Metalworking emulsions from industrial vegetable oils

In the present work, an attempt has been made to develop the indigenous formulation for metalworking lubricants by replacing mineral oils partially with non‐edible industrial oils like rapeseed and karanja oil. Metalworking formulations consist of vegetable oil, mineral oil, an emulsifier and commercial additives for better performance. Non‐edible vegetable oils such as karanja and rapeseeds are renewable, biodegradable and cheaper than synthetic fluids. The constituent vegetable oils and mineral oils were evaluated for physico‐chemical characteristics and blended as per the saponification value and viscosity requirements of the reference oils. The so formulated oils are taken as 5% oil‐in‐water emulsion and tested for lubricity, load bearing capacity, particle size distribution, wear test, weld load test and plate‐out test. Performance of all formulated oils was compared with that of the reference oils, and optimized to meet the market requirements. Copyright © 2008 John Wiley & Sons, Ltd.     

Anti‐friction,anti‐wear and load‐carrying characteristics of environment friendly additive formulation

The extreme pressure (EP), anti‐wear and friction‐reducing characteristics of some of the commercial additive formulation and individual components on which these formulations are based have been studied and compared to characteristics of the components synthesised from naturally available non‐traditional vegetable oils and cashew nut shell liquid that have been refined and partially hydrogenated to improve stability. It has been shown that individual components from sulphurised and phosphosulphurised vegetable oils, esters and hydrogenated cardanol (derived from cashews) have better anti‐wear and friction‐reducing characteristics than the sulphurised olefins and alkylaryl phosphorothioates normally used as EP and anti‐wear additives, while the load‐carrying characteristics of a number of the combination of these derivatives are comparable. It has been shown that all these formulations are rapidly biodegradable and non‐toxic in nature as compared to traditional EP, anti‐wear and friction‐reducing additives, which fill in the category of slightly toxic to harmful. It is possible to formulate energy‐efficient EP gear oils that are fully biodegradable and non‐toxic by a combination of vegetable oil‐based additives of sulphurised vegetable oils, phosphosulphurised methyl recinoleate and phosphosulphurised hydrogenated cardanol amine borate, which meet all the performance characteristics of US steel 224 eg 52100, M‐50 AISI 1010 requirements. Copyright © 2007 John Wiley & Sons, Ltd.     

Lubricant components from vegetable oils of indian origin

A number of transesterified and alkarylated derivatives have been synthesised from available vegetable oils of Indian origin. The viscosity, viscosity index, freezing points, load-carrying characteristics, friction coefficient, and thermo-oxidative stability of these derivatives as compared to highly refined hydrorefined hydrocarbon oils have been studied. It has been found that several esters of fatty acids of these vegetable oils have a high natural viscosity index, low pour points, and high thermooxidative stability, and can meet the requirements as base fluid components for energy-efficient, eco-friendly, long-drain interval, multigrade oils. These oils have markedly lower viscosities at 40°C, higher load-carrying characteristics, and lower friction coefficients than the base fluids of currently marketed multigrade oils. A 50% blend with hydrorefined hydrocarbon oils could prove highly viable. The above results clearly establish the potential for utilising these esters, either alone, or in combination with mineral oils, for formulating cost-effective high-performance, energy-efficient, and environmentally friendly lubricants. Performance characteristics of these oils as engine oils, automotive gear oils, and 2 stroke oil with conventional additives and with alternative additives are under investigation in comparison to the most advanced hydrocarbon based multigrade oil formulations of long-drain interval.     

Sulphurised vegetable oils as EP additives for industrial gear oil formulations

Renewable sources can provide, besides fuel, a wide range of feed stocks for the organic chemicals industry. Utilisation of non-edible vegetable oils and speciality chemicals has, therefore, become relevant in recent times. Sulphurisation of three triglyceride oils (karanja, rapeseed, and castor oils) and liquid wax (jojoba) has been investigated in detail in order to examine the potential of sulphurised vegetable oils for use as extreme-pressure (EP) additives for developing formulations for industrial gear oils. The capacity of these oils with respect to the uptake of sulphur, the limitations of some of the sulphurised products for use as EP additives, and the problems in developing such formulations for industrial gear oils, are discussed.     

