Grinding fluids

The highest G-ratios are obtained when grinding with straight oil coolants. Such oils reduce power, increase maximum depth of cut, and produce smoother finishes. Disadvantages include inabiUty to remove heat from the work, oil mist in the work area, fire hazard, and tendency to hold grinding swarf (fine metal chips and abrasive particles produced in the grinding process) in suspension. Reference 51 is an excellent survey article for grinding fluids. 

Poly(alkylene glycol)s are also used as lubricity additives ia water-based synthetic cutting and grinding fluids (36), and ia aqueous metalworking fluids. Under the high frictional heating at the tool or die contact with the workpiece, the polyalkylene glycol comes out of solution ia fine droplets which coat the hot metal surfaces. 

Material Finished particle size Mill size Production, Ibh Grinding fluid used... 

Efl49 Nitrosamines in synthetic metal cutting and grinding fluids. 

Provision, use and maintenance of hygiene facilities for work with asbestos insulation and coatings Nitrosamines in synthetic metal cutting and grinding fluids (withdrawn)... 

The five largest uses for PCBs prior to 1970 were dielectric fluids in capacitors, plasticizers, lubricants, transformer fluids, and hydraulic fluids. They were also used widely in protective coatings, sealers, putty, grinding fluids, printing inks, pattern waxes, carbonless paper, etc. (see Chap. 1). Because of this widespread PCB use they are found throughout the environment [363-365]. A number of important properties of PCBs are discussed below along with information on their distribution and persistence in the environment. 

Miscellaneous. Volatile nitrosamines can escape into the atmosphere from a variety of other sources. Automobile and diesel engine exhausts may contain N-nitroso compounds, including NDMA at trace levels (5). Nitrosodiethanolamine (NDEIA) is a likely air contaminant in machine shops which use cutting and grinding fluids contaminated with high concentrations of NDElA (10). Several herbicides, known to contain appreciable levels of volatile nitrosamines (9), are applied as aqueous sprays it is likely that worker exposure via inhalation may be appreciable. 

V-Nitrosodiethanolamine has been found in many complex matrices such as cutting and grinding fluids and cosmetics. Analysis for V-nitrosodiethanolamine is complicated by the matrix and a clean-up technique with derivatization is typically required before quantitation of the analyte to achieve adequate sensitivity and selectivity. Ammonium sulfamate may be added to the sample to prevent the artifactual formation ofV-nitrosamines. Derivatives of V-nitrosodiethanolamine have been prepared by acylation, trifluoroacylation, trimethylsilylation and methylation. The derivatives have been analysed by gas chromatography using flame ionization and mass spectro-metric detectors (Occupational Safety and Health Administration, 1990). 

In 264 metal grinders analysed for urinary excretion of /V-nitrosodiethanolamine, 166 showed positive results (> 0.5 pg/kg (L)) with levels up to 103 pg/kg (L) urine. The amount of/V-nitrosodiethanolamine in grinding fluids (0.04-90 mg/kg) was predictive of the amounts detected in workers urine. Data from quantitative excretion studies (24-h urines) indicated accumulation of /V-nitrosodiethanolamine during a working week (Spiegelhalder e/a/., 1984, 1987). 

Grinding fluids or coolants are fluids employed in grinding to cool the work being ground, to act as a lubricant, and to act as a grinding aid. Soluble oil coolants in which petroleum oils are emulsified in water have been developed to impart some lubricity along with inst-pieventive properties. 

The loop mill (Fig. 21-71c), also called Torus mill, was designed by Kidwell and Stephanoff (1940). The grinding fluid is brought into the grinding section. The fines leave the mill through the cfassification section. 

Lubrhophos. [Rhone-Poulenc Surf. Rhone-Poulenc France] Phosphate esters lubricant, rust inhibit , emulsifier, pressure additive for lubricating and roUii% (, hydraulic, cutting and grinding fluids. 

Synkad . [Ferro/Keil] Borate or car-boxylate salts corrosion inhibitor fur synthetic cutting, towing, and grinding fluids. 

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