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The titanium alloy has a low thermal conductivity of 1/8th that of common metals and half that of stainless steel. The heat dissipation is poor during dry cutting, so the cutting temperature rises above about 600°C. Due to this, the quality of the cutting surface decreases during machining, and rapid tool wear occurs. To solve this, the use of cutting fluid is essential, but the chemical composition of the cutting fluid has a negative effect on the body and the environment. In the current cutting process, in order to minimize this effect, eco-friendly processing using minimum quantity lubrication (MQL) is performed. The machining method using both MQL and a cryogenic gas separately applies the MQL and the cryogenic gas to both sides of the cutting tool. In this case, the oil mist cannot penetrate the cutting zone due to the spray pressure of the cryogenic gas. Therefore, it is necessary to design a hybrid nozzle that can spray oil mist and cryogenic gas into a single flow. Besides, although the study on the effect of MQL and cryogenic machining on the cutting temperature should be preceded, most of the titanium MQL processing papers only study the material surface and tool wear. Accordingly, in this study, we designed and fabricated the hybrid type nozzle of CryoMQL which combined MQL and a cryogenic gas to improve the spraying concentration. And the cutting temperature generated by the process was measured, and the effectiveness of the proposed nozzle on decreasing the cutting temperature was evaluated. Besides, cutting force and tool wear were analyzed according to each cutting method.

The machining efficiency of hardened steel molds can be significantly improved through high-speed deep milling. However, under these circumstances, the temperature and milling force increase greatly, and the end mills are subjected to rapid wear. A feasibility study of the oil-on-water (OoW) method in the high-speed end milling of P20 hardened steel was conducted. The experimental results show that the tool life of OoW is significantly longer compared with that of dry cutting and compressed air cooling. Moreover, the OoW method promotes tool life under low- and high-speed milling conditions. Thermal wear phenomena (e.g., adhesion) are evidently suppressed, and the development of the milling force and tool wear is considerably slowed down in OoW processing. The main reason for the excellent cooling and lubrication performance of the OoW method is that a two-layer film (oil film + water film) is formed when the OoW droplets collide with the cutting interface. The evaporation of the water film removes much heat and prevents the high-temperature failure of the oil film. Moreover, the single use of oil mist and water mist leads only to a single-layer film, resulting in an evidently shorter tool life than that of the OoW method. In the OoW cutting process, the chipping belt of the flank face is discontinuous, and the wear of the adhesion/attrition is less severe compared with those of the other processing modes. In addition, the tool wear and chipping belt occur with a certain amount of material peeling, and the thermal fatigue and mechanical behavior of the tool substrate in a certain temperature range are the main reasons for the discontinuity of the chipping belt in the OoW process.

The number size distributions of submicron oil mist particles generated by three industrial metal (steel) machining processes—lathe machining, cutting, and grinding—were measured using an electrical mobility analyzer and an optical particle spectrometer. The measured number concentration of ultrafine particles (UFP; ~30 nm diameter) reached 107 particles cm–3 during each machining process. The condensation of thermally evaporated oil vapor was considered to be a major route of ultrafine particle generation during lathe machining and grinding, which used an oil-in-water emulsion and an insoluble lubricant oil, respectively. Cutting, which did not use lubricant oil, also produced a steep increase in the number concentration of UFP; these particles may have formed from residual oil-in-water emulsion on the surface of the workpiece after lathe machining. A simplified numerical simulation was used to quantify the particles arising from machining and leakage when the apparatus was opened. Although local ventilation effectively reduced the concentration of the oil mist in the apparatus and prevented the diffusion of this substance when the apparatus door was opened, leakage was observed when the workpieces were exchanged; this leakage was attributed to entrained particles on the workpieces. Hence, countermeasures to prevent entrained oil mist are necessary to improve the air quality in working environments.

The present paper highlights investigation on hard turning of high strength EN24 steel using multilayer coated carbide insert (TiN/TiCN/Al2O3/ZrCN) under minimum quantity lubrication environment for surface roughness. Measured surface values are found to be less than 1 µm which is much below the surface roughness criteria of 1.6 µm. It indicates that quality components can be obtained during MQL assisted machining of high strength EN 24 steel. This indicates proper cooling and lubrication of machining zone occurred due to application of pressurized oil mist. Developed regression model has been found to be significant because determination coefficient i.e. R2 close to unity (0.9) and p-value is less than 0.05 at 95% confidence level. Hence, environmental friendly minimum quantity lubrication machining can be effectively utilized for production of quality components in industrial shop floors for ecological and economical benefits.

The disadvantages of minimum quantity lubrication (MQL) are its poor cooling capability and environment and health hazard as a result of mist formation, resulting in considerable limitations on its widespread application. There is an urgent need to improve its cooling/lubrication performance and environmental performance. Electrostatic atomization is a method where the liquid is electrostatic charged and broken into fine charged droplets by means of electrical forces. This paper investigated the role of electrostatic atomization lubrication (EAL) and nanofluid electrostatic atomization lubrication (NFEAL) on tool wear in end milling of Ti-6AI-4V alloy, and evaluated their environmental performance in non-machining experiments in terms of oil mist concentrations of PM10 and PM2.5. For this research, electrostatic atomization milling system was designed and fabricated. A comparison with the results obtained under MQL condition is also provided. The experimental results show that there was a considerable reduction in tool wear and oil mist concentration for EAL and NFEAL as compared with MQL condition. Furthermore, NFEAL was more effective than EAL for reducing tool wear. But NFEAL yielded slightly higher oil mist concentration than EAL. Therefore, EAL and NFEAL seem to be potential cooling/lubricating approaches for the machining substituting MQL from view point of machining performance, health, and environment.

