Lubrication Environment Research Articles

Environmentally friendly drilling of intermetallic titanium aluminide at different aspect ratio

There is an increasing attempt to implement green manufacturing in almost all fields of engineering. Minimum quantity lubrication is considered as a relevant and promising candidate in promoting environmentally friendly machining since it bridges the gap between dry and wet condition. It can keep the work material temperature lower than those in a dry environment by reducing the frictional heat generated during the machining processes and deliver certain amount of cooling effect in the tool-workpiece contact region. The present work is focussed on the drilling of this intermetallic titanium aluminide alloy at low and high aspect ratio under minimum quantity lubrication environment and is compared with dry and wet environments. The feasibility of using minimum quantity lubrication is evaluated based on the thrust force and torque. Burr, being an important factor in drilling have also been studied, and the findings show the presence of uniform burr in minimum quantity lubrication condition. In a complex process like drilling, chip flow is restricted only through the flutes and hence there occurs transformation of chip shape, chip thickening and changes in force and torque as the depth of hole progresses. In order to study these changes peck drilling was adopted and the depth at which the transformation of chip shape occurs is identified.

RETRACTED: Optimization of machining parameters and cutting fluids during nano-fluid based minimum quantity lubrication turning of titanium alloy by using evolutionary techniques

Abstract In metal cutting operations, the proper selection of machining parameters and cutting fluids affects the cutting mechanism, which is associated to the cutting forces, tool wear, cutting temperature and surface finish of the machined part. For this purpose, the effect of cutting fluid types is investigated as a function of three machining parameters (cutting speed, feed rate and approach angle) on responses (cutting force, cutting temperature, tool wear and surface roughness) while turning titanium alloy under Nano-Fluid based Minimum Quantity Lubrication (NFMQL) environment. The experiments are conducted based on response surface methodology and a combined objective function using the output parameters was generated. Further, the parametric optimization was performed through two evolutionary techniques, i.e., Particle Swarm Optimization (PSO) and Bacterial Foraging Optimization (BFO). The results are analyzed and also compared with the traditional desirability function approach technique.

Wear behavior of PVD TiN coated carbide inserts during machining of Nimonic 90 and Ti6Al4V superalloys under dry and MQL conditions

This paper mainly deals with the tool wear characteristics of PVD TiN coated carbide inserts during turning of two aerospace alloys (Nimonic 90-Ni based alloy and Ti6Al4V- Ti based alloy). To fulfill the sustainability criteria the experiments have been conducted under dry and minimum quantity lubrication environment (MQL). To further enhance the effectiveness of MQL the specially prepared biodegradable emulsion of sunflower oil in water has been used as the cutting fluid. For better understanding of the cutting characteristics the same set up is employed for both the aerospace alloys. Due to high chip tool contact during machining of Nimonic 90, more intense nose wear has been observed over the cutting inserts. High strength of Nimonic 90 as compared to Ti6Al4V also resulted in high notch wear over the tool inserts during turning. The use of biodegradable emulsion under MQL mode has produced better results for Ti6Al4V. The attributes like good wettability and high penetration provided significantly less flank wear and rake wear during machining of Ti alloy under MQL condition. Furthermore due to the controlled wear during turning of Ti6Al4V, the cutting forces were found to be stable and significantly low as compared to Nimonic 90.

The effects of concentration of cutting fluids on machining performance during end milling of steel St60

Lubrication plays an important role in increasing efficiency of a machining operation when high temperature and friction are two major issues. In the current study, two various types of lubricant SAE10 oil and vegetable oil were tested in end milling of a steel St60 block and the results were compared with dry condition. To have a clear understanding of the lubrication effects, three different concentrations for each lubricant using proper solvent were made and surface roughness (Ra), machining power and tool wear were compared in three distinct machining conditions. These conditions differ in depth of cut and machining speed (in a constant feed rate) according to real application. Among the lubrication environments, SAE10 assisted machining in low spindle speed showed better results. Moreover, it was observed that dry machining and machining in presence of vegetable oil especially in the cases of cutting fluids with lower oil content in fairly high tool velocity lead to process productivity improvement. Finally, dry machining resulted in more wear on cutting tool.