The influence of lubricating fluid type on the properties of biodegradable greases

The lubricating ability of a grease depends on both the base oil and the thickener. As a result of their intrinsic properties and/or because of their com‐patibility with thickeners and specific additives, base fluids have different influences upon the properties of grease formulations. It is well known that mineral oils are the most widely used lubricant bases due to their inherent lubricity and lower cost, but recent environmental concern has led to consideration of the use of vegetable oils and readily biodegradable synthetic fluids as raw materials in lubricating grease formulations. As well as the base materials, the additives for biodegradable greases should also be biodegradable. This requirement limits the kind of products that may be used in environmentally friendly greases. This paper presents comparative data concerning the tribological and physico‐chemical properties of biodegradable greases formulated with certain vegetable oils, such as rape seed oil, castor oil, and soybean oil or their mixtures, and synthetic esters. The improvement of the load‐carrying properties of biodegradable greases and the antioxidative effect of some suitable additives have also been studied, and the results are presented here.     

Mixtures of vegetable oils and di‐2‐ethylhexyl‐sebacate as lubricants

Lubricants based on vegetable oils are growing in popularity in various applications. Environmentally friendly, vegetable oils and their derivatives constitute alternatives to mineral‐based lubricants. Soybean oil, sunflower oil and rapeseed oil have better viscosity indices than mineral oils and even some synthetic oils, are biodegradable and have low production costs. However, vegetable oils have disadvantages, such as poor thermo‐oxidative stability due to the carbon–carbon double bonds and poor low‐temperature properties, which limit their use as lubricant base stocks. This study describes new base‐stock oils obtained from mixture of vegetable oils and di‐2‐ethylhexyl‐sebacate synthetic oil, which become lubricants when additives are introduced. These mixtures offer a large range of kinematic viscosities, while their pour points are under −33°C and their flash points over 240°C. The copper strip corrosion test result is 1a. The diameters of wear scars measured under four‐ball testing (40dyn) are less than 1mm. A differential scanning calorimetry study and a thermo‐gravimetric study under a nitrogen atmosphere for the mixed oils are reported. In the former study two‐endothermic processes were observed between −15°C and −50°C. In the thermo‐gravimetric analysis curve the weight loss is specific for each vegetable and synthetic oil component. From these studies a higher thermal stability was observed for vegetable oils than for ester oils, and it was concluded that the mixtures of vegetable and synthetic oils of diester type are physically homogeneous mixtures. The low production cost of lubricants based on vegetable oils makes them attractive alternatives for mineral oil based lubricants. Overall the mixtures of vegetable and ester oils can be competitive base oils for environmentally friendly lubricants. Copyright © 2006 John Wiley & Sons, Ltd.     

A potential biodegradable lubricant from castor biodiesel esters

Worldwide, 12 million tonnes per year of lubricants are disposed of in the environment through leakages, exhausted gas, incorrect disposal, water–oil emulsions and so on. Some are resistant to biodegradation, representing an environmental threat. One solution to modify this situation is the replacement of mineral oils by biodegradable synthetic lubricants. Esters, whose chemical structures are similar to natural triglycerides, are excellent substitutes for mineral oils. Castor oil contains around 90% ricinoleic acid, and as a result, castor oil has a higher viscosity and a lower viscosity index, compared with other vegetable oils. This work was based on the production of biodegradable lubricant base fluids from castor biodiesel esters, using various chemical catalysts to yield products with interesting properties, such as high viscosity index and good oxidation stability, compared with mineral oils. This route to lubricants is safer, more economical and more efficient. Copyright © 2012 John Wiley & Sons, Ltd.     

Developments in the formulation and application of vegetable oil-based metalworking fluids in turning process

In the beginning, metalworking fluids consisted of simple oils applied with brushes to lubricate and cool the machine tool. As cutting operations became more severe, metalworking fluid formulation became more complex. There are now several types of metalworking fluids in the market and the most common can be broadly categorized as cutting oils or water-miscible fluids. In this paper, attention is focused on recent research work on formulation and application of vegetable oil-based metalworking fluids in turning process. In addition, the performances of various vegetable oil-based metalworking fluids based on some process parameters such as thrust force, surface roughness, temperature developed at the tool chip interface, and tool wear during turning process using different tool materials were highlighted.     