As a typical representative of green lubrication/cooling mode, minimum quantity lubrication (MQL) is widely recognized by the industry for its excellent machining performance. However, the oil mist generated from oil-based MQL machining process has a direct impact on the ambient air quantity and then does harm those who permanently work in this environment. To alleviate this defect, a novel lubrication strategy named magnetic minimum quantity lubrication (mMQL) allocated with water-based Fe3O4 nanofluid as cutting fluid was proposed. The effect of different magnetic induction on the kinetic viscosity and atomization performance of water-based Fe3O4 nanofluid was investigated. The deposition property of water-based Fe3O4 nanofluid droplets produced by mMQL and LB-2000 vegetable oil droplets produced by MQL were compared, and the corresponding oil mist concentrations (PM10, PM2.5) were also measured. Eventually, the machining performances of water-based Fe3O4 nanofluid mMQL and LB-2000 vegetable oil MQL applied in milling of 430 stainless steel were compared. Results exhibited that water-based Fe3O4 nanofluid presented higher kinetic viscosity and larger droplet size under higher magnetic induction intensity. Water-based Fe3O4 nanofluid mMQL with magnetic induction intensity of 60–100 mT displayed lower PM10 and PM2.5 concentrations, tool flank wear value, milling force, and surface roughness value in comparison with LB-2000 vegetable oil applied in MQL. This water-based Fe3O4 nanofluid used in mMQL showed higher kinetic viscosity and atomized larger droplet-size and thus presented further deposition quantity, which demonstrated alternative cutting performance and lessened the oil mist particles floating in the operating environment.

The oil-based cooling media is one source of pollution and made from non-renewable resources. The use of cooling in machining with a mist cooling system will reduce the amount of oil consumption in for cooling media, decreasing of oil make the amount of pollutant decrease but still produce pollutant event in small quantity. Replacing oil with palm oil will remove pollutants caused by the use of oil as a cooling media in the machining process.This study sets out to reveal the surface roughness of St 60 steel machined by milling process using different spindle speeds (360, 490, and 720 rpm) and mist cooling pressures (0.5; 1.5; and 2.5 bars). The milling process carried out using up milling with the feed rate of 75 mm/min. The surface roughness was tested using surface roughness tester at 3 different points to obtain the average arithmetical surface roughness value (Ra). The results showed that the enhancement of surface roughness occurred along with the increase of mist cooling pressure, however, it dropped when the pressure reached the value of 2.5 bars. On the other hand, the higher spindle speed applied could reduce surface roughness. These phenomena can be explained due to the less optimum of the spraying process on cutting region when the pressure below 2.5 bars was used. Yet, along with the further addition of pressure, the spraying occurred on the cutting region turned to be more effective due to the better ability of oil mist to penetrate the narrower cutting crevice. The highest average Ra value has resulted in the spindle speed of 360 rpm and the mist cooling pressure of 1.5 bars with the Ra of 2.65 µm. Conversely, the lowest one can be observed on sample cut using the spindle speed of 720 rpm and mist cooling pressure of 2.5 bars with a value of 1.29 µm.

The oxidative potential (OP) measures the ability of pollutants to oxidize a chemical/biological probe. Such assays are starting to gain acceptance as integrative exposure metrics associated with inflammatory-based pathologies. Diseases such as asthma, rhinitis or cancers are reported for workers exposed to oil mist, which are aerosols of metal working fluids (MWF) emitted during the machining of metals. Measuring oil mist in the air is challenging, and exposures are often quantified as the mass fraction, which does not account for exposures to the gaseous fraction. Consequently, exposures are underestimated and furthermore, the hazardous property of oil mist is not assessed. We postulate that it is more relevant to assess occupational exposures to the hazardous fractions of oil mist by measuring OP than by simply measuring mass. We characterized exposures to straight and water-based MWF among workers in the French and Swiss mechanical industry using standard methods for oil mist and the ferrous orange xylenol assay for OP assessment (OPFOX). Considering the particulate fraction, the water-based MWF presented the greatest OPFOX. The OP was associated with organic carbon and iron content. The gaseous fraction of the oil mist presented also an important redox activity, particularly in workshops where straight oils were used. The hexanal concentration was associated with this OPFOX. The OPFOX measurement is thus integrative of multiple parameters, and bring complementary information when assessing MWF exposures. Our results highlight that OPFOX account for MWF type and could be an interesting parameter to characterize such exposure.

We examined cutting point temperature and tool wear in driven rotary cutting. Cutting tests under dry and minimum-quantity-lubrication (MQL) conditions of stainless steel (SUS304) were carried out. Cutting point temperature was measured using a tool-work-thermocouple method at various cutting speeds. Cutting point temperature tends to increase with increased cutting speed. In driven rotary cutting, cutting point temperature was lower than that of non-rotation cutting. At high-speed cutting of 500 m/min, cutting point temperature was over 1200 °C in the non-rotation tool, but 1000 °C with driven rotary cutting. In addition, when driven rotary cutting was used with MQL, cutting point temperature was decreased to 900 °C. The magnitude of tool wear corresponded almost precisely to cutting point temperature. Severe adhesion on the rake face was observed and resulted in progressive wear on the rake face in rotary cutting at a cutting speed of 100 m/min. The appropriate cutting speed range passively shifts higher from the viewpoint of cutting temperature with rotary cutting.

For all dry machining process, temperature generated in the cutting zone is the major challenge. It causes tool failure and results in unsatisfactory surface finish. Application of flood coolant method during machining processes can significantly reduce the temperature and consequently extend the cutting tool life. However, it has serious concerns regarding environmental pollution, operator health and manufacturing cost. These issues are usually attempts to be overcame by using minimum quantity lubrication (MQL) technique. This method merges the advantages of both dry cutting and flood cooling by spraying a small amount of lubricant to the cutting zone using vegetable oil. In this paper, another technique is proposed in order to further enhance the machineability of the stainless tool steel (STAVAX ESR 48 HRC). This involves using of nitrogen gas (N 2 ) and air as cooling medium in combination with oil mist lubricant (MQL). The results show that the combination between nitrogen and oil-mist lubricant much more prolonged the tool life and improved the surface finish than the air-oil mist lubricant medium.

