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Case study: mist control following installation of air cleaners on machining centers.

Yacher-JM; Heitbrink-WA; Sullivan-MA
Metalworking Fluids Symposium II, The Industrial Metalworking Environment: Assessment and Control of Metal Removal Fluids. September 15-17, 1997, Detroit, Michigan. DA Felinski, JB D'ARcy, eds., Washington, DC: American Automobile Manufacturers Association, 1998 Nov; :311-318
At a machining center used to produce transaxle and transmission parts, aerosol instrumentation was used to quantitatively evaluate size-dependent mist generation of a synthetic metalworking fluid (MWF) consisting primarily of water and triethanolamine (TEA). This information was used to select an air cleaner for controlling the mist. During most machining operations, the MWF was flooded over the part. These machining operations were performed in a nearly complete enclosure that was exhausted to an air cleaner consisting of three sections: a fall-out chamber, a filter section to capture metal chips and mist, and a 1.13 m3/s (2400 cfm) blower. To quantitatively study the effect of machining operations on mist generation, air was isokineticly sampled upstream and downstream of the air cleaner. The following instruments measured aerosol concentration and size distribution as a function of time: a time-of-flight aerosol spectrometer and an eight-channel optical particle counter. The observed penetration through the air cleaner was consistent with the manufacturer's specifications on the air cleaner's filters; the 95% efficient ASHRAE filters appeared to collect all particles larger than 3 um. However, coolant accumulated on the bottom of the air cleaner and relatively large particles were being generated from this accumulated liquid. This source of mist production was eliminated by increasing the size of the drainage holes in the bottom of the air cleaner. After modification, 25 air cleaners were installed at machining centers throughout the shot and at fluid recycling stations. The facility implemented a maintenance program for the air cleaners that involves regularly scheduled filter changes; performance is ensured by monitoring static pressure. Air sampling was conducted before and after the control measures were installed. Area triethanolamine concentrations were reduced from a geometric mean of 0.26 mg/m3 to 0.03 mg/m3. Personal total particulate concentrations were reduced from 0.22 mg/m3 to 0.06 mg/m3. These results show the effectiveness of this combination of enclosure, ventilation, and filtration to greatly reduce the exposure to MWF mist generated in modern machining centers.
Case-studies; Quantitative-analysis; Metalworking; Metalworking-fluids; Metalworking-industry; Air-sampling; Air-samples; Aerosols; Ventilation-systems; Oil-mists; Machine-operation; Machine-operators; Machinists; Air-monitoring; Air-purification; Air-quality-measurement; Aerosol-particles; Metal-workers; Air-quality-monitoring; Air-quality
National Institute for Occupational Safety and Health, 4676 Columbia Parkway, Cincinnati, OH 45226-1998
Publication Date
Document Type
Conference/Symposia Proceedings
Felinski-DA; D'Arcy-JB
Fiscal Year
NIOSH Division
Source Name
Metalworking Fluids Symposium II, The Industrial Metalworking Environment: Assessment and Control of Metal Removal Fluids. September 15-17, 1997, Detroit, Michigan
Page last reviewed: September 2, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division