К РАСЧЕТУ ПРОСТРАНСТВЕННОГО РАСПРЕДЕЛЕНИЯ ДАВЛЕНИЙ В СЖИМАЕМОМ СМАЗОЧНОМ СЛОЕ ЦИЛИНДРО-ПОРШНЕВОГО СОПРЯЖЕНИЯ

The description of the numerical solution of a task of lubricant of a side surface of the piston of the internal combustion engine based on model of a current of the compressed lubricant environment is provided. In work main assumptions of the theory of hydrodynamic lubricant are accepted, at the same time influence of thermal load of the piston and accounting of cavitation and foaming of lubricant is carried out by introduction to model of the determining temperature and parameters of gas content. Two methods of linearization of a task are considered, first of which uses the iterative procedure of the decision on the basis of Newton's method, and in the second the idea of approximating linearization of the numerical scheme is used, at the same time rectangular ranges of definition of a task allow to receive the decision in the direction of spatial coordinates of an object by method of the variable directions. Spatial distributions of pressure in a layer at reciprocating motion of the piston are received and its integrated characteristics, influence of gas content and parameters of a profile on characteristics of a lubricant layer is estimated. The comparative analysis of each of the used approaches is carried out. The efficiency evaluation is executed by comparison of size of time of the solution of a task before accomplishment of conditions of frequency with an identical accuracy shows some efficiency of use of the iterative procedure – time of the solution of a task on 25...30 % are less, than at alternative approach. Also, indirectly, tells about efficiency of the iterative decision also an interval of parameter values of gas content in case of which convergence of the numerical procedure of the decision without change of steps of a grid is provided. However, simplicity of implementation of the numerical scheme on the basis of approximating linearization, ease of ensuring stability of a numerical task taking into account constantly increasing opportunities of computer facilities allow to recommend this approach. The conclusion about need of “calibration” of model on the known type of the engine is drawn that will provide elimination of the arbitrary behaviour, which is available in it in the form of the determining temperature and gas content and will make possible calculation of future modifications of a design of the cylinder-piston group of the chosen type

チャンネル型微細溝を有したPVD硬質厚膜の形成とその摩擦特性

A PVD thick film forming technique has been developed to produce a channel-type microgroove exhibiting a lubricant retention effect. This technique uses hard Cr plating with a channel-type microgroove prepared by etching as a PVD film underlayer. Surface morphology of the hard Cr plating with a channel-type microgroove is inherited by the PVD film. This study clarified that this technique can form a channel-type microgroove that penetrates from the underlayer surface to the surface of a PVD thick film with thickness greater than 10 μm. In Scratch tests and Rockwell indentation tests, the CrN thick film with the channel-type microgroove showed a higher adhesion than the conventional CrN thick film. In Pin-on disks test under a liquid paraffin and MoS2 lubricant environment, the CrN thick film with the channel-type microgroove maintained a low friction coefficient without seizing in conditions where general CrN thick film seized to the pin. In Cupping tests, the CrN thick film with the channel-type microgroove showed a lower drawing force and a higher lubricant retention capability than the conventional CrN thick film.

