Polymer Additives as Mist Suppressants in Metalworking Fluids Part IIa: Preliminary Laboratory and Plant Studies - Water Soluble Fluids

Mist generated from water-soluble fluids used in machining operations represents a potentially significant contribution to worker exposure to airborne particles. Part I of this study [1], discussed polymer additives as mist suppressants for straight mineral oil metalworking fluids (MWF), which have been successfully employed at several locations. This paper focuses on recent developments in polymer mist suppressants for water-based MWF, particularly in the production environment. The polymer developed and tested in this study functions on a similar basis to that for straight oil anti-mist additives. This water soluble polymer suppresses the formation of small mist droplets and results in a distribution of larger droplet sizes. These larger droplets tend to settle out near the point of machining, resulting in a significant decrease in the total airborne mist concentration.

This new polymer additive has the added property of re-associating with itself after shear stresses break it apart, so that the anti-mist effect of the polymer is maintained for extended periods in the recirculated cutting fluid systems. Preliminary laboratory and plant pilot testing shows 40-60% reduction in oil mist levels using 1000-1250 ppm of the additive, with the effect lasting at least 2 weeks, the longest test duration to-date. To determine concentration of the polymer is a treated coolant system, a viscosity comparison technique has been identified which can readily be performed in the plant environment. In addition, no adverse impact on wastewater treatability, part quality, nor seals have been observed.