. Among these, the two most commonly investigated parameters in the past are tool flank wear and average surface roughness (Ra). The use of flank wear and average roughness in assessing the effectiveness of the oils as cutting fluids, however, has resulted in confusing and contradicting findings in many of the published literature. One common anomaly found in many of the published works is the improvement in surface roughness in spite of an increase in tool flank wear. This contradiction is mainly due to the poor correlation between the major flank wear and average roughness Ra. Moreover, since Ra is a measure of the average absolute height of the roughness profile, and thus is insensitive to changes in the overall morphology of the surface profile of the workpiece as a result of tool wear, the use of Ra as the sole roughness measure could potentially lead to erroneous conclusions. In this paper, the major issues and anomalies in previously published research are highlighted and discussed critically. More reliable measures of surface finish quality that could be used to assess the effectiveness of vegetable oils as cutting fluids are proposed and demonstrated using simulated and real surfaces produced by finish turning. The cross-correlation method is shown to provide a more reliable means of assessing the deterioration of the surface morphology due to gradual and excessive tool wear compared with Ra.

Effect of Ultrafine Bubbles on Pseudomonas Aeruginosa and Staphylococcus Aureus During Sterilization of Machining Fluid

Bacterial growth is one of the common causes of putrefaction and deterioration of water-soluble machining fluid. The 16S ribosomal DNA metagenome analysis of the bacterial species composing the microbial flora present in the machining fluid derived after processing demonstrated a high amount of species belonging to the Pseudomonas genus. Therefore, we prepared two types of ultrafine bubbles water (gas species: air and CO2) containing different types of gas and confirmed the bactericidal effect on Pseudomonas aeruginosa (ATCC 10145), a typical Pseudomonas species. The grinding fluid was prepared using sterile purified water containing ultrafine bubbles (hereafter referred to as UFB) as diluted water, and the Pseudomonas aeruginosa was inoculated to obtain 106 CFU/mL. The sterilization rate of the number of bacteria was determined immediately after immersion in each fluid and subsequently after two hours. The sterilization rate was determined to be 100% in the test group using the ultrafine bubbles water of CO2 (CO2-UFB water). As a comparative control, a similar test was performed on Staphylococcus aureus IFO12732, and the sterilization rate was determined as 0%. Fluorescence microscopic observation of bacteria after immersion in the CO2-UFB water demonstrated damage to the cell wall as the cause of death of the Pseudomonas aeruginosa. Therefore, CO2-UFB demonstrated sterilization of machining fluid by killing Pseudomonas aeruginosa in the machining fluid. The bactericidal mechanism of UFB involved the induction of damage in bacterial cell walls. This can be attributed to crushing due to the increase in the particle size of UFB.

Predicting the Decrease in Cutting Force in Alloy Turning by Lubrication

A method is proposed for predicting the decrease in cutting force in turning structural-alloy workpieces due to lubrication (the use of machining fluid), without the need for tests on machine tools. The influence of the machining fluid’s properties on the change in cutting forces is established.

Economic and ecological evaluation of high-pressure cutting fluid supply in milling of Ti-6Al-4V

The high-pressure cutting fluid supply has proven its technological, economic and ecological benefits in turning. In milling, there is fundamental knowledge regarding the impact of the focused high-pressure supply on tool wear and chip removal. However, for multiple row shell milling cutters, investigations regarding the feasibility and the effects of the changed boundary conditions for the application of high-pressure are lacking. In this work, investigations for machining of aerospace structural parts of Ti-6Al-4V, including an economic and ecological evaluation between conventional and high-pressure cutting fluid machining, are presented. A case study verified the feasibility and revealed economic and ecological benefits.