Machining Parameters Optimization of Titanium Alloy using Response Surface Methodology and Particle Swarm Optimization under Minimum-Quantity Lubrication Environment

The present paper depicts an application of response surface methodology (RSM) and particle swarm optimization (PSO) technique for optimizing the machining factors in turning of titanium (Grade-II) alloy using cubic boron nitride insert tool under minimum quantity lubricant (MQL) environment. The three machining factors, i.e., cutting speed (Vc), feed rate (f) and side cutting edge angle (approach angle π), are designed as three factors by using RSM design, which is withal subject to several constraints including tangential force (Fc), tool wear (VBmax), surface roughness (Ra) and tool-chip contact length (L). The multiple regression technique was used to establish the interaction between input parameters and given responses. Moreover, the results have been presented and optimized process parameters are acquired through multi-response optimization via desirability function as well as the PSO technique. The lower values of Vc (200 m/min), f (0.10 mm/rev) and higher values of ϕ (90°) are the optimum machining factors for minimizing the aforementioned responses. It was also observed that the selected responses predicated on PSO are much closer as that of the values acquired in view of the desirability function approach. Henceforth, PSO has the potential to cull appropriate machining factors while turning titanium (Grade-II) alloys under MQL conditions.

Flank Wear Characterization in Aluminum Alloy (6061 T6) With Nanofluid Minimum Quantity Lubrication Environment Using an Uncoated Carbide Tool

This study is focused on the categorical analysis of flank wear mechanisms in end milling of aluminum alloy AA6061 with minimum quantity lubrication (MQL) conditions using nanofluid. Wear mechanisms for the water-based TiO2 nanofluid with a nanoparticle volume fraction of 1.5% are compared with conventional oil-based MQL (0.48 ml/min and 0.83 ml/min) using an uncoated cemented carbide insert. Micro-abrasion, micro-attrition, and adhesion wear leading to edge chipping are identified as the main wear mechanisms. Aluminum deposits on the tool flank surface are observed. Results show that the water-based nanofluid shows potential as a capable MQL cutting media, in terms of tool wear, replacing the conventional oil-based MQL.

Environmental performance evaluation of different cutting environments when milling H13 tool steel

Limited availability of natural resources and the negative environmental burden of industrial processes are driving environmental awareness and resource efficiency improvements in manufacturing. Issues of concern in mechanical machining arise from the significant use of electrical energy and oil-based coolants/lubricants. Process innovation through high speed machining has enabled manufacturing cycle times to be reduced and in some cases promoted dry machining or the use of minimum quantity lubrication. However, the environmental assessment of these innovations has hardly been explored. In this study, the environmental benefits of minimum quantity lubrication environments in machining tool steel at transition speed regime through electrical energy consumption were evaluated and compared to its competitors. The work then assessed the energy using a customized electrical energy model proposed in this study and hence the environmental performance in the process level. Tool life might be of concern in selecting between MQL, dry machining and flood machining, however, this study found that in respect to total energy requirement and environmental benefits, MQL is more promising than flood machining. The work is fundamentally important in assessing the direct energy consumption and the environmental credentials of machining processes.

Wear Characteristic of Stainless Steel 304 Sliding against Cast Iron under Lubrication Environment of Palm Biodiesel Fuel

The used of palm-biodiesel fuel in automotive industry is increasing rapidly nowadays. Among the reasons are high efficiency modern fuel injection system of diesel engines and the shortage of petroleum diesel fuel from fossil resources. Among the parts affected by the fuel switch are fuel pumps components, including the fuel injection needle. Those components, working under the lubrication environment of the fuel, have to be prevented from excessive wear to maintain their high performances. This paper discussed the wear characteristics of stainless steel 304 sliding against cast iron under the lubrication environment of palm-biodiesel fuel with the concentration of 7.5% palm methyl ester in the petroleum diesel fuel. The material pair is chosen because of their widely used as mechanical components. The tests were conducted using a ball on disk tribometer. The results show that wear of the stainless steel ball is smaller in the environment with the presence of palm methyl ester content in the diesel fuel compared to that in the environment without the presence of the palm methyl ester content. The results suggested that palm-biodiesel fuel is favorable in decreasing the wear of the material.