In recent decades, there has been increasing interest in the study of Minimum Quantity Lubrication (MQL) due to its outstanding performance despite the minimal usage of cutting oil. However, study focusing on the behavior of oil mist during the MQL machining process is still scarcely reported. It is important to clarify this matter in detail as to explain how the lubricant oil mist can successfully reach the narrow cutting zone. The aim of this study was to investigate the cutting speed effects on the behavior of lubricant oil film by measuring its thickness accumulation on the workpiece after the MQL milling process. Measurement was conducted by using Laser Induced Fluorescence (LIF) method. Results showed that the average thickness of oil film generated at the center of milling path was approximately at 0.37 mm. Penetration ability of lubricant oil to reach the narrow cutting zone dropped with increasing cutting speed and subsequently leading to accumulation of thicker oil film at the cliffs of milling path. Further investigation is needed to clarify whether the nozzle position or the cutter flute may be the attributor of this phenomena. Moreover, it was found that the MQL machining must be conducted appropriately to ensure the oil mist can successfully lubricating the cutting zone on the entire workpiece.

Minimum quantity lubrication (MQL) machining is an advanced near dry cutting technology in modern machining field. However, the cutting oil mist produced during the process of oil-based MQL affected the ambient air quality and endangered the health of employees. To avoid this drawback, a novel lubrication/cooling method called electrostatic minimum quantity lubrication (EMQL) which used SiO2 water-based nano-lubricant as cutting fluid was proposed. The charge mass ratio, surface tension and contact angle of SiO2 water-based nano-lubricant and vegetable oil with different charging voltages were compared, and the penetration performance of these two lubricants was analysed using capillary dynamics equation. The adsorption and deposition properties of oil mist produced by different lubrication methods were investigated, and revealed the adsorption and deposition mechanisms of the charged droplet. The influences of the charging voltage, flow rate, air pressure, spindle speed and cutting depth on PM10 and PM2.5 concentrations under different lubrication conditions were revealed. Finally, the milling performance of SiO2 water-based nano-lubricant EMQL of stainless steels was evaluated comparatively. The results showed that SiO2 water-based nano-lubricant presented better chargeability compared with vegetable oil, and thus displayed stronger penetrability, adsorption and deposition capacity. SiO2 water-based nano-lubricant EMQL with -4 kV showed the lowest oil mist concentration and similar machining performances compared with the vegetable oil MQL, and the concentration values were close to the standards set by the National Institute for Occupational Safety and Health (NOISH). The charged SiO2 water-based nano-lubricant droplets with excellent charging performance presented better adsorbability and penetrability, so that the charged droplets were prone to be electrostatic adsorbed in the machine tool and penetrated into the cutting region, which reduced the oil mist content in the machining environment and presented alternative cutting performance.

Effective lubrication and cooling are very critical to control friction and heat generation in metal-cutting processes. Conventionally, cutting fluids in flood form are employed during the processes; however, their usage is frequently seen to raise major environmental, economic, and employees’ health concerns. All these factors have urged researchers to search for alternatives to minimize or even eliminate cutting fluid usage. To serve that purpose, a new near-dry machining technique called “electrostatic minimum quantity lubrication” (EMQL) has been innovated and developed. EMQL is a technique using the synergetic effects between electrostatic spraying (ES) and minimum quantity lubrication (MQL), wherein a very small amount of lubricant, negatively charged by the electrostatically contact charged method, is directed into the machining area in the form of a fine, uniform, and highly penetrable and wettable oil mist. The focus of this study is to evaluate the performance of EMQL in end milling of AISI-304 stainless steel in terms of tool wear, cutting force, tool life, and surface roughness. The influence of EMQL process parameters such as charging voltage, air pressure, lubricant flow rate, and cutting speed is determined based on an experimental study. A comparison with the results obtained in completely dry, wet, and MQL machining is also provided. The experimental results show the effectiveness of EMQL as a viable alternative to conventional wet and MQL machining through the reduction in the friction at the tool–chip interface. It is found that the charging voltage is an important factor influencing the effective application of EMQL oil mist. EMQL with −5 kV voltage is recommended because it provides not only lower tool wear and cutting force but also higher tool life and better surface finish. In addition, it is found that there are the optimum lubricant flow rate and air pressure in end milling of AISI-304 stainless steel with EMQL. The proper selection of the above parameters can lead to a low-cost and eco-friendly machining.

Titanium alloys have been widely used in the aerospace, biomedical and automotive industries because of their good strength-to-weight ratio and superior corrosion resistance. However, it is very difficult to machine Titanium alloy materials due to their poor machinability, resulting in short tool life. The effects of oil mist and air jet flushing on tool wear in the milling of Ti6Al4 V were investigated at a cutting speed of 300 m/min in this study. Tests with various flushing directions of oil mist and air jet during up, and down-cut were carried out. Tool wear and chip shape were measured and analyzed. As a result of these cutting tests and considerations, it was revealed that up-cut with oil mist flushed from any direction and air jet flushed from the side were desirable, and dry down-cut was also desirable.