The Study on Applied Status Stability of Water-Based Cutting Fluids at Numerical Control Machining of Aviation Aluminum Alloy

When water-based cutting fluid is used in aviation aluminum alloy NC machining, soap precipitation and emulsification often occur due to its poor stability. It can cause the metal plate or equipment parts to scale or block the cutting fluid pipeline and filter system, which seriously affects the service life of the cutting fluid and the normal use of the equipment. At present, there is a lack of suitable evaluation standard for the stability of application state of water-based cutting fluid. In this paper, through the analysis of the state stability of four kinds of water-based cutting fluids, the state stability evaluation test is formulated. The hard water stability test and emulsion stability test are carried out for two kinds of semi synthetic cutting fluid and two kinds of fully synthetic cutting fluid. The test results show that this evaluation test can effectively evaluate the state stability performance of aviation aluminum alloy cutting fluid, and provide guidance for the optimization and management of cutting fluid in numerical control machining.

Analysis of kerf accuracy in dry micro-wire EDM

Mineral oil–based liquids are normally used as the dielectric fluid in electrical discharge machining (EDM) where it has the ability in improving the efficiency of the machining process. Nevertheless, these dielectric fluids have the tendency to cause environmental problems. Therefore, as an alternative, gas has been introduced as the dielectric fluid also known as dry EDM (DEDM) process. However, kerf variation in dry micro-wire EDM (DμWEDM) process remains a critical issue. Thus, the objective of this research is to investigate kerf accuracy in DμWEDM. Experimental investigation was carried out on a stainless steel (SS304) with a tungsten wire as the electrode and compressed air as the dielectric fluid using integrated multi-process machine tool, DT 110 (Mikrotools Inc., Singapore). Central composite design (CCD) was used to design the experiment using two controlled parameters: capacitance and gap voltage. Analysis of variance (ANOVA) was used to analyse the results and to evaluate the adequacy of the developed model. The results were obtained by measuring the kerf using a scanning electron microscope (SEM) (JEOL JSM-5600, Japan). The investigation of kerf was divided into two responses which were upper kerf and bottom kerf. Empirical models were developed, and it was found that both parameters (capacitance and gap voltage) have high influence on both responses. The optimum parameters for both minimum upper and bottom kerf were found to be 0.1 nF capacitance and 91 V gap voltage. The developed models were found to be adequate since the percentage error is relatively small (< 3%).

Experimental Investigation of Stability of Vegetable Oils Used as Dielectric Fluids for Electrical Discharge Machining

One main drawback of electrical discharge machining (EDM) is related to the dielectric fluid, since it impacts both the environment and operator health and safety. To resolve these issues, recent research has demonstrated the technical feasibility and qualitative performance of vegetable oils as substitutes for hydrocarbon-based dielectric and synthetic oils in EDM. However, due to the higher content of unsaturated fatty acids, vegetable oils lose their stability, due to several factors such as heating or exposure to light or oxygen. The present study is a first attempt to analyze the extent to which the physic-chemical properties of vegetable oils change during EDM processing. Refractive index, dynamic viscosity and spectra analyses were conducted for sunflower and soybean oils. The results revealed that, under the applied processing conditions, no structural changes occurred. These findings are very promising from the perspective of EDM sustainability.

Surface Machining of Corundum-Ceramic Components by Free Abrasive

The surface machining of corundum-ceramic components by free abrasive is discussed. The influence of the following factors on the final surface roughness is determined: the type of machining (tumbling or vibrational tumbling), the shape of the abrasive bodies, the presence or absence of machining fluid, the machining time, and the drum speed in tumbling. On that basis, recommendations are presented.

Effect of nanoparticles in cutting fluid for structural machining of Inconel 718

ABSTRACT Recently nanofluids have pinpricked a tremendous research interest among the institutions and manufacturing industries because of a good coefficient of conductive heat transfer and a high impact of lubrication in machining. In this study, nanofluids of powders (Al2O3 and TiO2) each with concentrations of 0.5 and 1 gm in 100 ml of ACTIV 4T SAE20W40 engine oil were prepared and compared with dry and lubricant condition for the turning of Inconel 718 superalloy using MQL methodology. Turning was being done in MTAB CNC lathe machine with 200, 300 and 400 rpm speed keeping a constant feed of 0.05 mm/rev and constant depth of cut 0.5 mm by using carbide insert with a positive rake angle of 15 degrees. Machining characterisation through SEM was carried out. The experimental results show that the surface roughness, chip thickness and chip morphology are more suitable at a speed of 400 rpm for machining of Inconel 718 for a concentration 1 gm of Al2O3. The influence of cutting parameter and nanoparticle concentration was also being analysed with ANOVA. The machining results obtained for every concentration are analysed so that the optimisation of different parameters is to be obtained for the structured machining of Inconel 718.