A Study of Minimal Quantity Lubrication with MWCNTs in Turning of AISI 304L Steel

This paper proposes a new lubricant environment when MWCNTs was used in MQL for AISI 304L in the turning machine. The effects of dry cutting, MQL cutting, and MWCNTs/MQL were compared to the surface roughness of work pieces, cutting temperature and the tool wear. In the past, the studies have shown that the MQL process can prolong tool life and improve surface accuracy in machining. The purpose of using MWCNTs suspensions is to increase the thermal conductivity of cutting fluid and to reduce the temperature during the cutting and decrease the thermal wear of tool simultaneously. The present study investigated the characterization of the MWCNTs was applied into MQL during the turning process of AISI 304L experimentally. The results showed that the MWCNTs will be a very good additive to MQL, not only with the benefits of improving surface roughness but also with ability of prolonging life of tool by reducing the cutting temperature in turning AISI 304L.

Elastohydrodynamic Lubrication Analysis of Point Contacts With Consideration of Material Inhomogeneity

Inhomogeneities in matrix may significantly affect the performance of mechanical elements, such as possible fatigue life reduction for rolling bearing due to stress concentration induced by inhomogeneities; on the other hand, most components operate under lubrication environment. So far the numerical algorithms to solve lubrication problems without the consideration of inhomogeneities or inclusions are well developed. In this paper, the combination of elastohydrodynamic lubrication (EHL) and inclusion problem is realized to consider the effect of material inhomogeneity on the lubrication performance and subsurface stress distribution, etc. The matrix inhomogeneity will induce disturbed displacement, which will modify the film thickness and consequently result in the change of lubricated contact pressure distribution, etc. The matrix inhomogeneity is treated as the homogeneous inclusion with equivalent eigenstrain according to equivalent inclusion method (EIM), and the disturbed displacement is calculated by semi-analytical method (SAM). While the pressure and film thickness distributions are obtained by solving Reynolds equation. The iterative process is realized to consider the interaction between lubrication behavior and material response. The results show the inhomogeneity in contacting body will greatly influence the lubricated contact performance. The influences are different between compliant and stiff inhomogeneity. It is also found that different sizes and positions of inhomogeneity can significantly affect the contact characteristic parameters.

Antifriction properties increasing of ceramic MAO-coatings

In the past years, the most promising technology of producing ceramic coatings is a method of microarc oxidation. This method is characterized by universal properties of surface layer, which combines high-wear resistance, corrosion resistance, heat, and erosion resistance. The aim of the present work is to improve the tribological properties of microarc oxidation coatings using additional filling layer of coating as a thin film of polymer material. Ultra-high-molecular weight polyethylene was chosen as a polymer material. This composition material was tested under different friction conditions and showed significant decrease in friction coefficient for many friction pairs in different lubricant environment. The proposed technology of antifriction characteristics improvement of microarc oxidation coatings will significantly expand their application.

Attaining High Levels of Bearing Performance with a Nanocomposite Diamond-Like Carbon Coating

Mechanical systems that operate in agricultural, construction, and mining and mineral processing applications typically operate in debris-containing and thin-film lubrication environments. Consequently, the lives of rolling element bearings in these applications are often limited by surface fatigue arising from thin-film lubrication, damage from the debris, false brinelling, and scuffing. Traditional approaches utilizing specialized heat treatments and lubricant additives can sometimes delay the onset of early raceway fatigue, but even in these cases the actual bearing life is still usually less than that for which the bearing was designed. Bearings with a highly durable W-aC:H coating applied to the rolling elements are shown to have significantly longer fatigue lives in debris-containing and thin-film lubrication environments and are highly resistant to wear from false brinelling and scuffing.

