Contamination Of Metalworking Fluids Research Articles

Zinc oxide nanoparticles from leaf extract of Eclipta prostrata: Biosynthesis and characterization towards potential agent against film forming bacteria in metal working fluids

Industrially important metal working fluids are reported to be vulnerable to microbial growth, leading to loss of its working efficiency. The present study is dedicated towards the green synthesis of Zinc Oxide (ZnO) nanoparticles using Eclipta prostrata leaf extract and investigated for antimicrobial activity. Characterization studies using Scanning Electron Microscopy (SEM) and Fourier Transform Infrared spectroscopy (FT-IR) displayed the presence of agglomerated rod shaped ZnO nanoparticles with characteristic peak between 700 and 500 cm−1, respectively. Antimicrobial testing against gram-positive and gram-negative bacteria, as well as fungi, showed the ZnO nanoparticles' effectiveness. Against gram-positive bacteria, inhibition ranged from 0.48 to 1.51 at concentrations of 25 μl to 100 μl. Against gram-negative bacteria, inhibition ranged from 0.82 to 2.02, and against fungi, inhibition ranged from 1.20 to 2.34, all at the highest concentration tested. The results of the study indicate that the ZnO nanoparticles were effective against both fungi and bacteria, more effectively against gram negative bacteria. The results suggest that the green synthesized ZnO nanoparticles from Eclipta prostrata can be exploited to reduce the load of microbial contamination in metal working fluids.

Experimental investigation on application of emulsifier oil based nano cutting fluids in metal cutting process

The purpose of cutting fluids in metal cutting process is to provide cooling and reduce the friction between tool and work piece at the shear zone. In dry cutting, the work piece is machined under dry conditions. The air surrounding the work piece acts as the cooling agent. Since air has low thermal conductivity it acts as a poor coolant. High temperatures at tool-work piece interface causes failure of cutting tools, formation of micro cracks and surface roughness of work piece is compromised. In wet cutting, the work piece is machined under wet conditions. Most cutting fluids constitute ninety five percent of water and five percent of cutting oil. Usage of cutting fluids have shown significant changes in thermal properties, tool wear, surface roughness and cutting forces on tool and work piece respectively.A study by few American institutes states that 60% companies are spending 20% more amount on their coolants/lubricants in a cutting operation than on cutting tool being used for machining. Uncontrolled microbial contamination of metal working fluids represents both economic and health risk. Minimum quantity lubrication (MQL) is alternative to this problem which uses minute amount of cutting fluids which is about three or four times less than that of the amount commonly used in a flood cooling condition.MQL requires a fluid with high heat carrying and lubricating properties. The present work investigates upon the usage of nano-graphite, nano -boric acid and nano-molybdenum disulphide in emulsifier oil based cutting fluids in MQL application. The primary work is to prepare a cutting fluid by including 0.3 wt% of nano particles and to check its stability, as dispersion of nano particles in base fluid is a challenging process. The prepared cutting fluids with nano inclusions are applied at a flow rate of 10ml per minute while performing turning operation under constant cutting conditions. Performance of cutting fluids are evaluated by measuring cutting forces, cutting temperature near chip –tool interface, tool wear and surface roughness for each turn. The results are compared with dry and MQL application with emulsifier oil without nanoinclusions.

The microbiology of metalworking fluids

Metalworking fluids (MWFs) are complex mixtures of chemicals and are indispensable materials in industry. They are used as cooling and lubricating agents in different machining process such as grinding, milling, and cutting. The quality of MWFs is affected by physical, chemical, and microbial contaminates. In particular, MWFs are highly vulnerable to microbial contamination, which may act both as potential pathogens and deteriorgens. Microbial contamination is of major concern due to potential health hazards such as skin dermatitis and hypersensitivity pneumonitis. The contaminated MWFs can exhibit high degrees of microbial loading, ranging from 10(4) to 10(10) colony-forming units (CFU)/ml. Wide varieties of microorganisms are reported to colonize MWFs. Traditional culturing techniques are not only laborious and time consuming but also underestimate the actual distribution of the microorganisms present in the contaminated MWFs. Therefore, rapid molecular methods such as real-time PCR and fluorescent in situ hybridization are implemented to monitor the microbial load. In industry, biocides are presently used to control microbial contamination. However, it has its own disadvantages and therefore, in recent years, alternative methods such as UV irradiation were evaluated to reduce microbial contamination in MWFs. Microbes inhabiting the MWF are also capable of forming biofilm which is detrimental to the MWF system. Biofilm is resistant to common disinfectant methods, and thus further research and development is required to effectively control its formation within MWF systems. This review is intended to discuss the overall microbiological aspects of MWF.