Modeling of tool wear in machining of AISI 52100 steel using artificial neural networks

Machining is an arduous process for both the cutting tool and workpiece material. Conducting a series of machining tests involves a lot of money and time. It is important to prevent time consuming runs and prioritize technology. Hence, in this investigation, artificial neural network (ANN) approach is employed to estimate the cutting tool wear. From the experimentally obtained values, the input variables chosen for ANN modeling are cutting speed, feed and depth of cut corresponding to the output variable tool wear. The ANN modeling comprises Levenberg-Marquardt (trainlm) and tangent sigmoid (tansig) as training and testing functions respectively. Optimum architecture 3–6-6–1 is obtained based on the mean sum squared error (MSE) and average error (AE) of input data. Tool flank wear is assessed in three different machining environments such as dry machining, wet machining (flood cooling) and minimum quantity lubrication (MQL) machining. The emulsifier oil based cutting fluid is used as cutting fluid in wet and MQL machining. ANN model predicted values are compared with experimental results. Based on the correlation coefficient factor, it was observed that the prediction of ANN is high, showing a significant harmony between predicted response and experimental output.

Experimental Analysis of Canola Oil as Dielectric Fluid in Electric Discharge Machining of AISI D2 Steel

Electric Discharge Machining (EDM) is a thermo-electrical disintegration process, utilized to cut hard materials into complex shapes. In EDM, the three vital components are work-piece material, electrode material and dielectric liquid. The significant function of the dielectric fluid is to produce a breakdown voltage for creating a spark between work-piece and electrode. This spark creates ionization by plasma generation and it expels the material from work-piece. In most cases, hydrocarbon-based dielectric liquid is preferred in the EDM process. This kind of dielectric liquid generates hazardous gases which are harmful to people, environment and ecological balances. In this experiment, Canola oil is utilized and the outcomes are compared. The input parameters are Pulse on/off time, current and gap voltage. Copper, Brass and Tungsten-Copper (Alloy) are used as electrodes. The output values from the experiments are Surface Roughness (SR), Electrode Wear Rate (EWR) and Material Removal Rate (MRR). The outcomes demonstrated that Canola oil-based dielectric fluid has comparable properties of conventional based dielectric fluid. This Canola based dielectric gives more prominent MRR value than EDM oil-based dielectric liquid and furthermore higher EWR and SR values are recorded. The proposed Canola oil-based dielectric fluid is biodegradable and has improved suitability in machining.

Research on ECM Finishing Process using Wire Electrode

In wire electrical discharge machining (WEDM), discharge craters and heat-affected zone impair the surface roughness and generate micro cracks and residual stress. Hence, this study aimed to finish the WEDMed surface by electrochemical machining (ECM) using the same setup, wire electrode and machining fluid used in WEDM. Ultrashort bipolar pulses were used to improve the finishing speed and surface roughness. To realize electrochemical finishing on a WEDM machine, first the influences of the electrolyte concentration on machining characteristics were investigated, and it was found that machining can be performed even if the electrolyte concentration of NaNO3 aqueous solution is diluted to 0.2 wt%. With lower electrolyte concentration, smaller surface roughness was obtained at smaller machining depth. Next, the material of the wire electrode was changed from platinum to brass which is commonly used for WEDM, and the wear rate of the brass wire was investigated. Although the wear rate was 20 times higher than that of platinum, wire breakage did not occur in most of the experiments conducted in the present work. Then, machining was performed with an equal current density for different thicknesses of workpiece, and influences of the workpiece thickness on the process characteristics were investigated.