Wear of UHMWPE from sliding, rolling, and rotation in a multidirectional tribo-system

For total knee replacements (TKR), wear of the ultra-high molecular weight polyethylene (UHMWPE) tibial bearing surface is a frequent cause for long term revisions and failure. In order to better understand the link between cross-shear motions and wear in TKR, a custom multidirectional tribo-system was developed and used to investigate the individual and combined effects of the different motions in TKR: two-directional (2D) sliding, rolling, and rotation, for a total of eight separate kinematic conditions. The wear rates and wear factors for these different motions were measured and compared, and the surfaces of the wear scars were examined to elucidate wear mechanisms in UHMWPE for a range of kinematic conditions. To mimic the tribological conditions in a TKR, polished cobalt–chromium (CoCr) spheres were articulated against flat, polished UHMWPE disks with physiologically relevant loading, speed, and lubrication environments. Wear factors of UHMWPE were found to have a range between 0.3 and 8.7×10−6mm3/(Nm). The higher values corresponded to increasing motion complexity and cross-shear, with the "figure 8 shape"sliding path having the greatest effect. These results indicate that knee kinematics may have a significant effect on the longevity of TKR and should not be neglected when designing TKR.

地球環境と潤滑

地球環境と潤滑

Corrosion Assessment and Characterization of Aerospace-Bearing Steels in Seawater and Ester-Based Lubricants

The corrosion behavior of bearing steels was screened using potentiodynamic scans in seawater. The results of electrochemical testing provided a relative ranking of the bearing steels when tested in aqueous chloride-containing solution. The corrosion behavior of bearing steels in the lubricant environment has been observed to be quite different than in aqueous solution. Both the amount of water contamination in oil and chloride content of the water impact the observed corrosion rates in oil-water mixtures. All steel compositions tested demonstrated localized corrosion damage when exposed to oil with water added; however, inherently less corrosion-resistant alloys had more widespread shallow attack, whereas higher Cr-containing alloys displayed more localized severe attack. The mechanism of corrosion in the two-phase, oil plus aqueous phase system appears to be controlled by an aqueous corrosion process dependent on steel microstructure and emulsified or free water and likely limited by oxygen availability...

Air jet assisted machining of nickel-base superalloy

Nickel-base superalloy has various excellent properties. However, in machining of this alloy, acceleration of tool wear results in short tool life and deterioration of the surface integrity. Therefore, it is difficult to conduct high-speed machining of this alloy. In this study, nickel-base superalloy was finish-turned with a coated cemented carbide tool at higher cutting speeds. A new lubrication method called air jet assisted (AJA) machining was applied for improving cooling and lubrication environment. The results of cutting experiments showed that the air jet assistance to the conventional wet machining extended the tool life to a certain extent effectively. Flow of cutting fluid was visualized through computational fluid dynamics analysis and improvement of cooling environment and tool life by means of air jet assistance in AJA machining were discussed from the heat transfer at the tool flank face.

OS2127 ホワイトメタルの種々の潤滑条件における摺動摩耗メ力二ズム

It is necessary to grasp wear properties of the materials under various kinds of lubrication conditions. Pin-on-disk wear tests were conducted for the above purpose using WJ2 type, i.e., lead free white metal. The lubrication environments were top water, two kinds of lubricating oil. The test was also conducted in atmosphere for a comparison purpose. The influence of the lubrication condition on the wear rate was investigated, and its mechanism was discussed on the basis of the experimental results.

Tribological behavior of an ultrahigh molecular weight polyethylene in lubricated environments

AbstractThe wear and friction performance of GUR 1020 grade ultrahigh molecular weight polyethylene (UHMWPE) polymer was studied in distilled water, HASS (Hank’s balanced salt solution) and several protein lubrication environments. Wear tests were carried out using polymer pin -on AISI 304L stainless steel disc apparatus. Tests conditions were room temperature, 40N, 80N and 120N applied loads and 0.5 m/s sliding speed. For the range of load and speed value of this work, the coefficient of friction and wear rate for UHMWPE polymer decreases with the increase in applied load values. The coefficient of friction is highest and the specific wear rate values is lowest under HASS +HA solution lubricant. The average specific wear rate values for UHMWPE polymer under distilled water and HASS+HA (Hank’s balanced salt solution with Hyaluronic acid) lubrication conditions are in the order of 9x10-15 m2/N and 3x10-15 m2/N respectively. The wear mechanism includes abrasion and adhesive processes.