Bacterial Microflora of Contaminated Metalworking Fluids

ABSTRACTMetal working fluids (MWF) are commonly used in manufacturing and machining industries. There are four major classes of MWF: (i) which contain lubricant base oils without water (straight oils), (ii) composed of an aqueous oil emulsion with oil in high concentration (soluble oils) or (iii) lower concentration (semi-synthetic MWF) and (iv)formulated with no petroleum oils (synthetic fluid). Historically, microbial contamination of metal working fluids has been a problem in the metalworking industries, primarily because of potential adverse health effects and microbial growth effects on fluid quality and performance. Metalworking fluids are chemically complex mixtures. Such mixtures render MWFs potentially toxic to the environment. One solution to the disposal problem is on-site biological treatment of waste MWFs, using bioreactor systems. Bioaugmentation with selected strains may improve the opportunity to create more reproducible system.In this study the bacterial microflora of soluble oil and synthetic metalworking fluid in-use was quantified, isolated and tentatively identified. An indicator plates for dehydrogenase activity were used in attempt to demonstrate the potential of bacteria isolated from contaminated metalworking fluids to utilize hydrocarbons—a component of MWFs.

Respiratory symptoms, immunology and organism identification in contaminated metalworking fluid workers. What you see is not what you get

Metal working fluids (MWF) constitute a significant respiratory hazard, although symptoms experienced by workers are often poorly investigated and attributed. A single possible case of extrinsic allergic alveolitis (EAA) led to a formal workplace investigation. It was clear that other exposed workers were affected. The aim of this study was to accurately quantify the clinical, immunological and microbiological findings in MWF workers following presentation of a sentinel case. Eleven of 21 individuals participated; eight were assessed by symptom questionnaire, spirometry and serology and three workers provided blood samples only. The microbes cultured from MWF and air samples were used to determine the presence of precipitating antibodies. Work-related respiratory symptoms were reported in six of eight individuals questioned, two of these complaining of 'flu-like' symptoms. Personal breathing zone measures identified 2.1 x 10(3) to 1.1 x 10(5) colony-forming units/m3 air (CFU/m3). Pseudomonas fluorescens was isolated from air samples. Despite visible 'fungal' contamination of MWF, airborne fungi were detectable in only one sample, at 486 CFU/m3 air. MWF cultured Eurotium sp., Fusarium sp. and Pseudomonas sp. Precipitating IgG antibodies to Pseudomonas sp. were identified in 4/11 and to an extract of the MWF in 3/11. IgG to Pseudomonas was elevated in the two individuals who had the strongest precipitating bands to Pseudomonas sp. Workplaces with possible EAA must be investigated promptly, thus allowing clinical assessment to be contemporary to exposures and accurate microbiological profiling included to identify the likely cause.

Flow cytometric detection and quantification of mycobacteria in metalworking fluids

Abstract Mycobacteria are relevant target microorganisms in metalworking fluids (MWFs), owing to their recent recovery from industrial systems and their potential implication in respiratory illness. Whereas a number of detection technologies are available to monitor microbial contamination in MWF, no methods have been developed for the detection of mycobacteria in these matrices. We report here a novel method for detecting Mycobacterium parafortuitum in a semi-synthetic MWF with nonspecific nucleic acid dyes using flow cytometry (FCM). Following disaggregation of bacteria through (probe) sonication, the emulsion was destabilized using isopropanol (IPA) to minimize the nonspecific binding of the fluorescent dye to MWF components. The quantitative results show good correlation with direct counts using epifluorescent microscopy (EFM) within the range of 2.31×104 to 2.31×10 7 cells ml −1 . The time required to complete FCM and EFM enumeration was 10 and 300 s sample −1 , respectively. These results lend support to the applicability of FCM, a multiparametric data acquisition technique, for microbial detection in these complex fluids.

Inflammatory Effects of Inhaled Endotoxin-Contaminated Metal Working Fluid Aerosols in Rats

Exposure to aerosols generated from water-soluble metal-working fluids (MWF) is associated with numerous respiratory symptoms consistent with an acute pulmonary inflammatory event. Previous studies in mice and guinea pigs have implicated endotoxin contamination of MWF as the causative agent responsible for inducing pulmonary neutrophilia and decrements in airway conductance. However, little information is known about the relationship between endotoxin-contaminated MWF exposure and changes in airway physiology. The present study, utilizing a rat model, has demonstrated that exposure to 10 mg/m 3 with endotoxin (0 to 3.2 w g/m 3 ) resulted in a time- and concentration-dependent migration of neutrophils in the lung tissue's interstitial spaces as well as the lavageable airways. In contrast to other airborne toxicants, where neutrophil infiltration of the lung has been associated with hyperresponsive airways, the endotoxin-induced neutrophilia observed in the present study was not associated with airway hyperresponsiveness to challenge with the muscarinic agent methacholine or with permeability damage to the lung. Bronchoalveolar lavage (BAL)-recovered neutrophils demonstrated no adverse effects as a result of endotoxin-contaminated MWF exposure. In contrast, a population of alveolar macrophages was observed to be enlarged in size and demonstrated an increased sensitivity to oxidative metabolism when challenged with phorbol myristate acetate, consistent with being at a relatively high state of activation. These results suggest that while endotoxin contamination of MWF is capable of producing an acute inflammatory event, other predisposition factors may be required to induce alterations in pulmonary physiology.