This paper explains environment friendly water oil mist spray (WOMS) cooling method which is used to obtain lower cutting temperature and higher lubrication at tool chip interface during Ti6Al4V twist drilling process. WOMS is Ester oil based minimum quantity lubrication (MQL) technique but different than neat oil or straight oil based MQL techniques due to combined application of water and oil. Drilling experiments at maximum cutting speed of 50 m/min and 167mm 3 /s material removal rate (MRR), using a 8mm diameter TiAlN coated solid carbide twist drill are conducted under dry machining and WOMS cooling environment. The effect of WOMS are mainly discussed with different cutting parameters, twist drill geometry and compared with dry cutting conditions. A comprehensive evaluation on the cooling effects of WOMS was carried out by spray characterization and subsequent drilling tests. This work is focused on the combined study of tool wear evolution, drill geometry, quality of machined holes under WOMS cooling environment. Drilling under WOMS condition observed 66% higher tool life than dry cutting environment. Experimental results indicated that drilling under WOMS cooling had better cooling effects, higher tool life, optimum cutting parameters.

This paper discusses the cutting temperature and cutting force in end milling difficult-to-cut materials cooled with several types of mists and low-temperature air. The cutting tool was a throwaway end mill with a carbide tip coated with titanium aluminum nitride. The Ti-6Al-4V titanium alloy and AISI D2 hardened steel were used as workpieces. The tool flank temperature and cutting force were measured simultaneously during side milling. The temperature was measured using a two-color pyrometer with an optical fiber. Oil mist and water mist from a mist generator were supplied to the cutting point along with cold air at approximately -27 °C. Compared with dry cutting, the cooling effects of supplying an oil mist and/or cold air were less than for other supply conditions in titanium alloy cutting. However, when water mist was added, the tool flank temperature clearly decreased. The cutting force increased for cases that included water mist. The adhesion of the titanium alloy to the cutting edge of the worn tool was significantly suppressed by supplying water and oil mist with cold air. Tool flank wear also decreased under those lubrication conditions.

In the article the state of knowledge regarding the functions and supply methods of the cooling liquid into the grinding zone were presented. The new system for centrifugal supply of oil mist was described. The results of experimental investigations conducted into the internal cylindrical grinding process were given. The life of the wheel, machined surface roughness, grinding power and temperature in the machining zone were analyzed. Experimental results showed that compared to flood cooling, this new system provides double the lifespan of the wheel, significantly reducing the volume of wheel wear and enabling the slightly reduced roughness of machined surface and grinding power. Using a new coolant supply method caused an increase in the workpiece temperature, compared to the flood cooling.

Minimum quantity lubrication (MQL) or as it’s called semi dry cutting is a technique which spray a small value of lubricant flow rate to the cutting zone area. MQL has been used in many machining process with different cutting tools and workpiece materials due to its green environments and economically advantageous. MQL has become an attractive option to dry and flood cutting in terms of reduce the temperature in the cutting zone and reduce the cost of the product. However, in MQL seems to be machining limited by cutting temperature, because at high speed the effect of oil mist becomes evaporated. Therefore another alternative cooling approach was used with oil mist in this research. This research presents study the performance of nitrogen gas as a coolant and oil mist as lubricant in turning of hardened stainless tool steel (STAVAX ESR) with hardness 48 HRC. Using a gas as coolant with oil mist is a new solution for enhancing machinability. Turning experiments are carried out on CNC turning machine. The cutting insert grade is KC5010 (PVD-TiAlN wiper coated carbide). The experimental results were: 1) nitrogen gas with oil mist prolongs tool life compare with air with oil mist. 2) better product surface finish by using nitrogen gas with oil mist.

Conventional coolant/lubricants have some drawbacks such as high cost, pollution, and unsatisfactory product quality. New cooling approach by using gases to enhance machinability has been investigated. This study presents the finding of nitrogen gas and nitrogen-oil-mist as conditions when turning of hardened stainless tool steel (STAVAX ESR) with hardness 48 HRC. Turning experiments were carried out on CNC turning machine using rhomboid type wiper coated carbide cutting inserts. The result show that better product surface finish and longer tool life, as well as decrease cutting temperatures could be achieved by using nitrogen-oil-mist condition compared to nitrogen gas condition.

This paper discusses the utilization of the minimum quantity lubrication (MQL) method in end milling using a coated carbide tool for stainless steel and titanium alloy workpieces. The effects of MQL were mainly evaluated by tool flank temperature, cutting force, tool wear behavior, and surface roughness. In MQL cutting of stainless steel and titanium alloy at cutting speed v = 25 m/min, the tool flank temperature decreased by approximately 50 and 100 °C, respectively, in comparison with dry cutting. The effect of MQL on tool flank temperature was especially pronounced at low-cutting speeds. Conversely, the tool flank temperature in MQL cutting of titanium alloy was higher than that of dry cutting at v = 100 m/min or more. In high-speed cutting of titanium alloy, it was observed that several chips had adhered to the cutting edge of the rake face, which reached a high temperature due to the heat generated by cutting. In the cutting of titanium alloy, the tool flank temperature at both a higher feed rate and depth of cut was lower than that in high-speed cutting under conditions where the cutting efficiency was the same. Peeling of the coating film covering the tool in dry and air-blow cutting of stainless steel and titanium alloy was more pronounced than that in MQL cutting. The surface roughness was greatly improved by supplying an oil mist in low-speed cutting of stainless steel.

Experimental studies that simulate grinding of hardened alloyed steel cams have demonstrated that these workpieces can be machined with a minimum work surface heating by using highly porous cubic boron nitride wheels with the oil mist cooling or without cooling. It has been found out that for minimizing the thermodynamic stress level in the dry grinding mode it is advisable to preset machining conditions with maximum possible depth of cut and minimum workpiece rotational speed.