Preparation and Application of a Novel Water-Based Viscoelastic Polishing Fluid for Abrasive Flow Machining

Abstract Based on the excellent physical and mechanical properties, high surface quality monocrystalline silicon has become a typical material for manufacturing Biological Micro Electro Mechanical Systems (Bio-MEMS). Abrasive flow machining (AFM) with the chemical mechanical effect is an effective polishing process to improve the surface quality of monocrystalline silicon and such hard and brittle materials. Thus, an aqueous viscoelastic polishing fluid with absorbent polymer and thickener compounded hydrogel as the carrier was developed and its microstructure and dynamic characteristics were analyzed. Then, polishing experiments were carried out and the surface of monocrystalline silicon with a roughness of 6.18nm was obtained.

Modelling of transient behaviour of roughness reduction in ball end magnetorheological finishing process

Ball end magnetorheological finishing (BEMRF) process provides nano level of surface finish for materials which are magnetic as well as non-magnetic in nature. The available literature on this process has been vastly limited to establishing its finishing capabilities on materials of different nature. This research work deals with theoretical investigations into surface roughness reduction in BEMRF process, performance of machining parameters during long time periods and providing their representation in mathematical terms. Starting with the mechanism of abrasive wear in BEMRF process, this work advances to find out prolonged effect of abrasive rubbing on a ferromagnetic workpiece surface. The study finds out a phenomenon termed as transient roughness reduction in which the material removal by abrasive wear in BEMRF process is diminished with time and a particular combination of machining parameters and fluid composition reduce roughness only up to a critical value, beyond which no further reduction is achieved. A mathematical model is developed to depict this transient roughness reduction phenomenon, the model is then experimentally verified and the close proximity of the experimental results with the theoretical ones validates the model and the transient roughness reduction phenomenon in BEMRF process.

Feasibility study of using microorganisms as lubricant component in cutting fluids

This work intends to lay the basis for a Biological Transformation in Manufacturing (BTM) industrial breakthrough aimed at developing new sustainable microbial-based cutting fluids for greener machining processes. The point of departure is that conventional cutting fluids for machining are either entirely based on mineral oils or, in the case of water-based cutting fluids, contain significant percentages of mineral oils. The world annual consumption of cutting fluid concentrate amounts to several billion litres, highlighting their importance for the manufacturing industry and their criticality in terms of environmental impact. Furthermore, the depletion of mineral oil reserves worldwide is already driving cutting fluid industries to search for new renewable raw materials. A contribution to the solutions of these problems can be provided by the development of microbial-based cutting fluids, incorporated in the machine tool, that contain microorganisms with significant lubricating properties in order to substitute mineral oil-based cutting fluids for use in metal alloy machining.

Die-sinking of super dielectric based electrical discharge machining using 3D printed electrodes

Electrical discharge machining (EDM) is a popular nonconventional manufacturing process for the machining of complex or hard materials that are difficult to machine by the conventional machining process. In the EDM process, the electric current is used to ablate the material, and there is no contact between the tool and workpiece. One of the variants of the EDM process is the die sinking EDM where the electrode shape is mirrored in the workpiece, and die sinking electrodes are usually manufactured using conventional machining process. However, in the die sinking EDM process, the material removal rate is significantly lower than the conventional machining. Due to this fact, the regular die sinking EDM process is unable to meet the demands of today’s fast moving manufacturing industry. This study presents an innovative electrode design strategy together with a super dielectric machining fluid to tackle the low-efficiency issue of the die sinking EDM process. In general, flushing becomes very important when deep features are machined. In the die sinking EDM process flushing holes in the tool electrode is considered impractical, and the regular method of flushing is not effective because of the accumulation of a large amount of debris in the machining zone. In this study, 3D printed die sinking EDM electrode with multiple through electrode flushing channel for high-pressure flushing is introduced. In addition, an innovative super dielectric based EDM fluid is proposed in this study, which provides high capacitive plasma in the machining process and ensures better machining efficiency. The effect of super dielectric fluid on the EDM plasma has been analysed and compared with the plasma physics theory. The performance of the proposed 3D printed multi flushing channel electrode together with super dielectric fluid for the feature manufacturing has been demonstrated by making multiple features efficiently in hard to cut materials.

