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Minimum Quantity Lubrication (MQL) results a better cooling effect than the boundary lubricated and dry environment, besides being environmental friendly. Very few investigations have been carried out on the influence of MQL parameters, such as oil flow rate and air pressure on grinding performance. Since grinding comprises both cutting and sliding, it is necessary to provide a balanced environment of heat extraction and lubrication. Thus it requires a controlled grinding environment such as MQL. The current study is an experimental investigation on the significance of the MQL parameters on grinding performance of Inconel 751. Inconel is an ideal material for high temperature applications although it poses difficulties during machining, especially grinding. It was found that better results were obtained for the optimal MQL condition in grinding in terms of reduced grinding force, temperature, and roughness. Also it was found that there is hardly any crest flattening on the surface being ground with minimum quantity lubrication. Induction of MQL facilitates considerable reduction in the grinding forces, temperature, and roughness, apart from the absence of visible grinding burns. [ABSTRACT FROM PUBLISHER]

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 × 101 to 1.5 × 103 CFU (colony forming units) m- 3, even for metalworking fluid highly contaminated by bacteria (up to 2.4 × 109 CFU mL- 1). Inhalable dust varied between < 0.1 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. [ABSTRACT FROM AUTHOR]

The objective of this study was to develop regression models to predict concentrations of oil mist and oil vapor in the workplace atmosphere in the shale shaker area of offshore drilling installations. Collection of monitoring reports of oil mist and oil vapor in the mud handling areas of offshore drilling installations was done during visits to eight oil companies and five drilling contractors. A questionnaire was sent to the rig owners requesting information about technical design of the shaker area. Linear mixed-effects models were developed using concentration of oil mist or oil vapor measured by stationary sampling as dependent variables, drilling installation as random effect, and potential determinants related to process technical parameters and technical design of the shale shaker area as fixed effects. The dataset comprised stationary measurements of oil mist (n = 464) and oil vapor (n = 462) from the period 1998 to 2004. The arithmetic mean concentrations of oil mist and oil vapor were 3.89 mg/m3 and 39.7 mg/m3, respectively. The air concentration models including significant determinants such as viscosity of base oil, mud temperature, well section, type of rig, localization of shaker, mechanical air supply, air grids in outer wall, air curtain in front of shakers, and season explained 35% and 17% of the total variance in oil vapor and oil mist, respectively. The developed models could be used to indicate what impact differences in technical design and changes in process parameters have on air concentrations of oil mist and oil vapor. Thus, the models will be helpful in planning control measures to reduce the potential for occupational exposure. [ABSTRACT FROM AUTHOR]

The American Conference of Governmental Industrial Hygienists (ACGIH®) has recommended that the threshold limit value (TLV®) for mineral oil mists be dramatically lowered, based on epidemiological evidence of respiratory health effects among machinists exposed to various metalworking fluid mists. A review of the literature regarding respiratory health effects from either metalworking or non-metalworking fluids suggest that machinists may have experienced slightly higher prevalence of common respiratory symptoms and mild and reversible cross-shift changes in some measures of pulmonary function. However, the inconsistency and potential for both random and systematic error in this body of literature argue against drawing definitive conclusions. There is also no substantive evidence that any of these effects led to permanent disease or impairment. The most likely causal agents for respiratory effects in these workers are microbial contaminants in water-based metalworking fluids, not straight mineral oils. This is consistent with the epidemic outbreaks of hypersensitivity pneumonitis, bronchitis, and asthma reported at some work sites using water-based metalworking fluids. This highlights the importance of frequent cleaning and fluid changes for metalworking fluid reservoirs, as part of a systematic approach to managing metalworking fluid aerosol exposures. A dramatic drop in the TLV for mineral oil mists would not resolve this problem. [ABSTRACT FROM AUTHOR]

Effective, economical control of metalworking fluid mists at the source is important, because exposure to these mists may cause adverse health effects. This study investigated performance changes over time for industrial collectors that removed metalworking fluid mist in the laboratory and in a transmission plant. Aerosizers were used to measure the efficiency of each stage in several multistage collectors as a function of mist droplet diameter, for up to one year of continuous operation. Metal-mesh, first-stage filters operated at low pressure drops and were effective at removing droplets larger than 3 to 5 Θ m in diameter. Some second-stage filters worked better than others. Both ''65 percent'' and ''95 percent'' cartridge filters failed after only a few weeks; their efficiencies decreased substantially over that time. Pocket filters and cylindrical cartridges used as second-stage filters also decreased in efficiency for submicron droplets. Whereas filters for solid particles load continuously to form a dust cake that increases efficiency, mist filters form no cake and load only to the point where collection equals drainage. As a mist filter loads, the interstitial gas velocity increases, so that efficiency decreases for small droplets that collect by diffusion. Although a third-stage 95 percent DOP filter showed important decreases in efficiency over time for submicron droplets, third-stage HEPA filters operated with efficiencies that consistently approached 100 percent for droplets of all sizes, even after one year of operation. These results suggest that the performance of second-stage filters can be improved if they can be made to drain collected liquid more effectively. For high efficiency, mist collectors should use a HEPA filter as a final stage. [ABSTRACT FROM AUTHOR]

Sampling methods to determine occupational exposures to metalworking fluid mists are subject to bias. Light-scattering devices may respond differently to variations in particle size, shape, and refractive index. Gravimetric samplers are prone to evaporative losses of semi-volatile components. The performance of two light scattering devices, an electrostatic precipitator, and filters followed by gravimetric analysis was investigated when measuring metalworking fluid mist in laboratory and field settings. Laboratory tests with soluble oil and field tests with soluble oil, straight oil, and semi-synthetic fluid showed significant evaporative losses from filters. Light-scattering devices tended to overestimate mist concentrations when mass median diameters were less than about 2 mum and to underestimate mist concentrations when mass median diameters were larger. Filters will underestimate occupational exposures to metalworking fluid mists when semi-volatile components are present. conditions. [ABSTRACT FROM AUTHOR]

Oil mists can cause respiratory distress and have been linked to skin and gastrointestinal cancers in workers. Standard concentration assessment methods call for sampling these mists with fibrous or membrane filters. Previous experimental studies using glass fiber (GF) filters and polyvinyl chloride and polytetrafluoroethylene membrane filters indicate that mist sampled onto filters may volatilize. A model has been developed to predict the evaporation of mist collected on a fibrous sampling filter. Evaporation of retained fluid from membrane filters can be modeled by treating the filter as though it is a fibrous filter. Predictions from the model exhibit good agreement with experimental results. At low mist concentrations, the model indicates that evaporation of retained mineral oil occurs readily. At high mist concentrations, significant evaporation from the filters is not expected because the vapor accompanying the airborne mist is already saturated with the compounds in the oil. The findings from this study indicate that sampling mineral oil mist with filters in accordance with standard methods can lead to estimates of worker exposure to oil mist that are too low. [ABSTRACT FROM AUTHOR]

The notice of intended change for the threshold limit value (TLV®) for mineral oil mist contains a notation for human carcinogenicity. A description is provided of the current European regulatory approach used to distinguish between carcinogenic and non-carcinogenic mineral base oils on the basis of oil refining process and chemical marker information. This approach has proven effective in creating a market situation in the countries of the European Union where many customers require severely refined, non-carcinogenic oils. It is recommended that ACGIH® consolidate the distinction between poorly and severely refined base oils in the recommended TLV for mineral oil mist and use different toxicological considerations to derive exposure control guidelines. [ABSTRACT FROM AUTHOR]