Suitable additives for vegetable oil‐based automotive shock absorber fluids: an overview

Formulation of a cost‐effective, high‐performance and eco‐friendly lubricant, largely depends on the base oil quality, then the selection of suitable additives and their proportions. Vegetable oils, identified to be eco‐friendly, renewable, future‐available and cost‐effective treasures for lubricant formulation, apart from processing, will rely much on suitable additives to meet the performance requirements for automotive shock absorber (ASA) fluids. Additives that will guarantee performance, longevity and eco‐friendliness of formulated vegetable‐based functional fluids have to be uncommonly effective, resistant to depletion, non‐toxic and highly biodegradable. Their selection in these regards will require skills and experience, which will harness the various arms of synergism as effective tools to succour the known weaknesses of the base oil. This is a review on additives that could be used in formulation of vegetable oil‐based (ASA) fluids. The outcome shows that there are customary and novel additives that are suitable for formulating vegetable oil‐based ASA fluids. Copyright © 2016 John Wiley & Sons, Ltd.     

Modification of the chemical structure of an environmentally‐friendly castor oil lubricant

Widely used mineral‐oil based lubricants are often released into the environment and cause pollution. Therefore importance is attached to developing environmentally‐friendly lubricants. Vegetable oils have been used as lubricants since ancient times. These materials, similar to synthetic esters, have better biodegradability than mineral oils. They are also renewable. Vegetable oils have some shortcomings, such as a higher pour point and a lower viscosity index than synthetic esters. They have a limited viscosity range and lower oxidative stability due to the presence of unsaturated bonds. Therefore vegetable oils as such cannot satisfy all the requirements of modern machine lubrication. In this paper, the chemical structure of natural castor oil is modified by an isomerisation reaction and by extending the carbon chain, so as to lower the pour point and improve the viscosity index. The results show that structurally modified castor oil has very good lubrication characteristics. Its viscosity at 40°C is 150 mm²/s, its pour point is −40°C, and its viscosity index is improved. The antiwear and friction characteristics are better than those of mineral oil of the same viscosity and comparable to pentaerythritol esters and diisocapryl sebacate.     

Vegetable oil derivatives: environment‐friendly lubricants and fuels

A critical appraisal is made of the applications of vegetable oils, the fatty esters complex and synthetic esters as rapidly biodegradable and non‐toxic lubricants and fuels in the developed countries of America, Europe and Asia. The criteria employed for assessing the toxicity and biodegradability of the various fluids and limits set by various state and regional organizations are reviewed. The properties of vegetable oils, fatty esters, chemically modified esters and synthetic esters relevant for performance as lubricants in various applications such as hydraulic oils, refrigeration oils, chainsaw lubricants, metalworking fluids, engine oils, two‐stroke oils, mould release lubricants, greases, gear and transmission oils vis‐à‐vis conventional mineral oils and greases for corresponding applications are compared. The advantages, such as high lubricity, viscosity–temperature relationship, low lubricant consumption, energy efficiency combined with public health, safety and environmental contamination, more than offset the disadvantages of initial costs in most of these applications. It has been suggested that modified and stabilized oils of wasteland and forest origin and other non‐edible oils and their chemically modified derivatives can be produced at relatively cheaper cost than similar oils marketed in the developed world and can be introduced in India with immense environmental and performance benefits, particularly in applications involving high environmental contamination safety and public health. When blended with highly refined diesel fuels, methyl esters can work as highly efficient environment‐friendly fuels particularly for applications in passenger transport, light commercial vehicles and generators. Copyright © 2006 John Wiley & Sons, Ltd.     

Vegetable oils as a potential cutting fluid—An evolution

A review is made here to understand the application of vegetable oils as potential metal working fluids. The study highlights the contributions from more than sixty authors on vegetable based oils as emerging environmental friendly cutting fluids. The performance of these oils as emulsions and straight oils for various materials and machining conditions are reported. The study focuses on the evolution of vegetable oils as cutting fluids in manufacturing sector, particularly, metal cutting and metal forming.It is observed that, most of the contributions are directed to develop and commercialise the cutting fluids based on vegetable oils. However, soyabean, sunflower and rapeseed seem to possess the relevant properties as a potential cutting fluid.     