A brief study on effects of nano cutting fluids in hard turning of AISI 4340 steel

Hardened AISI 4340 alloy steel increments the cutting temperature during machining and is crucial output parameter for quality of machined part. Nano cooling mechanism is the burning issues in machining of hardened steel. More friction and temperature is generated during hard turning posing a difficulty in terms of tool span life. Controlling these tribological issues is the major challenges for accurate cutting. Significant improvement in the field of Nano assisted cooling can be applied in minimum quantity lubrication. Nano fluid is the colloidal suspension of Nano particles that is commercially available to the base conventional fluid was assessed to minimize the wear effect and friction to improve machinability. This Nano fluid is the heat transfer fluid representing as innovative machining fluid because of improved tribological and thermal characteristics. Motivated by this innovative concept, this review presents the significance of Nano fluid, various types of Nano fluids used throughout the hard material of AISI 4340 steel turning. At last, the concluding analysis with some future prospects have been has been pointed out. Moreover, this review analysis will provide the better answer to the manufacturing industry where the high strength low alloy steel is used using nano cutting fluid.

Electrical Discharge Machining using Copper Electrode made by Additive Manufacturing

In electrical discharge machining (EDM), it is important to evacuate EDM debris from the discharge gap for machining stability and accuracy. Especially in the processing of deep slots with high aspect ratio, EDM debris accumulated in the bottom of the groove often causes short circuit and false discharge, resulting in process instability. The tool electrode having micro holes for the machining fluid, which flush debris out of the discharge gap, enables efficient EDM machining of the deep slots. However, in conventional machining, it is difficult to drill high aspect ratio micro holes. Recently, the additive manufacturing (AM) technologies with the selective laser melting (SLM) method using metal powder attracts attention as a promising technique which can produce various complicated shapes efficiently. By using the AM method, it is possible to fabricate a high aspect ratio EDM electrode with micro holes inside. This paper describes the application of electrodes fabricated by the AM method to electrical discharge machining. Almost fully dense additive manufactured copper electrode (AM-Cu electrode) having more than 99.7% relative density was obtained by optimizing the laser scanning parameters for Cu-1.3mass%Cr (Cu-Cr) alloy powder. EDM properties of the AM-Cu tool electrode and the machinability of deep rib slots by using that electrode with micro holes inside were investigated. As a result, it was confirmed that EDM properties of the AM-Cu tool electrode were almost the same as those of conventional Cu tool electrode. Moreover, it was shown that use of the AM-Cu tool electrode with micro holes inside was found to shorten the processing time and improve machining accuracy significantly compared with the conventional solid Cu tool electrode.

A study of viscosity and thermal conductivity of vegetable oils as base cutting fluids for minimum quantity lubrication machining of difficult-to-cut metals

The properties of environmentally friendly, sustainable, and renewable cutting fluids are very important to effective machining of difficult-to-cut materials under minimum quantity lubrication (MQL). This paper presents the experimental investigation of viscosity and thermal conductivity of three vegetable oils for use as base cutting fluids: modified high oleic soybean oil (HOSO), refined low oleic soybean oil (LOSO), acculube LB2000 (LB2000) oil, and mineral oil–based emulsion cutting fluid (EC) as benchmark and at temperature from 25 to 70 °C. The results show that viscosity of all vegetable oils decreases exponentially with temperature, and are significantly higher than that of EC. HOSO shows an enhanced viscosity of 6.03% compared to LB2000, 25.69% compared to LOSO, and 4688.30% compared to EC at 30 °C temperature. Thermal conductivity of soybean oils and LB2000 is similar, decreases gradually from 0.192 to 0.179 W/mK, not significantly affected by temperature and very low compared to EC. EC increases from 0.698 to 1.857 W/mK between 25 and 50 °C and decreases from 1.857 to 0.762 W/mK between 50 and 70 °C. Critical temperature of EC is around 50 °C. Shear stress–shear rate plots of vegetable oils show linear relation typical of Newtonian fluids. The R-square of HOSO was greater than 0.99 at all investigated temperature and better than the observed values for LB2000, LOSO, and EC. HOSO with higher oleic fatty acid composition shows the most significant viscosity enhancement and oxidation stability, and is recommended as alternative to EC and based-cutting fluid for MQL machining.