A number of studies have shown that compared to dry machining; MQL technique substantially enhances cutting performance in terms of increasing tool life and improving the quality of the machined parts. But, there have been a few investigations about the influence of process parameters on the results, such as MQL nozzle position and cutting parameters (cutting speed, depth of cut and feed). The current study aims to show through experiment, the effects of the above parameters on turning performance such as machining forces, surface roughness and temperature. Furthermore, this paper presents a new method to calculate average temperatures and the heat partition to the tool, workpiece and chip during MQL turning. This model also can be used for other turning operations such as dry and conventional wet turning processes. In other words, to more accurately predict machining temperatures and heat fluxes, convection heat transfer coefficient of MQL/fluid in the rake and flank faces of the tool have been made to the thermal model. The tool–chip interface temperature of turning AISI 4140 steel in which the oil mist is supplied from both nozzles to the rake and flank faces is approximately 350 °C lower than that in dry turning. If the oil mist is supplied only to rake face, the tool temperature is about 200 °C lower than that in dry turning. Additionally, in wet turning, the tool–chip interface temperature is about 300 °C lower than that in dry turning.

The paper addresses the influence of composition of highly porous cBN grinding wheels on the efficiency of grinding hardened steel with oil mist cooling and without cooling. Experimental investigations and statistical analysis of test data have demonstrated that the power intensity of the material removal process, workpiece heating, and ground surface roughness depend on the amount of cBN, pore-forming fillers, and vitrified bond in the abrasive mix composition.

The experimental platform for high-speed grease is an important tool for research and development of high-speed motorized spindle with grease lubrication. In this article, the experimental platform for high-speed grease is designed and manufactured which consists of the drive system, the test portion, the loading system, the lubrication system, the control system, and so on. In the meantime, the high-speed angular contact ceramic ball bearings B7005C/HQ1P4 as the research object are tested and contrasted in the grease lubrication and oil mist lubrication. The experimental platform performance is validated by contrast experiment, and the high-speed lubricated bearing performance is also studied especially in the relationship among the rotating speed,load and temperature rise. The results show that the experimental platform works steadily, accurate, and reliable in the experimental testing. And the grease lubrication ceramic ball bearings B7005C/HQ1P4 can be used in high-speed motorized spindle in the circular water cooling conditions when the rotating speed is lower than 40,000 r/min or the DN value (the value of the bearing diameter times the rotating speed) is lower than the 1.44 × 106 mm r/min. Grease lubrication instead of oil mist lubrication under high-speed rotating will simplify the structure design of the high-speed motorized spindle and reduce the pollution to the environment.

Different parameters (air pressure, quantity of minimum quantity lubrication (MQL) oil, position of nozzle, etc.) of an MQL system have different effects on the milling force and milling temperature. The cutting force and cutting temperature, which are closely related to lubrication and coolant, play significant roles in improving/reducing the cutting quality of a workpiece and extending/shortening the tool life. The present work investigates experimentally the effects of different MQL parameters (air pressure, quantity of oil consumed, and position of the nozzle) in end-milling titanium alloy (Ti–6Al–4V). The experimental results show that the penetrating ability of MQL oil mist has a significant effect on the milling forces and milling temperatures. When the values of air pressure and spraying distance were either too large or too small, it is not good for oil mist to penetrate into the contact zones. The spraying angle of the nozzle position has a minimal impact on the penetration ability. Conversely, the amount of oil delivery is the most important part of MQL application. The minimum quantity of oil consumption can be obtained. The results will help to select optimum MQL parameters in end-milling titanium alloy.

Promising alternatives to conventional dry and fluid coolant applications are minimum quantity lubricant (MQL) or near dry grinding. Despite several researches, there have been a few investigations about the influence of MQL parameters on the process results, such as oil flow rate, air pressure, MQL nozzle position and distance from the wheel–workpiece contact zone. The current study aims to show through experiment and modeling, the effects of the above parameters on grinding performance such as grinding forces and surface roughness. The results show that the setting location of the nozzle is an important factor regarding the effective application of MQL oil mist. It has been shown that optimal grinding results can be obtained when the MQL nozzle is positioned angularly toward the wheel (at approximately 10–20° to the workpiece surface). In addition, it is found that the efficient transportation of oil droplets to the contact zone requires higher mass flow rate of the oil mist towards the grains flat area and longer deposition distance of an oil droplet. Applying the new setup, considerable reduction in the grinding forces and surface roughness has been achieved.

Respiratory problems are observed in machinists using soluble metalworking fluid (MWF). Evidences suggest that these problems could be related to the aerosolized microorganisms and their byproducts from MWF. To establish MWF aerosol exposure thresholds and to better understand their effect on human health, these aerosols must be fully characterized. This article evaluates airborne microorganisms and aerosols from soluble MWF in the working environment. Air quality parameters (endotoxin levels, culturable airborne microorganisms, fluid mist, inhalable dust and air exchange rates) were evaluated at 44 sites, in 25 shops in Quebec, Canada. Microorganism concentrations were also measured in MWF. Culturable airborne bacteria concentrations were low, ranging from 1.2 x 10(1) to 1.5 x 10(3) CFU (colony forming units) m(-3), even for metalworking fluid highly contaminated by bacteria (up to 2.4 x 10(9) CFU mL(-1)). Inhalable dust varied between0.1 to 2.6 mg m(-3), while air exchange rates were mostly below the standard (4 h(-1)) for this type of workplace, between 0.6 to 14.2 h(-1). Only nine of 44 sites respected the suggested minimum value for air exchange rates. Fluid mist ranged from 0.02 to 0.89 mg m(-3), which is below the threshold limit value (TLV) (ACGIH) of 5 mg m(-3). Airborne endotoxin concentrations ranged from undetectable to 183 EU m(-3) (endotoxin units), showing no correlation with airborne microorganisms or inhalable dust. Most workstations respected the suggested minimum values for fluid mist and showed low concentrations of airborne endotoxin, culturable microorganisms and inhalable dust despite fluid contamination, even when air exchange rates were below the recommendations. Airborne Pseudomonas pseudoalcaligenes was recovered from many sites at significant concentrations. Health-associated risks following exposure to this microorganism should be further investigated.