Performance testing of lubricants based on high oleic vegetable oils

Owing to growing environmental concerns, vegetable oils are finding their way into lubricants for industrial and transportation applications. Vegetable oils can of Ser significant environmental advantages with respect to resource renewability and biodegradability, as well as offering satisfactory performance in a variety of applications. Synthetic ester-based fluids may also offer these advantages, however their cost can be prohibitively high. Formulating with vegetable oil does, however, present unique challenges. These are, most notably, the oxidative and hydrolytic instability and low temperature problems associated with the triglyceride. However, through advanced plant breeding techniques, vegetable oils are becoming available which exhibit excellent thermal and oxidative stability and other improved performance properties. The cost of these oils is much lower than synthetic esters, thereby making them attractive ‘environmental’ base fluids.     

Development of novel sustainable neat-oil metal working fluids for stainless steel and titanium alloy machining. Part 1. Formulation development

This paper introduces and describes the development and application of methodologies for the formulation of novel sustainable neat-oil metal removal fluids. A further paper will describe the methodologies being employed and the results of the performance benchmarking of the final fluid formulations for stainless steel and aerospace-grade titanium alloy materials. In this paper, a stepwise approach to the development of novel sustainable neat-oil metal removal formulations is described with a detailed discussion and analysis of the approach taken and the methodologies developed and applied. Two target applications were identified for cutting stainless steel and aerospace-grade titanium alloys. The key required properties of the fluids for these applications were combined with targets identified for cost, low temperature properties, kinetic viscosity (KV) and oxidative stability. Samples of base oils were obtained and characterised. The oils ranged from commodity commercial and specialist natural vegetable oils to chemically modified vegetable-oil-derived fatty acid esters and polyols. The selected oils were used to create blends which were screened for their key properties. From this work, four blends of base oils were identified for being taken forwards to the formulation screening stage. These blends represented a range of natural and modified oils blended in such a way as to achieve all of the required key properties of cost, KV, melt/pour points and oxidative stability. To determine if the oils were likely to also perform well as metal cutting fluids, they were subjected to a range of tests with and without the addition of certain additives, and their performances were benchmarked against a range of mineral oil and polyol-ester-based commercial fluids currently supplied to the target applications areas. The tests employed were: SRV, microtap and oxidation stability. The issues involved in the extrapolation of results from tribological testing to the prediction of fluid cutting performance are highlighted and discussed. From this work, one base oil blend for each of the two target applications was identified and the best performing mineral and polyol ester benchmark fluids were selected. Full-scale drilling and rigid torque tapping tests were used to refine formulations and to screen other additives identified in parallel microtap tests. The durability, oxidation stability, machine tool compatibility and misting potentials of the final formulations were also benchmarked using a range of standard and novel methodologies—this work will be described in a later paper.     

Impact of environmental contaminants on machining properties of metalworking fluids

Increased attention to metalworking fluid (MWF) management has neglected to assess the effect of continued use on the functionality of contaminated fluids. To address this, experiments have been conducted to evaluate the lubricating, cooling, corrosion inhibition, and surface roughness functionalities of metalworking fluids subjected to both extended industrial use and contamination in a laboratory setting. The results of these experiments show no reduction in any evaluated functionality for used metalworking fluids. Metalworking fluids artificially contaminated with calcium, chloride, or hydraulic oil only exhibited reduced lubricating and cooling functionality when calcium levels were so high as to cause emulsion destabilization.     

Surface integrity and part accuracy in reaming and tapping stainless steel with new vegetable based cutting oils

This paper presents an investigation on the effect of new formulations of vegetable oils on surface integrity and part accuracy in reaming and tapping operations with AISI 316L stainless steel. Surface integrity was assessed with measurements of roughness, microhardness, and using metallographic techniques, while part accuracy was measured on a coordinate measuring machine. A widely diffused commercial mineral oil was used as reference for all measurements. Cutting fluid was found to have a significant effect on surface integrity and thickness of the strain hardened layer in the sub-surface, as well as part accuracy. Cutting fluids based on vegetable oils showed comparable or better performance than mineral oils.     

