Characterization of metalworking fluid aerosols in bearing grinding operations

The concentrations and size distribution of metalworking fluid aerosols wer e investigated in grinding operations in the bearing manufacturing industry . Fifteen paired open- and closed-face cassette samples and five cascade im pactor samples were obtained in each of three types of grinding machinery ( face, microcentric, and progressive). Aerosol mass concentration as measure d by open-face filter sampling ranged from 0.34 to 2.43 mg/m(3). As measure d by closed-face sampling the range was 0.14 to 2.01 mg/m(3). For each grin ding process, open-face concentration was significantly higher than the clo sed-face concentration (paired t-test, p <0.05). Mass median aerodynamic di ameter (MMAD) ranged from 3.33 to 6.26 <mu>m. The percentage of mass greate r than 9 mum ranged from 8.0 to 45.3. The MMAD and fraction greater than 9 Lm were significantly greater for the aerosol produced by the face grinder compared with the other two processes. The results indicate that (1) closed -face sampling results in a lower aerosol mass concentration, as compared w ith open-face sampling, with the degree of difference being somewhat depend ent on grinding process; and (2) the particle size distribution and concent ration of metalworking fluid aerosols may vary with the type of grinding op eration sampled.