Cold air cutting is a kind of environmetnally friendly cutting technology. The present study investigated the influence of cold air and cold air with oil mist on cutting temperature, cutting force and tool wear in the machining of Cr12 tool steel. For comparision, dry and flood coolant was also used as the cooling/lubrication conditions in the experiments. The findings of the study show that cold air with oil mist was the most effective cooling/lubrication condition in reducing the cutting temperature, cutting force and tool wear during the machining of Cr12 tool steel.

Environmentally conscious hard turning and technology have placed increasing importance on the machining process. Cutting fluids have a significant impact on the environment, thus numerous research works are being performed to minimize their use. However, tool wear is very severe in hard turning cemented carbides without the use of cutting fluids. In this research, the effects of dry and wet cutting methods (vegetable oil mist and mineral oil) and tool material on cutting resistance and wear characteristics of cutting tools were experimentally investigated to study the possibility of creating an environmentally conscious hard turning of cemented carbides. Mist and wet cutting of the cemented carbides using poly-crystalline diamond (PCD) cutting tools were adopted to investigate how tool wear on the basis of micro-cutting in the Scanning Electron Microscope (SEM) can be reduced. Additionally, the poly-crystalline cubic boron nitride (PcBN) and the usual cBN cutting tools were compared with the PCD cutting tools.

Applying cutting fluid in a metal-cutting process can reduce the rate of tool wear and improve surface quality. However, cutting fluid has negative effects on the working environment and the use of cutting fluid also increases the total production cost. Therefore, there is a need to reduce the use of cutting fluid during machining. To serve that purpose, a minimal-cutting-fluid technique was studied. In the present work the cutting fluid was applied in a form of a high-velocity, narrow, pulsed jet at a rate of 2 ml/min. The performance of machining with pulsed-jet application was studied in high-speed milling of hardened steel, compared to dry machining and machining with flood application. The results clearly show that compared to dry machining and machining with flood application, machining with pulsed-jet application lowers cutting forces, reduces tool wear, increases tool life, and improves surface roughness, especially when machining with high cutting velocity. Moreover, the amount of cutting fluid consumed at the rate of 2 ml/min is a drastic reduction compared to flood application. Also, no harmful oil mist is generated during the pulsed-jet application. In conclusion, the pulsed-jet application can be applied to milling process of hardened steel using ball end mills; it reduces the negative effects to the environment, improves machining performances, and consequently reduces total production cost.

Minimum quantity lubrication (MQL) machining is one of the promising solutions to the requirement for decrease in cutting fluid consumption. This paper describes MQL machining in a range of oil consumption

Environmentally conscious hard turning and technology has placed more importance on the machining process. In this research, the possibility of environmentally conscious hard turning of cemented carbides was studied. The effects of cutting methods of dry and wet (vegetable oil mist, and mineral oil) and work material on cutting resistance and wear characteristics of cutting tools were experimentally investigated. The turning and micro-cutting process in SEM was carried out by using four kinds of tungsten carbides with the PCD cutting tools. Specifically, an emphasis was put on the effect of WC and Co additives in four kinds of cemented carbides on machinability and tool wear characteristics. The tool wear width and the cutting resistances were measured, and the worn flank was observed.

In this study, the effects of dry, oil mist and wet cutting methods were investigated in turning wear resistant cemented carbides to achieve a systematic understanding of the machining characteristics of cutting and tool wear in environmentally conscious machining. The turning and orthogonal cutting were carried out using the PCD tool. The main results obtained are as follows: (1) In mist or wet cutting, the tool wear was effectively reduced on the flank where the thickness of the removal stock was large, due to the lubricating property. (2) In mist or wet cutting, the residual stock was increased for the lubricating property. Therefore a removal of grains contained in the cutting tool was suppressed and the tool wear was not severe. (3) The flank angle in the worn tool edge became negative, and the magnitude of that angle increased as the thickness of removal stock became large. In mist or wet cutting, in the tool edge where the thickness of removal stock was small, the magnitude of that angle became smaller than that in dry cutting, resulting in an increase of the tool wear width.

The tribological action of MQL media and atmospheric carrier gases was investigated using controlled atmosphere cutting apparatus. The investigation demonstrated their adsorption behavior onto metal surfaces was in close connection with the cutting performance of a lubricant synthetic ester and carrier gases in practical MQL machining. In particular, the presence of oxygen resulted in unfavorable cutting phenomena in MQL machining of aluminum. A unique technique of MQL media treatment was further proposed to prepare oil mist sprays containing microdroplets of water. This advanced technique provided some possibilities of improving the tribological action of MQL media in machining of aluminum.

In drilling, the temperature of the cutting edges of a drill is measured using a two-color pyrometer with an optical fiber. A cemented carbide drill with a diameter of 10 mm is used as a cutting tool, and carbon steel, cast iron and aluminum die-cast alloy are used as work materials. The temperature distribution along the cutting edge of a drill is measured and the influence of spindle speed and feed rate on the tool temperature is investigated. The maximum tool temperature is observed during the drilling of carbon steel. The effect of oil mist supplied from oil holes in the drill on the tool temperature is examined and the result is compared to that in turning and end milling. The temperature reduction in oil mist turning is approximately 5%, while in oil mist end milling it is 10–15% and that in oil mist drilling is 20–25% compared to the temperature in dry cutting.