Influence of humidity on the tribological performance of unmodified soybean and sunflower oils

In general, vegetable oils exhibit superior lubrication properties but lack the thermal stability of petroleum base stocks. However, vegetable oils could make an ideal candidate as a base stock for lubrication applications involving high humidity levels, such as marine and offshore applications. This study focuses on the friction and wear rate of unmodified soybean and sunflower oils in comparison with an unformulated mineral oil at various levels of relative humidity, ranging from 10% to 98% RH. It was observed that the vegetable oils retain their friction and wear reducing capabilities much better than the mineral oil at high humidity levels. This was attributed to their inherent ability to react with the metallic contacting surfaces and form multilayers of soap films. Furthermore, the soybean oil provided a superior level of wear resistance when compared with the sunflower oil at extremely high levels of relative humidity due to its lower viscosity and differences in chemical compositions. Copyright © 2011 John Wiley & Sons, Ltd.     

Study of some non-edible vegetable oils of Indian origin for lubricant application

Due to growing environmental concerns, eco-friendly processes and materials have become one of the key interests of research and in the area of tribology, natural esters are gaining popularity as lubricants. Natural esters are being used in many applications as eco-friendly lubricant base. In Europe, canola/rapeseed oil and sunflower oil are mainly used, whereas in the USA, soybean oil is in use for formulating environmentally friendly lubricants. Native and genetically modified high oleic varieties of these oils are being widely used. In the Indian scenario, since the above-mentioned oils are scarcely available for industrial applications, there is a need to look for other viable alternatives. Some candidate non-edible vegetable oils of Indian origin were selected which were unexplored or less explored in the field of lubricant application, and their suitability in lubricant application focusing mainly on physico-chemical characteristics, thermo-oxidative stability and lubrication characteristics was studied. These oils were found to be promising candidates for application in lubricants in view of their physico-chemical characteristics and better thermo-oxidative and hydrolytic stability. Copyright © 2007 John Wiley & Sons, Ltd.     

Development of ecologically responsive lubricants

As a result of growing environmental concerns, vegetable oils are finding their way into lubricants for both industrial and transportation applications. These oils can offer significant environmental advantages with respect to resource renewability and biodegradability, as well as offering satisfactory performance in various applications. Formulating with vegetable oils does, however, present unique challenges. These are, most notably, the oxidative and hydrolytic instability, and low temperature rheological problems associated with triglycerides. However, through advanced plant breeding techniques, vegetable oils are becoming available which exhibit good thermal and oxidative stability and other improved performance properties. An overview comparing the physical and chemical characteristics of vegetable oils with those of mineral oils, with particular emphasis on their oxidative stability and wear performance, is presented. Development of lubricant formulations for, in particular, farm tractors and hydraulic fluids, using combinations of vegetable oils and additives, will be discussed in comparison with field trial data.     

Total vegetable oil greases

A grease has two major constituents, namely, a lubricant, that performs the function of lubrication; and a gellant, that provides a solid continuous phase, occludes the lubricant, and gives apparent physical structure to the grease. Generally, the gellant is 5–30% and the lubricant 65–90%, additives and fillers making up the rest. In conventional greases, the gellant is a vegetable oil soap, and the lubricant is a liquid oil of petroleum origin or is a synthetic. Such greases have limited biodegradability, because the major constituent, i.e., the lubricant, is normally not biodegradable. In total vegetable oil grease, both the gellant and the lubricant are derived from vegetable oils, giving a grease of potentially high eco‐compatibility. Esters, dibasic acid esters, and alkylated esters of vegetable oil are known to be high‐quality lubricants. These can be used with soap stocks prepared from vegetable oils to give a grease of total vegetable oil origin. The vegetable‐oil based lubricants and soaps are prepared separately and combined in appropriate proportions to give a grease of the required specifications. Alternatively, esterification and saponification can be carried out simultaneously to give a grease of the desired specifications, where an alkali will be the catalyst for esterification, and reactant for saponification. In this paper, the process parameters, and kinetics of these simultaneous reactions are discussed. The results of experimental evaluation of some of these greases are also presented.