A Model for Predicting Endotoxin Concentrations in Metalworking Fluid Sumps in Small Machine Shops

In British Columbia, Canada, nineteen small machine shops which used water-based metalworking fluids (MWF) were examined. One bulk MWF sample was taken from each independent sump (N=140) and tested for endotoxin using the Limulus Amoebocyte Lysate assay. Factors that might influence the MWF sump endotoxin concentration were investigated using mixed effect multiple regression modelling to control for repeated measures within shops. The geometric mean (GM) endotoxin concentration was 6791 EU/ml. Contamination of MWF with tramp oil, MWF pH, MWF temperature, and MWF type were significant predictors of sump fluid endotoxin concentration (model P=0.0001, ordinary least squares R(2) =0.36). Concentrations of endotoxin in sump fluids were increased by MWF contamination with tramp oils such as hydraulic oils, preservative oils, spindle oils, slidway lubricants, gear lubricants, and greases (model predicted GM=17400 EU/ml vs. 1600 EU/ml without tramp oil). Concentrations were also elevated where pH was lower than 8.5 (predicted GM=10600, vs 3600 EU/ml for pH 8.5 to 9.5), where soluble fluids were used (predicted GM=11800 vs. 2800 EU/ml for synthetic fluids), and where sump fluid temperatures were higher (predicted GM=2600 EU/ml at 11 degrees C vs. 21500 EU/ml at 32 degrees C). The within-shop correlation of sump bulk fluid endotoxin concentrations was 38%. Minimizing tramp oil contamination, using synthetic fluids, and monitoring pH and temperature would be valuable tools for controlling endotoxin contamination in MWF sumps. In addition, since there was correlation within-shop, contamination of one sump in a shop may suggest changing the fluids in all.

A model for predicting endotoxin concentrations in metalworking fluid sumps in small machine shops

Methods: In British Columbia, Canada, nineteen small machine shops which used water-based metalworking fluids (MWF) were examined. One bulk MWF sample was taken from each independent sump (N=140) and tested for endotoxin using the Limulus Amoebocyte Lysate assay. Factors that might influence the MWF sump endotoxin concentration were investigated using mixed effect multiple regression modelling to control for repeated measures within shops.Results: The geometric mean (GM) endotoxin concentration was 6791 EU/ml. Contamination of MWF with tramp oil, MWF pH, MWF temperature, and MWF type were significant predictors of sump fluid endotoxin concentration (model P=0.0001, ordinary least squares R2 =0.36). Concentrations of endotoxin in sump fluids were increased by MWF contamination with tramp oils such as hydraulic oils, preservative oils, spindle oils, slidway lubricants, gear lubricants, and greases (model predicted GM=17400 EU/ml vs. 1600 EU/ml without tramp oil). Concentrations were also elevated where pH was lower than 8.5 (predicted GM=10600, vs 3600 EU/ml for pH 8.5 to 9.5), where soluble fluids were used (predicted GM=11800 vs. 2800 EU/ml for synthetic fluids), and where sump fluid temperatures were higher (predicted GM=2600 EU/ml at 11°C vs. 21 500 EU/ml at 32°C). The within-shop correlation of sump bulk fluid endotoxin concentrations was 38%.Conclusions: Minimizing tramp oil contamination, using synthetic fluids, and monitoring pH and temperature would be valuable tools for controlling endotoxin contamination in MWF sumps. In addition, since there was correlation within-shop, contamination of one sump in a shop may suggest changing the fluids in all.

Detection of microbial antigens in metal working fluids

In recent years there have been several reports of hypersensitivity pneumonitis (HP) or an HP-like illness occurring among machinists working with water-based metal working fluids (MWF). Microbial contamination of the MWF is common and microbial agents have been suspected to be causal agents for the HP-like illness, but no specific etiologic agent has been identified to date. In particular, gram negative bacteria and biocide resistant mycobacterial species may colonize the MWF, and may stimulate an inflammatory response if inhaled. Because direct culture techniques provide data only about viable organisms present at the time the sample was collected, we have been evaluating techniques to detect microbial substances (antigens) that may be present and persist in the MWF. We have found that the endotoxin of gram negative bacteria can be detected in MWF using the limulus amoebocyte lysate (LAL) assay, and may be present in high concentrations. In addition, MWF samples have been analyzed by Western Blot techniques using polyclonal antibodies to mycobacteria to demonstrate the presence of mycobacterial antigens in these samples. The use of non-culture-based techniques for the assessment of microbial contamination of MWF may help to determine the role of microorganisms in the etiology of HP associated with MWF exposure.

A rapid technique for determining microbial loads in metalworking fluids

An indirect method for estimating the degree of microbial contamination in metal working fluids is described. The technique circumvents the time delay associated with plate counts or dipslide procedures by correlating the microbial count with specific microbial enzyme levels. The 15 min procedure was evaluated in synthetic, semi-synthetic and petroleum base metalworking systems under laboratory conditions. The microbial load of a 18 925 litre (5000 US gal) industrial system was also monitored over a three month period using both standard plate counts and the indirect technique. The results indicated that the method could rapidly assess the microbial load in industrial metalworking coolants. In addition, laboratory tests showed that the technique can detect preservative effectiveness in a coolant within a one hour period. The ability to determine the microbial load and biocide effectiveness without an excessive time delay should greatly enhance rancidity control in the metal working industry