U radu se predstavljaju rezultati istraživanja utjecaja uvjeta stvorenih djelovanjem emulzijske i uljne izmaglice na oblik strugotine i površinsku hrapavost nehrđajućeg čelika X10CrNi18-8 tijekom tokarenja. Uspoređivane su sljedeće vrste obrade: na suho, hlađenje MQCL metodom (minimalne količine maziva za hlađenje), hlađenje MQL metodom (minimalne količine maziva). Ispitivanje je provedeno u dva stadija. U prvom je određen utjecaj protoka mase aktivnog medija na oblik strugotina i Ra i Rq parametre hrapavosti obrađivane površine. U drugom je stadiju trebalo odrediti utjecaj MQL i MQCL metode na izabrane indekse postupka obrade u odnosu na obradu na suho kao funkcije promjenljive brzine rezanja. Ustanovljeno je da je, u MQL i MQC uvjetima, područje stvaranja elementarnih strugotina i onih u obliku kratkih spirala šire, u usporedbi s tokarenjem na suho. S povećanim protokom mase emulzije i ulja, stvaraju se zamršene strugotine. Hlađenjem MQL i MQC metodom dolazi do smanjenja vrijednosti izabranih parametara hrapavosti za 2 % do 42 % u usporedbi s obradom na suho., The paper presents the results of investigation of the influence of conditions of forming emulsion and oil mist on the chip shape and surface roughness of X10CrNi18-8 stainless steel during turning. In the tests, the following machining operations have been compared: dry machining, cooling by the MQCL (Minimal Quantity Cooling Lubricat) method, cooling by the MQL (Minimum Quantity Lubricat) method. The tests have been performed in two stages. In the first stage, the influence of the mass flow of the active medium on the chip shape and on the Ra and Rq roughness parameters of the machined surface have been determined. The purpose of stage two was to determine the influence of the MQL and MQCL method on the selected indices of the machining process as compared to dry machining as a function of variable cutting speed. It has been found that, under MQCL and MQL conditions, the area of formation of elemental chips and ones with the shape of short spirals is wider as compared to dry turning. With increased mass flow of emulsion and oil, tangled chip is formed. Cooling by the MQCL and MQL method results in reduction of the selected roughness parameter values by 2 % to 42 % as compared to dry machining.

High-speed machining of titanium alloys generates high cutting temperature in the cutting zone, which decreases tool life rapidly. So the improvement of the tool life in the high-speed machining of titanium alloys very much depends on the effectiveness of the cooling/lubrication provided. In this paper, coated cemented carbide tools were used in high-speed end milling of Ti-6Al-4V. Experiments were conducted under various cooling/lubrication conditions to find the optimal cooling/lubrication condition to improve the tool life. Dry, flood coolant, nitrogen-oil-mist, compressed cold nitrogen gas (CCNG) at 0, and −10 °C, and compressed cold nitrogen gas and oil mist (CCNGOM) as the cooling/lubrication conditions were studied. For this research, a new cooling system was used to lower the temperature of compressed nitrogen gas. The experimental results show that the cooling/lubrication condition for CCNGOM provided the best tool life among all the cooling/lubrication conditions employed. SEM analysis was carried out on the worn tools to determine tool failure modes and wear mechanisms. Flank wear was the dominant failure mode under the cooling/lubrication conditions, including dry, nitrogen-oil-mist, CCNG and CCNGOM. Excessive chipping at the cutting edge and fracture on the flank face were responsible for tool failure under flood coolant condition. Analyses based on SEM suggest that diffusion wear and thermal fatigue wear were the predominant wear mechanisms of the coated tools under the cooling/lubrication conditions employed.

The performance of minimum quantity lubrication (MQL) in high-speed cutting was evaluated in grooving 0.45%C carbon steel with a carbide tool coated with TiC/TiCN/TiN triple coating layers. MQL with supplying vegetable oil at a small and constant rate of 7 ml/h reduced the corner and flank wears more effectively than a solution type of cutting fluid at high cutting speeds of 4 and 5 m/s. In MQL grooving, the wears decreased drastically with increasing the pressure of air supply. This suggested that the air supply took an important role in transporting the oil mist to the interface between the flank wear land and machined surface. Then, a controlled oil mist direction (COD) tool was devised and its performance was proved to be high at a reduced rate of oil supply.

In this paper, the influence of oil mist on the tool temperature in cutting is investigated experimentally. The turning of a carbon steel with oil mist applied is performed, and the temperature of the alumina tool at the tool-chip interface is measured using a two-color pyrometer. The tool temperature in dry cutting at a cutting speed of 300 m/min is ∼1060°C, but it is ∼1000°C when oil mist is supplied. In intermittent turning, the oil mist has more effect on the tool temperature because it is supplied more efficiently to the tool-chip interface. In end milling with the oil mist applied, the tool temperature at the flank face is ∼580°C at a cutting speed of 400 m/min, though in dry cutting it is ∼660°C.

本論文では, 超耐熱合金であるインコネル718への環境対応型切削加工技術を確立することを目的とし, 各種材質の工具チップを用い, 逃げ面およびすくい面方向からクーラント, エアーおよびオイルミストを吹きつけながら旋削を行い, これらが工具寿命, 仕上げ面粗さ, 加工寸法に及ぼす影響について実験的に明らかにした.

Ferritic spheroidal graphite cast irons generally exhibit intergranular fracturing even if the specimens are strengthened by silicon in solid solution when tested under wet conditions. The maximum area fraction of intergranular fracture is closely related to the microstructural feature and ambient aqueous environment that caused the deterioration in vibration fracture resistance. In spite of the increasing silicon content, experimental evidence confirms the overall D-N curves can be generalized into three characteristic regions. Intergranular cracks initiated in the vicinity of the nodular graphite; the existence of nodular graphite acting as porosity should be considered as a dominant microstructural factor on the initiation of intergranular fractures. It should be noted that the intergranular cracks can be prevented, resulting in better vibration fracture resistance, when a specimen is covered with oil film. Based on experimental results, when the silicon content is increased, the vibration fracture resistance in general will be improved for all specimens whether they are tested in oil mist, air or aqueous environments. In particular, when the deflection amplitude is fixed, the vibration fracture resistance can be significantly raised for a high silicon sample (4.4Si).

The measurement of oil mist derived from metalworking fluids formulated with light mineral oils can be highly inaccurate when using traditional filter sampling. This is due to evaporation of oil from the filter. In this work the practicability of an alternative approach measuring total oil mist and vapor was investigated. Combinations of inhalable particle samplers with backup sorbent vapor traps and standard vapor sampling on pumped and diffusive sorbent tubes were evaluated with gravimetric, infrared spectroscopic, and gas chromatographic analytical methods against the performance requirements of European Standard EN 482. An artificial aerosol was used to compare the methods against a reference method of filter sampler in series with three impingers. Multi-orifice samplers were used with standard 8-mm diameter charcoal tubes at 2 L/min without any signs of channelling or significant breakthrough, as were conical inhalable samplers with XAD-2 tubes at 1 L/min. Most combinations of samplers had a bias of less than 3 percent, but solitary pumped charcoal tubes underestimated total oil by 13 percent. Diffusive sampling was affected by impaction of mist particles and condensation of oil vapor. Gravimetric analysis of filters revealed significant potential sample loss during storage, with 4 percent being lost after one day when stored at room temperature and 2 percent when refrigerated. Samples left overnight in the balance room to equilibrate lost 24 percent. Infrared spectroscopy gave more precise results for vapor than gas chromatography (p = 0.002). Gas chromatography was less susceptible to bias from contaminating solvent vapors than infrared spectroscopy, but was still vulnerable to petroleum distillates. Under the specific test conditions (one oil type and mist particle size), all combinations of methods examined complied with the requirements of European Standard EN 484. Total airborne oil can be measured accurately; however, care must be taken to avoid contamination by hydrocarbon solvent vapors during sampling.

This paper discusses the application of an eco-grinding system using a mixture of compressed cold air and vegetable oil. The feasibility of the system was assessed using the surface grinding of plain carbon steel 1045 with a BWA60MVA1 wheel. The investigation showed that cold air can be used to suppress surface burning under certain material removal rates and has an advantage of reduced grinding forces. With the addition of very small amount of vegetable oil, a larger depth of cut can be performed without burning while keeping a good grinding quality. Grinding chips were of lamellar and leafy shapes, indicating a shearing mechanism of chip formation. There was no significant difference in subsurface hardness of the components ground with coolant or with cold air and oil mist (CAOM), although the latter showed a stronger dependence of surface residual stresses on the depth of cut due to the limited cooling capacity of CAOM.

Objectives. To determine whether exposure to five different occupational substances contributes to respiratory symptoms in aluminium smelter workers. Methods. A cross-sectional survey of 1,615 male employees of two Australian aluminium smelters was conducted in 1995. Subjects underwent spirometry and were asked about respiratory symptoms and the relationship of those symptoms to work. Their job histories were combined with a task exposure matrix to produce individual quantitative measures of cumulative exposure to fluoride, sulphur dioxide, inspirable dust, the benzene-soluble fraction of coal tar pitch volatiles (BSF), and oil mist. Results. After adjusting for smoking and age, we found that subjects with the highest cumulative exposure to fluoride (>0.16 mg/m3 years) and inspirable dust (>2.9 mg/m3 years) were two to four times more likely to report work-related wheeze and chest tightness than were unexposed subjects. Lower prevalence ratios for the same symptoms were seen with sulphur dioxide and BSF. Levels of lung function decreased slightly with exposure to oil mist, but not with cumulative exposure to other substances. Conclusions. This study suggests that the relevant causative agents for respiratory symptoms in aluminium smelters are fluoride and inspirable dust.

Environmental and cost adaptabilities of machining with the minimum quantity of lubricant (MQL) machining are first presented. Then, tribology in MQL machining is to be described in fine detail for those readers who are not quite at home in the tribological mechanisms in machining. Next, MQL machining technologies shall be reviewed with regard to oil mist generation, milling, turning, and drilling. Finally, machining with a tiny amount of lubricant of less than 1 ml h − 1 , or micro-MQL machining, and future-oriented MQLs shall briefly be introduced, followed by the concluding remarks of this chapter.

Sampling was conducted in 79 small machine shops to assess airborne exposures to metalworking fluids (MWFs). Measured exposures were compared with data from the literature and exposure criteria currently recommended by the National Institute for Occupational Safety and Health and the Occupational Safety and Health Administration MWF Standards Advisory Committee. Sixty-two percent of 942 personal samples collected were less than the recommended exposure limit (REL) of 0.50 mg/m3 for total particulate. However, at least 1 sample exceeded the REL in 61 of the 79 facilities studied; 100% of the samples collected in 10 shops were greater than the REL. Similar trends were found for thoracic particulate exposures where 75% of 238 samples were below the thoracic particulate REL of 0.40 mg/m3. The ratio between thoracic and total particulate for 238 paired samples was 0.55 (r2=0.73). Workers exposed to straight fluids had the highest exposures (GM=0.67 mg/m3) when compared with workers exposed to other classes of MWFs. The highest exposures were measured for grinding and hobbing (GM=0.67 and 0.60 mg/m3, respectively). Measurements using personal impactors indicated that particle size distributions of MWF aerosols had an average mass median aerodynamic diameter of 5.3 microm. Straight oils and soluble fluids tended to be associated with larger particles than were other fluid types; grinding and turning produced the largest particles, whereas hobbing resulted in the smallest. In general, exposures were similar in magnitude and particle size to those previously reported in large automotive plants. Therefore, workers in these small shops may have risks of adverse health effects similar to those demonstrated in the automotive industry.